After reading a recent blog post about the use of Instagram to engage the public in scientific research, I realized that I never shared several photographs, which happen to be fairly Instagram-esque. These were composed for a science communication class that I participated in last semester and the concept was to have an art exhibit depicting some general science concept. I chose sexual dimorphism and its many manifestations in beetles. Specimens used for the photographs were borrowed from the Essig Museum of Entomology and the images were altered using the online program Pixlr-o-matic. I hope you enjoy and learn a little about the wonderful world of beetles.
[Alternate blog post title: Mmmmmm....sexual dimorphism]
Sexual dimorphism occurs across many different groups of beetles and manifests itself in many different ways from antennal length to overall body size to extreme pronotal horns. A recent article describes a different expression of sexual dimorphism, which the authors refer to as EMM or enlarged male mandibles. The EMM discussed in this particular article focused on the beetle family Chrysomelidae, particularly those within the subfamily Crytocephalinae. In addition to discussing the EMM, the authors described three new species – two from New Caledonia and one from Borneo. All three of the species have incredibly impressive and very different expressions of EMM. Below is the newly described species Scaphodius drehu with male and female comparisons along with the male’s obvious cartoon doppleganger.
Mandibles of this male more closely resemble Dick Dastardly’s mustache than they do the female’s mandibles.
So what are these incredibly modified mandibles used for? Why do some groups of beetles have them while others don’t? It doesn’t appear that they are used as a clasping device to hold onto females during mating because the head is a poorly placed area for such a function in many chrysomelids – many species are rotund and so the head of the male is far away from the female during copulation. Instead the authors hypothesize that the mandibles are used in agonistic behavior – prying off other males that are already mating with females. Interestingly, the authors surveyed the presence and absence of EMM across the Chrysomelidae and found that they are generally restricted to certain groups, indicating that this character may be phylogenetically informative. Most of the species that have EMM have barrel-shaped bodies with high centers of gravity that are unstable, further supporting the hypothesis that the mandibles are used to dislodge opponents.
So, basically if you are an adorable rotund chrysomelid beetle, you’re more likely to have EMM than other chrysomelids that are not as adorably round. Answering this question within a phylogenetic context would be interesting – are sexually dimorphic male mandibles correlated with body shape when accounting for shared ancestral history? This can really only be addressed with a well-resolved phylogeny and to do that we need more research on Chrysomelidae taxonomy and systematics.
Check out this open access article – the pictures of the male mandibles for the newly described species are truly remarkable.
Reid CAM, Beatson M (2013) Chrysomelid males with enlarged mandibles: three new species and a review of occurrence in the family (Coleoptera: Chrysomelidae). Zootaxa, 3619 (1): 079–100.
Beetles are everywhere around you. Don’t worry though, considering the vast number of species, beetles are a surprisingly innocuous bunch, at least towards humans. They live basically everywhere and if you want to collect a variety of species, you need to employ a variety of collecting techniques. My personal beetle collecting method of choice is using a beating sheet – taking a large sheet and placing it beneath a tree, lightly hitting that tree with a stick, and waiting for insects to fall onto the sheet. But there are myriad methods to employ. A few weeks ago, I traveled out to Portola Redwoods State Park* with my PI and a handful of additional arthropod lovers to set up some traps for some itsy, bitsy blind subterranean beetles. As I mentioned, beetles are everywhere, including living between rock spaces underneath the ground. So we lugged shovels, picks, and axes into the woods and buried traps up to a meter down beneath the surface. We baited the traps with stinky things like rotten cheese and rotten meat…hopefully irresistable for the beetles. The traps are currently sitting out there, collecting beetles and waiting for our return – fingers crossed! The traps will be checked in May to see if they actually did attract any creatures – beetles or otherwise.
If you would like to learn more about the details of this collecting method, I suggest you read the blog post here. (you’ll see that I also make a cameo in the post!)
Here are some photographs taken throughout the day:
*You should definitely not go out and attempt this method in your nearest state park – this is sure to ruffle some feathers. We had express permission and the proper paperwork needed to conduct this work. If you are thinking of trying this method, please make sure you have gone through all the proper channels to ensure that beetle collectors one and all keep their shiny [elytral] reputations. Thanks!
