LOSS OF BIODIVERSITY: MEANING, CAUSES, CONSEQUENCES - BIOLOGY - 2025

The loss of biodiversity refers to the decrease in the number of species in the world, to the detriment of genetic diversity among species and to the deterioration of their local habitats, such as ecosystems. In general terms, the loss of biodiversity diminishes the variety of life.

Biodiversity is a broad concept, and different statistical parameters are used to quantify it. These include the number of species in a delimited region and their respective abundances.

Source: By Collage: user: MathKnight-at-TAU + 19 others, from Wikimedia Commons

Among the most relevant causes that lead to the loss of biodiversity, is the impact of man on habitat fragmentation, pollution, introduction of invasive species, among others.

The loss of biodiversity leads to the disappearance of key species in ecosystems, which provide essential ecosystem services (such as pollination and seed dispersal). Likewise, there are species that have intrinsic value.

Conservation biologists can tackle this problem in different ways: by directly conserving species or by maintaining the functioning of ecosystems and the species that live there.

According to the principles of systematics, not all species have equal value - in terms of maintaining biodiversity and conservation. For example, if a species has a wide range, it is less important from a conservation point of view than one with a limited range.

What is biological diversity?

Biodiversity refers to the variety and variability of living organisms and the ecological complexes where they live and develop. Historically, the term was coined in 1985 as a contraction for "biological diversity."

The three levels of biodiversity

Biological diversity is often measured as the number of different "elements" in terms of their relative frequencies. These elements are organized in three levels. They include everything from the basic elements of its molecular structure - genes - to properties of complex ecosystems.

In other words, diversity includes the relative abundance of genes, species, and ecosystems.

A gene is the basic unit of heredity, encoded in a portion of DNA. Gene diversity refers to genetic diversity. Similarly, a species includes highly related, morphologically similar organisms that play a particular role in the ecosystem.

The last level is the ecosystem, defined as a functional system of organisms in a natural community along with the physical environment. This level varies according to each area studied. Examples of this are forests or coral reefs. According to the terminology, we have species diversity and genetic diversity.

How is biodiversity measured?

If we want to avoid the loss of biodiversity, we must have tools to measure it and to be able to infer if we are facing an event of loss of diversity - or to verify if a certain conservation plan has had a positive effect on the region that was implemented.

Biologists use statistical indices to measure this parameter. These combine the total number of species and their relative abundances in the ecosystem.

The simplest measure of biodiversity is the count of species in a delimited area, and is called "alpha diversity" or species richness. Only the presence and not their abundance is taken into consideration when the species is counted directly.

There are some downsides to the species count. First, they are not always complete; no matter how rigorous the study may be, there may be copies left on the outside.

Furthermore, identification errors can occur at the taxonomic level. Finally, it is suggested that the account should be related to abundance.

What does loss of biodiversity mean?

The known diversity of living things is incredibly overwhelming. Currently 1.7 million species of animals, plants and fungi are known. Biodiversity is not homogeneously distributed on planet earth. In contrast, it is located accumulated mainly in the tropical regions.

However, scientists have not been able to catalog all species in their entirety. It is estimated that there could be between 8 to 9 million species, while others believe that they could exceed 30 million.

The loss of biodiversity implies the loss of this number. The problem is so serious that there are species that have been lost without being described, that is, they never had the opportunity to be protected.

The sixth mass extinction

Although extinction is a normal process that has occurred since the origins of life, human action has increased the speed of the process, by an order of magnitude of up to 1,000.

In the history of geology, five mass extinction events have been reported (the best known being the extinction of the dinosaurs, 65 million years ago) and it is estimated that we are currently experiencing the sixth mass extinction.

Affected groups

The loss of biodiversity is affecting all lineages, from small invertebrates to amphibians and large mammals, including the numerous aquatic fauna - so important for human consumption, since many populations feed mainly on food from the sea.

Logically, some groups are more threatened than others, mainly by the destruction of their habitat. According to the information available in the "red list" there are 25% of threatened mammals, 41% of amphibians and 13% of birds.

With regard to invertebrates, it is estimated that 75% of flying insects have been lost in Europe in the last 25 years.

Causes

In the last century, the massive presence of the human species on the planet has had a strong negative impact on the change of ecosystems and the loss of biodiversity in all regions of the planet.

