Abstract: Biodiversity
1. Introduction
2) Types of diversity
Species diversity
・Genetic diversity
Diversity of communities and ecosystems
3) Key species and resources
4) Measuring biodiversity
5) Optimal and critical levels of diversity
6) Where is the biodiversity?
7) Extinction types
8) Goals of biodiversity management at the present stage
9) Ethical arguments for biodiversity conservation
10) Conclusion
11) List of used literature
MINISTRY OF EDUCATION OF THE RUSSIAN FEDERATION
ROSTOV STATE UNIVERSITY
PSYCHOLOGY FACULTY
ESSAY
at the rate:
"Concepts of Modern Natural Science"
"The role of biodiversity in wildlife"
Performed:
4th year student, 1 group
day department
Faculty of Psychology
Bronevich Marina
Rostov-on-Don
According to the definition given by the World Wide Fund for Nature (1989), biological
diversity is “all the variety of life forms on earth, millions of species
plants, animals, microorganisms with their sets of genes and complex ecosystems,
that form living nature." Therefore, biodiversity should
considered at three levels. Biodiversity at the species level
covers the entire set of species on Earth from bacteria and protozoa to the kingdom
multicellular plants, animals and fungi. On a smaller scale
biodiversity includes the genetic diversity of species,
formed both by geographically distant populations and by individuals within
the same population. Biodiversity also includes
diversity of biological communities, species, ecosystems formed
communities and interactions between these levels (Fig. 1).
Rice. 1 Biodiversity includes genetic diversity
(hereditary variability within each species), species diversity(kit
species in a given ecosystem) and diversity of communities/ecosystems (habitats and
ecosystems in the area)
All levels are necessary for the continued survival of species and natural communities.
biological diversity, all of them are important for humans. Variety of species
demonstrates the wealth of evolutionary and ecological adaptations of species to
various environments. Species diversity is a source of human
variety of natural resources. For example, tropical rainforests with their
richest set of species produce a remarkable variety of plant and
animal products that can be used for food, construction and
medicine. Genetic diversity is essential for any species to survive
reproductive viability, disease resistance, ability to
adaptation in changing conditions. genetic diversity of domestic
animals and cultivated plants is especially valuable for those who work on
breeding programs to maintain and improve modern
agricultural species.
Community-level diversity is the collective response of species
for various conditions environment. Biological communities characteristic
for deserts, steppes, forests and flooded lands, maintain continuity
normal functioning of the ecosystem, providing its “maintenance”,
e.g. through flood control, soil erosion protection,
air and water filtration.
2. Species diversity
At every level of biological diversity – species, genetic and
diversity of communities, specialists study the mechanisms that change or
maintain diversity. Species diversity includes the entire set of species,
living on earth. There are two main definitions of the concept of species. First:
species is a collection of individuals, which, for one reason or another
morphological, physiological or biochemical characteristics differ
from other groups. This is the morphological definition of the species. Now to differentiate
species that are virtually identical in appearance (e.g. bacteria) are increasingly
use differences in DNA sequence and other molecular markers.
The second definition of a species is a set of individuals between which
free interbreeding, but there is no interbreeding with individuals of other
groups (biological definition of the species).
3. Genetic diversity
Genetic intraspecific diversity is often provided by reproductive
behavior of individuals within a population. A population is a group of individuals of the same
species that exchange genetic information among themselves and give fertile
offspring. A species may include one or more distinct populations. population
may consist of several individuals or millions.
Individuals within a population are usually genetically distinct from each other.
Genetic diversity is associated with the fact that individuals have little
different genes - sections of chromosomes that code for certain
proteins. Variants of a gene are known as its alleles. Differences come from mutations
- changes in DNA, which is located in the chromosomes of a particular individual. alleles
genes can affect the development and physiology of an individual in different ways. Breeders
plant varieties and animal breeds, selecting certain gene variants,
create high-yielding, pest-resistant species, such as cereals
crops (wheat, corn), livestock and poultry.
4. Diversity of communities and ecosystems
A biological community is defined as a collection of individuals of various
species living in a certain area and interacting with each other.
Community Examples − coniferous forests, tall grass prairies, humid tropical
the woods, Coral reefs, desert. The biological community in conjunction with
its habitat is called an ecosystem. In terrestrial ecosystems, water
evaporates by biological objects from the surface of the Earth and from water
surfaces to fall again in the form of rain or snow and replenish
terrestrial and aquatic environments. Photosynthetic organisms absorb light energy
which is used by plants for their growth. This energy is absorbed
animals that eat photosynthetic organisms or are released as
heat both during the life of organisms and after their death and
decomposition.
During photosynthesis, plants take in carbon dioxide and
produce oxygen, while animals and fungi take in oxygen during respiration and
emit carbon dioxide. Mineral nutrients such as nitrogen and
phosphorus, cycle between the living and non-living components of the ecosystem.
Physical properties of the environment, especially the annual temperature regime and
rainfall, affect the structure and characteristics of the biological community and
determine the formation of either forests, or meadows, or deserts or swamps.
The biological community, in turn, can also change the physical
environment characteristics. In terrestrial ecosystems, for example, wind speed,
humidity, temperature and soil characteristics can be determined
influenced by the plants and animals that live there. In aquatic ecosystems,
physical characteristics such as turbulence and transparency of water, its
chemical characteristics and depth determine the qualitative and quantitative
composition of aquatic communities; and communities such as coral reefs are themselves
significantly affect the physical properties of the environment. Inside
biological community, each species uses a unique set of resources,
which constitutes its niche. Any niche component can become limiting
factor when it limits the size of the population. For example, species populations
bats with highly specialized requirements for environmental conditions,
forming colonies only in calcareous caves may be limited
the number of caves with suitable conditions.
