On the 15th and 16th April we had one of my favourite events at Trinity College Dublin: the annual School of Natural Sciences Postgraduate Symposium. Over the course of two days many of our PhD students presented their work to the School. We also had two amazing plenary talks from Dr Nick Isaac (CEH) and Professor Jennifer McElwain (UCD). For those of you who are interested in exactly what we work on here at EcoEvo@TCD, here are the abstracts from the PhD student presentations. Check out the TCD website for more details! Continue reading “School of Natural Sciences Postgraduate Symposium: Part 2/4”
Postgraduate students from Trinity College Dublin’s School of Natural Sciences
On the 15th and 16th April we had one of my favourite events at Trinity College Dublin: the annual School of Natural Sciences Postgraduate Symposium. Over the course of two days many of our PhD students presented their work to the School. We also had two amazing plenary talks from Dr Nick Isaac (CEH) and Professor Jennifer McElwain (UCD). For those of you who are interested in exactly what we work on here at EcoEvo@TCD, here are the abstracts from the PhD student presentations. Check out the TCD website for more details! Continue reading “School of Natural Sciences Postgraduate Symposium: Part 1/4”
I love fish. Not (just) to eat, but to study and learn about and at times just marvel at their beauty. They are arguably the most diverse vertebrate group (and easily arguable if you take the cladistic view that all vertebrates are, at heart, just highly modified fish). But even focusing solely on actinopterygians (ray-finned fish) every aquatic niche is filled by one species or another, from the poles to the equator, from the high Tibetan plateau to the depths of the ocean where sunlight is a distant memory. If there’s water chances are there’s fish.
My particular passion is for deep-sea and polar fish. They have, in my opinion, some of the weirdest adaptations to their environment and I’ve reached a point (right around the time a fish with atransparent headwas filmed in the wild!!) where nothing they can do can surprise me.
Despite my jaded outlook I like to keep an eye out for interesting news stories and the other day I stumbled across a story in the Independent about a ‘mysterious fish with clear blood’. I read the story with increasing disappointment as I realised the fish was mysterious only to the reporter, but it provides a perfect opportunity to share the wonders of icefish with a wider audience.
Icefish (Channichthyidae) live in the Southern Ocean. They are a family in the suborder Notothenioidei, a group found in the Antarctic and sub-Antarctic, and have been a love of mine for almost a decade. Notothenioids live in water which reaches sub-zero temperatures, but where their softer, lower-latitude relatives would freeze instantly, they swim merrily on. They can do this due to adaptations, one shared by most Notothenioids and one unique to icefish.
The first adaptation is, in every sense of the word, the coolest I know – they have evolved antifreeze! Antifreeze glycoproteins to be exact. These AFGPs inhibit the growth of ice crystals and prevent the blood and tissues from freezing.
The second adaptation, found only in icefish, has resulted from the interplay of two properties: at low temperatures fluids become viscous and large molecules, such as haemoglobin, increase this viscosity further still; and oxygen solubility increases as water temperature decreases. Icefish have exploited this second property to counter the first. Haemoglobin is an oxygen carrier, but at low temperatures it becomes more of a hindrance than a help. Icefish have a leathery skin instead of scales, allowing oxygen to be transported across their skin as well as their gills, and the high oxygen concentration in the water means that the haemoglobin can be lost with little reduction in oxygen capacity which is exactly what they have done. It helps that these fish aren’t exactly active, preferring to wait for prey to come their way than actively seek it out, but even so I think there are few other animals that could lose haemoglobin and still be alive, let alone live with few negative consequences.
The most striking consequence of this loss is that icefish have white flesh and gills. Normally gills are one of the reddest parts of a fish due to the need for blood to collect oxygen as water passes over them. But in icefish their gills are white; freakily so.