It is true that extinction processes have always occurred, as have environmental changes (for example the extinction of dinosaurs and the presence of ice ages). However, these events are currently occurring at an uncontrolled rate due to human action.

The impact of the human species includes: loss and fragmentation of the habitat of the species, unsustainable use of natural resources, introduction of invasive species in regions that do not correspond, pollution and promotion of global warming.

Many times human action seeks to "help" the ecosystem, but the lack of knowledge turns this work into a negative event. To exemplify how the introduction of species affects biodiversity, we can mention the case of pines.

When these trees are planted on land that is not suitable for “reforestation”, their presence causes acidification of the soils, catastrophically affecting native fauna and flora.

The main causes of biodiversity loss are:

Destruction of natural habitats

Human activities cause irreparable damage to the natural habitats of many species. Many ecosystems have been destroyed due to activities such as agriculture, mining, deforestation, the construction of roads, dams and residential complexes, among others.

Faced with habitat loss, species must seek a new environment and adapt to its conditions. Many are unable to establish themselves in a new area so they die from lack of food or from disease.

Contamination

Pollution is related to the destruction of natural habitats. In the beginning, pollution does not destroy ecosystems but alters them both physically and chemically. It should be noted that over time, pollution can destroy a habitat.

Pollution introduces foreign elements to the ecosystem. On many occasions, these elements are toxic to members of the population, causing many to perish.

There are various types of pollution, among which are aquatic, terrestrial, aerial and sonic. An example of aquatic contamination occurs when sewage and sewage come into contact with clean bodies of water. This affects the marine, lake and river ecosystems.

For its part, the use of insecticides and pesticides, acid rains and global warming affect both terrestrial and aquatic ecosystems, causing the loss of many species.

Finally, loud and intense sounds (for example, the noise of ships and industrial machinery) disturb ecosystems. The arctic whale is one of the examples of endangered species due to sonic pollution.

Hunting and fishing

Another of the ways in which species are lost is through hunting. Wild animals are hunted and used to obtain various products: meat, leather, skins, cosmetics, medicines, among others.

An example of how hunting has diminished species diversity is the African black rhino. About 95% of the black rhino population has been exterminated by poachers due to the properties of this animal's horns.

Other species have been victims of poaching. In the 1990s, a third of Africa's elephants were hunted for ivory. Likewise, the scarlet macaw, once typical of South America, is now an endangered species.

Some cats with spotted fur (such as the jaguar) have been endangered by the demand for this fur that exists in the market. Fishing generates the same effects as indiscriminate hunting. Hundreds of aquatic animals have been endangered by these practices.

In the last century, about 70,000 whales were killed to sell their meat and blubber. However, international trade in whale products has now been banned.

Collection of species for zoos and experimental research

Zoos collect animal species to exhibit in these establishments. This means moving the species from its natural habitat to an artificial one, negatively affecting them.

On the other hand, representatives of the species of the five kingdoms (Monera, Protista, Fungi, Plantae and Animalia) are collected and taken to biological laboratories to experiment with them).

Many times these experiments are beneficial for humans but are done to the detriment of other biological species.

For example, primates such as the monkey and the chimpanzee are used in research due to the anatomical, genetic and physiological similarities that exist between them and humans. Thousands of these primates have been euthanized in the name of science.

Introduction of exotic species

A species is considered exotic when it is found in a habitat other than its own, either because it was accidentally introduced or because it was deliberately transported.

Sometimes species adapt without major problems, but other times the introduction of exotic species generates imbalances in ecosystems, as native species have to compete for space and food with new species.

Deliberate introductions are made for financial reasons. An example of this is the eucalyptus, a species native to Australia and deliberately introduced to India. The wood of this species is valuable.

These higher plants are harmful from an ecological point of view, since their presence suppresses the growth of other plant species in the area. An example of accidental introduction are the bacterial and viral species that were brought to America by European colonizers.

Climate changes

The warming or cooling of the earth's surface represents a change in the conditions of the ecosystems. Many species are unable to cope with these changes so they die.

Natural disasters

Biodiversity is affected by natural disasters such as floods, droughts, forest fires, volcanic eruptions, epidemics, earthquakes and tidal waves.

For example, forest fires wipe out large portions of ecosystems and are the ruin of thousands of plant and animal species.

Range of species distribution

The smaller the range of a species, the greater its risk of becoming infected.

