Biodiversity

by | Feb 7, 2022 | Biology, Science

Biodiversity, intuitively, is made up of differences observable in the living world. Since this definition is very broad and chaotic, biodiversity can be organized in levels depending on the size of the sample we are considering: two individuals, a family, a herd, a population, a species, the animal kingdom, an ecosystem, etc.
Nowadays diversity is considered more a handicap than an ace in the hole, the same concept of beauty and harmony is embodied by homogeneity, rigor, symmetry; think of a lawn, a garden, the bank of a river: surely the image that presents itself to the mind represents a meadow razor, composed only of blades of grass, perhaps some shrub or some bushy tree, both arranged marginally, probably there are no insects, nor visible earth. Rarely, when we think of a meadow, we think of a field of brushwood closely tangled with each other, and yet this is exactly what we will have to think of if we try to imagine a healthy ecosystem.
The health of an ecosystem is generally measured based on the interconnections between biotic cycles (hence the links between living beings) and abiotic cycles (the recycling of organic and inorganic nutrients), although different ecosystems have different numbers of relationships, it is possible to rely on standardisation which also takes into account the climatic conditions of the study subject (an ecosystem rich in water and resources, with constant temperature and not limiting will have numerically more inhabitants than an ecosystem with extreme temperatures, little water and few nutrients – a terrestrial ecosystem will have more specific wealth, compared to marine ecosystems, where the diversity of the large taxonomic groups predominates).

BIODIVERSITY AND SURVIVAL

Why different types of biodiversity are fundamental to life

Diversity is essential for the ecosystem to be autonomous and to be able to link fruitfully with other autonomous ecosystems, thus guaranteeing the future of natural selection and subsequently the birth of new diversity.
Three levels of biodiversity are formally recognised:
– Genetic: understood as a variety of information in individuals of the same species, each individual has its own genome, which with very high probability will be different from that of any other similar. The origin of this diversity can be random (during replication there was a point mutation) or hereditary (two individuals with albinism transmit the character to the progeny, which in turn will transmit it along the phylogeny).
– Taxonomic: it is represented by the whole of the species living in the considered area, defined by some alpha-diversity authors, this level also considers the relations present between the calculated species;
– Ecosystemic: the variety of places with similar characteristics on our planet (at a wider level can also be considered the biomes, vast areas where physical conditions are similar);
The presence of diversity is fundamental, as it represents the foundation of survival, from the smallest to the largest group.
Life on earth can be seen as a balance between the force of chaos and the ordering force, chaos is the birth of diversity: random genetic code changes, speciation events, the birth of new conquerable ecosystems, All this increases exponentially; the ordering force is natural selection, which acts as a sieve for diversity. It is now necessary to specify that the individual is invisible in terms of selection, this also acts on him – of course -, but the true unity in the eyes of selection is represented by the species, is this that can undergo different selective thrusts, extinction, bifurcation, or further speciation; individuals are only reproductive units.
Time: the ability of organisms to survive is given by how much they can adapt to the changes that may occur in their habitat, therefore by how much a species can respond to the change in time; if the species is rich in diversity, it is very likely that some individuals may already be more adapted than others, therefore with better reproductive chances. If, on the contrary, the population is uniform, homogeneous, a change will weigh on all the individuals, preventing them from reproducing and therefore from renewing the generations of the species, in this way the uniformity leads to the extinction. We consider that in place of a species can be considered any other more or less vast group of individuals.
If several organisms evolve together in the same habitat, in close relation to each other, we speak of For example, the shape of some particular flowers can only be explained if in relation to the shape of the beak of its pollinating bird, the hummingbird. Coevolution contributes both to the creation of biodiversity, and in the case of natural selection: in the first case creating a possibility, in the second alloy two or more organisms along the path of evolution, defining guidelines for selection.
Let’s go back to imagining the lawn from before.
A species of plant, at most three or four, no species of insects, nor of moulds, bacteria or worms, few animals exclusively belonging to the class of mammals or to the group of birds. In the absence of insects, the plants could not reproduce, because the first vectors of pollination would be lacking; once these died, the animals that feed on them and then the carnivores would die; at this point, however, in the absence of decomposers no nutrient could become available in the soil, so this would become impoverished until it becomes desert.
Let’s take the case, now, of a normal ecosystem of lawn type.
Surely the soil will have definite chemical values, which identify the amount of inorganic nutrients present (usually various ions and water), these nutrients generally derive from the processing of organic waste and are not immediately available in the soil, only the processing by worms, earthworms, fungi, molds, insects and bacteria will make these substances usable for use; made available these substances in the soil, plants can use them to synthesize tissues and molecules; herbivores will be able to eat and develop thanks to the growth of plants, as a direct consequence carnivores will be able to do the same; both these groups will feed different parasites, that are useful to keep under control the number of the population of their guests. The dead bodies of plants and animals will be reused and consumed by bacteria, fungi, molds, insects and worms, for the recycling of inorganic nutrients.
Now that we have clarified some of the concepts, let’s look at the broader level of biodiversity: Biomes.

