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Martin and Dr. Qi have taken the lead on our yearly China adventure as I am busy writing up my thesis! This year our plans are to get some display behaviour from a few more toad-headed agama species in Xinjiang province. Martin is filling me in on details as they come, but it’s shaping up to be another exciting trip! They have driven a tonne and have already found a couple species. You can read up on the excitement on Martin’s webpage. Just click the link below:
Touring China’s deserts in search of toad-headed agamas!
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Recently, the Pryke Lab published its first paper on a reptile—the iconic Frillneck Lizard (Chlamydosaurus kingii). Both males and females have frills and until now, the consensus has always been that frills play a role in anti-predator behaviour. Not only does the frill startle a would-be predator, but it may also bluff them into thinking that their potential dinner might be dangerous and risky to catch. While this hypothesis still remains to be tested, Hamilton et al. explore an alternative hypothesis: that the frill might also play a role in sexual selection and signal fighting ability. They used optic spectrophotometry to objectively measure the colour of the frill and also measured a range of morphological and functional traits before size matching lizards in staged contests in neutral arenas. Surprisingly, traits such as frill size, head size and bite force did not predict contest outcome. Instead, males with brighter and more colourful frills were more likely to dominate opponents and take gold. They also took skin samples back to the lab to determine the source of pigments that generate the colour. Lab tests confirmed the presence of carotenoids which is an exciting result because while carotenoids have been the source of considerable study among birds, we know little about the role of carotenoids in lizards. This might be the first example of a carotenoid-based signal of fighting ability in a lizard. This is a must read study, very cool stuff!
To read more and download the paper check out Martin’s webpage and facebook post.
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Our new paper on female polyandry in E. quoyii has just been published in Behavioral Ecology. In this paper we tested a series of predictions that assessed the roles of direct and indirect genetic fitness benefits females may receive by mating with many males. Direct fitness benefits are those benefits females gain directly by mating with many males, which increases their lifetime reproductive success. This can include increased help rearing young (as in birds), increased probability of fertilizing ova, or a reduction in costly male harassment, just to name a few. In contrast, indirect genetic benefits are those that affect the survival and reproductive success of a given females offspring. Water skinks are great because we know they don’t have any parental care and we also know that male harassment in this species is not high and females can resist mating with males. This makes the possible direct benefits females may receive more simplistic. We tested predictions from these hypotheses by measuring fecundity of females classified as single and multiple paternity moms. We also measured five surrogates of fitness in offspring from these females [body size and mass at birth, growth rates (captive and wild), sprint speed and endurance]. Indirect genetic benefits models predict that offspring from multiply mating moms would have increased mass, body size, growth rates, sprint speed and endurance. However, our models suggest that offspring from multiply mating moms are not any ‘better’ in the above traits compared with offspring from singly mating moms…So do females receive any benefits from mating with multiple males? It appears that they do indeed get direct fitness benefits by getting a ‘boost’ in litter size. When we compared multiply mated moms with singly mated moms we found that moms mating multiply produce almost twice the number of offspring! This holds even when controlling for female body size, mass and condition which are strongly related to clutch size in this species. Our results are pretty cool because it suggests that females may be mating multiply, in part, to get either increased quality sperm or increased quantity of sperm and supports the ‘fertility assurance’ hypothesis as a plausible mechanism promoting the evolution of polyandry in water skinks.
Interested readers can download and read the paper in more detail HERE or you can check out my publications page where you can read the abstract and a whole lot more.
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