From the field: Studying endangered northern quolls on Groote Eylandt

It's a new year, which means there's new research to be done as I delve into my PhD. But before I start writing about that, I want to write about a somewhat related experience I was lucky enough to have last year.

In August/September, I got to join my labmates Ami, Jaime, and Gwen up on Groote Eylandt, which is a large island off the coast of the Northern Territory owned and run by the Anindilyakwa people. The reason: to help them out with their research on the endangered Northern Quoll (Dasyurus hallucatus).

Catwoman, a pretty little female Northern Quoll (Dasyurus hallucatus). 

Catwoman, a pretty little female Northern Quoll (Dasyurus hallucatus). 

A classy addition to any accessory collection. Image credit: Wikimedia Commons. 

A classy addition to any accessory collection. Image credit: Wikimedia Commons. 

Now, if you’ve ever been to Australia, you probably have heard the story of the Cane Toad (Rhinella marina) – even if it’s just via one of the many delightful novelty souvenirs available in Australian tourist shops.

The cane toad is an extremely successful invasive species that was introduced into Australia in 1935 to eat a beetle that was negatively affecting the cane industry (which it didn’t), and since then it has spread down the East coast and across the Northern Territory, and is slowly making its way down the West coast as well. One of the reasons Groote Eylandt is so amazing is because it is one of the few areas up North that has remained cane toad-free. Because of this exclusion, it is the last stronghold population of the endangered Northern Quoll, whose numbers have been decimated via their predation on this toxic species. This makes Groote an ideal location to study the quoll in its natural habitat, as numbers are high enough for recapture studies to generate useful amounts of data.

A magical sunset in the bush next to the highway to Umbakumba.                                              Ami measuring one of our little darlings. 

I was on Groote Eylandt for 5 weeks helping Ami with data collection for her PhD project. As well as stunning landscapes and amazing native animals, Groote Eylandt is also home to a large manganese mine. All animals need some amount of manganese to function, but like any heavy metal it can be toxic in high concentrations. For her PhD, Ami is looking at how quolls from different parts of the island (that have been exposed to different amounts of manganese) perform in motor control and cognitive function tests. We are lucky enough to have access to laboratory facilities at the Anindilyakwa Land and Sea Ranger Station, where we get to work with the Rangers to figure out how to do our research in a way that is compatible with indigenous culture.

We went out every night and set 30-60 traps in one of our three trapping areas various distances from the manganese mine, which we then checked first thing the next morning. If we were lucky, we’d see white spots and hear some angry growling – otherwise it was rather likely that we’d caught one of the other marsupials that populate the area. We then transported our precious bundles back to the lab at the Anindilyakwa Ranger Station where we sexed them, weighed them, took various morphological measures and a hair sample (to get their internal manganese concentration from) and pit- and ear-tagged them.

Alfred, a feisty (and adorable) little male. 

Lastly, we’d gather information on their level of motor control. I won’t give away too many details, but we basically assessed their performance at various speeds and analysed how many mistakes they made depending on the difficulty of the task and the speed at which they performed it. We would expect that as speed and/or “difficulty” of the task increases, the quolls will make more mistakes. The reasons for this are very intuitive and you will probably have observed them in your own life; as you do things faster you have less control over your movements and are more likely to make an error. Similarly, if a task is difficult, you’re more likely to make a mistake than if it’s relatively easy. What Ami wants to know is whether the manganese concentration the quoll has been exposed to enhances this effect – i.e., whether high manganese concentrations affect motor control.

Back to the bush you go.                                                                                                                              Having a sniff out of the corner of his bag. 

Ami also wants to look at whether manganese concentration affects cognitive function in the quolls – but that’s for her to write about! She’ll continue to run these experiments for the next two years, and hopefully get some excellent results. I was very lucky to be involved in helping out with this project, as many of the techniques she used will be helpful in my own PhD.

Although quolls were the main attraction for us, Groote Eylandt has plenty of other amazing qualities that made my trip there one of the most memorable ventures into the field that I’ve ever had. We are extremely privileged to be able to conduct research there, and I learned more about indigenous culture than I ever thought I would. I also saw loads of awesome animals and plants, and got to spend a lot of time in the field – which is definitely one of the best ways to spend it.

A Mertens' Water Monitor (Varanus mertensi) chilling by Milyerrngmurramaja (the "Naked Pools"). These guys are also threatened by ingestion of the cane toads. A Striated Pardalote (Pardalotus striatus) that was nesting next to the Anindilyakwa Ranger Station.

A Burton's Legless Lizard (Lialis burtonis) we found while we were setting traps near Alyangula. A Helmeted Friarbird (Philemon buceroides) next to the highway to Umbakumba.

I’d like to say a huge thank-you to my lab for this opportunity, but most especially to Ami, Jaime and Gwen for teaching me so many new skills and being the best bush-buddies ever. I’m looking forward to future adventures with the Wilson Performance Lab as I start my PhD on another kind of carnivorous marsupial… the Yellow-footed Antechinus (Antechinus flavipes)!

Sunset on the beach at Ayangkwa ("Tasman Point"). 

All images by Rebecca Wheatley unless otherwise credited.

Performance Trade-offs

Everything about an organism's life can be looked at as a trade-off. The energy acquired from eating a banana, for example, can be used for skeletal growth or to augment fat reserves or invested in gametes; but the same energy cannot be distributed in multiple places at once. Choices - however unconscious - must be made.

Performance trade-offs occur at many different levels. At the level of the whole-animal, we know that particular types of muscles perform better for sprinting than endurance running, and that the rapid growth of tadpoles associated with certain thermal environments can affect their post-metamorphic jumping abilities. Specialised morphology that makes an animal a better fighter may also hinder its ability to escape from predators.