BIOMES AND MAN: AN OVERVIEW

What are and how can interactions vary

The Biomes are vast areas of the biosphere (all the part of the planet that contains life), characterized by the same climatic conditions and the same dominant vegetation; from the definition must then take a step back, since the dominant vegetation is determined by climatic factors: temperature, precipitation, seasonality, type of soil, it is now common use, however, consider the vegetation an integral part of the definition of a biome.
The different biomes can be obtained through a cross-map of physical conditions (for simplicity we will use the sample list used in high schools and universities – but this is only a simplification of the schemes now taken into account – there is also no classification of aquatic biomes):
– Temperature: may be hot/cold/medium;
– Precipitation: intense/scarce – seasonal/constant;
– Seasonality: marked/absent (refers to temperatures and precipitation);
– Soil: clayey/sandy/stony – poor/rich;
Depending on the choices made in the list we will get a different biome.
For example:
– High temperatures, constantly low rainfall, no seasonality, sandy soil: Hot desert;
– Average temperature, intense and seasonal precipitation, marked seasonality and clay soil: temperate forest;
Here is the list of the main biomes: Rainforest, savannah, jungle, steppe, prairie, hot desert, cold desert, Mediterranean scrub, temperate rainforest, temperate deciduous forest, taiga, tundra, poles.
The differentiation of the flora has been due to the adaptation to the physical conditions and to the conquest of the pioneer organisms (organisms that manage to survive to really critical conditions, are part for example the lichens, the heather or the birches), these organisms begin to work a series of substances to make available their discards (usually inorganic substances that other beings can use to feed themselves) thus helping the colonization of the area by higher plants. The physical conditions in the biome will allow the survival of plants with certain characteristics – cacti retain water because it is scarce in deserts, mangroves have aerial roots to prevent tissue decay due to poor oxygen in water, the needle shape of the needle leaves prevents the snow from settling and therefore the sap from freezing – which will then become the vegetation typical of the biome, also entering the discriminating characters for its recognition. Subsequently, also the animals will move in the new zone to be colonized, they too will be subjected to selection from the physical characteristics of the biome, as well as from the vegetation and the availability of resources (a carnivore will only be able to colonize the territory if preys are already present).
The evolution, however, never stops and every time the environmental conditions change, slowly also the biocenosis adapt to the change; this process takes place in very long times (order of the billions of years) but sudden events can occur that drastically change the abiotic characteristics of a biome, such as volcanic eruptions, earthquakes, floods, storms, landslides, etc… all these events cause destruction in a vast geographical area and their future is not proportional to the wealth expressed in terms of biodiversity of a territory. These destructive phenomena are called “natural pollution” and are considered not harmful because the time that separates two similar events corresponds to a very long period, so the system has the possibility to absorb the shock and recover; these events, after all, are only part of the natural selection, can – as they might not even do – lead to events of speciation or extinction and in some cases, for example the flooding of the Nile, are also part of the biological cycle of the communities present in the area (the deposited silt makes the soil fertile).

