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Department of Zoology

 

Student Conference for Conservation Science celebrates its 20th Birthday in style

News from this site - Thu, 28/03/2019 - 12:39

"How do you think we can stay optimistic in our research when faced with so many bad news and events happening in recent years?" Inês Maria Simões Silva from Portugal asked Sir David Attenborough, he replied: "We must be optimistic - we don't have an option, we have to point out successes, and show that we are happier...

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Departmental Seminar Day 2019

News from this site - Tue, 26/03/2019 - 15:29

This year’s Departmental Seminar Day saw the department come together for its annual gathering to showcase its research on 22nd March 2019. Short talks were given from across the broad range of subjects currently researched in the department. The talks provide an opportunity for researchers, from all levels, to highlight...

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Department Administrator Vacancy

News from this site - Wed, 13/03/2019 - 16:01

After 15 years as Department Administrator in Zoology Julian Jacobs has decided now is the right time to move on to something new. Julian writes "In this time I have had the good fortune to work in partnership with three supportive HoDs. I treasure the atmosphere of collaboration and collegiality that characterizes Zoology...

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Mighty mites give scrawny beetles the edge over bigger rivals

Cam ac uk zoology department feed - Wed, 06/03/2019 - 00:00

In a study featuring a miniature ‘gym’ for beetles (complete with beetle treadmills), researchers from the University of Cambridge found that beetles who consistently lose out to members of their own species have the most to gain by forming a mutually-beneficial cross-species partnership.

The researchers studied the relationship between the burying beetle and the tiny mites that hitch a ride on their backs. The researchers found that mites function like a warm jacket on smaller beetles, and cause them to heat up when the beetles exercise. This made them more successful in face-offs with larger opponents.

For larger beetles, the mites actually reduced their level of fitness. They needed no help from mites to win ownership of a dead body and then lost out because the beetle larvae had to compete with mites for food. The results are reported in the journal Evolution Letters.

Relationships between two species where both benefit – such as flowering plants pollinated by insects – is known as mutualism. These relationships are widespread and are key to maintaining biodiversity and ecosystem function, but they are highly variable.

“When the costs of a mutualistic relationship start to outweigh the benefits, it will break down,” said Syuan-Jyun Sun, a PhD candidate in Cambridge’s Department of Zoology and the paper’s first author. “We wanted to find out if competition within species might be one of the reasons why we see such variety in mutualistic relationships.”

In competitions for food or a mate, there will inevitably be winners and losers. The Cambridge researchers wanted to test whether ‘losers’ might be more likely to have a mutualistic relationship with another species in order to gain an advantage over their stronger rivals. At the same time, ‘winners’ may not need any help to win battles, so a mutualistic relationship wouldn’t bring any advantage and might even break down into a form of parasitism.

The researchers tested this idea with experiments on burying beetles and their mites. The mites Poecilochirus carabi are benign passengers on their host burying beetles Nicrophorus vespilloides. The beetle flies around, seeking out the bodies of freshly dead small animals like mice and birds. Both the beetle and the mites onboard use the dead body as food for their young.

However, beetles face fierce competition for the ownership of a carcass, such as a dead mouse, and smaller beetles often lose the territory to larger rivals. Since the beetles need the carcass to breed, how do smaller beetles manage to reproduce?

“We wondered whether mites could give these ‘losers’ a helping hand in fights over a carcass,” said Sun. In the lab of Professor Rebecca Kilner in Cambridge, the researchers staged contests over a dead mouse between two beetles that were matched in size. One carried mites, while the other did not. They filmed the fights with infrared thermography, and found that beetles with mites were hotter and more aggressive, and therefore more likely to win.

To investigate how such thermal benefits arose, the researchers built a ‘gym’ for beetles and exercised them on custom treadmills. Beetles either carried mites, or a weight that was equivalent to the mites, or they carried nothing.

“We found that carrying extra weight caused beetles to generate extra heat as they exercised,” said Sun. “We also discovered that this heat was trapped by the mites because the mites form an insulating layer when travelling on beetles.”

These effects were most pronounced for smaller beetles because mites covered a relatively larger surface area than on large beetles, suggesting that mites are likely to be disproportionally beneficial to smaller beetles.

To test this idea directly, the researchers again staged fights between two beetles over a dead mouse. This time, the two rivals differed in body size. They also let beetles lay their eggs on a mouse, with and without mites.

The researchers found that small beetles were much more likely to win a fight for a carcass when they were carrying mites. However, the mites slightly reduced the beetles’ reproductive success, because they competed with beetle larvae for carrion. Nevertheless, the huge benefits of acquiring a carcass for reproduction outweighed these small costs. For smaller ‘loser’ beetles, mites are mutualists because they increase beetle fitness.

The findings were different for larger beetles. They needed no help to win a carcass, so they gained nothing from associating with mites. To make matters worse, they then lost fitness to the mites when they bred alongside each together on the carcass. For larger ‘winner’ beetles, mites are antagonistic rather than mutualistic because they reduce beetle fitness.

The research was funded in part by the Cambridge Commonwealth Trust, the Royal Society and the European Research Council.

Reference:
Syuan-Jyun Sun et al. ‘Conflict within species determines the value of a mutualism between species.’ Evolution Letters (2019). DOI:10.1002/evl3.109

Smaller beetles who consistently lose fights over resources can gain a competitive advantage over their larger rivals by teaming up with another species. 

