Fri. Oct 23rd, 2020

Biodiversity

There is a lot of talk about biodiversity in the media, and many columnists have stressed its unquestionable value. However, we rarely find out from the mainstream what it means to us beyond the romantic, spiritual, natural and cultural value that we should, according to popular belief, preserve for future generations.

Meanwhile, there are many pragmatic reasons why biodiversity is basically fundamental to the ecological balance in the biosphere and to human civilization. This does not diminish its spiritual value. On the contrary, it supports it.

What is biodiversity?

Biodiversity is an indicator of genetic, species and ecosystem diversity. What exactly does this mean? Genetic biodiversity is a collection of genetic traits of species resulting from gene versions and other DNA sequences.

They are the basis for intra-species diversity (different coat colour of fur, different expression of genes encoding antioxidant proteins or participating in lipid metabolism, different shape of ears, psychological features and many others) and inter-species diversity, which is an intensification of the former, leading to a clear separation in behavior, appearance, metabolism and – what is extremely important – reproduction.

Some species lead a nightlife, others a day life. Sociability and the need to establish social contacts are other features that are very complex in themselves. As a rule, differences between higher taxa (between families, rows, clusters or types) are more pronounced, although evolution in similar conditions favours the development of similar traits in far related species (e.g. the eyes of cephalopods and dolphins).

Another small explanation is needed to describe biodiversity in the context of ecosystems. Ecosystems are living (biocenosis) and non-living (biotope) elements and various interactions between them, forming a system in which the flow and circulation of energy and matter takes place.

Producers, i.e. plants and microorganisms (or symbiotic organisms), use “dead” parts of the system, such as photons or inorganic compounds, to produce organic matter. Autotrophic microbes and flora are food for consumers (heterotrophs): animals, fungi, parts of protists (protozoa). There are, of course, various exceptions.

Consumers themselves also become a source of nutrients (after all, we also eat mushrooms and animals), but they are not producers, because they do not have the aforementioned skills that bacteria, algae and plants possess (photosynthesis or chemosynthesis of organic matter from inorganic or light.

At the end (or at the beginning) of this circle there are reducers – bacteria, fungi, nematodes, rings and other animals (mainly invertebrates) – decomposing organic matter.

The division of ecosystems is not strict. We can talk about aquatic and terrestrial ecosystems, but also natural (e.g. primary forest) and artificial (e.g. garden) ecosystems. A more accurate classification applies to forest and steppe ecosystems, marine and freshwater ecosystems, lowland ecosystems, upland and mountain ecosystems, deep-sea ecosystems, pelagic ecosystems (open waters) and coastal ecosystems.

In the geographical context, however, there is talk of biomes: areas with certain ecosystem characteristics. Among the basic terrestrial biomasses there are, inter alia, rainforests, temperate zone forests, mountain forests, mangrove forests, taiga (northern coniferous forests), tundra (polar terrain covered mainly with mosses and lichens and shrubs), savannah, bush, deserts, semi-deserts, ice deserts.

The main marine biomes include: coastal waters, pelagic waters, deep waters, coral reefs. The diversity of ecosystems (between and within them) is the third component of biodiversity.

How is the degree, diversity or poverty of biodiversity determined? Biologists involved in ecology, nature conservation and evolution have different measuring tools. The simplest, but very inaccurate and general, is the species richness – an indicator that informs only about the number of species occurring in a given area.

To calculate it, the following data are needed: number of species from the studied area, number of all individuals of all species and number of individuals of a given species. The second widely recognized method is the calculation of Shannon-Wiener’s index, which describes the probability of drawing two different species from a given sample.

There are also more advanced methods of assessing the degree of diversity, including phylogenetic diversity or species diversity of ecosystem biodiversity.

Mass extinction and decline and increase in biodiversity

The level of species and genetic and ecosystem biodiversity varies over time, as does the rate of change. With a faster decline in the number of species caused by relatively sudden changes in the environment, scientists are isolating mass extinction. Discussions are still ongoing on how many of them have been there so far.

The most controversial issue is the so-called sixth extinction, which will be discussed in a moment. The first extinction we know about took place in Ordovician over 400 million years ago. The second was the devonian extinction, which, like the Ordovician extinction, was deadly to aquatic organisms.

The third, Permian, extinction was also in relation to developed land forms: insects, amphibians, reptiles, forkbeards, ferns and horsetails. At the end of the Triassic, successive rows of marine and terrestrial organisms disappeared, and at the end of the Cretaceous, dinosaurs were exterminated.

Since the time distance here is the shortest, we know the most about it. Probably it was more violent than the previous extinction, it was probably caused by the collision of the Earth with the asteroid. It could have lasted for thousands, but not millions of years.

The period of extinction was followed by stabilization of environmental conditions and adaptation to them through biological evolution (and with the participation of genetic drift) by living organisms. Released and undamaged ecological niches and new habitats allowed for numerous specialties, i.e. the creation of new species, as a result of which biodiversity grew after extinction.

Currently, we are dealing with a very high species and genetic diversity (according to available fossil evidence, the Earth has enjoyed the greatest biodiversity for the last few million years), but the rate of extinction of species, genera and families is also fast. In part, this is the case – the more species, the more species will die.

The last few hundred years have been a period of progressive decline in biodiversity in terms of both the number of species and the integrity and functioning of ecosystems.

What does biodiversity mean for humans?

What is the value of biodiversity for us? First of all, it ensures, mainly through plants, the production of organic carbon from atmospheric (or water) carbon through photosynthesis. A by-product of this process is also oxygen, which is very important for life on Earth. What makes up biodiversity is the basis for the already mentioned circulation of matter and energy in the system.

It enables the creation or access to various nutrients. Ecosystem biodiversity provides many different habitats. These are basic ecosystem ‘services’, from which a whole series of successive, more specific and more precise ones emerge.

Biodiversity of the organisms on the ground can create a soil rich in nutrients and minerals. This is extremely important for agriculture, even though fertilisers are used to support the crop. Genetic diversity is important for the variety of subspecies and plant species that produce fruit and vegetables, as well as fish and farm animals.

It allows us to create varieties that are beneficial from the point of view of food, business, environment or society, including those created by genetic engineering, i.e. GMOs, or by editing the genome (CRISPR/Cas).

It also performs important functions in medicine, e.g. by enabling the production of medicinal proteins or obtaining all kinds of chemical compounds, often of herbal origin, with pro-health properties or even being direct or indirect starting points for the creation of medicines.

The role of biodiversity in the development of science has been, and continues to be, of considerable importance. It allows to develop biochemistry, genetics, cytology, histology, anatomy, toxicology, animal experiments and many others.

Biodiversity provides us with the regulation of numerous phenomena occurring on Earth, the proper course of which is necessary to maintain relatively stable conditions and avoid local, regional or global disasters. Carbon sequestration, i.e. the absorption of carbon by photosynthetic organisms, i.e. primarily plants, is a leading example today.

This is nothing more than climate regulation, the warming of which is largely due to too high a concentration of CO2 in the atmosphere. Another example is the decomposition of harmful substances by microorganisms that are rich in biodiversity.

It is to a large extent these that will result in the decomposition of waste for decades, hundreds and thousands of years. Genetic biodiversity (genes encoding proteins for decomposition and detoxification), species (species of decomposing organisms) and ecosystem biodiversity are therefore an important part of the self-purification of air, water and soil.