Mate Choice and Parasite Resistance

posted Jun 19, 2019, 7:51 PM by Bruno Buzatto   [ updated Jun 19, 2019, 7:55 PM ]

For a few years now I have been involved in a unit at the University of Western Australia that consists on short research projects that get conducted individually by the students. This is not a mock exercise, but an actual research experiment that generates valuable data, and my publication with Kyana Pike (JEB, 2017) was the first one generated from one of these projects. This week I just published another paper (in Behavioral Ecology) that was half generated by a project in that unit.

Together with Larissa Assis, a student who took the unit in 2017, Leigh Simmons and I investigated female preference for male dung beetles who have higher parasite resistance. We did a cool little switch in the usual design of such experiments, and tested female preference for different males first, and then investigated their resistance to parasitic mites, in order to disentangle female choice based on the males' history of parasitism, but instead focus on whether females can assess the males' resistance to parasites per se. And we found that they can (no idea how!)!.

In the figure you can see that males who (later) had more mites (therefore they are less resistant) mated for longer with females. The order of the mating trial (first) and the experimental exposure to parasites (second) is not without problems (we discuss them in our paper), but we think we might have shed some new light on the problem. If females are in control of copula duration, and if that impacts the fertilization success of males (reasonable assumptions in my opinion), then we showed female choice for parasite resistance per se, which is cool and supports the parasite mediated sexual selection (PMSS) hypothesis by Hamilton and Zuk (1982).

Importantly, we also added data collected years ago by Janne Kotiaho (another author on the study) on the heritability of parasite resistance in these beetles, which showed strong heritability — another important assumption of the PMSS hypothesis!

My new "lab" at full steam!

posted Jun 4, 2019, 5:02 PM by Bruno Buzatto




I haven't posted anything here for quite a while, which is a reflection of how busy I get in the first semester while I am convening the unit "Organisms to Ecosystems" for over 240 students here at Macquarie University. However, if at one hand that unit has been keeping me super busy, it has also allowed me to expose my mite research to the great cohort of first year students here at MQ, which resulted in recruiting a number of fantastic volunteers to my group!

At the moment I have my research really picking up and starting to go at full steam again after my initial phase of adaptation to a new university and the whole slowing down in research due to moving from WA to NSW as well. And it's only picking up right now because of two vital things: (1) Macquarie Uni granted me a New Staff grant, worth $18K, with which I've been buying new research toys (like the microscope in the photo to the right) and (2) my army of amazing volunteers, with special thanks to Niah Delamotte, Pouya Zadbar, Daniel Allman, Betty Huang and Ryan Cuthbert. My New Staff grant also allows me to pay Joshua Hobbs (a second year undergrad) and Poncho Aceves (one of Mariella's PhD students) to do research assistant work for me, and together these 7 people have been absolutely crucial for my research to keep moving — massive thanks to you guys, you absolutely rock!! If I get a Nobel Prize I will share the money with you, I swear!

Fellow of the HEA

posted Feb 21, 2019, 11:23 PM by Bruno Buzatto   [ updated Feb 21, 2019, 11:25 PM ]

Last week I was granted the status of Fellow of the Higher Education Academy (an institution now known as Advance HE), which means that my teaching practice has been recognized as achieving the UK Professional Standards Framework for teaching and learning support in higher education. I am absolutely stoked with this awards, as it's the first official recognition of my teaching skills in higher education. This also allows me to use the postnominal FHEA after my name, which looks very serious and important! 

Getting this fellowship was not easy, and involved attending workshops, being trained in writing reflective accounts of my practice, and finally submitting a 3,000 application to the HEA. But it was a fantastic experienced, I learned a lot, and I hope it's just the first of my accomplishments as a university lecturer. Also, Macquarie University keeps a page with the record of their staff holding these fellowships (here), and I am happy to see my name already in there under the Faculty of Science and Engineering tab.

