Biodiversity is life!

Biodiversity ensued from a long history that started billions of years ago, just when life appeared on the earth.

From that time, life evolved according to the variations of the environment and, through critical periods and particularly productive periods, reached the spectacular species richness now existing.

However, at the present time, a single species, the species often considered the top of evolution, i.e. HOMO SAPIENS is giving rise to a new, very rapid, crisis: a number of scientists think that at least half of the species at present still existing will disappear in the next 50 years|!

 Why is biodiversity extremely important? What would happen with its drastic reduction?

 Three levels must  be considered

I. Genetic biodiversity.

Genetic biodiversity refers to the variety of genes within a species or population. It's the total number of genetic characteristics consisting of identical individuals!

This genetic variability is so much important that in the majority of the species evolved and established, sexual reproduction, that involves the fusion of two different genetic apparatuses creating a new apparatus with also new genes combinations! Even in most microorganisms, prokaryotic or eukaryotic, that usually reproduce by binary fission there are sexual phenomena allowing intraspecific genetic variability.

 

                 IN ALL THE SPECIES EACH MEMBER IS

                 GENETICALLY DIFFERENT, IS UNIQUE      

 

 

              Try to find perfectly identical shells of the same species!|

Since they started to raise domestic animals and  to grow edible plants humans applied artificial selection i.e. an evolutionary process in which they consciously select for or against particular features in organisms.

 In this way, for example, humans have bred food crops from wild plants and animals.

Now most human activities are performed on a large scale often  causing the reduction of  intraspecific biodiversity. For example we all experienced that flies and mosquitoes are at present more resistant than some years ago to the most common insecticides. What happened? Not necessarily mutations: simply only members with more resistant genes survived, reproduced and transmitted their genes to the following generations.

  

                                                        A mosquito in action

 

           II. Number of species diversity 

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The present biodiversity is the fruit of the  billion years interaction  between life and earth. The earth provided the environment and the materials and life used fantasy creating organisms able to make good  fuse of every ecological niche.

Probably even at present we do no know the real number of the species living with us on the planet!

First of all a countless number of species exist among unicellular prokaryotic organisms. For example bacteria ere very similar in their morphology but greatly differ in their metabolism and, for this, are able to use different, special resources.

Eukaryotic unicellular and pluricellular organisms  differ  instead from each  other in morphology, sizes, metabolism and behavior.

                                                                                                                                                                                                                                                            

                                    

S                                           Shells of different Phoraminiphera.

Why did so many species evolve and why their maintenance is vital  for us? Because biodiversity is the most precious and important thing we have without which our entire as well as support system for human, animal life, would collapse.

    Indeed the elements available to maintain life are limited  on the hearth and the living organisms provide to recycle them each one using its specificity.

 

So there are:

       1) Producer organisms, also known as autotrophs, i.e. living things able to create their own food, typically through photosynthesis or chemiosynthesis.  To form new cells they need: energy provided by the sun, hydrogen and oxygen present in the water, carbon they take from carbon dioxide present in the atmosphere or dissolved in the water. Anyway some molecules present and necessary in every living being like proteins and nucleic acids contain also sulphur and phosphorus so producer organisms need also nutrient salts like phosphate and nitrates they find in the ground.

Producer organisms include plants, algae and some bacteria.

 

2. Consumer organisms, or heterotrophs, are living things that cannot produce their own food and instead obtain energy by consuming other organisms, whether plants or animals. There are different levels of consumers.  Dietary specialization i.e. the adaptation of certain species to primarily consume specific types of food resources, has a very important ecological role. For example even at the level of Protists there are species eating bacteria, species eating algae (able to chose their pray on the basis of size, cathabolites emission, type of movement) and species able to pray other protists often using special hunting  “devices” . 

A ciliate full of ingested algae

             

                                                       

                          The voracious predator ciliated Didinium attacking the ciliate                                                         Paramecium with poisonous extrusomes.

 

                                             

                                           Didinium ingesting Paramecium.  

 

 

  Both producer and consumer organisms release organic waste an leave dead bodies. To avoid the  transformation of the earth in a dump nature evolved also:

3. Saprophitic and decomposer organisms. In particular bacteria and mushrooms.  They are true chemical laboratories! They transform organic materials coming from dead bodies and waste in mineral salts again available for producers. Different species evolved for each element and environment and the life cycle so closely integrated can be interrupted by the lost of even  a single species.

 

                           Food chains in the sea and in the forest

 

 

II. Habitat biodiversity

 

The main habitats of the world are forests, grasslands, deserts, mountains, polar regions, and aquatic habitats (freshwater and marine). These diverse biomes are defined by their unique environmental conditions and are home to a vast array of plant and animals. However each one is subdivided in a lot of different sub-habitats that, with the organisms they host, form various ecosystems in which  each species plays a role.

But humans are modifying ecosystems very rapidly without a global vision of their characteristics.

Consider for example the massive destruction of  the forests!

A forest is a habitat that provides food, water, and shelter for a wide variety of plants and animals, structured in vertical layers including the forest floor, herb, shrub, understory, canopy, and emergent layer, which support different species and create a complex food web.

In forests productivity is very high. The large amount of organic substances produced fall down on to the ground where are rapidly decomposed by saprophitic organisms. The nutrients are as much rapidly absorbed by plant’s roots. So in any moment there are few mineral salts in the soil. When nutrients are insufficient, productivity decreases. Moreover removing trees leads to severe soil erosion, which washes away the topsoil. The exposed soil then loses its fertility, and can become barren and unable to support crops effectively. 

So deforestation causes direct damages in the climate without important increase in agricultural production.

                           

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While the traditional model of growth has often resulted in environmental degradation, new approaches such as sustainable development, green technologies, and circular economies are proving that it is possible to achieve economic prosperity without harming the planet

To reconcile economy and climate would be the challenge for modern policy.