Performance is also strongly affected by an individual's behaviour. Time - like energy - must be allocated throughout the day, and time spent doing one activity inhibits other activities. For example, time spent hiding from predators means less time for feeding - which we know to have important carry-on effects on growth, development and motor performance. 

Trade-offs in performance even occur within cells and tissues, because the allocation of energy and the waste by-products of motor performance (e.g. lactic acid, reactive oxygen species, etc) affect other essential, non-motor systems like immunity. Currently, we're interested in how these mechanistic trade-offs facilitate variation in rapid growth, breeding and early death among populations of northern quolls.

UQ CIEF Grant awarded to the Performance Lab

- by Robbie Wilson

Last week I travelled back to Groote Eylandt to sign off on a collaborative research project with the Anindilyakwa Land Council worth $375,000 over the next two years. This supports an important project and recognizes our strengthening relationship with the people of Groote Eylandt with whom we've been working for the last five years. 

Indigenous dugong painting on Groote Eylandt

Indigenous dugong painting on Groote Eylandt

For our UQ-CIEF grant we'll be exploring the possible toxic effects of manganese from the local mining operations on the wildlife of Groote Eylandt. Groote hosts one of the world’s largest Mn mines - and despite considerable financials rewards for the local community, many locals are becoming increasingly concerned about the long-term impacts of Mn contamination for their environment. The toxic effects of Mn usually manifest in animals by affecting their cognitive and motor function, which places our research group in a unique position to tackle this research.

We'll examine the pattern of Mn accumulation in the local wildlife and then test whether any increased Mn affects motor function in our primary study animal, the northern quoll. This species offers a perfect model system because it is highly abundant across the island – both close and far from the mining operations – and we can easily adapt tests of motor control from protocols used in biomedical studies of rats and mice.

Groote Eylandt field work

Ami (PhD student) and Skye (Researcher) will be the main team members working on this project but, as always, everyone in the lab will contribute to the smooth running of the work. There is never a shortage of volunteers offering help!! We’re all excited about continuing our work with the Indigenous Rangers of Groote Eylandt and we hope they get as much out of our collaboration as we all do. My feeling is that you haven’t graduated as an Australian ecologist (or zoologist) until you’ve wandered through the bush with a real local and seen the land through their eyes. 

Thanks again to the Anindilyakwan people for their on-going trust and acceptance of our research team. We look forward to the season ahead.

Robbie 

I spent a late afternoon wandering rocky landscapes and avoiding crocodiles

In Search of Hot Mosquitofish

 

How do animals adapt to hot temperatures? What allows some animals to do well in hot conditions while others simply, well – die?

A natural thermal gradient - the hot bores of outback Queensland

A natural thermal gradient - the hot bores of outback Queensland

Seems like a pertinent question when one considers the world is getting hotter. And quickly.

My current ARC Discovery Project poses these very questions. I want to understand the mechanisms of adaptation to warmer temperatures and how this can shape a species' population dynamics and survival. It's not surprising then that my interest was piqued by rumours of an introduced species of freshwater fish (the ubiquitous mosquitofish) that can actually survive in the bath-hot bore drains of western Queensland.

Across the state's west, numerous deep bores tap into the rich underground water sources of the Great Artesian Basin. Water spews out of these pipes from depths of more than 1500m at temperatures in excess of 70°C, flowing into narrow drains and cooling – allowing livestock to persist in an environment that would be otherwise uninhabitable. Fish (well, so the rumours go) inhabit these open drains at year-round temperatures above 30°C and sometimes even greater than 40°C. The possibility of capturing and studying these fish was too tempting to ignore.

RA Skye Cameron + echidna

My RA and lab organising force Skye is used to my crazy, impetuous ideas, and she doesn't even seem surprised when my ideas are offered at stupidly short notice and without any respect for logistics. In this specific case, Skye laughed – and started packing – when I suggested we should head out west in search of some hot fish in just a few days’ time.

We would collect some fish from hot bores to study in the lab.

It was the prospect of teaming-up with some UQ colleagues that work out near Barcaldine (1200 km north-west of Brisbane) who know the local people, properties and bore-drain locations that lit a fire under my b-hind.

So - it was early on a Monday morning that Skye picked me up half-asleep (me, not her) and we set-off on our adventure with no guarantees of success (let's face it, little chance of success). By lunchtime on Tuesday we reached Barcaldine. We'd avoided suicidal kangaroos and emus playing chicken with every vehicle pelting along the highway, and we rendezvoused with Jeremy (RA) and Billie (Honours) – from my colleague Rod Fensham's lab group – at the local bakery. Incidentally, Rod and Jeremy work on the spring systems of Edgbaston - the site of Australia's most endangered freshwater fish, the red-finned blue-eye (more on this another time).

we had to stop driving at dusk as the emus and kangaroos made the roads dangerous

After the obligatory orientation tour of the town's pubs on Tuesday evening and a sampling (2 kgs) of the local beef (not by Skye), we set off in search of bores on Wednesday morning. It didn't take long before we found them.

The first property we visited had a bore flowing out at 55°C into a tiny, narrow drain. Over the course of 30 m, the water cooled down to temperatures of around 45°C, and as we walked along the drain we spotted our first hot candidates.

Little juvenile mosquito fish living at 42.8°C.

Holy be-jesus!! This temperature is higher than I thought possible for any mosquito fish to survive in.

It was incredible - fish living in water I found hot to the touch.

mosquitofish were found at temperatures as (naturally) hot as 42.8 degC

Walking along the drain revealed a beautiful temperature gradient that dropped down by around 1°C every 5 meters.

When we hit temperatures of around 35°C there was an absolute explosion of fish and the surface rippled with movement.