Some taxonomic groups of animals have inhabited the earth for much longer than mammals and we are used to saying – to simplify – that these animals have not evolved anymore because they are already perfect; this simplification, out of its context, leads to a serious error: these animals (such as spiders or insects) have actually continued to evolve, creating or losing species, but what we want to emphasize is that they have not varied their main traits, did not, that is, change a large taxonomic order and did not create a smaller taxonomic group within them, such as – for example – did instead sauropsids, which were divided into reptiles and birds. This dynamic of events is more applicable to invertebrates and generally more widespread in biomes with constant and non-cyclical physical characteristics; invertebrates are a very diverse group of animals that has developed really formidable survival strategies, The aquatic ones are usually protected by an environment that favors constancy (it is said that in the sea there is the largest number of Phyla, but on the earth there are more species for each Phylum), the terrestrial ones – among which stand out the members of the group of the arthropods – were the first colonizers of the emerged lands, immediately after the plants, have therefore adapted to a hostile world, where the competition for food resources was very high and the environmental conditions were not at all favorable: hence some of the fundamental adaptations that have been the key to the success of this group, as a strategy of r-selection, a hardened exoskeleton, a life cycle in several stages of which only one mature and the body divided into articles (this allows, especially in the legs, the development of enormous adaptive possibilities, to this follow the possibilities of colonizing environments very different from each other); in the light of this, the spiders still have the body divided into two portions, eight legs with the same number of articles, the same specializations for the appendices of the head and the same modalities of reproduction, however over time several events of speciation have occurred leading to the differentiation of the hunting strategies, the size, the presence of down and the development of the appendices of the head.
Often species in appearance very different from each other come from the same founder, whose descendants have developed in different environments and have, therefore, undergone different selective pressures; each of these species grows in close correlation with the environment that surrounds it, consequently with its vegetation; during this development each individual species establishes very close relations with the others belonging to the same biocenosis, which over time will tend to an ideal situation, as a function tends to an asymptote (in fact, a number of years beyond which the ideal can be considered reached is defined). This scale follows more or less strict rules depending on the biome: the tundra has a minimum tolerance of both climate change and the changes undergone by biocenosis, while the temperate forests have a higher tolerance. Unfortunately, all the biomes are linked to each other: they share the same air, the same water and some are also divided into migratory animal communities, the smallest change could generate a chain of events that can hardly be kept under control; The taiga, for example, is very sensitive to acid rain caused by industrial exhaust fumes, because these acidify the soil already acidified by the fall of the leaves (the needles lower the pH of the soil), this damages the trees and prevents their regeneration, consequently the roots lose their grip on the soil, some nutrients are no longer available (at pH above the mean range some ions bind in stable form creating unusable forms); this is only the furthest impact human activities have on terrestrial biomes, but we can go much further: deforestation (which can be practiced for various reasons: creation of space for livestock, housing, creation of wood prayed and not, sale of firewood, etc.) discovers the lower layers of vegetation, which are not accustomed to a certain exposure or temperature, the undergrowth ruins and so does the soil (it dries and many nutrients become unavailable), the small invertebrates that inhabited it disappear (dead or gone elsewhere), so it becomes more difficult for something to grow there; slowly the present variety decreases vertiginously.
A worst case is the fields and crops. In these places biodiversity is deliberately reduced to the minimum, thanks to the use of very aggressive means; monocultures represent the failure of evolution, its relegation, a point also very dangerous as preferred target of many diseases and parasites. Monocultures contain identical plants, the variation must be reduced to a minimum, to the point that many are rendered sterile (This is also because the seeds can now be patented, so you can now put the patent on a life form despite this does not belong to us), these plants obtained by cloning are identical, in the pros and cons; between the cons we find that they are identical in the resistance to diseases and parasites: a single parasite that attacks an individual can easily infect all other individuals with his progeny, Considering how small the vectors of these diseases can be, it is not difficult that they can grow so much in number that they can be moved in various areas of the world, ready to parasitize the target species as soon as they rest on it. In nature, the variation limits this phenomenon, creating individuals slightly different from each other, surely not homogeneous, but also resistant or weak to different diseases and parasites, the recombination can produce new mutants and the pollination nourishes various insects; but if there are no plants to pollinate, insects do not eat, if there are no insects there are no seeds and if the seeds are synthetic they will not be variable.
Slowly, in this way, the insects will die and will have to be replaced by industrial fertilizers, which allow the accumulation of pollutants in the soil, without worms the soil is not recycled, then the plant growth is slowed down, If there is a shortage of plants, there is a shortage of food for herbivores and if there is a shortage of herbivores, carnivores will also be short-lived. Our entire food supply could collapse on itself at any moment. We also remember that the plants provide us with the air we breathe every day and that if you can stay without drinking for three days, the maximum time we can resist without oxygenating the brain does not exceed six minutes (permanent brain damage from anoxia or hypoxia).