The composition of communities is largely determined by competition and predators. Predators
often significantly reduce the number of species - their prey - and may even
push some of them out of their usual habitats. When predators
exterminate, the population of their victims may increase to a critical
level or even go over it. Then after exhaustion of the limiting resource
the destruction of the population may begin.
Test work >> EconomicsOn save alive nature, structure protection...), save biodiversity and provide... form a sphere his livelihoods, contribute to ... farming). concept and content... 9, 2003. Zhigaev A.Yu. Role public debt in a market economy...
Conservation factors biodiversity Astrakhan region in protected reserves
Diploma work >> Ecology2001). Very large role in the fate of the reserve... resources. 3.2. Definition concepts"biological diversity" In ... a fundamental property alive nature, reflecting the multitude... 5. Raise awareness of biodiversity and his security at the local and...
Conservation measures biodiversity
Abstract >> EcologyThe source is still live nature. It is used in construction... river runoff, stabilizes his and plays role a kind of "water buffer" ... - the inclusion of terms and concepts associated with biodiversity, to all relevant legislative ...
LECTURE 3
TOPIC: Causes of biodiversity decline
PLAN:
1. Species extinction rates
2. Causes of species extinction
2.1. Habitat destruction
2.2. Habitat fragmentation
2.3. edge effect
2.4. Habitat degradation and pollution
2.5. Overexploitation of resources
2.6. Invasive species
2.7. Diseases
3. Susceptibility to extinction
1. Species extinction rates
The most significant question for conservation biology is how long this species survive until extinction, following an extreme decline in numbers, degradation or fragmentation of its habitat? When the population decreases to a certain critical level, the probability of its extinction becomes very high. In some populations, individual remaining individuals may live for years or decades, and even reproduce, but still their further fate– extinction, unless drastic measures are taken to conserve them. In particular, among woody vegetation, the last isolated non-reproductive specimens of the species can exist for hundreds of years. Such species are called potentially extinct: even if the species is not formally extinct, the population is no longer able to reproduce, and the future of the species is limited by the lifetime of the remaining specimens. To successfully conserve species, scientists need to identify those human activities that affect the stability of populations and lead to the extinction of species. They must also identify factors that increase populations' susceptibility to extinction.
The first noticeable impact of human activity on the rate of extinction was manifested in the example of the destruction of large mammals in Australia, North and South America by people who settled these continents thousands of years ago. Shortly after the arrival of humans, 74 to 86 percent of the megafauna—mammals weighing more than 44 kg—disappeared in these areas. This may have been directly related to hunting and indirectly to the burning and clearing of forests, as well as the spread of brought diseases. On all continents and numerous islands, there is a variety of striking evidence that the change and destruction of habitats produced by prehistoric man coincides with high rates of species extinction.
The extinction rates of birds and mammals are currently the best studied, as these relatively large animals are highly visible. The extinction rates of the remaining 99.9% of the world's species remain quite approximate today. But the scale of the extinction of birds and mammals is also very inaccurate, since some species that were considered extinct were rediscovered, while others, on the contrary, were considered still existing, may actually turn out to be extinct. According to the best estimates available, about 85 species of mammals and 113 species of birds have disappeared since 1600, representing 2.1% of mammal species and 1.3% of birds that existed during this period. At first glance, these figures do not seem alarming in themselves, but the trend towards an increase in the rate of extinction over the past 150 years has become frightening. Between 1600 and 1700, the rate of extinction of birds and mammals was about one species per decade, and during the period from 1850 to 1950, they increased to one species per year. This increase in the rate of species extinction indicates a serious threat to biodiversity.
At the same time, there is some evidence that over the past decades there has been a decrease in the rate of extinction of birds and mammals. Part of this can be attributed to ongoing efforts to save species from extinction, but at the same time lies the illusion created by the procedure adopted by international organizations, according to which a species is considered extinct only if it has not been seen for more than 50 years or if specially organized searches did not allow us to find a single remaining specimen. Many species, formally not yet completely extinct, have been severely undermined by human activities and have survived only in very small numbers. These species may be considered ecologically extinct because they no longer play a role in community organization. The future of many such species is uncertain.
About 11% of the world's remaining bird species are threatened with extinction; similar figures were obtained for mammals and trees. Just as great is the danger of extinction for some freshwater fish and shellfish. Plant species are also in a difficult position. Gymnosperms (conifers, ginkgo, cycads) and palm trees are especially vulnerable. Although extinction is natural process, more than 99% of disappearances modern species can be attributed to human activity.
2. Causes of species extinction
The main threats to biodiversity stemming from human activity are habitat destruction, fragmentation and degradation (including pollution), global climate change, human overexploitation of species, invasion of exotic species and increasing spread of disease. Most species are facing at least two or more of these problems, which are hastening their extinction and hampering efforts to protect them.
All of these seven threats are caused by the increasing use of natural resources with an exponentially growing population. Until the last few hundred years, population growth has been relatively slow, with birth rates only slightly exceeding death rates. The greatest destruction of biological communities has occurred over the past 150 years, when the population of the Earth has grown from 1 billion people. in 1850 to 2 billion people. in 1930, and on October 12, 1998, it amounted to 6 billion people.
2.1. Habitat destruction
The main threat to biodiversity is the disturbance of habitats, and therefore the most important thing for the conservation of biological diversity is their protection. Loss of habitats is associated with both direct destruction and damage in the form of pollution and fragmentation. For most endangered plants and animals, habitat loss is the primary threat.
In many parts of the world, especially on islands and areas of high population density, most primary habitats have already been destroyed. In Old World countries such as Kenya, Madagascar, India, the Philippines and Thailand, more than 50% of key forest habitats have been destroyed. Slightly better position Democratic Republic Congo (formerly Zaire) and Zimbabwe; more than half of the habitats still exist in these biologically rich countries wild species. Many highly valuable wild species have lost much of their original range, and few remaining habitats are protected. For example, an orangutan ( Pongo pygmaeus), a large ape that lives in Sumatra and Borneo, has lost 63% of its habitat, and only 2% of its original range is protected.