We'd found our hot fish – and in truly staggering numbers. The air temperature was just a little over 20°C – and it was dropping nightly to below 5°C – yet the fish were enjoying balmy water. These fish had found their stable, warm conditions and were clearly loving it.

kangaroos - as far as the eye could see

By the end of the next day, we'd collected mosquitofish from two more sites and were ready to head back to Brisbane with a troop-carrier full of bore water and thermophilic fish. All we had to do was avoid those roos and make it back for my daughter Nelle's birthday party by 11am Saturday (Happy Birthday Princess).

And we did. I was only 30 minutes late to the party …

Robbie

The Grand Slam: How Hard Should You Hit?

Squirrels know what’s going down (or do they)? Image source: Wikimedia commons.

Squirrels know what’s going down (or do they)? Image source: Wikimedia commons.

The trade-off between performance and accuracy is a problem faced by a lot of different animals in a variety of situations. For example, consider a squirrel running along a bare branch to get from one tree to another; the faster it runs, the less time it spends exposed to predators. However, as the squirrel runs faster, it also increases its chances of mis-stepping and falling to its potential doom. 

So, to get the best of both worlds, the squirrel needs to optimise its running speed depending on its chance of slipping (the width of the branch) and the cost of falling off (the height from the ground).

These sort of performance/accuracy trade-offs are also commonplace in the human world. How fast should you smash out a text message to your supervisor asking him (politely) to email back your latest draft before the number of typos makes the whole thing unintelligible?  In particular, these trade-offs are of a great deal of interest in elite sports. An awesome example of a sport where this trade-off is of utmost importance is in singles tennis.

Serving hard: Heather Watson, Roger Federer and David Ferrer. Image source: Wikimedia commons.

In tennis, it’s pretty well accepted that if you serve really hard, it’s more difficult for your opponent to return the ball. But the harder you serve, the more likely it is that you’ll miss the service area and fault. So, players will usually belt it out on their first serve, but if they miss the first serve they’ll hedge their bets and serve softer the second time round to make sure they don’t double fault.

A/Prof Robbie WilsonDr Chris Brown and I have been testing this idea about performance trade-offs and optimal strategies using data from the men’s singles in the 2013 Australian Open. We’ve found this observation to be generally true: the probability of winning the point increases as the serve speed approaches its maximum, but the probability of faulting increases as well (for most players – some players are really consistent at getting it in regardless of how fast they serve). This was reflected in the frequency of high serve speeds in the first and second serves.

Jérémy Chardy, Andy Murray and Janko Tipsarevic. Image source: Wikimedia commons.

We’ve also constructed an optimality model which predicts the optimal serve speed taking into account the probability of faulting and the cost of a fault. An optimality model is, in essence, a mathematical model where you input the risks and rewards of a specific situation for a given individual, and it will tell you the optimal response for that individual if it wants to both minimise the risks and maximise the rewards. 

Optimality modelling is useful because it allows us to calculate the optimal response of specific individuals to any situation. We are looking at whether their opponent’s world ranking (ability to return a fast serve) and the point they’re going for or defending against (normal, game, set or match) affects their serve speed in relation to their optimum, but more on those results later.

Rafael Nadal, Caroline Wozniacki and Jérémy Chardy. Image source: Wikimedia commons.

We hope that our research can teach us more about how animals optimise their behaviour and physical efforts to improve their chances of successfully performing a given task. Depending on what we find, we might even be able to offer specific recommendations to tennis players wanting to improve their service game – who knows what the future might hold!

Andrew Hunter, a PhD student in our lab, is looking at performance/accuracy trade-offs in soccer. Will the results be similar between an individual and a team sport? We don’t know yet, but it will be interesting to find out.

Novak Djokovic, Agnieszka Radwańska and Venus Williams. Image source: Wikimedia commons.

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Can water dragons actually run on water?

Today's guest poster is Dr Christofer Clemente. After postdoctoral stints at Cambridge and Harvard, Chris obtained an ARC DECRA and joined the Wilson lab at UQ. You can keep up with Chris's adventures on his science blog, Biomechanics Downunder.

I have long been impressed with the ability of the South American Basilisk lizard to run on water. There are plenty of videos of it on youtube, that show 2 important aspects of its locomotion: 

  1. it's able to lift the whole body out of the water, and 
  2. it's able to do so for quite long distances (around 10-15m). 

Some lizards' ability to run on water has been documented quite well by a series of papers by a group at Harvard University, particularly Tonia Hsieh. They've done some great work, including describing how smaller lizards are better able to support their body weight than are larger lizardsmodelling 3D forces andrecording 3D kinematics of the lizards' stride. Below is a gif showing some of the detailed kinematics of the lizard stride from George Lauders lab webpage. 

(NOTE: just click on the gifs if they are not running)

One other important point reported in these papers, based on the description given in Hsieh (2003), is it seems the lizards' kinematics change when running on water, such that the limb moves behind the hip, rather than being both in front and behind the hip.   

This is shown quite well in the gif above. So given this information on how Basilisk runs on water, we can then ask the question, Can the water dragon (Intellagama lesueurii) also run on water?

I was led to believe it may be able to from two dominate and convincing lines of logic. 

  1. they are water dragons! - it might behoove them to be able to do so and 
  2. I heard reports of the juvenile lizard being observed doing so from a fellow researcher. 