Normal fish gill (Thunnus fallai)Icefish gill (Champsocephalus esox)
The news story, originally from AFP and posted almost verbatim on several websites, was extraordinarily hyperbolic. It gave the impression that haemoglobin- and scale-loss were unique to this species. Yet, as I’ve said, haemoglobin loss is found in all members of the icefish family and scale loss is found in many species.
The real story is that they have managed to get the species to spawn in captivity, which is a fantastic achievement as anyone who knows anything about closed life-cycle aquaculture will know. Unfortunately it seems that this legitimate success is not sufficiently newsworthy and so a false story has been created. The upside I get to talk about one of my favourite fish so I guess it’s not all bad news!
Any designer will tell you that choosing the right colour combinations are essential to strike the right tone and balance in a room, particularly if your goal is to attract clients. Well, what if your room is a web and your client is a moth?
This is just the situation the rather drab and dreary coloured Cyrtophora unicolor finds itself in. These spiders live almost exclusively on large moth prey, which are attracted by pale colours and twinkling lights, a problem if your evolution has led you to optimize your “I’m a brown leaf” appearance. Enter the small but enchanting Argyrodes fissifrons (a member of the dewdrop spiders). These spiders by contrast are endowed with a glistening silver and black pattern. These little guys face a rather different dilemma: they are kleptoparasites (food thieves!), meaning that they use the web of another larger spider species for feeding and reproductive territory.
Somewhere along the lines these two species found each other and struck up what is the first recorded example of an arthropod predator mutualism based on colour. Predator mutualisms, where both species benefit from the relationship, are rare due to conflicts of interest. Most dewdrop spiders live off the webs of others and suffer high levels of aggression from the hosts (somewhat understandably!). It was noticed however that A.fissifronsand C.unicolor seemed to coexist quite happily and that webs of C.unicolor even seemed to intercept more prey when A.fissifrons was present. The reason: The twinkling silver body of A.fissifrons. Against a leafy background the silver A. fissifrons is quite conspicuous and even attractive to the primarily visually oriented Hawkmoth prey. It is thought that the moths read the silver as some kind of a cue, potentially reflecting the moonlight at a similar intensity or wavelength as the stars, used by the moths for celestial navigation. These large moths however are much to big for little A.fissifrons to tackle; they prefer the smaller “accidental” prey. The result: These two species live quite contentedly side-by-side, one providing the house and the other the decoration.
Most animals that use colour signals use them as warnings, as mating indicators, service providers (as is the case in cleaner fish), camouflage and mimicry. If your ecological and evolutionary pressures demand a more low-key and less vibrant costume, adding a splash of colour from a friend with similar interests it seems may lead to joint benefits. Co-evolutionary related colour patterns, such as those associated with mimicry, usually arise from antagonistic interactions among species so it is interesting to see examples like these and wonder whether some might also arise from, or might eventually evolve as a result of, synergistic interactions among species.
I’d like to ask the question many paleontologists have to face when they (foolishly) venture out of their museum storage: “So you’re studying fossils right? But what will that bring to the people? A cure for AIDS?”. There are many possible answers from a punch in the face to more mature responses. But I was recently asking myself the question from a biologist’s point of view: “What can biologists really do with the fossil record?”. Well obviously, we can use it to recreate and understand the history of our planet (like in Nature last week) or to do use some nice methods in trying to understand ancient ecosystems. People even might feel lyrical and do some serious work on paleo-poetry! But all of these guys are paleontologists right? They live in their museums and only go out for a movie once every 10 years… How about the other biologists?
Think about it, when ever you’re studying any organism, it is obvious (thanks to this bearded ape) that they had a 3.5 billion year history behind them. Ignoring that might lead to a misunderstanding? As an example, I’d like to use my favorite PhD-presentation example: the crocodiles. When we talk about crocodiles, we automatically think about the few species of big lizard that live in rivers in the tropical/sub-tropical latitudes. But, after a quick look at the history of our planet, the only description that is more or less correct is “lizard” (archosaurians to be more precise). Crocodiles are composed of many species (8 genera today – soon to be 6 – but >70 in prehistoric times) that lived in rivers as much as in the sea, on the ground or even sometimes in trees and in tropical to temperate climates (remains of crocs were found in Normandy – France).
