PhD accepted, and new position!

Thrilled that my PhD was accepted without revision two weeks ago! Grateful to the two examiners for their very kind feedback. The remaining chapters should be coming out as papers over the next year, but in the meantime – please let me know if you would like a copy.

Another little belated update; I am excited to have started a new position as a postdoc with Craig Moritz at ANU in Canberra. I’ll be continuing to work on population genomics of native Australian reptiles and mammals, and on the genomics of Gehyra geckos!

New paper on the cover of Evolution

On the cover

Roycroft EJ, Nations JA, Rowe KC. 2020. Environment predicts repeated body size shifts in a recent radiation of Australian mammals, Evolution 74:3, 694-695.

Our new paper made the cover of the March issue of Evolution! This lovely little Notomys is part of Melbourne Museum’s Live Exhibits. Photo by David Paul.

Closely related species that occur across steep environmental gradients often show clear body size differences. Generally, species living in colder habitats or environments tend to be larger, while species in hotter habitats are smaller. This pattern is predicted by a biogeographic principle called ‘Bergmann’s Rule’.

We were interested in looking at this pattern in the Australian endemic Pseudomys Division, a recent radiation of small mammals that live across a diverse range of habitats in Australia – from the arid central desert to wet forest in mountains!

In our new paper we collated body size data and occurrence records for 31 species in the Pseudomys Division and used Bayesian phylogenetic models to test whether the biome and environmental conditions each species lives in can predict their body size.

Our results show that body size in these species predictably increases in the mesic biome and decreases in arid and monsoon biomes, in concordance with Bergmann’s rule. It is possible that we see this pattern due to the thermoregulatory benefits for species that live in cold environments – i.e., being larger helps to keep you warm in the cold, while being smaller helps to dissipate heat in the hot! There are also more resources available in colder, wetter forest habitats than in the arid desert; which also likely contributes to this pattern.

Check out the paper here:

You can also see the nice ‘Digest’ write up by El-Deeb et al. on our article here:

Royal Society of Victoria Young Scientist Research Prize

I was honoured to receive the 2019 Young Scientist Research Prize from the Royal Society of Victoria, for research in Biological Sciences.

It was a great privilege to be among an amazing lineup of finalists, who competed by presenting talks in a public forum at the Royal Society on the 15th of August. The talks were also live-streamed online!

A big thank you to the Royal Society for a fantastic night highlighting the amazing research being done by Victoria’s early career researchers, and to the wonderful Priya Mohandoss, who wrote a feature article on my research in the Royal Society’s newsletter this month:

New paper out in Conservation Genetics!

This week, my honours work (and 1st first author paper!) went online in Conservation Genetics (you can find it here!). Very excited to finally share this research that was done under the wonderful supervision of Dr. Agnès Le Port and Dr. Shane Lavery, during my time at the University of Auckland.


Using nuclear and mitochondrial DNA from short-tail stingrays, we determined their population genetic structure across the southern hemisphere and showed strong evidence for male-biased dispersal within New Zealand.

We reported stronger mitochondrial DNA structure compared to nuclear DNA structure at a local scale (within New Zealand), as well as stronger structure among female individuals compared to males for both marker types. We also found that male individuals were significantly more likely than females to be migrants to the populations in which they were sampled from, suggesting that males tend to disperse a lot more than females. Our estimates suggest that male-mediated gene flow is at least five times that of female-mediated gene flow.

This pattern of ‘male-biased dispersal’ is well-described in mammals, and may be linked to the benefits that females experience by remaining in safe, known habitats for bringing up their offspring, as opposed to males, who benefit from spreading their genes. Recent studies in sharks have also reported male-biased dispersal, and our new paper adds to this growing body of research by providing evidence for the pattern in rays.

You can find a free, read-only copy here

Or you can request a downloadable .pdf copy here (via ResearchGate), and I will happily provide it!

Aussie rodents make it to CNN!

Native Australian rodents got a little bit of international press!

I spoke to Susan Scutti from CNN about what drove the diversification of the native rodents of Australia and New Guinea, as well as how human-mediated impacts have driven (and continue to drive!) massive extinctions and declines in the past 200 years.

You can check out the article on the CNN website here: “Before humans, Australia was colonized by rats”.

171130122750-western-mouse-restricted-exlarge-169Western chestnut mouse (Pseudomys nanus)