So I modified the lizard racetrack which I have here at the University of Queensland, by placing a short, water-filled aquarium across the water dragons' path which they must cross to get to the other side. Then I sat back and filmed them using the fastec high speed camera system. And this is a typical (read: absolutely best) result below

Well the first thing I noticed is that they are no basilisk lizards. The body is not held out of the water and progress is significantly slowed. The first step seems hardly effective at all, and the second step is much deeper, and seems like a breaking step, with the foot held flat. However, the following step seem to have some similarity to those of the basilisk. From steps 3 onwards, the foot does not appear to be pushed as far forward, and much of the stroke seems to be posterior of the hip, as in basilisk. Secondly the trapped air bubbles on the foot are interesting, and these are also observed for basilisk, where they are thought to be the result of tiny fringes along the toes of the south american lizard. Such fringes however, are not obvious in the water dragons. Below is a snapshot of the bubble being dragged down on the trailing edge of the foot. 

So I'm unsure what to make of this all. It does look like they are capable of some run/swim locomotion, but it certainly falls short of the amazing prowess of the basilisk.

Here are some less impressive runs. Though notice that the right hind foot is actually brought out of the water - suggesting they could be using surface effects to give more downward force. 

And this one below shows a similar stroke. 

So that's as far as I've got. Let me know whether you think it is sufficiently interesting to warrant detailed kinematic analysis, or whether you think water dragons are just a little impaired when it comes to running on water. 

Finally, I leave you with what happens after several trials and the dragons know the water is coming up. It led me to believe, that for water dragons, they sure do not like water! 

The boldest gecko: personality in a reptile

Today on the blog we're happy to have former Wilson Honour's student, Rebecca Wheatley, who describes her thesis work on gecko personality. Rebecca's currently working as a research associate in the Wilson lab, and plans to start a PhD next year. You can find out more about Rebecca on her science blog, The Adventures of the Integrative Ecologist.

Animal behaviour is a big field - and it's constantly expanding as research reveals gaps in our understanding of why animals do the things they do. One topic in animal behaviour that holds a great deal of interest for me is that of animal personality. This is a relatively new concept and, frankly, it's a little bit controversial. 

The word "personality" conjures up a variety of mental images, most of which pertain to one animal in particular: us. It goes without saying that people have different personalities; we experience it every day. But do other animals have personalities as well?

Image: Great tit (Parus major), beadlet sea anemone (Actinia equina) and pumpkinseed sunfish (Lepomis gibbosus); three species that display animal personality, from very different groups. Image source: Wikimedia commons.

In animal behaviour, the term "personality" is defined as consistent differences in behaviour displayed by individuals. An example of a personality trait is how an individual responds to a threatening situation, termed boldness or shyness. Bold individuals are undaunted by threatening situations and will approach the stimulus, while shy individuals will stay away or hide.

There are heaps of different personality traits that have been studied, including boldness, exploratory behaviour and aggression, amongst many others. Individuals' "personalities" are thought to range along a proactive-reactive continuum, where proactive individuals are aggressive and bold while reactive individuals are more passive and shy (sound familiar? It's not unlike a simplified version of the extroverted/introverted behaviour displayed by people).

There's growing evidence that "personality" is present within many groups of animals. Despite this, we don't really know much about what determines an animal's place along the proactive-reactive continuum or why this variation exists.

Image: My study species: the Asian house gecko (Hemidactylus frenatus). Image credit: Wikimedia Commons (1 & 3) and Rebecca Wheatley (2).

During my honours project, I investigated"personality" in male Asian house geckos (Hemidactylus frenatus). I measured the anti-predator behaviour (a proxy for boldness) of 100 geckos by filming each gecko for one hour and then by calculating the proportion of time it spent inside the shelter in its terraruim. 

Each gecko was measured under three different treatments:

  1. "empty terrarium": where nothing (aside from the shelter) was added to the terrarium, to give me a measure of each gecko’s normal amount of anti-predator behaviour
  2. "terrarium with novel object": where I added a novel object to the terrarium, to see what happened to their anti-predator behaviour when something new was added to the environment
  3. "terrarium with threatening stimulus": where I added a threatening stimulus, to see how their anti-predator behaviour changed when something scary was added to their environment

I found that different individuals reacted to the treatments in different ways, but the overall trend looked like this:

We can see that when a novel object was added to the environment, the geckos' anti-predator behaviour generally decreased when compared to their standard level of anti-predator behaviour. This might be because they wanted to check out the new object to make sure it wasn't food or some other valuable resource. 

However, when I added a threatening stimulus, their anti-predator behaviour jumped back up again to around the same as its standard level. 

So it seems that the threatening stimulus effectively cancelled out the novel object effect.

How do we know if these behaviours constitute as "personality"?

Well, I found that while different individuals displayed consistent anti-predator behaviour within treatments, they also responded to the treatments in different ways. Some displayed more anti-predator behaviour when the environment was altered (were "shyer"), while others displayed less (were "bolder"). 

Therefore, from our definition, we can see that their anti-predator behaviour is a personality trait: they display consistent differences in behaviour that are context-specific.

Checking on my gecko housing set-up. Image credit: Amanda Niehaus.

But why do individuals have different personalities?

Previous research has found that a few things can be associated with an animals' boldness or shyness. A large body mass is often associated with a bold personality, which is probably because heavier individuals are usually larger and more likely to win in a fight (so they have a good reason to be bold). Similarly, individuals with a hard bite force, a strong claw pinch or any other performance trait which would give them an advantage in a contest are usually bolder as well. 

The possession of traits that might make it easier for them to escape from a predator in a pinch, like fast running speed, have also been associated with boldness.

 In addition, resting (or "standard" for reptiles) metabolic rate has been linked to animal personality; it's thought that bolder, more aggressive individuals need a higher metabolic rate to keep up with their energetic demands.

