Hi Tweeters,

A number of people have recently posted the story regarding European
Blackcaps, the migratory population that has been wintering in the UK
(due to human feeding of the birds) since the 1960s instead of
southern Spain, and the implications of this in regard to evolution/
speciation.

If anyone wants to read the actual science article this story is
referencing, the article is in the Dec 2009 issue of Current Biology
and the title of the article is "Contemporary Evolution of
Reproductive Isolation and Phenotypic Divergence in Sympatry along a
Migratory Divide." (Sympatry is a term that refers to speciation
within a population not due to separation by a geographical boundary,
which is called allopatry). This article asserts that the differences
in migratory range, diet, and behavior of this UK-wintering population
of Blackcaps during the allopatric phase of their life (winter, where
they are physically separated from their close relatives in Spain)
have provided sufficient evolutionary force to drive speciation; the
UK birds show variations in wing shape, bill shape, and plumage and
mate preferentially with other similar UK birds during the sympatric
phase of their life, when both the UK and Spanish populations live
together in mixed populations in Germany.

One other interesting note from the paper is that this migratory
information appears to be partially if not entirely due to genetics,
as hybrids between the UK and Spanish Blackcaps migrate along an
intermediate route towards southwestern France/northern Spain.

Unfortunately the article is not free for those outside academic
institutions, but it is available for purchase through the Current
Biology website. Anyway I thought I would share that information in
case anyone wants to read into the matter further.

-Nathaniel Peters
Seattle WA

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