The plight of tropical rainforests is perhaps the most well-known case of habitat destruction, but other habitats are also in mortal danger.
The decline of biodiversity usually begins with the destruction of the natural habitat of species. The development of new technologies and the destruction of the environment as a result of human activity is proceeding at a rate that far exceeds the ability of species to adapt to new conditions. The exception is a few species of animals and plants, which we call weeds and with which we do not want to share the future of the planet. It is likely that such insects and weeds have a range of hereditary variability that allows them to adapt to the rapid environmental changes that occur as a result of its disturbance, but most larger plants and animals are not capable of this.
Human intervention often leads to a decrease in the diversity of natural conditions. For example, destroying different kinds tree species in mixed forests in order to create favorable conditions for the growth of pine used in the pulp industry, people inevitably reduce the number of ecological niches. As a result, in the resulting pure pine forests the species diversity of animals and plants is significantly reduced compared to the original mixed forest community.
The destruction of a natural habitat often begins with its fragmentation into separate isolated areas. In the spring, capercaillie roosters are going to the current. The area of the forest area required for the current should be at least 5-8 hectares. The reduction of forest areas suitable for lekking inevitably leads to a decrease in the number of this species.
2.2. Habitat fragmentation
Habitat fragmentation is the process by which a continuous area of habitat simultaneously shrinks and breaks up into two or more fragments. Habitat destruction may not affect only local areas. These fragments are often separated from one another by altered or degraded forms of the landscape.
Fragments differ from the original continuous habitat in that: 1) fragments are relatively large border zones adjacent to human activity and 2) the center of each fragment is located close to the edge. As an example, consider a square-shaped nature reserve with a length of 1000 m (1 km) on each side, surrounded by human-used land, such as farms. total area such a reserve is 1 km2 (100 ha) and its perimeter is 4000 m, and the point in the center of the reserve is 500 m from the nearest perimeter point. If domestic cats in search of food go deep into the forest 100 meters from the border of the reserve and interfere forest birds to breed chicks, then only 64 hectares of the reserve remain suitable for the calm breeding of birds. The peripheral strip unsuitable for reproduction occupies 36 hectares.
Now imagine a reserve divided into four equal parts by a road from north to south 10 m wide and a railway from east to west, also 10 m wide. The alienated area in the whole is 2 hectares (2x1000x10 m) in the reserve. Since only 2% of the area of the reserve is alienated by roads and railways, government officials argue that their influence on the reserve is negligible. But the reserve is now divided into 4 fragments, each with an area of 495 x 495 m, and the distance from the center of the fragment to the nearest point of the perimeter has been reduced to 240 m, that is, more than twice. Since cats can now feed in the forest, entering it both from the perimeter and from the roads, only the inner sections of each of the four fragments are left for birds to calmly breed offspring. In a separate square, this area is 8.7 hectares, and in total they occupy 34.8 hectares in the reserve. Even if the road and the railway took only 2% of the territory of the reserve, they reduced the habitats suitable for birds by half.
Habitat fragmentation threatens species in more complex ways. First of all, fragmentation limits the ability of species to disperse. Many species of birds, mammals and insects that live in the depths of the forest cannot cross even narrow lanes. open space because of the danger of getting caught by a predator. As a result, after the disappearance of a population in a fragment, some species do not have the opportunity to populate it again. Moreover, if animals responsible for the distribution of fleshy and sticky fruits disappear due to fragmentation, then the corresponding plant species also suffer. Ultimately, isolated fragments of habitats are not populated by many species that are originally characteristic of them. And since within individual fragments there is a natural disappearance of species due to regular successional and population processes, and new species cannot replenish their loss due to barriers, therefore, a gradual species impoverishment occurs in the fragment.
The second dangerous aspect of habitat fragmentation is that the foraging arena for many typical animals is shrinking. Many animal species, individuals or social groups that feed on widely dispersed or seasonally available foods and use seasonally distributed water sources, need freedom of movement over a wide area. The life-saving resource can only be used a few weeks a year or even once every few years, but with habitat fragmentation, isolated species are unable to migrate within their natural range in search of this rare, but sometimes so important resource. For example, hedges can prevent the natural migration of large herbivores such as wildebeest or bison, forcing them to graze in one place, which eventually leads the animals to starvation and habitat degradation.
Habitat fragmentation can also hasten population extinction because it results in a widespread population breaking up into two or more isolated subpopulations. These small populations are subject to their characteristic processes of inbreeding and genetic drift. If one integral large population can normally live on a large area of habitat, then often none of its fragments can support a subpopulation large enough for long-term sustainable existence.
2.3. edge effect
As shown above, habitat fragmentation greatly increases the proportion of marginal habitats relative to inland habitats. These boundary, “edge” microenvironments differ from the inner forest part of the fragments. Edge habitats are characterized by large fluctuations in light levels, temperature, humidity, and wind speed.
These edge effects spread deep into the forest up to 250 m. Since some species of animals and plants are very narrowly adapted to certain levels of temperature, humidity and light, they cannot withstand the changes that have occurred and disappear in forest fragments. Shade-tolerant species of wild flowering plants in forests temperate climate, late successional tree species rainforest and moisture-sensitive animals such as amphibians can disappear very quickly due to habitat fragmentation, which ultimately leads to shifts in the species composition of the community.
Due to the fragmentation of the forest, wind blowing increases, humidity decreases and temperature rises, and, as a result, the risk of fires increases. Fires can spread to forest fragments of habitats from surrounding agricultural land, where, for example, fires are fired during the collection of sugar cane, or in slash-and-burn agriculture.
