Thesis Statement: Biodiversity is very important for sustaining and balancing natural order. Species extinction and destruction of biodiversity is to a large extent an outcome of human unsustainable activity and use of resources as contrasted to natural processes of biodiversity change.
I. Forms of biodiversity
- Species diversity - the number of species present in different habitats
- Genetic diversity - a variety of genetic material within a population
- Ecosystem diversity - ecological diversity of the various terrestrial and aquatic habitats
II. Distribution of biodiversity
- Physical or environmental factors - aspects of geography such as the place, climate, temperature, and rainfall that drive the distributions of organisms and govern where certain life forms can live
- Biotic factors - influence the distribution of other life
- Evolutionary factors - a factor of change that can make some species adapt to new habitats and evolve.
III. Measuring biodiversity
- Simpson index - consider how many types of life there are as well as the relative contribution of each type of life and balanced number of species
- Shannon index - considers the importance of each species in ecosystem and the number of types of living things there within species
IV. Biological evolution
- Natural selection - the change in population’s genetic makeup through successive generations
- Stabilizing selection - those genes that give individuals particular average characteristic will also be favored and transmitted onto the next generation
- Diversifying selection - both of the extreme phenotypes would be favored such that those genes that were passed in the next generation while those of the average phenotype would be selected against and be reduced in number
- Directional selection - one of the two extreme phenotypes is favored and those genes are also passed onto the next generation.
- Microevolution - small changes that occur in its gene pool
- Mutations - changes of the genetic structure or number of the DNA molecules in a cell that can be inherited by offspring
V. Changes to gene pools
- Gene flow
- Migration - members of a population leave and take their genes with them reducing the overall genetic diversity of a population.
- Immigration - new members of a population enter into a group
- Genetic drift - the gene pool of a small population changes as a result of chance but not due to the specific selection
VI. Competition and ecological niches
- Competition - populations compete for scarce resources
- Predation - representatives of one species kill and eat those of another
- Symbiosis - two species populations live together in close association with one another to the benefit of one or both of the species
VII. Human Generated Pollution and Land Use Change
- Habitat destruction
- Global warming
VIII. Conservation of ecosystems
- Conservation biology
- Measures necessary to save the environment
Conclusion: two main factors influencing changes in biodiversity are nature itself with its regular processes of change, evolution and development, and human activities. Human unsustainable usage of natural resources and uncontrollable depletion of the Earth with massive deforestation and pollution is incomparable with anything and brings fatal damage to the world.
The purpose of this paper is to study biodiversity and explain the internal and external factors influencing its operating system and balance. Species extinction and destruction of biodiversity is to a large extent an outcome of human activity and to prove that this research will focus on uncontrollable use of nature and its resources by people as contrasted to natural processes of biodiversity change. In this paper I will discuss biodiversity and its components. I will be touching on factors that threaten biodiversity and measures that need to be taken in order to save it. As I touch on each factor you will understand the influence of natural selection, evolution, migration of species, climate, temperature, human activities on the amount and range of biodiversity that we have in today’s world. In addition, I will also go over scientific methods that experts apply to control and measure biodiversity in order to be able to monitor its present state and predict its future development.
Biodiversity and its forms
Biodiversity is the richness of life and areas where these different forms of life exist. There are four major components of biodiversity and the most obvious of them would be species diversity, which is the number of species present in different habitats; however, even amongst that species, there is going to be genetic diversity with a variety of genetic material that can be found within that population. It is that genetic material that allows for resilience in the population as genetic changes may allow for the population to change and survive in an ever-changing world. The storehouse role of that genetic and species diversity is the ecological diversity of the various terrestrial and aquatic ecosystems that are found on Earth. Finally, there is functional diversity, which is the biological or chemical processes such as photosynthesis, which assist with the flow of energy in an ecosystem or decomposers in their ability to recycle matter. Each of these pieces of functional diversity is important for the survival of individual species and the support of whole ecosystems. Biodiversity is an essential component of the natural capital, and it provides people with many natural resources such as food, fuel, and medicine. Biodiversity also provides important natural services such as the ability to purify air and water, increase soil fertility, and remove unwanted pests and disposable wastes.
