Follow this link for a recent paper from the Shuker lab (University of St Andrews) examining the genetics and fitness consequences of a pale mutation in the normally brightly-coloured seed bug Lygaeus simulans. I was involved in the early stages of this project, generating initial pure-breeding populations of the pale morph, but Vicki Balfour has done the hard work figuring out all the rest!
A piece I wrote about my research is now available on the Leverhulme Trust website, in the grants in focus section (link here). The piece gives a very brief overview of my current research focus- context-dependent mate choice.
This week one of my X-Ray micro-CT images of mating seed beetles was published in Molecular Reproduction and Development, in the VISIONS: the art of science category. This image has not previously been published in a journal article, though it was made at the same time as those seen in my recent Proceedings B paper.
The image is of a mating pair of seed beetles flash-frozen during mating. In this reconstruction, the cuticle was made semi-transparent in order to visualise the internal anatomy. Notable structures include the highly-stained leg and wing muscles in both sexes, as well as the female reproductive tract (the circular structure inside the female abdomen) with the male sperm package being deposited.
This week my collaboration with Lauren Guillette from the University of Alberta has just been published online here (and see the publications page for a pdf). In the paper we use meta-analysis to test whether there is a relationship between learning ability and several personality traits (including boldness, exploration, aggression and sociability) across a range of animal species (though mainly fish, birds and mammals). The work is part of a special issue called: ‘Causes and consequences of individual differences in cognitive abilities’, which includes 14 other empirical and review papers on a range of topics relating to animal cognition. They're all worth a look!
This week I attended the European Conference for Behavioural Biology in Liverpool. The conference was great; there were plenty of good talks and I met some very interesting people! I also presented a poster (see below), describing the results of an experiment using the Indian meal moth I have been running for the last few months.
I'm very excited to have been awarded an Early Career Research Fellowship from the Leverhulme Trust and the Institute of Integrative Biology at the University of Liverpool. I'll take up the fellowship in September 2018, and I plan to use meta-analysis to examine which physical and social factors influence mate choice across animals. I can't wait to get started!
I have recently begun a postdoctoral position at the Institute of Integrative Biology at the University of Liverpool, UK, based in the lab of Dr Zen Lewis. I will be carrying out a project examining whether male mate choice evolves in response to changes in the population sex ratio, using the Indian meal moth Plodia interpunctella. The Lewis lab has been maintaining meal moth populations under experimentally altered adult sex ratios for 130-140 generations, thus providing an excellent system for examining the extent to which mate choice evolves in the lab. This work is funded by a research grant from the Association for the Study of Animal Behaviour (ASAB).
This month has also seen the publication of another paper of mine (in collaboration with Leigh Simmons), again in Proceedings B, but this time using micro-CT to examine the timing and location of female copulatory wounding in Callosobruchus maculatus. For this project I performed micro-CT scans of 19 mating pairs of C. maculatus that had been flash-frozen in liquid Nitrogen at different stages of mating. We then used these scans to examine the interactions between male and female genitalia during mating, and visualise these interactions in unprecedented detail.
Importantly, we were able to use the scan data to detect copulatory wounding of females without having to wait for an immune response, which is needed when assessing wounding using a light microscope. We could therefore use the micro-CT technique to examine how tract damage accumulates during mating, and how the timing of damage relates to female mating behaviour.
This paper is also a showcase for the power of micro-CT to aid our understanding of reproductive behaviour and morphology, and I hope it inspires more people to use this technique in the future!
Please follow this link, or the relevant link on the publications page, to read the full paper.
I'm very excited to say that my newest paper was published online a few weeks ago in Proceedings B, looking at sexual conflict in the seed beetle Callosobruchus maculatus. This is the first paper from my work at UWA, and is the result of a collaboration with several researchers at UWA (Emile van Lieshout, Kathryn McNamara & Leigh Simmons) as well as Göran Arnqvist at Uppsala University. The project benefitted especially from the use of C. maculatus lines that Göran has been maintaining at Uppsala for many years.
In the paper we show that there has been correlated evolution between the size of the male penis spines and three defensive female adaptations (the thickness of the female reproductive tract lining, and two measures of female immune activity), across 13 C. maculatus population that have been isolated in the lab for over 100 generations. Importantly, we also show that the amount of copulatory wounding females receive during mating is related to the relative thickness of the female reproductive tract in relation to male spine length (as shown in the image below). This is strong evidence that males and females of this species are locked in an evolutionary arms race driven by sexual conflict.
Follow the link here to read the paper, or go to the publications page for the pdf.
A few months ago I wrote here about my work using X-Ray micro-CT to study the coevolution of male and female genitalia in insects. I also used that post to present some early images of the male and female genitalia of the seed beetle Callosobruchus maculatus I made from those scans.
In this post I would like to present some more CT images, but focusing on a different species: the Indian Meal Moth Plodia interpunctella. This time we are looking at the interaction between the region of the female reproductive tract where the male deposits his sperm (known as the bursa), and the structure containing the male’s sperm, known as the spermatophore.
In several insect groups, including butterflies and moths, the male sperm is not deposited freely but is instead transferred in a discrete package known as a spermatophore. In Plodia interpunctella the spermatophore has an elaborate structure. Below is a 3d volume rendering of a spermatophore inside a female. The spermatophore has two main parts: a hollow, spherical sac which contains the sperm mass, and an elaborate chitinous neck.
The spermatophore is passed to the female in liquid form, which then solidifies and hardens during mating into the characteristic shape seen here. Inside the spherical sac are around 30 large sperm bundles, each formed of many sperm cells (see below). Once in the spermatophore has been deposited, the sperm move along the neck and out of the hole at the top.
Once the sperm has been transferred to the female the spermatophore shrinks but is not broken down by the female (see below). This is useful because it means that we can count the number of times a female has mated (either in the wild or in the lab) by dissecting out the bursa after she has died and counting the number of spermatophores present.
The female bursa is a large hollow organ into which the spermatophore is deposited. Sperm are not stored here, but instead are stored in a much smaller organ called the spermatheca. To get to the spermatheca the sperm need to be moved along a narrow duct which opens into the bursa. Surrounding the entrance to this duct on the wall of the bursa is a row or sharp teeth known as lamina dentata or signa (see below). The teeth vary in size and shape within this species.
In other moth and butterfly species these teeth are used to physically pierce the spermatophore capsule, thus releasing the spermatophore contents into the bursa. One reason why females may want to pierce the spermatophore is because the presence of a full spermatophore in the bursa may prevent the female from remating. Males generally benefit from preventing female remating as it may reduce his paternity share. Therefore one hypothesis fur the function of bursal teeth is that they allow the female to regain some control of her remating rate by speeding up the breakdown of the spermatophore. Males could then evolve larger or thicker spermatophores in response, leading to an ‘arms race’ between bursal anatomy and spermatophore anatomy.
I have been using micro-CT to examine potential coevolution between bursal teeth morphology and spermatophore morphology in the Indian Meal Moth. This work is being done in collaboration with Leigh Simmons at Kathryn McNamara at UWA, and Nina Wedell at the University of Exeter. Watch this space for news on future publications!