In Borneo and the Brazilian Amazon, millions of hectares of tropical rainforest burned during an unusually dry period in 1997 and 1998. To this ecological disaster cited a combination of factors resulting from forest fragmentation due to agricultural activities and patchy settlement and the associated scattered accumulation of debris and, accordingly, outbreaks of local fires.
Habitat fragmentation makes, among other things, the inevitable contact of wild animals and plants with domestic ones. As a result, domestic animal diseases spread rapidly among wild species lacking appropriate immunity. It should be borne in mind that such contact also ensures the transmission of diseases from wild species of plants and animals to domestic ones, and even to humans.
2.4. Habitat degradation and pollution
Environmental pollution is the most universal and severe form of its destruction. It is most often caused by pesticides, fertilizers and chemicals, industrial and urban wastewater, gas emissions from factories and cars, and deposits washed up from hills. Visually, these types of pollution are often not very noticeable, although they occur around us every day in almost every part of the world. Global Impact pollution on water quality, air quality and even climate on the planet is in the spotlight not only because of the threat to biodiversity, but also because of the impact on human health. Although sometimes environmental pollution is very visible and frightening, for example, in the case of massive oil spills and 500 fires in oil wells that took place during the Gulf War, but the most threatening are latent forms of pollution, mainly because their effect is not immediately apparent.
2.5. Overexploitation of resources
In order to survive, man has always been engaged in hunting, gathering fruits, using natural resources. As long as the population was small and its technology primitive, man could use his environment sustainably, hunt and harvest without desired views before disappearing. However, as the population increased, the pressure on the environment increased. Crop farming methods have become incomparably larger and more efficient, and have led to the almost complete exclusion of large mammals from many biological communities, resulting in strangely “empty” habitats. In the rainforests and savannahs, hunting rifles have replaced bows, darts and arrows. In all the oceans of the world, powerful fishing motor vessels and fish processing “floating bases” are used to catch fish. Small-scale fishermen are equipping their boats and canoes with outboard motors, allowing them to catch their catch faster and from a larger area than was previously possible. Even in pre-industrial society, overexploitation of resources led to the decline and extinction of native species. For example, the ceremonial cloaks of the Hawaiian kings were made from the feathers of one of the types of flower girls. (Drepanis sp.). For one cloak, feathers of 70 thousand birds of this now extinct species were required. Predatory species can reduce the number if their main prey is overfished by humans. It is estimated that it is overexploitation in the United States that threatens the existence of about a quarter of endangered vertebrate species, and of these, about half are mammals.
In traditional societies, restrictions are often imposed on the overexploitation of natural resources: the rights to use agricultural land are strictly controlled; hunting is prohibited in certain areas; there are prohibitions on the destruction of females, young animals and animals with low numbers; collection of fruits is not allowed in certain seasons of the year and time of day, or barbaric methods of collection are prohibited. These types of restrictions allow traditional societies to use natural resources on a long-term sustainable basis, such as the severe restrictions on fishing developed and proposed by the fisheries of many industrialized countries.
However, in many parts of the world, resources are currently being exploited at maximum intensity. If there is a demand for a certain product, the local population finds ways to find and sell it. Whether people are poor and hungry or rich and greedy, they use every means available to get this product. Sometimes decisions are made in traditional societies to sell ownership of a resource, such as a forest or a mine, in order to use the money received to buy desired or needed goods. In rural areas, traditional methods of controlling the consumption of natural products are weakened, and in many areas with significant population migration or where civil unrest and war occur, such controls do not exist at all. In countries involved in civil wars and internal conflicts, for example in Somalia, former Yugoslavia, the Democratic Republic of the Congo and Rwanda, the population received firearms and the food distribution system was destroyed. In such situations, natural resources are used by anyone who wants it. At the local or regional level, developing countries ah, hunters penetrate into newly inhabited territories, into national parks, and other places where roads pass, and hunt any large animal here in order to sell the so-called “wild meat”. This leads to the formation of "forest wastelands" - lands with almost intact plant communities, but without characteristic animal communities. In order to satisfy legal and illegal requests, entire biological communities. Collectors fish out great amount butterflies and other insects, orchids, cacti and other plants are removed from nature, sea mollusks for shells and tropical fish for aquarists.
In many cases, the mechanism of overexploitation is notorious. A resource is identified, a market for it is determined, and then the local population is mobilized for its extraction and sale. The resource is consumed so widely that it becomes scarce or even disappears, and the market replaces it with another type, resource, or opens up a new region for exploitation. According to this scheme, industrial fishing is carried out, when one species after another is consistently produced until depletion. Loggers often do the same, gradually cutting down less and less valuable trees in successive cycles until only single commercial trees remain in the forest. Hunters, too, are gradually moving farther away from their villages and from the loggers' camps in search of animals and trapping them for themselves or for sale.
For many exploited species, the only hope for a chance of recovery is when they become so rare that they are no longer of commercial value. Unfortunately, the population size of many species, such as rhinos or some wild cats, is already so severely reduced that these animals are unlikely to be able to recover. In some cases, their rarity can even increase demand. As rhinos become more rare, the price of their horn rises, making it a more valuable commodity on the black market. In rural areas of developing countries, desperate people, in order to feed their families, actively seek out the last remaining rare plants or animals in order to sell them and buy food for their families. In such situations, one of the priorities of conservation biology is to find ways to protect and support the remaining members of these species.
