What is Biodiversity?
Biodiversity is, put simply, the diversity of life. Or, according to the dictionary, diversity among plant and animal species in an environment. By some estimates, there are close to ten million species in existence, of which we only know of a little over a million. While this number may not seem too low, all things considered, keep in mind that the proportion of known to unknown is not consistent; that ratio can be far lower, depending on what ecosystem and what part of the world you’re discussing.
For instance, In the Amazon the unknown species far outweigh the known. Stories have been told of insect surveys in the rainforest that always return new organisms. Recent research seems to indicate that previous episodes of climate change played a role in creating this diversity, though deforestation and a changing climate may play a role in eliminating some of this incredible diversity.
Facets of Biodiversity
This diversity takes on a number of different facets. Visible characteristics are (for humans) a key means of distinguishing between species and our only means when looking into the past via fossil records, but those characteristics are not the only means of determining what makes a species a species. (For instance, it is our own peculiarities inside our skulls even more so than our lack of fur and upright gait that sets Homo sapiens apart from other animals.)
From a scientific point, the line of demarcation is drawn when two species cannot interbreed. This is a clear indication that two populations of organisms are not the same, even if they do otherwise share similar characteristics. Organisms are considered to have adaptations, particular physiological characteristics that suit them to survive and thrive within a certain ecological niche (think of a niche as a job description). In the arctic, for instance, the polar bear occupies the niche of a top predator, thanks to its keen sense of smell, superior insulation, and remarkable ability at swimming.
Change & Adaptation
Changes in environmental conditions are ultimately the impetus to diversify; after all, if all regions of the world were identical in topography and climate, then all biological designs would be equally successful in all locations. From time to time, extinctions occur and leave a particular niche open, making room for another species to diversify and change to fit that particular slot.