Two new postdoctoral positions in ecological network & vegetation modelling announced

21 07 2017

19420366_123493528240028_621031473222812853_n

With the official start of the new ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH) in July, I am pleased to announce two new CABAH-funded postdoctoral positions (a.k.a. Research Associates) in my global ecology lab at Flinders University in Adelaide (Flinders Modelling Node).

One of these positions is a little different, and represents something of an experiment. The Research Associate in Palaeo-Vegetation Modelling is being restricted to women candidates; in other words, we’re only accepting applications from women for this one. In a quest to improve the gender balance in my lab and in universities in general, this is a step in the right direction.

The project itself is not overly prescribed, but we would like something along the following lines of inquiry: Read the rest of this entry »





It’s not all about temperature for corals

31 05 2017

CB_ClimateChange6_Photo

Three of the coral species studied by Muir (2): (a) Acropora pichoni: Pohnpei Island, Pacific Ocean — deep-water species/IUCN ‘Near threatened’; (b) Acropora divaricate: Maldives, Indian ocean — mid-water species/IUCN ‘Near threatened’; and (c) Acropora gemmifera: Orpheus Island, Australia — shallow-water species/IUCN ‘Least Concern’. The IUCN states that the 3 species are vulnerable to climate change (acidification, temperature extremes) and demographic booms of the invading predator, the crown-of-thorns starfish Acanthaster planci. Photos courtesy of Paul Muir.

Global warming of the atmosphere and the oceans is modifying the distribution of many plants and animals. However, marine species are bound to face non-thermal barriers that might preclude their dispersal over wide stretches of the sea. Sunlight is one of those invisible obstacles for corals from the Indian and Pacific Oceans.

If we were offered a sumptuous job overseas, our professional success in an unknown place could be limited by factors like cultural or linguistic differences that have nothing to do with our work experience or expertise. If we translate this situation into biodiversity terms, one of the best-documented effects of global warming is the gradual dispersal of species tracking their native temperatures from the tropics to the poles (1). However, as dispersal progresses, many species encounter environmental barriers that are not physical (e.g., a high mountain or a wide river), and whose magnitude could be unrelated to ambient temperatures. Such invisible obstacles can prevent the establishment of pioneer populations away from the source.

Corals are ideal organisms to study this phenomenon because their life cycle is tightly geared to multiple environmental drivers (see ReefBase: Global Information System for Coral Reefs). Indeed, the growth of a coral’s exoskeleton relies on symbiotic zooxanthellae (see video and presentation), a kind of microscopic algae (Dinoflagellata) whose photosynthetic activity is regulated by sea temperature, photoperiod and dissolved calcium in the form of aragonite, among other factors.

Read the rest of this entry »





Species-area & species-accumulation curves not the same

30 05 2016

IBI’ve just read an elegant little study that has identified the main determinants of differences in the slope of species-area curves and species-accumulation curves.

That’s a bit of a mouthful for the uninitiated, so if you don’t know much about species-area theory, let me give you a bit of background for why this is an important new discovery.

Perhaps one of the only ‘laws’ in ecology comes from the observation that as you sample from larger and larger areas of any habitat type, the number of species tends to increase. This of course originates from MacArthur & Wilson’s classic book, The Theory of Island Biography (1967), and while simple in basic concept, it has since developed into a multi-headed Hydra of methods, analysis, theory and jargon.

One of the most controversial aspects of generic species-area relationships is the effect of different sampling regimes, a problem I’ve blogged about before. Whether you are sampling once-contiguous forest of habitat patches in a ‘matrix’ of degraded landscape, a wetland complex, a coral reef, or an archipelago of true oceanic islands, the ‘ideal’ models and the interpretation thereof will likely differ, and in sometimes rather important ways from a predictive and/or applied perspective. Read the rest of this entry »





Ice Age? No. Abrupt warmings and hunting together polished off Holarctic megafauna

24 07 2015
Oh shit oh shit oh shit ...

Oh shit oh shit oh shit …

Did ice ages cause the Pleistocene megafauna to go extinct? Contrary to popular opinion, no, they didn’t. But climate change did have something to do with them, only it was global warming events instead.

Just out today in Science, our long-time-coming (9 years in total if you count the time from the original idea to today) paper ‘Abrupt warmings drove Late Pleistocene Holarctic megafaunal turnover‘ led by Alan Cooper of the Australian Centre for Ancient DNA and Chris Turney of the UNSW Climate Change Research Centre demonstrates for the first time that abrupt warming periods over the last 60,000 years were at least partially responsible for the collapse of the megafauna in Eurasia and North America.

You might recall that I’ve been a bit sceptical of claims that climate changes had much to do with megafauna extinctions during the Late Pleistocene and early Holocene, mainly because of the overwhelming evidence that humans had a big part to play in their demise (surprise, surprise). What I’ve rejected though isn’t so much that climate had nothing to do with the extinctions; rather, I took issue with claims that climate change was the dominant driver. I’ve also had problems with blanket claims that it was ‘always this’ or ‘always that’, when the complexity of biogeography and community dynamics means that it was most assuredly more complicated than most people think.