2.6. Invasive species
The geographic ranges of many species are limited mainly by natural and climatic barriers. The mammals of North America are not able to cross the Pacific Ocean and reach Hawaii, fish caribbean can't cross Central America and reach Pacific Ocean, a freshwater fish from one African lake they cannot cross the land and get into other neighboring isolated lakes. Oceans, deserts, mountains, rivers - they all restrict the movement of species. Due to geographical isolation, the paths of evolution of animals in each part of the world took place in their own way. By introducing alien species into these faunistic and floristic complexes, man has disrupted the natural course of events. In pre-industrial eras, people, developing new territories, brought here with them cultivated plants and domestic animals. European sailors, in order to provide themselves with food on the way back, left goats and pigs on uninhabited islands. In the modern era, either intentionally or accidentally, a great many species have been introduced into areas where they never existed. The introduction of many species was due to the following factors.
· European colonization. Arriving at new places of settlement in New Zealand, Australia, South Africa, and wanting to make the surroundings more familiar to look at and provide themselves with traditional entertainment (in particular, hunting), Europeans brought hundreds European species birds and mammals.
· Horticulture and agriculture. A large number of species ornamental plants, agricultural crops and pasture grasses are introduced and grown in new areas. Many of these species "broke free" and settled in local communities.
The vast majority of exotic species, that is, species that have found themselves outside their natural range due to human activities, do not take root in new places, because the new environment does not meet their needs. However, a certain percentage of species are very well established in their new “homes” and become invasive species, that is, those that increase in numbers at the expense of the original species. Through competition for a limiting resource, such exotic species may crowd out native species. Introduced animals may exterminate the latter to the point of their extinction, or may alter habitats in such a way that they become unsuitable for the original species. In the US, invasive exotic species are a threat to 49% of endangered species, and they are especially dangerous for birds and plants.
Invasive species have shown their influence in many areas the globe. The US now has over 70 exotic fish species, 80 exotic shellfish species, 200 exotic plant species, and 2,000 exotic insect species.
Many flooded lands in North America are absolutely dominated by exotic perennials: in the swamps of eastern North America, loosestrife dominates ( Lythrum salicaria) from Europe, and Japanese honeysuckle ( Lonicera japonica) forms dense thickets in the lowlands of the southeastern United States. Intentionally introduced insects such as European honey bees ( Apis mellifera) and bumblebees ( bombbus spp.), and randomly introduced Richter ants ( Solenopsis saevissima richteri) and African honey bees ( A. mellifera adansonii or A. mellifera scutella) created huge populations. These invasive species can have a devastating effect on the local insect fauna, leading to a reduction in the number of many species in the area. In some areas of the southern United States, due to the invasion of exotic Richter ants, the diversity of insect species has decreased by 40%.
The influence of invasive species can be especially strong in lakes, rivers and entire marine ecosystems. Freshwater communities are like islands in the ocean in that they are isolated habitats that are surrounded by vast, uninhabitable spaces. Therefore, they are particularly vulnerable to the introduction of exotic species. In water bodies for the sake of commercial or sport fishing, species that are not inherent in them are often introduced. More than 120 fish species have already been introduced into marine and estuarine systems and inland seas; and while some of these introductions were intentional to improve fisheries, most of them were the unintended result of canal construction and ship-borne ballast water transport. Often, exotic species are larger and more aggressive than the natural fish fauna, and as a result of competition and outright predation, they can gradually drive native fish species to extinction.
Aggressive aquatic exotic fauna, along with fish, includes plants and invertebrates. In North America, one of the most alarming invasions was the appearance in the Great Lakes in 1988 of the river zebra mussel ( Dreissena polymorpha). This small striped animal from the Caspian Sea was undoubtedly brought from Europe by tankers. In two years, in some parts of Lake Erie, the number of zebra mussel reached 700 thousand individuals per 1 m2, which forced out local species of mollusks. As it moves south, this exotic look causes enormous economic damage to fisheries, dams, power plants and ships, and devastates aquatic communities.
2.7. Diseases
Second, an organism's susceptibility to disease may be an indirect result of habitat destruction. When habitat destruction crowds a host population into a small area, this often results in poor environmental quality and reduced food availability, leading to malnutrition, weakened animals and therefore greater susceptibility to infection. Overcrowding can lead to social stress within the population, which also reduces the resistance of animals to diseases. Pollution increases the body's susceptibility to pathogenic infections, especially in aquatic environments.
Third, in many protected areas, zoos, national parks, and new agricultural areas, wild animals come into contact with new species, including humans and domestic animals, that they rarely or never encounter in the wild, and therefore exchange pathogens with them.
Some dangerous infectious diseases, such as the human immunodeficiency virus (HIV) and the Ebola virus, are likely to have spread from wild animal populations to domestic and human populations. Once infected with exotic diseases, animals cannot be returned from captivity to the wild without the threat of infecting the entire wild population. In addition, species that are resistant to a particular disease may become the custodians of that pathogen, which can then infect populations of less resistant species. For example, when kept together in zoos, perfectly healthy African elephants can transmit the deadly herpes virus to their relatives. Asian elephants. In the early 90s in National Park In the Serengeti in Tanzania, about 25% of the lions died from canine distemper, apparently infected through contact with one or more of the 30,000 domestic dogs living near the park. Diseases can affect more ordinary species: North American chestnut ( Castanea dentata), very widespread throughout the western United States, was virtually destroyed in this region by actinomycete fungi brought here with the Chinese chestnut brought to New York. Now introduced fungi are destroying the Florida dogwood ( Cornus florida) throughout most of its native range.
3. Susceptibility to extinction
When the environment is disturbed by human activities, the population size of many species is reduced, and some species become extinct. Ecologists have noticed that not all species have the same chance of extinction; certain categories of species are particularly susceptible to it and require careful protection and control.
· Species with narrow ranges. Some species are found only in one or a few places geographically limited areas, and if the entire range is subjected to human activity, these species may become extinct. Numerous examples of this are extinct species of birds that lived on oceanic islands. Many species of fish that lived in a single lake or in the basin of a single river also disappeared.
