2.1.1 Species
Definition
Charles Darwin wrote in The Origin of Species about variability within nature.  We know use the word biodiversity as short hand for what Darwin described as the both the origin and end point of evolution :
'Why, if man can by patience select variations most useful to himself should nature fail in selecting variations useful, under changing conditions of life, to her living products?
What limit can be put to this power, acting during long ages and rigidly scrutinising the whole constitution, structure, and habits of each creature favouring the good and rejecting the bad? I can see no limit to this power, in slowly and beautifully adapting each form to the most complex relations of life.'
If this was true when Charles Darwin first presented his thoughts about evolution in 1858, it is equally true today. Biodiversity is life around us. It is a wonder and a delight, but it is also a concern and a responsibility.
It is vital to bear in mind that in effect life is not created on earth today; all living cells are descended, in an unbroken line, from some remote ancestor in the distant geological past. We are a part of nature, the biosphere being an intricate tapestry of interwoven life forms which help to constitute the marine, freshwater and terrestrial landscapes of the world and which give the richness to our natural heritage in the United Kingdom.
And yet this natural inheritance is increasingly under threat. Human activities are changing and destroying habitats, natural ecosystems and landscapes on an increasing scale. This has led to a demonstrable rise in the level of concern amongst scientists and the wider public. It is now recognised that biodiversity must be treated more seriously as a global resource to be managed with the objectives of protecting and conserving ecosystems and species. Management systems are applications of the theories and principles of biodiversity to the goals of ecological, economic and social sustainability. How to protect and enhance biodiversity were therefore among the critical management issues addressed at the Rio Earth Summit in 1992.
Explaining biodiversity
Biodiversity is an outcome of the animate economy driven by photosynthesis which is the ultimate source of all human biological resources arising from other living things.  The term is in common usage as the result of a form of bureaucratic shorthand required by the writers of conservation strategies for the variety of life and all that creates and maintains it.
That plants and animals constitute natural kinds, or species, had become clear by the end of the 17th century when John Ray defined them as groups of individuals that breed among themselves. In general, species were accepted like other aspects of nature as the result of special creation in each case, and there was little incentive to inquire further.
In the 18th century, doubts began to arise concerning the immutability of species.  These doubts set philosophers and a small number of naturalists arguing theoretically about difficulties in distinguishing between varieties of cultivated plants and domestic animals, which were recognised as the diversified products of species, and species themselves which were supposed to be unchangeable. Some naturalists, including Linnaeus himself in his later years, adopted a compromise allowing that species could have descended with modifications from genera, but that genera were immutable.
With the increase in detailed knowledge of the flora and fauna of the world consequent upon the final stages of exploration, the problem of the distinction between varieties and species became acute. With a boldness and a breadth of vision amounting to genius, the French naturalist Lamarck cut the knot by proclaiming that there was no essential difference between species and varieties, that species like varieties were subject to change, and that' transformism', not immutability, of species was the basis of life. As it happened, there were two reasons why Lamarck's ideas were not accepted. The first was that he undertook no analysis to provide evidence for his notion of evolution it flashed across his mind and he assumed its truth without taking the trouble to prove it. Secondly, he attempted to give an explanation of the causes of evolution which, unfortunately, raised opposition to the acceptance of the concept of evolution itself. He supposed that as result of new needs experienced by the animal, its 'inner feelings' or subconscious activities produced new organs which satisfied those needs. Not only was such a supposition unacceptable for the solution of the problem of the origin of species of animals, but it was totally inapplicable to plants. On the other hand, Lamarck elaborated the view originally put forward by Aristotle, and held by Maupertuis Diderot, Buffon, and Erasmus Darwin, but which is now known to be without foundation, namely that the effects of use and disuse of an organ during the lifetime of the individual could be directly transmitted by inheritance to its offspring. There for a time the matter rested.
Somehow the principle of divergence never got quite enough emphasis in the Origin of Species, though it was essential to explaining the history and directions of evolution. Nonetheless, Darwin now realised that nature could be said to have a discernible goal: that of a constantly increasing diversity of organic types in any area. In effect, diversity was nature's way of getting round the fiercely competitive struggle for limited resources. So long as all organisms conformed to fixed types, all wanting the same resources, conflict was inevitable. In contrast, deviance from the norm could open a more peaceful route and a well-rewarded one. The organism that was born different might find a way to use its uniqueness and establish itself without the need for competition. It might come to occupy its own special place that none had ever occupied before, and not at the expense of another's survival. The possibility did exist and had been realised, not by one or two, but by several million enterprising founders of new species and varieties. Eventually, of course, their descendents might exhaust those newfound riches, and then only a fresh initiative could avoid the resurgence of conflict.

Advantages of conserving biodiversity

With the politics of environment after Rio came a need to produce strategic plans aimed at improving the lot of the world's wildlife as a human resource.  The advantages of conserving ecosystems and wildlife had to be listed to support the goals of global and local strategies.
Preservation of natural resources
Diverse ecosystems hold significant quantities of untapped, yet precious, biological resources.
About 80% of the world’s medicines are derived from life forms.
Potential goods and services may be unlimited, and the possible harms of destruction unknown.

Recreation 
There are opportunities for hunting certain kinds of game, offering an historical recreational environment.
We need places to roam freely and engage in outdoor athletic and recreational pursuits.

Life-support 
Unbroken forests remove carbon dioxide from the atmosphere and replenish its oxygen.
There is a parallel between the good of the system and that of the individual.
Wilderness related activities enhance and even remedy our physical health.
Contact with nature has potential psychological benefits to offset the mental dysfunctions that arise from urban life.

Aesthetic experience 
None of nature’s landscapes are ugly so long as they are wild.
Wild areas provide inspiration for the artistically and intellectually inclined.

Spiritual values 
Wild places are the closest thing we have on earth to the original work of Creation.
Conservation has value as a symbolic gesture of love and respect for our evolution and a defence of our future.
Contact with large-scale biodiversity is necessary for the process of self- realisation by establishing a relational reality of all things including the non- human world.
Nature reserves are resources in the search for meaning, for a new creation story or mythology that places humans in a cosmic context, at one with all creatures.
If the Earth is alive as Gaia it deserves moral consideration.

Indicators of land health 
Natural ecosystems provide a base line, or measure, of land health, and as models of a normal ecologically balance landscape.

Research and education 
Maintaining genetic reservoirs intact is instrumentally important because they function as a great safety device holding a large portion of the world's accumulated evolutionary and ecological wisdom.
Nature reserves are outdoor classrooms for teaching proper human values and developing a sense of valuation of all living things.
Diverse ecosystems provide scientists with unprecedented locations and the raw materials for all kinds of scientific enquiry.

Cultural support 
The rich diversity of the world’s cultures reflects a corresponding diversity in the ecosystems that gave them birth.
The resident species helped form, and continue to enshrine national cultural values, and wilderness is the raw material out of which civilisations have been created.
Wild areas are potential sanctuaries from oppressive government.
Wilderness preservation shows respect of the needs of the minority and is therefore indicative of good democracy
Living in a wilderness, even for a short time, strengthens social bonds through sharing skills with one another.
Wildlife is a legacy we are obligated to pass on to future generations.
Wild nature is valuable because it exists regardless of, or in addition to, its value as a means to some other utilitarian end.

Disease sequestration 
Microorganisms will adapt from shrinking nature to prey on urbanised humans.

Animal welfare 
Animals, like we, have the right to live unmolested and unharmed.