Indeed, maybe I wont have to wait quite so long to tick that trio of
Gouldian species
-----Original Message-----
From: L&L Knight
Sent: Monday, 7 December 2009 8:54 PM
To: Andrew Bell
Cc: Birding Aus
Subject: Backyard birdfeeders driving avian evolution
In species that breed every year, I would think that consistent divergence
could lead to speciation in time periods of the order of thousands of years.
Regards, Laurie.
On 07/12/2009, at 7:30 PM, Andrew Bell wrote:
> Hi all
>
> Some more thoughts on a very intriguing subject, it was an interesting
> article.
>
> Google: evolution rapid finches
>
> There are many examples of such minor changes in bird populations
> being cited as evidence for observable evolution, including melanotic
> urban rock doves. Darwin hypothesised that the development of all
> species was due to the gradual accumulation of just such minor
> variations over very long periods of time. He also investigated at
> length the inheritance of variation in domestic animals including
> dogs. He didn't have any knowledge though of how novel variations
> appeared. He would have revelled I think in modern genetics -
> rearrangement of genes, mutation of DNA and pondering of the possible
> role of all that "junk" in controlling and changing gene expression.
>
> "Species" is of course an arbitrary division of a continuous, if
> mostly extinct, chain of variation, with more than one definition to
> choose from - the old one of genetic isolation certainly doesn't work
> very well, many "species" hybridize and produce fertile offspring. In
> the example discussed it is entirely reasonable to suppose we are
> seeing the first discernable link in this chain - we're just not
> going to be around nearly long enough to observe separation into
> "species". If we had observed this process in warblers, would we yet
> recognise as speciated the Willow Warbler and the Chiff Chaff, of for
> that matter the Northern, Mangrove and Grey fantails?
>
> The recent ABC Catalyst on Gouldian's certainly set me thinking. It
> discussed the strong tendency of Red heads to select Red heads as
> mates with subsequent increased breeding success. The explanation
> offered was of previous geographical isolation and merging of diverged
> populations when the climate changed. It certainly suggests early
> speciation and raises the possibility of continued now sympatric
> speciation within actual flocks. Who knows, if they survive another
> million years of climate change there might be an additional "tick" to
> wait for.
>
> Cheers
>
> Andrew Bell
>
> -----Original Message-----
> From:
> On Behalf Of Peter Shute
> Sent: Monday, 7 December 2009 8:24 AM
> To: ;
> Cc: ;
> Subject: Re: [Birding-Aus] Backyard birdfeeders driving avian
> evolution
>
> I don't know much about genetics, but I was wondering the same thing
> (I think).
>
> Dogs have been selectively bred till we have an astonishing range of
> breeds of varying sizes and traits, that breed true. Yet I'm told if
> you let them inter breed they quickly revert back to something like
> their ancestors.
>
> I've never heard of this being offered as an example of evolution.
>
> Peter Shute
>
>
> --------------------------
> Sent using BlackBerry
>
|