· Species formed by one or more populations. Any population of a species can become locally extinct as a result of earthquakes, fires, disease outbreaks, and human activity. Therefore, species with many populations are less subject to global extinction than species that are represented by only one or a few populations.
· Species with a small population size, or “small population paradigm”. Small populations are more likely to disappear than large populations due to their greater exposure to demographic and natural changes and loss of genetic diversity. Species with small populations, such as large predators and highly specialized species are more likely to become extinct than those with large populations.
· Species in which the size of populations gradually decreases, the so-called "population reduction paradigm". In normal cases, populations have a tendency to self-repair, so the population, demonstrating stable signs the reduction is likely to disappear if the cause of the reduction is not identified and corrected.
· Species with low population density. Species with an overall low population density, if the integrity of their range has been violated by human activity, will be represented in each fragment by a low number. The population size within each fragment may be too small for the species to survive. It begins to disappear within its entire range.
· Species that require large ranges. Species in which individual individuals or social groups get food for large territories, are prone to extinction if part of their range is destroyed or fragmented by human activity.
· Types of large sizes. Compared to small animals, large animals usually have larger individual territories. They need more food, they often become the subject of human hunting. Large predators are often exterminated because they compete with humans for game, sometimes attack domestic animals and people, and besides, they are the object of sport hunting. Within each species guild, the largest species—the largest carnivores, the largest lemur, the largest whale—are the most affected by extinction.
· Species incapable of dispersal. In the natural course of natural processes, changes in the environment force species, either behaviorally or physiologically, to adapt to new conditions. Species unable to adapt to a changing environment must either migrate to more suitable habitats or face the threat of extinction. The rapid pace of human-induced change often outstrips adaptation, leaving migration as the only alternative. Species unable to cross roads, fields, and other human-disturbed habitats are doomed to extinction as their “native” habitats are transformed by pollution, new species invasion, or global climate change. The low dispersal ability explains why among the aquatic invertebrates of North America, 68% of mollusk species have disappeared or are threatened with extinction, in contrast to dragonfly species that can lay eggs by flying from one body of water to another, so for them this figure is 20%.
· seasonal migrants. Seasonally migratory species are associated with two or more habitats that are distant from each other. If one of the habitats is disturbed, the species cannot exist. The billions of songbirds of the 120 species that migrate between Canada and South America each year depend on the availability of suitable habitats in both areas for survival and reproduction. Roads, hedges, or dams create barriers between essential habitats that some species need to get through everything. life cycle. For example, dams prevent salmon from moving up rivers to spawn.
· Species with low genetic diversity. Intrapopulation genetic diversity sometimes allows species to successfully adapt to a changing environment. When a new disease, new predator, or other change occurs, species with low genetic diversity may be more likely to go extinct.
· Species with highly specialized requirements for an ecological niche. Some species are adapted only to unusual types of rare, scattered habitats, such as limestone outcrops or caves. If the habitat is disturbed by humans, this species is unlikely to survive. Species with highly specialized food requirements are also at particular risk. A vivid example of this is the types of ticks that feed only on the feathers of a certain type of bird. If the bird species disappears, the feather mite species disappears accordingly.
· Species living in stable environments. Many species are adapted to environments whose parameters change very little. For example, living under the canopy of the primary rain forest. Often such species grow slowly, are unreproductive, give offspring only a few times in their lives. When rain forests are cut down, burned out, or otherwise altered by humans, many species living here are unable to survive the emerging changes in the microclimate (increase in illumination, decrease in humidity, temperature fluctuations) and the emergence of competition with early successional and invasive species.
· Species forming permanent or temporary aggregations. Species that form clusters in certain places are very susceptible to local extinction. For example, the bats feed on at night large area, but the day is usually spent in a particular cave. Hunters who come to this cave during the day can collect the entire population to the last individual. Herds of bison, flocks of passenger pigeons and schools of fish are aggregations that were actively used by man, up to the complete depletion of the species or even extinction, as happened with the passenger pigeon. Some species of social animals cannot exist when their population falls below a certain level because they can no longer forage, mate and defend themselves.
· Species hunted or collected by humans. A prerequisite for the extinction of species has always been their utility. Overexploitation can rapidly reduce the population size of species of economic value to humans. If hunting or gathering is not regulated by law or local custom, species may become extinct.
These characteristics of endangered species are not independent, but are grouped into larger categories. For example, species of large animals tend to form populations with low densities and large ranges, all of which are features of endangered species. Identifying these characteristics helps biologists take early action to conserve species in particular need of protection and management.
QUESTIONS FOR SELF-CHECKING
1. What do you know about the rate of extinction of species and how does this problem relate to the concept of biological diversity?
2. What is the rate of extinction of species at the present stage?
3. List the most significant causes of biodiversity reduction caused by human activities.
4. What causes the destruction and fragmentation of habitats of living organisms? What are the consequences of these phenomena?
5. What is the "edge effect"?
6. What are the reasons for the degradation of living conditions for plants and animals?
7. What are the main sources of habitat pollution?
8. What does the overexploitation of flora and fauna resources lead to? Give examples.
9. Define the terms "invasive species", "introduction".
10. List the factors underlying the introduction of species.
11. What are the three basic principles of epidemiology to be based on the breeding of species in captivity and the management of rare species.