I investigated how some of these traits interact to effect boldness in my geckos. I measured each gecko's mass, standard metabolic rate, maximum running speed and maximum bite force and analysed their interactive effects on anti-predator behaviour. Contrary to what I expected (and to what the literature would lead us to predict), I found that none of these traits affected anti-predator behaviour. This could be due to a few different things: one possibility is that boldness and shyness in Asian house geckos has a hormonal basis. It could also be that "personality" in geckos develops based on experiences rather than any specific physiological or performance trait. To discover the answer to this question, further research into the interactive effects of such traits on personality needs to be done.

One of my geckos in his metabolic chamber. I did all my metabolic tests during the day (when they are least active, being nocturnal animals) so I could get an accurate estimate of their resting (standard) metabolic rate. Image credit: Amanda Niehaus.

Anyway, why does it all matter – why does "personality" even exist?

The fact is there are costs and benefits to being both proactive and reactive. Proactive individuals are bolder and more aggressive, so they are usually better at holding territories and getting laid – but they're also a lot more conspicuous to predators, so they tend to "live hard, die young". Reactive individuals, on the other hand, might not have the best real estate or as many mates at any given time, but their shy behaviour means they usually live longer. So, if we imagine an ecosystem where predation is low, it's better to be proactive and reap the benefits without the risk of being eaten. But if the ecosystem changes (for example, a bunch of predators move into the neighbourhood) and all the proactive guys die off – who is left? This is the most popular theory as to why different personalities exist; so that if conditions change quickly, some individuals survive and the population continues.

Although extremely interesting, these personality experiments were only one small aspect of my honours project, which aimed to answer questions about fighting ability (resource-holding potential) and fighting strategies. More on that later!

- by Rebecca Wheatley

Bit of a teaser for the rest of my project. Image credit: Amanda Niehaus.

What Determines Gecko Fighting Performance | An Honours Project by Rebecca Wheatley

This is Rebecca. She just submitted her Honours thesis, and is probably chilling with a vodka lemonade on a beach somewhere. Or else she's wishing she was.

A couple months ago, I asked Bec to describe her thesis - and to show me the experiments she had running. Here's what she said:

My research is using Asian house geckos as a model to answer questions about how morphology, performance, metabolic rate and personality interact to affect fighting ability in animals.

Rebecca's work is exciting because few studies have evaluated how morphology (or body size | shape), physiology, and personality work together to determine animal performance.

And can animals really have personalities? Of course, but not like you and I do. In the non-human world, personality can refer to repeatable differences in behaviour among individuals. For example, some individuals consistently tend to be shy, and others tend to be bold. Boldness | shyness is important for animals, as it can determine the likelihood of obtaining food or mates, or getting captured by predators.

When I caught up with Rebecca, she was measuring geckos' metabolism in purpose-designed jars, which were hooked up to specialised equipment that measures oxygen consumption. Oxygen consumption is one way that scientists assess metabolic rate in animals in the lab.

Collecting data on gecko metabolism

Rebecca was also video recording interactions between randomised pairs of geckos. Asian house geckos are aggressive little lizards, and will sort out dominance via displays of their open mouths, biting, and | or chasing. In her thesis, Rebecca looked at which animals were likely to be dominant, and whether that depended on their metabolism, morphology, and | or personality. 

collecting data on gecko fighting

And what did she find? The oversimplified version is that bite force, body mass, and running speed were most important in determining gecko dominance. Big, fast, hard-biting geckos were likely to be winners. The surprising thing was that metabolism and boldness didn't seem related to fighting performance.

There's a lot more to Rebecca's research: she used all the information she collected on morphology | physiology | behaviour to test important ecological theories about how individuals should interact (known as game theories). But we'll talk more about that another time - we don't want to give away everything just yet.

Thank you Rebecca, for taking the time to share your honours work with us, and for being such a wonderful labmate!

written and photographed by Amanda Niehaus, PhD

Fieldwork, Groote Eylandt, NT

Leaving Darwin, the propellers outside hummed loudly (reassuringly). We pressed our noses to the windows, looked out on the wild top coast of Australia. The fires lit by thousands of years of tradition. And then, we were there. Over the mines, into the red dirt.

the GEMCO manganese mine

the GEMCO manganese mine

On the deck with Jennifer and her niece; with Chopper; with MacBook Pro

We drove east to Umbakumba then headed into the bush on sandy tracks. We set up tents on top of a berm, feeling {relatively} safe from water-borne crocs and collected firewood from the beach. We watched a heavy moon pull itself up into the sky.

Picnic Beach, Groote Eylandt | Jaime and Eddie set out, bait, and mark quoll traps

Under Jaime's guidance, we set out traps for quolls, hoping to catch at least a few to obtain measurements and hair samples.

We caught 4. Plus a few bandicoots. It was good enough for Jaime to get her samples, and good enough for me - these were the first wild quolls I'd seen.

 

It was only a week ago we got back from Groote Eylandt. What a special place. Wild, and raw, and special. An island of contrasts, between a traditional culture and a modern mining industry. An island with a lot of crocodiles.

It was my first trip up, and Nelle came along. We met the Rangers and friends and family and Gavin and Kerry and the rest of the team and Alex-from-Stanford. We drank tea on the deck at the Ranger station, and packed up everything {but petrol} for a quoll-catching venture to the east side of the island. {Former labmate} Billy was appointed Ranger Coordinator. We learned our first Anindilyakwan words. We entertained Nelle, and learned the value of ABC for Kids downloads {and PhD students}.

A quoll curled up in its very own, custom-made pillowcase | fishing for dinner

We were almost as successful catching fish ... the ocean here teems with them {apparently} but we didn't have much luck. Three fish only made it into our bellies.

That's ok. We had plenty of patience ... and potatoes. 