The importance of function for allometry

posted Sep 9, 2018, 9:03 PM by Bruno Buzatto   [ updated Sep 10, 2018, 7:52 PM ]

The Quarterly Review of Biology has just published a paper that I am really honoured to be part of, entitled "Sexual Selection and Static Allometry: The Importance of Function". I was invited to be part of this work by the first author William Eberhard, who has had an invaluable impact on my career from the very start — I met Bill at an arachnology conference when I was still an undergrad (2003 I think), and he was extremely supportive with me in the poster session, giving me a lot of advice and insight into the work I was presenting in that poster. Not to mention Bill was incredibly influential for the fields of cryptic female choice (after Randy Thornhill 'started' it), allometry of sexually selected traits and evolution of alternative mating tactics. So you can imagine how honoured I felt when invited by him to contribute to this paper on the importance of function to predict the allometric slope of sexually selected traits — we argue that such allometries can be better predicted if we split them into courtship traits, threat signals and weapons. We expect positive allometry to be common for threat structures (which might include weapons), but less common for male courtship signals, and we provide evidence for these predictions. Some of my observations presented in that poster in 2003 were included in this work, and were the main reason to trigger my participation. If you want to know more about this paper, check it out here.

Morph specific selection in Proc B

posted May 24, 2018, 12:38 AM by Bruno Buzatto   [ updated May 24, 2018, 12:40 AM ]


Today Proc B published a paper I wrote with Huon Clark and Joe Tomkins (both at UWA) about our ambitious artificial selection experiment with the mite Rhizoglyphus echinopus. The experiment ran for about a year and a half, so we put a lot of our work (and lives!) into that experiment. The goal was simple — I wanted to test whether selection acting exclusively on one male morph (males of this species can conditionally be one of 2 morphs: fighters or scramblers) would affect the evolution of the other morph. Phenotypic plasticity theory predicts some level of developmental decoupling between morphs, and therefore potential for independent evolution, but we suspected the story was a bit more complicated than that. So we imposed selection for thicker (and thiner) legs on 6 lines of mites, always applying selection to fighter males only, focusing on their fighting legs.


After 9 generations we found that scrambler males (and females!) presented correlated evolution in the same direction as shown by fighters. This is not very surprising, as we already knew there were genetic correlations for this trait between male morphs and sexes. However, our approach is a powerful demonstration of a genetic constraint for the evolution of dimorphisms (between sexes and morphs), and goes one step beyond predicting correlated evolution through genetic correlations — we showed that correlated evolution in the lab! Now we know that, despite these constraints, the morphs did evolve (prior to the experiment!) very different morphologies, so what we demonstrated just shows that somehow male morphs overcame the genetic constraints (that are truly there!) to evolve divergent morphologies. But now we need to figure out how!









Move to Macquarie University!

posted Feb 11, 2018, 10:07 PM by Bruno Buzatto   [ updated Feb 11, 2018, 10:09 PM ]


I am extremely happy to announce that I just moved to Sydney to take a lecturer position at Macquarie University! I really wanted to announce this here and in social media a bit earlier, but the last few weeks have been so busy with the move that I am only 'pausing' to breathe and do 'less urgent' stuff now... After a long drive across the country (done in 9 days!), I am in Sydney for just over a week now, and currently in my second week here at Macquarie Uni. The place is amazing and the people fantastic, so I am sure this will be a great personal and professional experience. Macquarie Uni is beautiful and has an amazing infra structure, and Sydney is incredibly green (and hilly when compared to Perth!).

I already dearly miss Perth and all the amazing friends I have on the west side of the country, where I had the honour and pleasure to be part of the Centre for Evolutionary Biology at UWA for almost 9 years! But who knows, maybe I'll be back one day — my contract at MQ goes till mid-2019, so I'll be back to the job market after that. For now I hope I can make the most of this amazing opportunity here at Macquarie. By the way, I think there will be plenty of scuba diving, rock climbing, hiking, kiting, sailing, and kayaking to do around here as well ;)

Intralocus tactical conflict in JEB

posted Jun 12, 2017, 11:35 PM by Bruno Buzatto   [ updated Jun 12, 2017, 11:37 PM ]

The latest issue of the Journal of Evolutionary Biology features an article by Kyana Pike, Joe Tomkins and myself on a topic that I am fascinated about — the evolutionary conflict between different male phenotypes. In some species, alternative male phenotypes are linked to different tactics for securing matings, where large male morphs express weapons used to defend females or territories (like the thick legs of bulb mites or the forceps of earwigs displayed on the left), whereas small male morphs have reduced weaponry and sneak copulations. In these systems, theory predicts that the evolution of male dimorphism is facilitated if morphs are genetically uncoupled and free to evolve towards their phenotypic optima; however there is little evidence for male morphs responding independently to selection.


