BOBO ЙL d 9 9 9 9 9 9п+ Иєа џџ XБ И @ џџ Иєьџџ џ - Z џџџ Richard Northover f џџ B LOM! ` P џџ џ x H H _ џ§aѕ(ќ § Ф Ы lР Д - ^ь & ' џџ Й P l / Рc х j ЙЌ ИЌ И хc Иѓ0 ЗЌd Йd [ф џџџџџџџџ ] Qy DSET T о т о ЙЈИѕ$Иl И ђІЙќ Р X ; < Ч Ш Ѓ Є Ь о $ 3 @ ГЖВ4 ГИ К%ЙЈ Г((fiddler crabs))
At low tide, male fiddler crabs Uca annulipes stand at the entrance to their burrows and frantically waving one of their claws to attract passing females. Wavin g is the cue which females use to choose a mate - so why do some males wave more than others? The 'honest signalling' hypothesis explains why bigger males wave more than smaller males - waving is a costly activity, and only bigger, higher quality, crabs have enough energy reserves to bear the expense. Waving, in this case, is 'honest' because the cost means weaker individuals can't 'lie'.
But Michael Jennions at the Smithsonian Tropical Research Institute, Panama, and Patricia Backwell of the University of the Witwatersrand, Johannesburg, noticed that smaller males wave more towards the end of the lunar cycle. Instead of concentrating on the costs, Jennions and Backwell considered the benefits of waving at different times. Females need to produce their young when %tidal conditions are right. This means there is a limited period in which they must get their eggs fertilised by a male. As time goes by, finding a male of high quality becomes less important - females just need to find any mate before they miss the chance altogether.
Jennions and Backwell suggest that it pays the smaller males to save their precious energy and advertise their existence only when the females are becoming desperate and would consider smaller partners attractive, too
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