Distribution of Biodiversity and Its Importance
As a matter of fact, life is distributed unevenly on Earth and different organisms have different ranges and different distributions. Life exhibits distinct distribution patterns, distinct ranges and different overlapping ranges. The ranges of some species are large, some are small, but in fact, distributions clump. There are some places on Earth with the distributions overlap in larger numbers than in other places, and the reason for this is that every species has its own preferred place to live and sometimes the preferences overlap more in some places than in others. Every species tends to have a characteristic range, and there is a set of conditions in that range that allow the organism to get its food to reproduce and do the things that members of the given species have to do to survive in their habitat. Preferences are determined by three main factors: physical, biotic and evolutionary. Physical or environmental factors include such aspects as geography of the place, climate, temperature, and rainfall that drive the distributions of organisms and govern where certain life forms can live. Physical factors can be actual barriers to the movement of organisms and physically restrict organisms to a particular place. Biotic or living factors influence the distribution of other life; for example, places with low productivity, low biomass and low diversity are not good for other species to live in. Therefore, one type of life can dictate where other kinds of life might have their preferred habitats. The final factor in the uneven distribution of life is evolution. Life is constantly diversifying, and there is a factor of change that can make some species adapt to new habitats and evolve. Human activity is one of the factors that can restrict ranges of naturally occurring species, or in other cases, increase them. Farmers choose plants that they want to grow in order to enhance the ability to get food. They raise animals for their own use, as well; as humans move from place to place, they purposefully bring these organisms with them, and thus, those organisms have their ranges extended. It leads to the situation of huge biomass but low species richness. Humans can also decrease the size of organisms’ ranges simply by increasing their own ranges through building roads and highways, changing water courses and thus creating barriers to natural movements.
Species need to be defined in a certain way before scientists can measure their distribution and variety. It is essential to keep some kind of categorization of species and ensure that they are equally different from each other though according to the New York Times, only 1.75 million of the estimated 14 million species on Earth have even been documented, and there are many species that have not been categorized yet. Scientists measure the diversity in several ways: by simply counting and thus calculating their richness and evenness; applying Simpson index, which does not just consider how many types of life there are but also the relative contribution of each type of life and balanced number of species. There is also Shannon index, which considers the importance of each species in ecosystem and the number of types of living things there within species.
Taking into consideration fossil records, it is obvious that there are certain organisms that existed in the past but are no longer present today. This fact demonstrates that biodiversity has changed from the past to the present. According to scientific evidence, the major force in adaptation to changes in environmental conditions is biological evolution. Darwin shaped the concept of natural selection as the mechanism for biological evolution. He observed that in populations, there is a struggle for existence as not all individuals that are born can survive. Within that struggle, there are certain individuals that can possess characteristics or traits, which allow them to survive better than others; as a result, they are able to reproduce and pass that trait down to the next generation. Biological evolution by natural selection involves the change in population’s genetic makeup through successive generations. Evolution only works on populations, not individuals. In fact, there are three conditions necessary for biological evolution by natural selection: the first is genetic variation. Within a population, there must be varieties, and those varieties must be based on characteristics embedded in their traits, which can be passed from parent to offspring (heredity). Finally, some of those variations must be favorable, and that trait must lead to differential reproduction or survival of the fittest. A population may evolve because of small changes that occur in its gene pool, which is known as microevolution. All of the alleles all over the copies of genes in all of the organisms making up a population constitute the gene pool. It acts as a reservoir, from which the next generation will draw its genes. One way that a gene pool can change is in the result of mutations. Mutations are changes of the genetic structure or number of the DNA molecules in a cell that can be inherited by offspring, and they can happen to any cell, but only those taking place in reproductive cells are passed to offspring. Sometimes a mutation can result in a new genetic trait that gives an individual and its offspring a better chance for survival and reproduction. As a result, many scientists believe that mutations are the ultimate source of genetic variation in a population. Another way that a gene pool may change is in the result of natural selection individuals posses genetically based on the traits that cause them to survive and produce more offspring than others. There are three basic patterns of selection when it comes to changes in gene pools in a population. One example would be stabilizing selection. Here, those individuals that express the average physical appearance the average phenotype are favored. As a result, those genes that give them that particular average characteristic will also be favored and transmitted onto the next generation. The next pattern would be directional selection, in which one of the two extreme phenotypes is favored; as a result, those genes will also be passed onto the next generation. The last type is diversifying selection, in which both of the extreme phenotypes would be favored such that those genes that were passed in the next generation while those of the average phenotype would be selected against and be reduced in number.
