The Implications of Evolution

On another note, I was wondering what evolutionary evidence supports biodiversity? For instance, polar bears can be found in the arctic, but not the antarctic. For penguins, it's the opposite. Does evolution explain the diversity or does it simply point to a common ancestor that was once separated in that geographical region and then evolved?

The older an ecosystem is, the longer it exists in its current form in a given area - the more species live in that area.

The larger a geographic area/ecosystem is, the more species are found in that area.

But what kind of species can be found in a given area? The answer to this question is neither predetermined by size or age of the existing habitats in that area, nor is it given by the theory of evolution.

Instead the science biogeography seeks to answer this question. Biogeography and evolutionary theory are separate but overlapping sciences. Current and historic biogeography can only be understood, with the help of evolution and evolution can only be understood, with the help of biogeography. So it is no wonder, that both Darwin and Wallace, who as first scientist looked deeper at the distribution and diversity of plants and animals, developed very similar theories.

Because species divergence happens not only in the time dimension, but also in spatial dimensions, common ancestors originate in a particular geographical location. Thus, the spatial and geographical distribution of species should be consistent with their predicted genealogical relationships. The standard phylogenetic tree predicts that new species must originate close to the older species from which they are derived. Closely related contemporary species should be close geographically, regardless of their habitat or specific adaptations. If they are not, there had better be a good explanation, such as extreme mobility (cases like sea animals, birds, human mediated distribution, etc.), continental drift, or extensive time since their divergence. In this sense, the present biogeographical distribution of species should reflect the history of their origination.

www.talkorigins.org...

Does the present biogeographical distribution of penguins and polar bears reflect the history of their origination?

The common ancestor to all bears lived in the northern hemisphere:

The origins of Family Ursidae can be traced back to Cephalogale, a small, dog-like animal which lived in Europe during the early to mid-Tertiary. Cephalogale was the ancestor to Ursavus elmensis, the first bear-like carnivore. From this origin came the Ursidae family (Sacco 1997).

www.sfsu.edu...

The common ancestor to all penguins lived in the southern hemisphere:

The oldest known fossil penguin species is Waimanu manneringi, which lived in the early Paleocene epoch of New Zealand, or about 62 mya.[12] While they were not as well-adapted to aquatic life as modern penguins, Waimanu were generally loon-like birds but already flightless, with short wings adapted for deep diving. They swam on the surface using mainly their feet, but the wings were – as opposed to most other diving birds, living and extinct – already adapting to underwater locomotion.

en.wikipedia.org...

The answer, to why bears haven't yet reached Antarctica and penguins haven't settled in the Arctic was given by TheWalkingFox.

reply to post by Drunkenshrew


I got mixed up. Sometimes I get ahead of myself.

It was said that "true" BEARS are relatively new and that ANTARCTICA became isolated 23 Ma. I was confused in that I thought the isolation of Antarctica came before "true" bears but it wouldn't matter anyways because it's penguins that are found in antarctica. Sometimes I can really do a number on myself.

The earliest "penguin"-esque creature was around New Zealand when Australia was still connected with Antarctica, correct? Also, the separation from Australia-Antarctica came BEFORE the Drake Passage opened correct? ......(I'm just trying to get the timeline down correctly)

reply to post by Agree2Disagree
Yes, correct. Here the wiki-link to the geological history of Antarctica.
en.wikipedia.org...