I’m happy to say that our latest paper indeed demonstrates the complexity of megafauna extinctions, and that it took a heap of fairly complex datasets and analyses to demonstrate. Not only were the data varied – the combination of scientists involved was just as eclectic, with ancient DNA specialists, palaeo-climatologists and ecological modellers (including yours truly) assembled to make sense of the complicated story that the data ultimately revealed. Read the rest of this entry »





Ecological processes depend on …

14 05 2014
© Cagan Sekercioglu

© Cagan Sekercioglu

I have been known to say (ok – I say it all the time) that ecologists should never equivocate when speaking to the public. Whether it’s in a media release, blog post, television presentation or newspaper article, just stick to ‘yes’ or ‘no’. In other words, don’t qualify your answer with some horrid statistical statement (i.e., in 95% of cases …) or say something like “… but it really depends on …”. People don’t understand uncertainty – to most people, ‘uncertainty’ means “I don’t know” or worse, “I made it all up”.

But that’s only in the movies.

In real ‘ecological’ life, things are vastly different. It’s never as straightforward as ‘yes’ or ‘no’, because ecology is complex. There are times that I forget this important aspect when testing a new hypothesis with what seem like unequivocal data, but then reality always hits.

Our latest paper is the epitome of this emergent complexity from what started out as a fairly simple question using some amazing data. What makes birds change their range1? We looked at this question from a slightly different angle than had been done before because we had access to climate data, life-history data and most importantly, actual range change data. It’s that latter titbit that is typically missing from studies aiming to understand what drives species toward a particular fate; whether it’s a species distribution model predicting the future habitat suitability of some species as a function of climate change, or the past dynamics of some species related to its life history pace, most often the combined dynamics are missing. Read the rest of this entry »





Putting the ‘science’ in citizen science

30 04 2014
How to tell if a koala has been in your garden. © Great Koala Count

How to tell if a koala has been in your garden. © Great Koala Count

When I was in Finland last year, I had the pleasure of meeting Tomas Roslin and hearing him describe his Finland-wide citizen-science project on dung beetles. What impressed me most was that it completely flipped my general opinion about citizen science and showed me that the process can be useful.

I’m not trying to sound arrogant or scientifically elitist here – I’m merely stating that it was my opinion that most citizen-science endeavours fail to provide truly novel, useful and rigorous data for scientific hypothesis testing. Well, I must admit that I still believe that ‘most’ citizen-science data meet that description (although there are exceptions – see here for an example), but Tomas’ success showed me just how good they can be.

So what’s the problem with citizen science? Nothing, in principle; in fact, it’s a great idea. Convince keen amateur naturalists over a wide area to observe (as objectively) as possible some ecological phenomenon or function, record the data, and submit it to a scientist to test some brilliant hypothesis. If it works, chances are the data are of much broader coverage and more intensively sampled than could ever be done (or afforded) by a single scientific team alone. So why don’t we do this all the time?

If you’re a scientist, I don’t need to tell you how difficult it is to design a good experimental sampling regime, how even more difficult it is to ensure objectivity and precision when sampling, and the fastidiousness with which the data must be recorded and organised digitally for final analysis. And that’s just for trained scientists! Imagine an army of well-intentioned, but largely inexperienced samplers, you can quickly visualise how the errors might accumulate exponentially in a dataset so that it eventually becomes too unreliable for any real scientific application.

So for these reasons, I’ve been largely reluctant to engage with large-scale citizen-science endeavours. However, I’m proud to say that I have now published my first paper based entirely on citizen science data! Call me a hypocrite (or a slow learner). Read the rest of this entry »





Too small to avoid catastrophic biodiversity meltdown

27 09 2013
Chiew Larn

Chiew Larn Reservoir is surrounded by Khlong Saeng Wildlife Sanctuary and Khao Sok National Park, which together make up part of the largest block of rainforest habitat in southern Thailand (> 3500 km2). Photo: Antony Lynam

One of the perennial and probably most controversial topics in conservation ecology is when is something “too small’. By ‘something’ I mean many things, including population abundance and patch size. We’ve certainly written about the former on many occasions (see here, here, here and here for our work on minimum viable population size), with the associated controversy it elicited.

Now I (sadly) report on the tragedy of the second issue – when is a habitat fragment too small to be of much good to biodiversity?

Published today in the journal Science, Luke Gibson (of No substitute for primary forest fame) and a group of us report disturbing results about the ecological meltdown that has occurred on islands created when the Chiew Larn Reservoir of southern Thailand was flooded nearly 30 years ago by a hydroelectric dam.

As is the case in many parts of the world (e.g., Three Gorges Dam, China), hydroelectric dams can cause major ecological problems merely by flooding vast areas. In the case of Charn Liew, co-author Tony Lynam of Wildlife Conservation Society passed along to me a bit of poignant and emotive history about the local struggle to prevent the disaster.

“As the waters behind the dam were rising in 1987, Seub Nakasathien, the Superintendent of the Khlong Saeng Wildlife Sanctuary, his staff and conservationist friends, mounted an operation to capture and release animals that were caught in the flood waters.

It turned out to be distressing experience for all involved as you can see from the clips here, with the rescuers having only nets and longtail boats, and many animals dying. Ultimately most of the larger mammals disappeared quickly from the islands, leaving just the smaller fauna.

Later Seub moved to Huai Kha Khaeng Wildlife Sanctuary and fought an unsuccessful battle with poachers and loggers, which ended in him taking his own life in despair in 1990. A sad story, and his friend, a famous folk singer called Aed Carabao, wrote a song about Seub, the music of which plays in the video. Read the rest of this entry »