- written byAmanda Niehaus

Crabs will fake it to avoid a fight

Crabs will fake it to avoid a fight, research finds Dr Robbie Wilson, Head of the Performance Lab at UQ, where this study was conducted, said the research identified more than just some crabby behaviour. “This study is important because it reveals the general principles behind how liars and cheats are controlled and encouraged in nature.“Whether it's a soccer player diving to fool a referee or a crab trying to intimidate a rival with weak claws, our lab has shown that individuals cheat more when their deception is likely to go undetected,” Dr Wilson said.

Ms Candice Bywater who is finishing her PhD on fiddler crabs, said that she found that more males bluff their way through fights when they are less likely to get caught.

“When there are lots of crabs living in one area, there is lots of competition for resources like females and food. High competition means there is a greater chance of males having to fight each other to win resources compared to when there are not many crabs about. Those crabs might not have to fight at all,” Ms Bywater said.

“Crabs that have strong claws will generally win fights. Producing large and strong claws is important to their survival.

“Where crabs are likely to have to fight a lot, the crabs are producing large, strong, reliable claws. We found that when there are not many other male crabs in a population (low competition), males produce large but relatively weak claws (unreliable), as they don't have to fight as often and ultimately because can get away with it."

In nature, signals may be behavioural, as in growling or posturing, but are often structural, including the antlers of a deer, and the enlarged fore-claw of many crustaceans.

A male that overstates his quality could improve his ability to gain food or mates, but surprisingly, most signals are honest reflections of a male's prowess.

Written by UQ Media

Adaptation + Acclimation

Most animals live in environments that vary on some scale - temperatures change daily and seasonally; salinities change with rainstorms; even water levels change with the tides. Organisms must be able to respond behaviourally and physiologically to these changes in their environment, to maintain high levels of performance that keep them alive and reproducing.

In my lab, we study how changes in temperature influence animal performance. We focus on temperature because it varies naturally over days and months, and now with global climate change, over years as well. Human developments also affect temperature at a local scale - creating urban 'heat-islands' that get - and stay - hotter than surrounding areas. Understanding how animals respond to temperature is key to their conservation.

What is acclimation?

Acclimation is a general term for the physiological changes that occur in organisms in response to changes in the environment. Fundamentally, it's assumed that these changes allow performance to be enhanced - or at least maintained - in the new environment. Acclimation can be measured at many different levels, from whole-animal performance down to biochemical reactivity rates; and looking at multiple levels within a study allows us to get a complete picture of how animals deal with environmental change within their lifetimes.

What is adaptation?

Adaptation refers to genetic changes that occur across generations or among populations, in response to long-term changes in climatic conditions like temperature.

Why are adaptation and acclimation important?

Global climates are changing, and conservation of species depends on understanding how they will respond to these changes both in the short- and long-term. Our research examines the behavioural and physiological changes that animals make when temperatures change, the heritability of acclimation abilities among generations, and the difference in thermal tolerances and physiology among spatially-variant populations of the same species.

Our aims in this field

We want to understand

  • how performance relates to temperature
  • how behaviour and physiology are modified in new or changed environments
  • whether these modifications are heritable
  • how populations differ in the ability to adjust to new temperatures

Games + Strategies

What are games?

Two Tone Fiddler Crab - Andrew Mitchell

Two Tone Fiddler Crab - Andrew Mitchell

In the the fields of ecology and evolution, games refer to strategic decisions made by individuals or strategic adaptations made by genomes (respectively) to maximise survival and/or reproductive output. Usually, games refer to some sort of conflict, physical or otherwise.

In nature, organisms may:

  • compete with others to gain resources or mates;
  • evade predators; 
  • capture prey; 

and the formula for optimal success in life may differ between males and females, or even between parents and their offspring. All of these conflicts can be thought of as games or strategies, modeled using mathematical algorithms, and tested in natural systems to better understand how organisms use behaviour and physiology to get the most out of life.

Understanding deception

In my research group, we focus on the behaviour and physiology associated with deception. You might imagine that individuals could enhance their survival or reproduction by pretending to be better performers than they actually are - but in reality, deception is surprisingly rare in nature. We believe this is because deceptive individuals that get caught are punished severely, either physically or socially, resulting in a dramatic reduction in reproductive and/or lifespan potential.

Most of our work focuses on the physical performance among crustaceans, which are among the few animals to routinely use deception; crustaceans may use their enlarged claws to battle for dominance (and access to mates or resources), and our work has shown that claw size - which is used as a signal of strength - is not always an accurate indicator of actual strength. Though crustaceans with large-but-strong claws are likely to dominate, some individuals produce large-but-wimpy claws and seem to get away with it. How does this happen? Does the pattern of deception vary among populations, sexes, and species?

Why is this important?

Using our crustacean model, we are testing theoretical questions about the environmental and social factors that promote or limit deception in nature. Because we're testing general models, our work can be applied not only to crustaceans, but to all animals, including humans.

Photo: Anthony O'Toole

Photo: Anthony O'Toole

In fact, we're building on our research on crayfish and fiddler crabs to examine deception in human sport; specifically, diving in soccer. Our work is also relevant to other fields like economics, political science, and psychology.

Our aims in this field

Our work on deception will enable us to:

  • better understand the use of deception in animal communciation
  • advise sports authorities in ways to reduce deception in games
  • enhance game theoretic models

How to fight dirty

If you're a crayfish, your best bet is probably to grow an intimidatingly-large claw ...but pack the muscle (i.e. punch) into the other claw.

Many animals - like crayfish - signal their fighting prowess by displaying specialized limbs, musculature, or weaponry to others. In signaling, bigger is often better; but in a fight, rivals could gain advantage by concealing their real strength in less conspicuous limbs.