Changes to Gene Pools
Another way that gene pools can change is gene flow. When members of a population leave, this is called emigration; when they leave, they are going to take their genes with them, and this will reduce the overall genetic diversity of a population. When new members of a population enter into a group, this is called immigration. New members coming in are going to increase the genetic variation in the population. The last way that a gene pool may change is through genetic drift. Genetic drift occurs when the gene pool of a small population changes as a result of chance but not due to the specific selection. There are situations that can actually shrink population down to a smaller size, in which a genetic drift will have a greater impact. The first is the result of natural disasters such as earthquake, floods and droughts, or overhunting that may reduce the sizeable population such that the surviving populations’ genetic makeup is much different than the original. Any small random changes that take place in that population’s gene pool will influence its overall diversity significantly. The second situation that can shrink populations down to a size where genetic drift may have a greater impact is the founder effect when a few individuals colonize a new habitat with much smaller and more different genetic composition than the original population. Any small random changes that take place in this new population will be significant. If certain characteristics are not a part of a gene pool, they probably will never show up in future generations. Populations of diverse species that reproduce quickly such as weeds or bacteria oftentimes will adapt to environmental conditions that change more quickly than species reproducing more slowly and producing fewer offspring such as humans and elephants. The fittest individuals are not the strongest but those that live the most descendants. Traits are developed because an ancestor in the past had a gene that offered fitness over others, which allowed for that individual to survive and pass that trait onto the next generation. Evolutionary process is a random branching process that results in a variety of new species.
Competition and Ecological Niches
Ecological communities consist of all the interacting species populations within an ecosystem. Most species populations within an established community, such as the African savanna, have interacted with one another over a long period of time. The interactions that occur between populations in a community fall into three major categories: competition, in which populations compete for scarce resources; predation, in which representatives of one species kill and eat those of another; and symbiosis, in which two species populations live together in close association with one another to the benefit of one or both of the species. Thus, populations of a given biological community are intertwined with one another in an intricate coevolutionary process. Still, these self-sustaining balanced communities developed through gradual changes occurring over long periods of time, and during these periods of change, one type of community gives way to another until a balanced self-sustaining community is established. For example, none of the Earth’s majestic forests originally were forests of huge trees; rather, the land they now cover was initially inhabited by lichen, grasses and low-growing shrubs. It was only after a long period of time that the established forest ecosystems were formed. The process, by which ecosystems slowly change into balanced self-sustaining communities, is called succession. Each species has a unique niche in the community in accordance with all aspects of that species way of life. This concept does not only include a species physical home or habitat but also its food requirements, behavior and predators. This might be called the species role or occupation within its ecosystem. In addition, the species niche includes all the physical environmental factors necessary for its survival such as the range of temperatures, under which members of the species can survive, the amount of water they require, and in the case with the plants, the pH of the soil they can inhabit, the type of the soil nutrients required, and the degree of shade that can be tolerated. Although no two species can ever occupy exactly the same ecological niche for a sustained period of time, the niches of different species often overlap one another. The result of overlapping niches is competition.