12. What is the reason for the unequal probability of extinction of species?
BIOLOGICAL DIVERSITY (biodiversity), a concept that came into wide use in the 1980s in the fields of fundamental and applied biology, exploitation biological resources, policies in connection with the strengthening of the environmental movement, awareness of the uniqueness of each species and the need to preserve the diversity of life for the sustainable development of the biosphere and human society. This was reflected in international convention on biological diversity, adopted in Rio de Janeiro in 1992 (signed by Russia in 1995). In the scientific literature, the concept of "biological diversity" is used in broad sense to denote the richness of life as a whole and its constituent parts, or as a set of parameters of floras, faunas and communities (the number of species and a set of adaptive types, indices reflecting the ratio of species in terms of the number of individuals - evenness, dominance, and so on). Forms of biological diversity can be identified at all levels of life organization. They talk about species, taxonomic, genotypic, population, biocenotic, floristic, faunistic, etc. diversity. Each level has its own systems, categories and methods for assessing diversity. By the beginning of the 21st century, biologists counted up to 2 million species of all groups of organisms: multicellular animals - about 1.4 million species (including insects - about 1 million), higher plants- 290 thousand species (including angiosperms - 255 thousand), mushrooms - 120 thousand species, algae - 40 thousand, protests - 40 thousand, lichens - 20 thousand, bacteria - 5 thousand species. Some authors, taking into account the estimated number of species not yet described, estimate the richness of the modern organic world to be much a large number species - up to 15 million. In ecology, when analyzing the structure and dynamics of communities, the system of biological diversity of the American ecologist R. Whittaker is widely used. Of the categories of biological diversity he proposed, the most commonly used are alpha diversity ( species structure specific community), beta diversity (changes in a number of communities, for example, depending on temperature conditions) and gamma-diversity (the structure of the biota on the scale of the entire landscape). Syntaxonomy is intensively developing - classification plant community based on their species diversity.
Biodiversity is the main result and at the same time a factor evolutionary process. The emergence of new species and life forms complicates the environment and determines the progressive development of organisms. The most complex, evolutionarily advanced forms arise and flourish in equatorial and tropical belts, where the maximum species richness is observed. And life itself could develop as a planetary phenomenon on the basis of the division of functions in primary ecosystems, that is, at a certain level of diversity of organisms. The circulation of substances in the biosphere can only be carried out with sufficient biological diversity, on which the mechanisms of stability and regulation of the dynamics of ecological systems are based. Such key features their structures, such as interchangeability, ecological vicariate, multiple provision of functions, are possible only with significant species and adaptive (adaptive forms) diversity.
The level of biological diversity on Earth is primarily determined by the amount of heat. From the equator to the poles, all indicators of biological diversity are sharply reduced. Thus, the share of flora and fauna of the equatorial and tropical zones accounts for at least 85% of the total species richness of the organic world; species living in temperate zones make up about 15%, and in the Arctic - only about 1%. In the temperate zone, in which most of Russia is located, the most high level biological diversity in its southern strip. For example, the number of bird species from the forest-steppe and broad-leaved forests to the tundra decreases by 3 times, flowering plants - by 5 times. According to change natural belts and zones, the structure of all biological diversity naturally changes. Against the background of a general decrease in the species richness of the organic world towards the poles, individual groups retain its rather high level and their share in fauna and flora, as well as their biocenotic role, increase. The more severe the living conditions, the higher the proportion of relatively primitive groups of organisms in the biota. For example, the diversity of flowering plants, which form the basis of the Earth's flora, decreases much more sharply with advancement to high latitudes than bryophytes, which in the tundra are not inferior to them in terms of species richness, and are twice as rich in polar deserts. Under conditions of extreme climatic pessimism, for example, in the Antarctic oases, mainly prokaryotes and single species of lichens, mosses, algae, and microscopic animals live.
Strengthening the specificity of the environment, extremeness (very high or low temperature, high salinity, high pressure, the presence of toxic compounds, hyperacidity and so on) reduce the parameters of biological diversity, in particular the species diversity of communities. But at the same time certain types or groups of organisms that are resistant to this factor (for example, some cyanobacteria in heavily polluted water bodies) can multiply in extremely large quantities. In ecology, the so-called basic biocenotic law or Tinemann's rule has been formulated: biotopes with conditions that are sharply different from optimal are inhabited by a smaller number of species, which, however, are represented large quantity individuals. In other words, impoverishment species composition offset by an increase in the density of populations of individual species.
Among the areas of study of biological diversity, first of all, there is an inventory of species composition based on taxonomy. Floristics and faunistics, areaology, phyto- and zoogeography are associated with the latter. It is extremely important to know the factors and understand the mechanisms of evolution of biological diversity, the genetic foundations of the diversity of organisms and populations, the ecological and evolutionary role of polymorphism, the laws of adaptive radiation, and the processes of delimitation of ecological niches in ecosystems. The study of biological diversity in these aspects is connected with the most important areas of modern theoretical and applied biology. A special role is given to the nomenclature, typology and inventory of communities, vegetation and animal populations, the creation of databases on various components of ecological systems, which is necessary to assess the state of the entire living cover of the Earth and the biosphere, to solve specific problems of environmental protection, conservation, use of bioresources, many pressing issues of biodiversity conservation at the regional, national and global levels.
Lit.: Chernov Yu.I. Biological diversity: essence and problems // Successes of modern biology. 1991. Vol. 111. Issue. four; Alimov A.F. et al. Problems of studying the diversity of the animal world in Russia // Journal general biology. 1996. V. 57. No. 2; Groombridge V., Jenkins M.D. global biodiversity. Camb., 2000; Alekseev A.S., Dmitriev V.Yu., Ponomarenko A.G. Evolution of taxonomic diversity. M., 2001.
Currently, biodiversity refers to all types of plants, animals, microorganisms, as well as the ecosystems and ecological processes of which they are part.
Quantitative assessments of biodiversity are based on the use of various indicators: from a simple number of species in a community to calculations of various dependencies and indices based on mathematical and statistical approaches. In this case, the time factor is necessarily taken into account, since biodiversity can only be assessed at a certain point in time. Diversity indicators have gained great popularity, which reflect not only the total number of species, but also the characteristics of the composition of biocenoses.
