Tag Archives: evolution

A victory for invertebrates!

Last Saturday saw myself and some other Stirling-based researchers brave the resurgent snow to travel across to St. Andrews University for 2011’s Scottish Conference of Animal Behaviour (SCAB). This was a really great meeting, being small but still covering a variety of fields – my university was represented not only by attendees from ecology and evolutionary biology, but also from the psychology department, some of whom work in conjunction with the Living Links research station at Edinburgh Zoo.

The talks were all of a very high standard, and I had to prevent myself from exploding in a fit of jealous rage at some of the research being undertaken. Thibaud Gruber kicked things off in this vein, showing some fantastic videos of chimps singularly failing to learn how to use sticks to get at honey he’d secreted in holes in logs. My personal favourite was the experiment in which he actually placed the stick into the hole, only for a chimp to remove it, lick the honey from it, and then throw the stick away in favour of scrabbling around with its fingers and rolled-up leaves. As with all research, the combination of excitement and frustration was palpable…

2001 ape

Bonus video – chimps using sticks to ‘fish’ for termites:

Paris Veltsos of St Andrews gave a talk that was of great interest to me, discussing courtship song and cuticular hydrocarbons (CHCs) in populations of Drosophila montana. Veltsos and his collaborators found that various factors outside simply courtship effort contribute to net selection on song; they also saw differences in CHC selection between the two populations. I had a quick chat with Paris after the end of the meeting, and am looking forward to reading the paper that comes from this work (which I shall then review here).

There were also excellent talks on fish, including one which resulted in the lecturer driving us back to Stirling devising a project that should enable him to sit and watch the Tour de France all summer as ‘research’; another from the University of Glasgow’s Amy Schwartz, on sexual selection in guppies, made tantalising references to ‘Nature’s Laboratory’ in Trinidad. I bit my knuckles as I thought of the stark walls of my two controlled temperature labs. Perhaps I should put some posters up in there.

While I remained under no illusions as to the lack of romance in the laboratory setting of my work, I was clinging to the last vestiges of my pride by thinking, well, my crickets are kinda cute…

…and then came the presentations based on work using the rufous hummingbird.

I’m not sure even the most charismatic of my cricket hordes can really compete with that.

Still, there was to be a final sting in the tail – my friend Ros Murray, also working in the sexual selection lab at Stirling, won the prize for best student presentation. This was no mean feat, considering both the standard of the talks on show and the fact that she was discussing her work on sperm competition in the microscopic nematode worm Caenorhabditis elegans. It was a great talk, and covered some really elegant work that included the use of GFP (green flourescent protein) as a marker that was passed to the next generation by the ‘winning’ sire, clearly indicating to which of the competing males the offspring belonged. The award also comes after finding that this work has been accepted for publication in BMC Evolution journal, which is really excellent news. She probably deserves the reward after the mockery she’d put up with from some of us over her tiny, tiny worm sperm going head-to-head with monkeys and hummingbirds…

The Praying Mantis: an unfairly maligned sexual cannibal?

Recently, probably due to the incredible macro photography of Igor Siwanowicz that I linked to recently, I’ve become rather obsessed with mantises. Before then, I’d paid very little attention to these weird creatures, and will admit to having been mildly terrified of them in the past. This stemmed from an unfortunate incident many years ago, when I tried to brush one off the door handle of a holiday apartment, only to learn that they can fly – and can propel themselves rapidly towards a human face. The neighbours came rushing out because they had heard what they assumed to be the cleaning lady screaming. Anyway, possibly due to this, I thought that there was just a ‘praying mantis’, and had no idea that the order could range from this:

Mantis by Igor Siwanowicz

to this:

Mantises by Igor Siwanowicz

…and many more incredible shapes, sizes and colours. The displays that a mantis can produce when threatened are really quite incredible, and I have been told that they are great for use in undergraduate practical classes. Mantises are apparently relatively short-sighted, and so two can be placed on opposing ends of a mounted piece of string, and it will suddenly become very clear when they notice each other. Unfortunately, the ‘loser’ will signify defeat by flying off to a remote corner of the classroom, delaying the end of the lesson as the tutor (or, more likely, a hapless TA) climbs up to gingerly retrieve it. Here are two videos of different mantis displays, the first relying on sound and wing movement, the other on the large peacock-style eyes on its wings:

So, what wonders does the mantis have in store for the intrepid sex researcher? Rather distressingly, the answer is sexual cannibalism. Males are smaller than females, which have voracious appetites and can eat up to 16 crickets per day, and so put themselves in a rather precarious position both prior to and during copulation. There is a lot of evidence, including the video below (complete with rather breathless commentary), of females devouring their mates during intercourse, but a controversy remains over the function of this.

Does the male, as in the case of the redback spider, allow himself to be eaten in order that the bearer of his children has a large meal when times are scarce, therefore helping to furnish his offspring with added nutrition? Some other insects allow females to ‘nibble’ on them during sex, thus lengthening the duration of copulation and enabling more sperm to enter the female and fertilise the eggs – could it be that this is a poorly-judged version of this adaptation? The latter seems unlikely, as females generally remove the head first, and although the body continues its final mindless act, studies have shown that ejaculation tends to happen more rapidly after decapitation, if at all.

A 2010 study by Kate Barry, of Macquarie University in Sydney, Australia, investigated the state of female nutritional status on mating dynamics in a sexually cannibalistic praying mantid. Previous studies have shown that scramble competition is important in these mating systems, and thus males are selected for their ability to detect and locate females. Given that each copulation holds the risk of death for the male (and the inherent fitness costs of this occurring), and that condition has been shown to be positively correlated with fecundity in female mantises, then theory would predict the evolution of strong male choice for females in good condition. A female in good condition is not only likely to have more eggs, making her a good choice for a male wanting to ensure that he makes the most of the copulation should it be his last, but is less likely to be starved of food. Interestingly, Barry found that long-distance male attraction to females is somehow linked to female fecundity, with ‘low condition’ females still being attractive to males as long as they had a base level of fecundity. Nutritional status seemed to have no bearing on male choice, and so it would appear that females may produce a pheromone that indicates fecundity. Indeed, in a species of cockroach there exists a relationship between ovarian development and pheromone production, meaning an honest signal is produced to demonstrate a female’s egg-bearing capacity.

It would seem, then, that the unfortunate decapitated males may be those that were unable to secure copulation with high-fecundity females, and sacrificed themselves in a final desperate attempt to pass on their genes. Or perhaps, as can happen in many species, they simply read the signals wrongly.

Read KL Barry’s paper here: http://dx.doi.org/10.1016/j.anbehav.2010.05.024

Note: since becoming more interested in the mantis, I’ve even come so far around as to having decided to place an order with Ornamental Insects for a ghost mantis, after listening to their interview on John F Taylor’s Reptile Living Room radio show. However, you may be able to tell from the picture below that, perhaps, I haven’t quite conquered my fear outright…

Ghost mantis by Ornamental Insects

Free Online Video Lectures

For the last few months, I have been making use of the ‘iTunes U’ feature on Apple’s software to download lectures to listen to whilst making sure my crickets are living the high life in my lab. There are a lot of good courses there – the main ones I have been using are Stephen Stearns‘ Evolution, Ecology and Behaviour course from Yale, and some of Terrence Deacon‘s Anthropology course from Berkeley. You can have a look at what’s available here – in fact, the ‘featured lecture’ on this page is actually a ‘virtual tour of the Galapagos’ from the Open University’s David Robinson.

I was actually searching for some more information on a subject Stearns talks about in a sexual selection lecture when I found the CosmoLearning website. In its own words, CosmoLearning is “an educational website committed to improve the quality of homeschooling, teaching and student excellence, helping educators and self-learners alike anywhere in the world.” The biology section of the website contains a number of courses relevant to those with an interest in evolution, and include video lectures for the Stearns course available as audio on iTunes; this will come in very handy for those of us who have listened to the lectures and been left in the dark as he refers to images and graphs in his presentation!