Cryptic asymmetry occurs when differences in limb strength are unrelated to differences in limb size, and was previously considered only in primates; however, we found asymmetric strength in males of the slender crayfish, which use their claws in display and combat. 

Photo: Anthony O'Toole

Photo: Anthony O'Toole

In a paper just published in Biology Letters, Robbie and collaborator Mike Angilletta suggest that asymmetric strength could be used to confuse rivals and influence the outcome of fights.

(look over here... look over here... ) WHAM.

Big News at the Moment - Feb 2012

1. Robbie got his 69th publication, and for some reason thought that was funny.

2. Candice returned from the US, jet-lagged and culture-shocked. We've missed her.

3. Billy's still ... somewhere?

4. Jaime's officially started her PhD, and taken up the last desk in the Fun Zone.

5. Another of Candice's PhD papers just got accepted for publication! This one's:
Bywater, C & Wilson RS. 2012. Is honesty the best policy? Testing signal reliability in fiddler crabs when receiver-dependent costs are high. Functional Ecology (in press Feb 2012)

6.  Robbie decided it was time to get married. To me.

And that's February, 2012!

The Scent of a Predator (Well, Kind of)

The following article is adapted from a talk presented by Jaime Heiniger at SICB 2012, along with coauthors Billy Van Uitregt and Robbie Wilson. The original talk was called: "Fine tuning anti-predator responses: are the costs of inducible predator defences proportional to the magnitude of the responses?"

***

For amphibians, it's a mad, mad world. And - importantly - an unpredictable one. Natal pools might contain predators, or not; competitors, or not; food, or not; and conditions can change every day. As a result of all this unpredictability, many amphibians can alter their appearance and behaviour in ways that increase their likelihood of survival. But these defensive strategies usually come at a cost - slower growth, higher metabolic requirements, and smaller size at maturation are just a few common outcomes.

toadlets in the lab

To maximise the benefits and minimise the costs associated with predator defense, it's predicted that the magnitude of the defensive response should reflect the magnitude of the threat. Thus, more threat = more phenotypic change; and less threat = less phenotypic change. This is known as the threat-sensitive predator avoidance hypothesis (TSPAH), and although it's known that prey can fine-tune their responses to the degree of predation risk, it's unclear if the magnitude of threat-sensitive defensive responses relate to their associated costs.

{Jaime} tested this idea by examining the effects of increases in perceived predation risk on the expression of defences and their associated costs in larvae of the toad, Bufo marinus. She reared tadpoles in varying concentrations of predation cue* and quantified their growth, morphology and development, as well as metamorphic size, locomotor performance and oxygen consumption.

*for those curious, predation cue is actually water from around deceased tadpoles. Tadpoles are sensitive to the smell of their dead mates. (Aren't we all?)

taddies in the lab

{Jaime} found that tadpoles responded to increases in perceived predation risk by gradually decreasing their activity.

As a consequence of their more-sedentary lifestyle, individuals metamorphosed later, smaller and with reduced endurance. Toads that emerged from the different treatments didn't vary in maximum jumping distance but those from 'high predation' treatments metamorphosed with longer relative hind limbs - meaning they could jump farther for their body size.

jaime's metamorph habitats

 These are interesting results, because they show that
a) toads produce defenses that are proportional to the perceived threat
b) defensive behaviour is costly
c) the costs are in proportion to the amount of defense
d) but phenotypes produced in response to predation threat may aid the individual.

Cool stuff, Jaime!

Why Be Fake? Because Honesty is Too Expensive ...

In earlier posts, we've talked about the life of a crab ... and about the predisposition for some crabs to fake how strong they are. At SICB in January, Candice presented a talk detailing why exactly it pays to be weak.


image by Dan Hancox
Here's my recap on Candice's talk ...
Crustaceans are violent types, posturing and fighting for territories, mating partners, and resources. Because claws are such excellent weapons, fights are often decided by the individuals merely checking each others' claws out. Bigger claws = dominance. This ameliorates the risks associated with claw-battle, while still deciding dominance.


But Candice has found that the size of the claw is not always indicative of its strength - namely, some individuals are fakers. You see, claw muscles - which are used to clamp and tear in a fight situation - are hidden inside the chitinous claw. So a big-clawed crustacean might just lack big muscles underneath, meaning it's more likely to lose if the interaction escalates into a fight.

So why wouldn't a crustacean just grow the muscle? This is what Candice wondered. She noticed that crabs with re-generated claws tended to have wimpy claws, relative to their claw size. So, she measured the energy needed to maintain claw muscles in fiddler crabs with strong, original claws as well as crabs with weak, regenerated claws.



Candice believes that dishonesty in fiddler crabs is related to metabolic costs - namely, how much energy is required to keep that muscle active. Crabs with strong, original claws spent ~22% of their metabolic energy budget on their claw muscle - pretty close to the amount of metabolic energy humans use to support our large glucose-hungry brains.

In contrast, crabs with weak, re-generated claws used only ~12% of their daily energy on claw muscle.

That constitutes a massive energetic savings for fakers, unless they get caught ...

CB in DC

At this precise moment, Candice is working at the Natural History Museum in Washington, D.C. - measuring crustacean claws as part of a study for her PhD.


Or, she might be sleeping. (I can never get those time-differences right ... )

At any rate, this is her lovely little brownstone ...


She's even famous now, in a "The Lost Symbol" kind of way, toiling away in the crustacean collections in Pod 5* at the Museum Support Centre (MSC), a high-security warehouse in the sketchy part of town.

*The same section of the warehouse featured in Dan Brown's book ... in case you haven't read it yet.
 

And how does Candice spend her days in DC? She's on the bus at 7:30, heading to the Natural History Museum in downtown DC, where she catches the shuttle to the warehouse facility where the crustacean collections are housed.


