Science Daily has two evolution related articles up.
The first concerns the snail hunting by carabid beetles. Some carabids have large heads and are able to crush snail shells, others have smaller heads and are able to enter the snail shell to eat the snail. Recent research has found that:
Phylogenetic studies show that adaptations for snail feeding led to the diversification of beetle heads.
Interestingly, it has been demonstrated that the same trade-off diversifies shell morphology in studies of freshwater snails, where elongate shells are adaptive in protecting against entry attacks and rounded shells are adaptive in protecting against crushing attacks. “Trade-offs between force and fit have a significant, important role in both morphologies of snails and snail predators in evolution,” said Konuma.
The second article concerns the energetic costs of mate selection among female Galopagos iguanas:
Vitousek and colleagues measured how much energy female iguanas expend on mate choice in the wild using miniaturized data loggers developed by Anthony Woakes at the University of Birmingham. They found that females devote a surprising amount of effort to picking among males on a lek, even though they appear to gain only genetic material from their chosen mate. Visiting ‘attractive’ males (males that display more often) carries the highest costs. The longer female iguanas spend in the company of these appealing suitors the more weight they lose, and the smaller the eggs they subsequently produce.
Which raises the question of what the female iguana’s gain:
To make these costs worthwhile, the genetic or other payoffs females gain from their chosen mates must be substantial. Ongoing research is aimed at quantifying the magnitude of these benefits in order to gain a complete picture of the way mate choice works in this species.
The research is being published in PLOS One.