For someone such as myself, coming to evolutionary biology from another discipline (and having spent a number of years away from study), it’s really wonderful to be able to access such resources, teaching the fundamentals without my having to pay anything or rearrange my day in order to go to undergraduate lectures! A bonus feature of the CosmoLearning website is its documentaries section – the evolution section has a number of films, including the rather fantastic BBC production ‘Charles Darwin and the Tree of Life’. Perfect for winding down after a lecture on the finer points of genetic drift…

CosmoLearning biology section here (unfortunately, constricting the search to just ‘evolution’ in the toolbars actually removes several relevant courses)
CosmoLearning evolution documentaries here

The Rap Guide to Evolution

Due to spending a lot of time doing experiments in my cricket dungeon of late, I’ve been trying to divide my listening time between music, comedy podcasts, and scientific podcasts or lectures. Thankfully, I hit on something recently which crosses the boundaries – The Naked Scientists’ podcast from the Darwin Festival 2009 (download here) features The Rap Guide to Evolution from Canadian Baba Brinkman:

Award winning Canadian hip hop artist Baba Brinkman brings us his Rap Guide to Evolution, an hour of clever, witty and scientifically accurate rhymes that will have you seeing Darwin from a whole new perspective. Baba explores the history and current understanding of Darwin’s theory, combining hilarious remixes of popular rap songs with clever lyrical storytelling that covers Natural Selection, Artificial Selection, Sexual Selection, Group Selection, Unity of Common Descent, and Evolutionary Psychology.

I first happened upon Baba Brinkman (as, I imagine, did the majority of evolutionary biologists who have heard of him) when his performance at Robin Ince’s ‘Nine Lessons and Carols for Godless People was televised by the BBC in 2009. I’ll be honest – at that point, my interest in hip-hop probably superceded my interest in evolutionary biology, and I wasn’t expecting great things on either front. However, Brinkman – a literary scholar whose previous credits include ‘The Rap Canterbury Tales‘ – is a master at distilling complex ideas and presenting them in a logical, memorable and humourous manner.

Brinkman is now using the Crowdfunder site to help raise money for an educational DVD, including music videos for each track and a host of teaching resources. This money would add to initial funding from the Wellcome Trust, and your donations give returns to suit even the most braggadocious of evolutionary biologists – such as your own picture occurring in one of the music videos! Plus, as you’ll hear from the podcast, his is also a ‘peer-reviewed’ hip-hop show – so you can be assured that scientific accuracy takes precedence over his rhyming dictionary….

Donate to Baba Brinkman’s fund here.

The Masterplan..

My grand plan for the first post on this blog was to discuss what most people are likely to think when they hear the word ‘evolution’. For the vast majority, ‘evolution’ brings to mind phrases such as ‘natural selection’ and ‘the survival of the fittest’.  The ‘fittest’ individual, in common terms, would be the one that is most physically fit – stronger and healthier.  However, this is not how Darwin interpreted it when he appropriated Herbert Spencer’s phrase (coined after reading ‘On the Origin of Species’) as a synonym for his theory of natural selection.  The ‘fittest’, in this case, means those that are best adapted for the immediate environment.

Anyway, I say that this ‘was’ my grand plan, because not only did I swiftly realise that the subject is rather dry, but I also found that starting a blog on evolutionary biology whilst starting my first big experiment is probably the worst idea that I’ve had in some time.  As such, I shall devote most of the following entries – for the foreseeable future, anyway – to detailing the experiment that I am setting up, and generally how much I’m losing the will to live!  I keep receiving emails and texts asking me how my insects are doing, so now I can just send on the URL to this – mainly because I’m only a few days in, and already I cannot close my eyes without seeing rampaging hordes of cricket nymphs surging over my retinas…