In to her little lab in the wet collections rooms by 8:30, she starts taking photos of crab claws and measuring the sizes of the shell and legs - for different specimens and different species. It sounds like quick work, but given she has to take 3 measurements of each crab leg (and each crab has 8 measurable legs), she may just be there ... all year.


Not really. But I'm sure that's how she feels sometimes. 10-15 minutes per crab x a warehouse full of crabs = significant porters needed at the end of the day.


Candice measures claws on her own, but has lunch with the other 10-15 researchers who work at the warehouse measuring, cataloging and sorting other types of invertebrates. They all chat and sometimes have science talks, so it's been a great way to meet everyone else.

Then it's back home again, to forget about claws for 12 hours or so.


And why is she doing all this? Candice is looking for tradeoffs between claw size and other morphology among different crustacean species - compensatory mechanisms (like we just learned about with geckoes). We'll talk more about the science after she gets back.

(all the pictures in this post were provided by Candice. Thanks!)

Trade-offs in Gecko Design

Sounds glam, right? Gecko design?

At the 2012 SICB in Charleston, Skye presented research that shows how traits that improve bite force in geckos have negative impacts on the gecko's sprint speed. Meaning that males who are better fighters might also be less adept at escaping predators ...

Costly design indeed.


Let's learn more by having a look at Skye's abstract, with {comments in brackets from me}.


Trade-offs and compensatory traits: bite force and sprint speed pose conflicting demands on the design of male geckos (Hemidactylus frenatus)
by Skye Cameron, Melissa Wynn and Robbie Wilson

The evolution of exaggerated ornaments and armaments is driven by the benefits accrued to reproductive success and by the costs imposed on viability. {This means that} when traits are required to perform multiple functions that are important to both reproduction and viability, trade-offs can result in a compromised phenotype.

{Imagine, for example, a species of bird in which females are more likely to mate with males that have larger tails; but males with larger tails are more likely to be captured by predators. Both reproductive potential and survival are important to the male - so evolutionarily, the bird may end up compromising on tail length to make sure he both reproduces and survives.}

image

{Intuitively, we expect that exaggerated male traits (like super-long tails) would decrease locomotor capacity, resulting in lower survival rates due to predation.} Despite only mixed empirical support for such locomotor costs, recent studies suggest these costs may be masked as a result of the evolution of compensatory mechanisms that offset any detrimental effects.

{What are compensatory mechanisms? Imagine if that bird with the long tail-feathers developed longer wings, that enhanced its flying abilities. It might offset some of the survival costs of the long tail.}

In this study, {Skye} provides a comprehensive assessment of the importance of potential locomotor costs that are associated with improved male-male competitive ability by simultaneously testing for locomotor trade-offs and compensatory mechanisms. For males of the Asian house gecko (Hemidactylus frenatus), both fighting capacity and escape performance are likely to place conflicting demands on an individual’s phenotype.

image
Males that are highly territorial and aggressive are more likely to require greater investment in jaw size/strength in order to compete with rival males; {Skye} found that males with larger heads had stronger bites and showed greater prey-capture and fighting capacity. This performance trade-off was amplified for male geckoes with larger heads when {they were} sprinting up inclines.

image
{So, what does this mean? Geckoes with large heads are better at fighting and better at capturing prey, but may be worse at evading predators themselves. A compensatory mechanism would be something - like longer legs - that would enhance their ability to avoid predation.} {However, Skye} found little evidence for compensatory mechanisms that off-set the functional trade-off between bite force and sprint speed.

Ongoing work in this area includes testing the survival of male geckoes with different sized heads in controlled-but-natural conditions.

Bigger *is* Better: Phallus size and male physical performance across temperatures

The second presentation we'll discuss is Robbie's. Robbie's talk - though sadly fraught with technological difficulties - conveyed to the audience the answer to that age-old question:
does a bigger phallus actually mean the male is better?

I won't give away the ending just yet, (or maybe I will ... ) - in mosquitofish, anyway - the answer seems to be yes.




Bigger is Better in all environments: temperature-induced variation in phallus size is a reliable indicator of male physical performance and gamete quality

Males of many organisms possess elaborated structures that are used to engage in fights with other males and/or to attract females during courtship. The size and elaboration of these secondary sexual traits can be affected by the environment via its influence on the condition of an individual male. This link between male condition and the elaboration of male sexual signals is one of the most important mechanisms maintaining the reliability of these traits as signals of male quality.


male elk use extravagant antlers to battle for females

The role temperature plays in mediating the condition of individual males and the size and elaboration of their sexually selected traits is currently unknown. Males of the eastern mosquitofish (Gambusia holbrooki) possess a modified anal-fin phallus (gonopodium) that is used as both a signal of dominance and a stabbing weapon during male-male competitive bouts {as well as to fertilise females}.

image

{Robbie} examined the effect of temperature on the size of this putative sexual signal (phallus size) by chronically exposing males to either 20° or 30°C for four weeks. {He} also tested the influence of these thermal environments on various measures of male quality; including male territorial performance, swim speed and gamete function.


Males chronically exposed to 30°C possessed longer phalluses, greater ejaculate sizes, larger testes and faster sperm swimming speeds than those exposed to 20°C. This is the first study to show that environmental variation in phallus size can be a reliable indicator of male physical performance and gamete quality.

{And what does this mean, and why does it matter? Well, it means that mosquitofish may have higher reproductive outputs in warmer environments, and might do even better than they currently do when climates warm further. In Australia, mosquitofish are invasive and by out-competing and eating eggs and young of natives, they are aiding the decline of native fish populations.}

Not good. Who knew that global warming would increase phallus sizes ...