Consequences

All the resources that allow us the typical lifestyle of today's humanity come from the planet's biodiversity. Similarly, the basic needs of organisms such as the oxygen we breathe and the food we consume come from biodiversity.

According to the book The Ecology of Invasions by Animals and Plants, there are three main reasons why we should be concerned about conserving species.

First, every living being has the right to exist and it is ethically wrong to deprive it of it. Second, each species biodiversity has an aesthetic value and humans find it enjoyable to observe, study, and understand the wide range of biological diversity. Lastly, species are useful in the ecosystem and useful to humans.

This third reason has had the greatest impact on conservation plans. In other words, we must conserve it for both utilitarian and intrinsic reasons of threatened groups. If we do not conserve biodiversity, we will be deprived of these services.

Usefulness of species and ecosystem services

Some examples are widely known. Plants, for example, produce in photosynthesis (as a waste product) all the oxygen that we breathe. Bees, for their part, are essential pollinators that allow the existence of a wide diversity of fruits and seeds.

However, there are less obvious examples. Many species seem to have no direct contribution to humans. Bats, for example, make up an incredibly diverse order of mammals that contribute services like pollination and seed dispersal. In addition, they are avid consumers of hundreds of species of insects considered pests.

Other vertebrates, such as turtles and monkeys, are dispersers of the huge tree seeds that remove carbon dioxide from the atmosphere.

On the other hand, marine species also play an ecological role that can be exploited by humans. Coral reefs translate into protection for the coasts against environmental catastrophes, such as tsunamis or cyclones.

Biologists and researchers have found hundreds of examples of these interactions, involving advantages or positive aspects in the lives of human beings. Therefore, we should not underestimate the role of certain species in ecosystems, although at first glance it does not seem that they have a direct impact.

Aesthetic purposes and intrinsic values

Aesthetics, from the human point of view, is irrelevant in the scientific field. However, certain intellectuals (such as Professor Edward O Wilson) argue that species diversity should be conserved because - for many - they represent naturally created "works of art".

This approach is more philosophical, since certain animals have an intrinsic value for each person, whether for religious or other reasons.

Once the total extinction of a species occurs, it cannot be recreated again, thus losing everything related to it.

Solutions to the loss of biodiversity

Biodiversity is a complex and indispensable element for our planet. In fact, according to Oxford University Professor David Macdonald "without diversity, there is no future for humanity." That is why we must find solutions to maintain and preserve all the living forms that exist on planet earth.

To protect and maintain the species that live on our planet, we must first understand the biology of the organism and the interactions with other groups and with the environment. This body of knowledge is essential for the management of conservation plans.

Later, conservation plans can be established. Possible solutions to maintain biodiversity will be described below:

Understand biodiversity

On a daily basis, dozens of researchers manage to pinpoint and describe this valuable information. Thus, they can execute effective conservation plans that limit the loss of biodiversity.

This approach must be integrative and be approached from different branches of knowledge (such as molecular biology, ecology, evolution, among others) since biodiversity not only includes the number of species, but also their genetic variability and the distribution of species. in the different ecosystems.

For example, if we want to conserve certain organisms - suppose it is a threatened rabbit species - we do not gain much by building a reserve that houses genetically similar animals.

Inbreeding between individuals will generate loss of genetic diversity, which translates into loss of biodiversity.

Genetic diversity provides the basis for the protection and conservation of species. It is a critical factor for the resilience and persistence of ecosystems and the species that inhabit there.

Thus, to solve the loss of diversity in the hypothetical case raised, it is necessary to work with genetic studies of the rabbit population.

Habitat conservation

The most intuitive and immediate solution to preserve biodiversity on the planet is by conserving the different habitats and ecosystems where the species of interest live, rather than trying to save a single species.

There are dozens of conservation programs that seek to preserve particular species, call it blue whale, koala, among others. However, no organism exists in isolation. For this reason, if the species is at risk, it is likely that its habitat is too.

Government entities play a crucial role in habitat conservation, since they can designate protected areas - such as national parks, reserves, protected areas - where any activity that may have a negative influence is punishable by law.

According to the American Museum of Natural History (AMNH) there are currently about 100,000 protected areas that try to promote the conservation of biological diversity.

References

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5. National Research Council. (1992). Conserving biodiversity: a research agenda for development agencies. National Academies Press.
6. National Research Council. (1999). Perspectives on biodiversity: valuing its role in an everchanging world. National Academies Press.
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