Human Generated Pollution and Land Use Change
Humans are greatly contributing to the destruction of biodiversity and loss in the number and variety of organisms on Earth. For instance, if there were no different kinds of plants herbivores and carnivores, energy would not be transferred efficiently from producers to consumers and the carbon cycle would collapse. Our food supply depends on biodiversity because we need a variety of species to harness enough energy as biomass to sustain our population. In addition, many of the medicines are derived from exotic plants. Our complex bodies and lifestyles could not be supported if there were a limited number of species to draw our resources from. Though biologists are still trying to determine the bare minimums of a working ecosystem, they have yet to exclude the functional importance of many species. Some biologists are using a species to species approach to solve the biodiversity loss. Increasingly, they are considering strategies such as assisted migration: they will physically pick threatened out of degraded habitats and move them to where chances of survival are better. This trend shows that scientists are losing hope in protecting certain environments and are simply resorting to shifting species around. Due to the biological risk and efforts involved in species relocation, assisted migration has a potential at a last resort, but it fails to address the root cause of the problem – habitat degradation. The more holistic and scientifically sound approach requires large-scale efforts to preserve natural habitats. Urban sprawl, disease, climate change and logging represent a few of the many obstacles that must be overcome to put us on a path of environmental preservation and restoration.
One of the main causes of habitat destruction pertains to agricultural land usage for the cultivation of crops that feed the growing population around the world. Forests are cleared to provide agricultural grounds, and the cutting down of forests is also used to satisfy lumber demands. Pollution also plays a major role in environmental destruction. Carbon dioxide emissions are s form of pollution that currently threatens many of the world’s ecosystems. Climates are always shifting, but with today’s global warming patterns, they are shifting faster than species can adapt. In 2004, international team of scientists estimated that 15 to 37% of species would go extinct due to global warming. Global warming poses several types of threats to species living on Earth: rising sea levels, droughts and flash flooding, massive crop failures, rising air pollution levels, uncontrollable fires and the extinction of animal and plant species. Such threats as these must be under urgent consideration before global warming destroys life on Earth. The increase of undesirable natural responses in the form of severe hurricanes and storms is most attributable to the increase of CO2 emissions, which heat up the near surface temperatures. According to Earth Observatory, the average surface temperature has increased by 0.6 degrees Celsius over the last century (Earth Observatory, n.d.). According to scientific expert Farge, by the year 2020 Glacier national Park will have no glaciers left. This date is quite surprising and shocking as previously, 2030 was a date for glaciers to melt, which shows that nature changes even faster than we can predict. Due to human carelessness and ignorance, numerous bad habits have been developed. One way humans contribute to global warming is by cutting down the forests. Carbon levels rise because of deforestation, which is the main cause of global warming. Specious extinctions are occurring at a rate anywhere from 1,000 to 10,000 times faster than the standard background extinction rate. Some scientists have even said that humanity is in the middle of a mass extinction that can only lead to the demise of the human race.
Conservation of Ecosystems
Conservation is focused on protecting whole ecosystems. Most of the relationships that keep this fragile world in balance are unknown to people, and people are equally ignorant of the importance of every creature in the global ecology of the planet. Each and every one of the Earth’s ecosystems has an essential mission, which contributes to the development of life, and the main emphasis should be laid on the endangered species. There is no future for conservation of biodiversity, without integrating people and their needs. Conservation biology stresses the importance of responsible usage of natural resources and setting reasonable control over human activities harming nature. It is necessary to reasonably manage the number of goods and services that people greedily take from nature. People need to realize that uncontrollable usage of natural resources, which the world has seen since industrial revolution, needs to be stopped or future generations just will not have a chance to survive on scarce resources which modern people leave to them. Sustainable usage of nature ensures that the environment and the natural resources it provides will not be depleted or destroyed permanently and will be available for human use for a very long time.
So, as we can conclude two main factors influencing changes in biodiversity are nature itself with its regular processes of change, evolution and development, and human activities. Human unsustainable usage of natural resources and uncontrollable depletion of the Earth with massive deforestation and pollution is incomparable with anything and brings fatal damage to the world.