ÐÓ°ÉÔ­´´

Not many females would choose to spread labour over nine days, but for one reptile it seems to make sense.

Hatching asynchrony – in which eggs hatch sequentially over an extended period – is well known in birds. Geoff While at the University of Tasmania in Hobart has now found that the skink Egernia whitii can delay the birth of fully formed young.

Females that were allowed plenty of time to bask under warm light while pregnant gave birth over a much longer period, with a delay of up to nine days between their first and last born. Those whose basking time was reduced finished giving birth within three days. In birds delayed hatching is a result of poor environmental conditions; optimal conditions shorten the hatching spread and lead to a clutch of similar-sized offspring. So why the opposite in the skink?

While found that reduced exposure to light – akin to the later part of the breeding season – led to smaller, weaker young. Under these conditions, he thinks the offspring are better off if they are born quickly so that they can make the most of the dwindling sunlight. While was speaking this week at an evolutionary biology workshop at the University of Wollongong in New South Wales, Australia.