One way of investigating the potential for independent or correlated evolution between male morphs is by using quantitative genetics to estimate
the heritability and the intrasexual genetic correlations (between male morphs) of dimorphic and monomorphic traits, and comparing them. We did that with two different model systems, and found two contrasting patterns: earwigs exhibited low intrasexual genetic correlations for the dimorphic trait, suggesting that the conflict between male phenotypes is moving towards a resolution. Meanwhile, bulb mites exhibited high and significant intrasexual genetic correlations for most traits, suggesting that morphs in the species may be limited in evolving to their optima. It is surprising, however, that intrasexual dimorphism can evolve to be so evident in this system, despite such strong genetic constraints.

Another very cool aspect of this project is that it emerged from a short project in the unit 'Evolutionary Biology', here at the University of Western Australia. The lead author, Kyana, was at the time doing her honours at UWA with magpies, but Joe and I 'highjacked' her talent and hard work to our bulb mite project, and the result was this beautiful paper!

Benefits of polyandry in Molecular Ecology

posted May 12, 2017, 2:08 AM by Bruno Buzatto   [ updated May 12, 2017, 2:09 AM ]

Molecular Ecology just published a paper on dung beetles that Erin McCullough (the lead author), Leigh Simmons and I conducted here at the University of Western Australia. In a nutshell, we collected mated females of the dung beetle Onthophagus taurus from the field, allowed them to breed (make brood balls and lay eggs) in the lab, and then genotyped their offspring and used microsats (thanks to Erin's amazing molecular skills!) to estimate the (minimum) number of males each female mated with, and their relative fertilization success in each clutch. We found that females of the species are highly polyandrous (88% of them were, some having mated with at least 5 males in the field!!). We also found significant paternity skew (some males sired more offspring than others), suggestive of sexual selection in the field. Finally, the coolest thing was that paternity skew (the amount of sexual selection) was correlated with the number of offspring produced, suggesting a benefit of polyandry and a benefit of sexual selection! Dung beetles are just the coolest...

Conditional trimorphism in the J Theor Biol

posted Mar 22, 2017, 12:03 AM by Bruno Buzatto   [ updated Mar 22, 2017, 12:04 AM ]

A few years ago, my interest in male dimorphism led me to a collaboration with professors Mark Rowland and Clifford Qualls, from the University of New Mexico. Our collaboration had the purpose of putting forward a model for conditional trimorphisms, which is an extension of the 'environmental threshold model' from quantitative genetics, designed to account for trimorphisms with two thresholds, and compatible with the 'rock-paper-scissors model' of evolutionary game theory. Unfortunately, I was devastated to hear that Mark passed away in early 2015, at the very start of our collaboration. Publishing this paper then became a mission where Clifford and I joined forces (Clifford on the side of the maths, and myself with the evolutionary biology perspective) to make sure Mark's ideas would be published and available in the literature for anyone working on the rare but incredibly interesting cases of trimorphism in nature. The Journal of Theoretical Biology has just published this paper, and you can find it here.

Multiple male spawnings in a frog

posted Feb 14, 2017, 1:52 AM by Bruno Buzatto

This month's issue of Evolution features my latest paper on sperm competition in the Australian quacking frog Crinia georgiana, which I co-authored with Evan Thyer, Dale Roberts and Leigh Simmons. For this paper we video-recorded over thirty multiple male amplexus in this species, and then collected the offspring for molecular paternity analyses. We found that amplexus time and position were very important for fertilization success of males under competition (amplexing dorsally resulted in higher success!), and that testis size also had a positive effect on fertilization success, but only for males amplexing the female in the ventral position. It seems that in this species larger testes are an advantage in high population densities, where more multiple male spawnings occur and where males more commonly end up in a non-ideal amplexus position, such as holding on to the female in a ventral or lateral position.

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