There are three levels of biodiversity: genetic, species and ecosystem. Genetic diversity is the total amount of genetic information contained in the genes of organisms that inhabit the Earth. Species diversity is the variety of species of living organisms that live on Earth. Ecosystem diversity refers to the different habitats, biotic communities, and ecological processes in the biosphere, and the vast diversity of habitats and processes within an ecosystem.
The indicator of biodiversity at the global level is considered to be the ratio of areas of territories of natural complexes, to varying degrees subject to anthropogenic impact and protected by the state.
Biodiversity is the basis of life on Earth, one of the most important life resources, it is considered the main factor determining the stability of biogeochemical cycles of matter and energy in the biosphere. Causal relationships between many species play a large role in the cycle of matter and energy flows in ecosystem components that are directly related to humans. So, for example, animals - filter feeders and detritus feeders, not used by humans for food, make a significant contribution to the cycle of biogenic elements (in particular, phosphorus). Thus, even species of organisms that are not included in the human food chain can be useful to him, although they benefit indirectly.
Many species have played a major role in shaping the Earth's climate and continue to be a powerful climate stabilizing factor.
The evolutionary processes that took place in different geological periods led to significant changes in the species composition of the inhabitants of the Earth. About 65 million years ago, at the end of the Cretaceous period, many species disappeared, especially birds and mammals, dinosaurs completely died out. Later, biological resources were lost faster, and, unlike the great extinction of the Cretaceous period, most likely caused by natural phenomena, the loss of species is now due to human activities. According to experts, in the next 20 hours 30 years, approximately 25% of all species on Earth will be under serious threat of extinction.
The threat to biodiversity is constantly growing. According to forecasts, between 1990 and 2020, between 5 and 15% of species may disappear. Most important reasons species loss:
Habitat loss, fragmentation and modification;
Overexploitation of resources:
Environmental pollution;
Displacement of natural species by introduced exotic species.
The loss of species diversity as a life resource can lead to serious global consequences, as it threatens the well-being of man and even his very existence on Earth. Ecosystem resilience can be compromised when biodiversity is reduced; species that are not currently dominant can become dominant when environmental conditions change. It is not yet possible to predict how the loss of biodiversity will affect the functioning of the ecosystem, but experts suggest that such losses are unlikely to be favorable.
Active measures are being taken to conserve biodiversity. The Convention on Biodiversity was adopted in 1992 at KOSR-2. Russia ratified the Convention in 1995; adopted a number of laws related to the conservation of biodiversity. Russia is a party to the CITES convention (1976) as the legal successor of the USSR.
The following measures are being developed for the conservation of biodiversity and its sustainable use:
1) protection of a special habitat - the creation of national parks, biosphere reserves and other protected areas;
2) protection of individual species or groups of organisms from overexploitation;
3) preservation of species in the form of a gene pool in botanical gardens or banks;
4) reducing the level of environmental pollution.
The implementation of the planned measures is carried out through the development of international and national programs aimed at implementing these measures (for example, the DIVERS1TAS program). A Pan-European Strategy on Biological and Landscape Diversity (1995) has been developed. An information database BioNET is being created (in the UK), where data on all species of plants and animals known on Earth are concentrated; the world's first data bank on endangered animals and plants was created (in Germany).
Which spread and live in various natural areas. Such biodiversity is not the same in different climatic conditions: some species adapt to the harsh conditions of the arctic and tundra, others learn to survive in deserts and semi-deserts, others love the warmth of tropical latitudes, others inhabit forests, and still others spread over wide expanses of the steppe. The state of species that exists on Earth at the moment was formed over 4 billion years. However, one of them is the reduction of biodiversity. If it is not solved, then we will forever lose the world that we know now.
Causes of biodiversity decline
There are many reasons for the decline in animal and plant species, and all of them directly or indirectly come from people:
- expansion of the territories of settlements;
- regular emissions of harmful elements into the atmosphere;
- transformation natural landscapes in agricultural objects;
- usage chemical substances in agriculture;
- pollution of water bodies and soil;
- construction of roads and provision of communications;
- , requiring more food and territories for life;
- experiments on crossing plant and animal species;
- destruction of ecosystems;
- caused by people.
Of course, the list of reasons can go on. Whatever people do, they affect the reduction of the areas of flora and fauna. Accordingly, the life of animals changes, and some individuals, unable to survive, die prematurely, and the number of populations is significantly reduced, often leading to the complete extinction of the species. Much the same thing happens with plants.
The value of biodiversity
Biodiversity different forms life - animals, plants and microorganisms is valuable because it has a genetic and economic, scientific and cultural, social and recreational, and most importantly - environmental significance. After all, the diversity of animals and plants makes up the natural world that surrounds us everywhere, so it must be protected. People have already done irreparable damage that cannot be repaired. For example, many species were destroyed all over the planet:
Quagga
Sylph
Solving the problem of biodiversity conservation
In order to preserve biodiversity on earth, you need to make a lot of efforts. First of all, it is necessary that the governments of all countries pay special attention to this problem and protect natural objects from encroachments different people. Also, work to preserve the world of flora and fauna is carried out by various international organizations in particular Greenpeace and the United Nations.
Among the main measures that are being taken, it should be mentioned that zoologists and other specialists are fighting for each individual of an endangered species, creating reserves and natural parks where animals are under observation, creating conditions for them to live and increase populations. Plants are also artificially bred to increase their ranges, to prevent valuable species from dying.
In addition, it is necessary to carry out measures to preserve forests, protect water bodies, soil and atmosphere from pollution, and apply them in production and everyday life. Most of all, the preservation of nature on the planet depends on ourselves, that is, on each person, because only we make a choice: to kill an animal or keep it alive, cut down a tree or not, pick a flower or plant a new one. If each of us will protect nature, then the problem of biodiversity will be overcome.
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