Avid followers of this blog (….crickets chirping in the background….) will know that it’s been a while since my last post. Four months to be exact. What I have I been up to? Well, in short, fighting my way through a mass of preparations for leaving Australia and heading to Old Blighty. To York to be exact. Yep, I’ve left the colony and headed back to the old country. I’ll be here for the next two years visiting Prof. Chris Thomas at the University of York and Dr Jenny Hodgson at the University of Liverpool. Chris and Jenny have long standing interests in metapopulation dynamics, and so their respective labs represent a logical place to hone my metapopulation capacities (there’s a masterful in-joke in there if you can spot it…). I’m here courtesy of the Victorian Government, who have packed me off to learn some new skills and extend my professional networks. It is a wonderful opportunity and I’m hugely excited about it!
Just prior to Christmas, Conservation Genetics delivered us a present in the form of acceptance and rapid fire publication of a study we commenced way back in 2004. The publication process never ceases to amaze me. After years of toil collecting data, several more years of painstaking lab work, and finally the rigors of a multi-author drafting process, this paper took just weeks to go from being accepted, through proofing to online-early publication. In fact, to my astonishment, we received proofs a mere five days after the paper was accepted, two days of which were a weekend!
But back to the paper itself. In 2004 I was a shiny new PhD student, champing at the bit to decode the population biology of the growling grass frog. I began a mark-recapture study on the species north of Melbourne, and diligently went about obtaining tissue samples from each frog I captured for a later, prospective, genetics study. Two years and 800 frogs later, the opportunity arose to get that work underway. Josh Hale had just started his own PhD on the conservation genetics of frogs in urbanising landscapes, and was keen to collaborate on the growler project. Josh’s first task was to develop a microsatellite library for the species. He emerged from the lab a year later, gasping for air and 10 kilos lighter, bearing nine new microsatellite loci for our little green friends. You can read about those in another paper, found here. Josh then set about genotyping ~200 growlers from three population clusters that I sampled during my mark-recapture work. These clusters, which I prefer to call metapopulations, were distributed along the Merri Creek at roughly 5 km intervals. Each included pools along the creek, plus neighbouring wetlands such as quarries, swamps and farm dams. Josh used his microsatellite data to assess the pattern of population subdivision in this area, and to test the effect of geographic distance and urban barriers on genetic distance.
So what did we find? In short, remarkable levels of genetic sub-division. Growlers have long been thought to be highly dispersive; vagabonds that wander the landscape in search of optimal conditions. On the contrary, our genetic work indicates that while individual frogs may be able to undertake significant journeys, the majority either can’t or don’t. Josh’s work found strong genetic sub-divisions between each of the wetland clusters I sampled, and even some sub-division within population clusters. The latter is especially interesting because the distances involved are small – 2 km max. Thus, in line with our previous occupancy and mark-recapture work (described here), Josh’s genetic work suggests that the migration rates of growlers are low and strongly distance-limited.
Another important outcome was the fact that populations separated by housing estates, industrial estates or dual-carriage roads displayed relatively high genetic distances. We can infer from this that urbanisation does indeed fragment populations of growlers; something we’ve long suspected but lacked any specific evidence of. It’s not a surprising result – imagine yourself as a little green frog attempting to cross a dual-carriage highway. But it is a vital piece of the puzzle for our understanding of the effects of urbanisation on this species, and for mitigating those effects.
Where to from here? Well, now that you mention it, our molecular work continues. Claire Keely, a PhD student in the QAEG, is working on the broader genetic structure of growlers around Melbourne, the fine-scale determinants of gene flow, and the efficacy of alternate tissue sampling techniques. You can read more about Claire’s great work here. As for Josh and I, we have one more paper to go from our collaboration. It’s a gooden too – a comparison of contemporary genetic diversity in growler populations from the Merri with a now extinct population from the adjacent Plenty River catchment. Think ancient DNA techniques and pickled frogs collected way back in the 1960s. Oh yes, there’s an exciting blog post in that. Stay tuned…
Last week I was lucky enough to attend a workshop at the Australian Centre for Ecological Analysis and Synthesis (ACEAS) at the University of Queensland. ACEAS is part of the Terrestrial Ecological Research Network (TERN), funded by the Australian Government. Inspired the famous American version, ACEAS seeks to facilitate the integration, synthesis and modelling of ecosystem data to aid in the development of environmental management strategies.
Our job last week was to collate data on the distribution and demography of several Australian frogs, and to use those data to develop models of population dynamics under climate change. The objective: to assess extinction risks, and identify management options to mitigate those risks. See more on our group page.
Now, here’s the great thing about ACEAS. Autecologists like me are keen to tackle these sorts of projects, but often lack the modelling skills required. On the flip side, ecological modellers interested in these questions are often constrained by their knowledge of the species under study, particularly where to find the information needed to parameterise their models (which frequently hides in Honours or PhD theses, unpublished reports, someone’s hard drive or a dusty filing cabinet). ACEAS brings these two groups together, and harnesses their collective skills to tackle important questions in applied ecology.
Want a workshop of your own? Well, it just so happens that the next round of ACEAS funding is in October. You can enquire with ACEAS direct from here, and find instructions of how to apply here. I can highly recommend it!
I’ll write more about the frog project in blogs to come. For now, let me say a big thanks to Tracey Regan and David Keith for leading the charge and inviting me along, to all the group members for a great week (including our most recent member, Reid Tingley), and to ACEAS for their fantastic hospitality, and their broader efforts to bridge the gap between those with the data, and those with the models.