Climate Change Induced Evolution

Climate change has been a major cause of evolution lo these 4 billion years or so. Sometimes catastrophic, from asteroid hits or mega volcanoes, sometimes slowly over tens of thousands, nay thousands of thousands of years climate has forced living organisms to adapt to their environment, or die. And so it is today, and in the years to come. Some creatures will adapt, some will not. Now we are beginning to see it before our eyes.

A consortium of governmental agencies and conservation non-profts, called the North American Bird Conservation Initiative has just released its second annual State of the Birds [pdf] report, and how climate change is affecting, and likely to affect hundreds of bird species.

  • Birds in every terrestrial and aquatic habitat will be affected by climate
    change, although individual species in each habitat are likely to respond
  • The results indicate that a majority of birds dependent on oceans, and birds
    on Hawaiian Islands, are highly vulnerable to climate change. Birds in
    coastal, arctic/alpine, and grassland habitats, as well as those on Caribbean
    and other Pacific islands show intermediate levels of vulnerability. Most
    birds in aridlands, wetlands, and forests show lower overall vulnerability
  • All 67 oceanic bird species, including albatrosses, petrels, tropical terns,
    tropicbirds, frigatebirds, and puffins are vulnerable because of their low
    reproductive potential, use of islands for nesting, and reliance on rapidly
    changing marine ecosystems.
  • Rising sea levels are expected to inundate or fragment low-lying habitats
    such as salt marshes, sandy beaches, barrier islands, and mudflats. Increas-
    ing frequency and severity of storms and changes in water temperatures
    will impact quality and quantity of coastal habitats and alter marine food

The report is thorough, and sobering.

In separate, and confirming news, biologists from Switzerland and Pennsylvania have just issued a report following a study of 46 years of data on the size and weight of birds passing through a ringing station of the Carnegie Museum of Natural History in Pennsylvania. Over these years, a large percentage of birds have lost weight and wing breadth, thus confirming what is known as Bergman’s Rule — that animals tend to become smaller in warmer climates.

They examined the records of 486,000 individual birds that had been caught and measured at the ringing station from 1961 to 2007.

These birds belonged to 102 species, arriving over different seasons. Each was weighed. It also had the length of its wings measured, recorded as wing chord length, or the distance between the bird’s wrist to the tip of the longest primary feather.

Their sample included local resident bird species, overwintering species, and even long distance migrants arriving from the Neotropics.

What they found was striking.

Of 83 species caught during spring migration, 60 have become smaller over the 46 year study period, weighing less and having shorter wings.

Of the 75 species migrating in autumn, 66 have become smaller.

See the BBC article for more.

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