When the costs of a mutualistic relationship start to outweigh the benefits, it will break downSyuan-Jyun SunBurying beetle (Nicrophorus vespilloides) with mites (Poecilochirus carabi)


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Butterflies are genetically wired to choose a mate that looks just like them

Cam ac uk zoology department feed - Fri, 08/02/2019 - 10:35
A team of academics from the University of Cambridge, in collaboration with the Smithsonian Tropical Research Institute in Panama, observed the courtship rituals and sequenced the DNA from nearly 300 butterflies to find out how much of the genome was responsible for their mating behaviour.   The research, published in PLOS Biology, is one of the first ever genome studies to look at butterfly behaviour and it unlocks the secrets of evolution to help explain how new species are formed. Scientists sequenced the DNA from two different species of Heliconius butterflies which live either side of the Andes mountains in Colombia. Heliconians have evolved to produce their own cyanide which makes them highly poisonous and they have distinct and brightly coloured wings which act as a warning to would-be predators.   Professor Chris Jiggins, one of the lead authors on the paper and a Fellow of St John’s College, said: “There has previously been lots of research done on finding genes for things like colour patterns on the butterfly wing, but it’s been more difficult to locate the genes that underlie changes in behaviour. What we found was surprisingly simple – three regions of the genome explain a lot of their behaviours. There’s a small region of the genome that has some very big effects.”   The male butterflies were introduced to female butterflies of two species and were scored for their levels of sexual interest directed towards each. The scientists rated each session based on the number of minutes of courtship by the male – shown by sustained hovering near or actively chasing the females.   Unlike many butterflies which use scented chemical signals to identify a mate, Heliconians use their long-range vision to locate the females, which is why it’s important each species has distinct wing markings. When a hybrid between the two species was introduced, the male would most commonly show a preference for a mate with similar markings to itself. The research showed the same area of the genome that controlled the coloration of the wings was responsible for defining a sexual preference for those same wing patterns.   Dr Richard Merrill, one of the authors of the paper, based at Ludwig-Maximilians-Universität, Munich, said: “It explains why hybrid butterflies are so rare – there is a strong genetic preference for similar partners which mostly stops inter-species breeding. This genetic structure promotes long-term evolution of new species by reducing intermixing with others.”   The paper is one of two published in PLOS Biology and funded by the European Research Council which brought together ten years of research by Professor Jiggins and his team. The second study investigated how factors including mate preference act to prevent genetic mixing between the same two species of butterfly. They discovered that despite the rarity of hybrid butterflies – as a result of their reluctance to mate with one another – a surprisingly large amount of DNA has been shared between the species through hybridisation. There has been ten times more sharing between these butterfly species than occurred between Neanderthals and humans.   Dr Simon Martin, one of the authors of the second paper, from the University of Edinburgh, explained: “Over a million years a very small number of hybrids in a generation is enough to significantly reshape the genomes of the these butterflies.”   Despite this genetic mixing, the distinct appearance and behaviours of the two species remain intact, and have not become blended. The researchers found that there are many areas of the genome that define each species, and these are maintained by natural selection, which weeds out the foreign genes. In particular, the part of the genome that defines the sex of the butterflies is protected from the effects of inter-species mating. As with the genetics that control mating behaviour, these genes enable each butterfly type to maintain its distinctiveness and help ensure long-term survival of the species. But can the findings translate into other species including humans?   Professor Jiggins said: “In terms of behaviour, humans are unique in their capacity for learning and cultural changes but our behaviour is also influenced by our genes. Studies of simpler organisms such as butterflies can shed light on how our own behaviour has evolved. Some of the patterns of gene sharing we see between the butterflies have also been documented in comparisons of the human and Neanderthal genomes, so there is another link to our own evolution.”   “Next we would like to know how novel behaviour can arise and what kind of genetic changes you need to alter behaviour. We already know that you can make different wing patterns by editing the genes. These studies suggest that potentially new behaviours could come about by putting different genes together in new combinations.”   References Martin, S et al. Recombination rate variation shapes barriers to introgression across butterfly genomes. PLOS Biology; 7 Feb 2019; DOI: 10.1371/journal.pbio.2006288 Merrill, R et al. Genetic dissection of assortative mating behavior. PLOS Biology; 7 Feb 2019; DOI: 10.1371/journal.pbio.2005902

Male butterflies have genes which give them a sexual preference for a partner with a similar appearance to themselves, according to new research.

There’s a small region of the genome that has some very big effectsChris JigginsChris JigginsHeliconius melpomene amaryllis


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified.  All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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The magnificent glow of fly testes

News from this site - Mon, 04/02/2019 - 16:53

γ-Tubulin Ring Complex Heterogeneity Revealed by Analysis of Mozart1 Regulating the formation of new microtubules in both space and time is critical for a wide variety of cell processes and is mediated in part by the recruitment of γ-tubulin ring complexes (γ-TuRCs) to specific microtubule organising centres (MTOCs). This...

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University of Cambridge finalist in Global Solution Search contest

News from this site - Thu, 17/01/2019 - 12:11

Researchers, including our PhD Student Emma Garnett , and staff at the University of Cambridge, have been selected as top 10 finalists in a global contest designed to identify, reward, and spotlight innovative solutions for addressing climate change. This project was selected from a pool of nearly 200 entries in Solution...

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