On Fri, Sep 20, 2002 at 05:41:57PM +1000, Philip A. Veerman wrote:
> As below: No it does not make sense. In that the individual bird who
> is developing that feature is not going to be more successful than
> those other individuals that are not developing that feature, for the
> reason of benefiting the plant! ...
If Noisy Friarbirds were territorial and bill-knobs by improved
pollination produced better food supply within their territory on
timescales comparable to the friarbirds's generation time, then selection
for bill-knobs could occur even if improved pollination was the only
effect of bill-knobs.
But this is implausible, at least based on the litle I know of Noisy
Friarbird/plant biology.
Bill knobs are absent in some populations of Helmeted Friarbird (in PNG)
so it would be interesting to know any ecological differences between
these populations.
Sexual selection seems more likely to me, particularly as the explanation
for the retention of bill-knobs, if not their ancestoral origin.
Andrew Taylor
[ Heard my first Channel-billed Cuckoo for the season today (Callan Park,
Drummoyne, inner west Sydney) and the first Koel for my yard-list last weekend -
calling steadily but softly at 5am, and not heard since ]
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