HOW NATURE OVERCOMES PROBLEMS

Chernobyl teaches us that in this situation it is only we who lose

The flattening of diversity leads to the death of the system, in the same way that entropy guarantees the existence of energy in a physical system, without entropy the system is dead, the energy is zero and the particles are immobile. Without disorder we are destined to die: order is nothing but an illusion.
In addition, our approach to nature often does not take into account the differences inherent in nature itself: the soil of the tropical forest and that of the temperate forest are not the same; in the tropical forest the soil is particularly poor in nutrients, the high temperature allows the consumption of carcasses and materials in record time, so the nutrients are immediately available and, not being able to accumulate from the soil, are absorbed almost immediately: the tropical soil used as a culture medium, is reduced to unusable sand within a few years. On the contrary, the soil of temperate zones is rich in hummus and maintains its nutritional properties for much longer. Regardless of the time span sooner or later if the soil is not fed (dead bodies of animals and plants that are left to decompose by decomposers) it loses its properties, crumbles and tends to become dust. Every soil becomes desert if not nourished, therefore sterile, therefore no longer useful.
At this moment we are not only sacrificing our food, but also our water (to water increasingly arid soils), our space (the more we grow, the more we need space to live), our air (the more industries have to work, the fewer plants there are, the less we can breathe).
The longer we wait to solve these problems, the less time we have to solve them. Unfortunately, there is no simple solution, the solution is to be applied every day, with constancy, with stubbornness.
We need to protect what’s left and try to recover what we lost.
The least each of us can do is engage in the collection of waste, in recycling, in safeguarding the green, in informing ourselves properly in the face of scientific news, to feel that the responsibility to do something (even the smallest) is in the hands of each of us, also in the choice of expenditure (throwing a broccoli is not only throwing a broccoli, even if in the damp, it is throwing water to water it, the work of the workers, the fertilizers spent, the land consumed, the money thrown for packaging and the heat generated by the refrigerators that keep it fresh).
The solution is not, as many might think, in a particular diet chosen from among the many present, but in an awareness of what really makes up this diet.
On a large scale, the solution is drastic and to be applied in the long term: it will have to involve everyone and everyone will have to accept that science can do research regardless of how important its discovery may be economically, because not everything can be measured by money – which, incidentally, are nothing more than pieces of paper to which we have given the value of an object, before the objects were given a value in money: we gave power to that piece of paper -.
There is no matter more or less important in science, because as long as we study what surrounds us, this is never taken for granted or disconnected. The toil of a blade of grass is no less than the daily work of a star.
To conclude, I would like to say a few words about nature’s extraordinary recovery force. This topic is important to understand why our impact is so disastrous and serious.
We all know the disaster that happened at Chernobyl: the explosion of a nuclear reactor; more or less 33 years after that disastrous day the city was reborn. Biodiversity levels are not only higher than before the disaster, but also higher than before human settlement in the area. Of course, animals are exposed to radiation, but in this area they have multiplied and settled for a trivial reason: the lack of man.
33 years after the disaster, with still very high levels of radiation, the animals bear better the radiation of our presence, despite not being perfectly healthy (the radiation is however absorbed, but many species have developed adaptations). Even, the horses of Przewalski, almost extinct species, counts nowadays more than one hundred individuals, all settled in the former urban area.
One of the most incredible discoveries is how some animals are already developing adaptations to resist radiation, such as a different management of oxidants (birds) or darker colors of the epidermal layer (amphibians).
This event should underline that our presence can be drastically important for the ecosystems with which we come in contact and that, in the end, depend on us, but let us not delude ourselves: we are still ephemeral beings and all in all weak, We can be drastically important in the short term, but we can’t beat nature in patience.
She’ll have billions of years to make things right, we – if we keep this up – have maybe 30 years of breathable air.
When we die, the trees will take the carbon dioxide and turn it back to oxygen, making the ecosystems livable again for those who really have to inhabit them. Is that really what we want for the future?