Whenever I’m talking about my work as a scientist, especially to young children, I usually mention that a part of my job is describing new species. The fifth graders that I’ve been teaching find this absolutely amazing and always ask lots of questions: “How many have you described?” “What did you name them?” “How did you name them?” “How many are there still to describe?”
I always tell them that there are over 400,000 species of beetles and that there are thousands and thousands more to be described. The next time I see my students I’m going to mention a recent paper in which 138 new species of histerid beetles in the genus Operclipygus were described! They will love it. Just look at these amazing beetles! The common name for the Histeridae is the clown beetles…though I’m not sure why since they are often found near dung piles and carrion. Maybe I just don’t know that much about clowns…or maybe common names are just odd. You can see a lot more of these beetles because the data from this paper are all online at MorphBank including habitus images and scanning electron micrographs (SEMs). The article is also open access, so you can download and see for yourself what an impressive work it is. Be warned – if your internet connection is slow, it will take a while to get onto your computer. The paper is just so massive Oftentimes it takes quite a bit of effort to describe even one species as new, so describing 138 all in one publication is quite a feat!
Oh also, the authors state towards the end of the paper that even though “this study documents a large number of previously unknown species, it is very likely that many more remain to be discovered.” I’ll mention that to my students as well to perhaps encourage some future taxonomists!
Caterino, MS & Tishechkin AK (2013) A systematic revision of Operclipygus Marseul (Coleoptera, Histeridae, Exosternini). ZooKeys, 271: 1–401. doi: 10.3897/zookeys.271.4062
On this day in 1809, Charles Darwin was born. Across the country people are celebrating what has come to be known as Darwin Day. This recognition is to celebrate the discoveries and life of Charles Darwin, but also generally to highlight science and scientific pursuits.
Now, let me first say that I’m a fan of Darwin – a big fan. But as I always root for the underdog or, in this case, the lesser recognized, I just want to mention Alfred Russel Wallace. Especially since this year it is the centennial of his death and some are saying that 2013 is Wallace Year. Wallace was extremely influential in helping to shape Darwin’s ideas regarding natural selection. He is also known as the father of biogeography because he recognized different floras and faunas of geographic areas and split these into regions – ideas which are still being tested and revised to this day.
So keeping this in mind, I wanted to share the following clip with a fictional representation of Charles Darwin from the movie “The Fall” where he is dressed in bright pink flamingo feathers and a bowler hat. He is always accompanied by his quiet friend “Wallace” – an adorable monkey that he keeps in a bag. In the film, Wallace comes up with all the good ideas, which Darwin gets all the credit for.
This is not your stereotypical representation of Darwin as a bearded and scholarly British gentleman, but I like that. Scientists are often odd, flamboyant, fun people and think they should be portrayed as such more often.
I hope that you enjoy Darwin Day and if you are in Berkeley, California come by for a tour of the Essig Museum of Entomology this afternoon. Or find a local event in your area and learn a bit more about Darwin, Wallace, and the process of science.
A few weeks ago I went hiking in Mount Diablo state park, which is less than an hour’s drive from Berkeley. The area includes mixed oak woodland and chaparral. The summit of Mount Diablo, which I didn’t reach on this particular hike, is at an elevation of 3,849 feet. During the summer, the area becomes incredibly hot and almost unbearable, so decided to enjoy a hike in the wintertime. It was so wonderfully cool in the shade that there was actually frost on the ground for most of the trail. I also wanted to get in some camera practice, of course.
One tip that I can already give regarding the photography of insects- start shooting photos a good distance away, especially with those insects prone to flight. Better to have at least one photo with the insect in part of the frame than no picture at all.
An interesting note regarding Mount Diablo (found via Wikipedia) – the peak’s name comes from the escape of several Chupcan Native Americans in 1805 from the Spanish into a nearby willow thicket. The escapees seemingly disappeared and thus the Spanish soldiers called the area “Monte del Diablo”, which means “thicket of the devil”. English speakers later misinterpreted “Monte” to mean mount or mountain.