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Author Topic:   The limitations of Sexual Selection
aiki
Member (Idle past 4293 days)
Posts: 43
Joined: 04-28-2010


Message 31 of 36 (620392)
06-16-2011 4:26 AM
Reply to: Message 29 by Dr Adequate
06-16-2011 1:32 AM


Re: A Sexual Selection Question
In birds where the male is expected to feed the incubating female and later on the chicks, he can demonstrate his provider skills to the female with courtship feeding. He finds and offers food to the female, feeding her in the same way he would a begging chick. The extra food supplies also help bring her into breeding condition.
With species that share parenting equally, courtship often involves both members of the pair demonstrating a ritualised version of some aspect of parenting skills. For example, in Great Crested Grebes the courtship display is a synchronised dance in which both birds dive, tread water and offer pondweed (a nesting material) to each other. In many birds of prey the courtship involves elaborate aerobatics, with mid-air food passes (showing skill as a provider) and chases with talon-grappling (demonstrating ability to defend the territory from intruders).

This message is a reply to:
 Message 29 by Dr Adequate, posted 06-16-2011 1:32 AM Dr Adequate has replied

Replies to this message:
 Message 32 by Dr Adequate, posted 06-16-2011 7:45 AM aiki has replied

  
aiki
Member (Idle past 4293 days)
Posts: 43
Joined: 04-28-2010


Message 33 of 36 (620404)
06-16-2011 8:38 AM
Reply to: Message 32 by Dr Adequate
06-16-2011 7:45 AM


Re: A Sexual Selection Question
With birds in which the chicks are helpless and confined to the nest for weeks after hatching (altricial), they need sheltering, defending from predators, frequent feeding and their droppings taken away. It's a two-bird job, so if a male shags and immediately leaves to court another female, there's pretty much zero chance that any chicks he fathers will survive. However, sneaky extra-pair copulations between birds of neighbouring territories are VERY common among some of these supposedly 'monogamous' species.
You see obvious sexual dimorphism more often in species with precocial chicks, able to run about and feed themselves soon after hatching (eg ducks, chickens). The female (or in a few cases the male - eg in phalaropes and Dotterels the male does all the parental care) doesn't need a second helper so can select a mate solely on the basis of looks and vigour.
Edited by aiki, : clarify some bits

This message is a reply to:
 Message 32 by Dr Adequate, posted 06-16-2011 7:45 AM Dr Adequate has not replied

  
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