Well maybe that’s just because of this group. But if you think about it, many other groups have ecological or evolutionary features that becomes truly astonishing once you take into account their full history. For my PhD I decided, with Natalie, to look at this fun fact (life existed before yesterday and the people studying it don’t always focus on dinosaurs) through primates. My idea is to combine extant data based on DNA with extinct data based on morphology to have an integrative tree of all primate history. I agree that this sounds a bit too easy and naive, (the method is a bit more complex) and I’ll probably end up with something more humble. However I think the primates can be a good example to illustrate the point about the hidden diversity among extinct groups. The primate fossils are not dramatically different than the extant once (unlike crocs, there were no pelagic primates) but they still show some really interesting features, for the macroecology side, combined extant and extinct primates show massive variation in body mass in some groups (lemurs) but very few variations in others (tarsiers). Or on the macroevolution side, such an integrative tree could provide some further understanding to the old debate of primate origins! Well at least I hope so. For now I’m just comfortable with eating some burgers with a diet coke and a gun in a pickup truck while I’m scanning some primates in the Smithsonian Institution in Washington DC.
I’ve recently been spending a lot of time working with undergraduate students and marking their work and much of it has been on the subject of evolution and natural selection. This can be a difficult topic to clarify in the mind of younger students and it’s often difficult to recall specific examples which can be easily explained. Usually you have to come up with some hypothetical situation whereby some selection pressure drives a population towards evolutionary change. A newly published study in Current Biology by Brown and Brown however provides a beautiful (and more importantly brief) example of evolution and natural selection at work.
They have been studying populations of cliff swallows (Petrochelidon pyrrhonota) in Nebraska for almost thirty years, attempting to evaluate the costs and benefits of group living in these highly social birds. In an interview with John Dankosky lead author Charles brown explains how his habit of checking road killed birds for rings (or bands, as they are called in the US) led to an intriguing discovery. Firstly they noticed that over the years fewer and fewer birds were being killed on the roads (Figure 1), but also that these road killed birds tended to have longer wing lengths compared to individuals of the general population.
Figure 1. Change in wing length and number of road killed swallows (From Brown and Brown 2013).
So if you are a cliff swallow why does having a longer wing make you more likely to be run over by a car? Well it all comes down to the angle of escape. Birds with shorter more rounded wings are able to take off more vertically compared to individuals with longer more pointed wings, essentially shorter winged birds can get out of the way of oncoming traffic more quickly. It seems that this selection pressure from vehicles has been driving (I make no apology for the pun) the evolution of shorter wings in this population of cliff swallows.
Cliff swallows are migratory birds, travelling from South to North America annually and longer more pointed wings are generally seen as an advantage when it comes to long distance flight. Therefore it seems that the shorter winged individuals may pay an energetic cost compared to their longer winged conspecifics, but this cost may be outweighed by the benefit of being able to avoid traffic. Whatever the case may be I think this study provides a nice example of selection pressures steering morphological adaptations along the road to survival. Next time a student needs clarification on this I’ll remember, tyre pressure.
Why did Neanderthals go extinct while humans prospered? There are volumes full of speculations into the decline and fall of our burly cousin who last walked the Earth 30,000 years ago. Climate change may have reduced the large herbivores on which they depended for food. Humans may have inadvertently spread lethal diseases to them when we first came into contact. Perhaps the most sinister hypothesis is that we extirpated them in an ancient act of genocide (/speciescide?).
Researchers at Oxford now argue that Neanderthal orbit size gives us an insight into the reason for their downfall. They reason that, as Neanderthals had relatively larger eyes than humans, more of their brain was dedicated to visual systems. This was an adaptation to their habitats in the higher latitudes where light conditions were poorer. This came at a cost though because the evolved brain can’t be a master of all trades, there must be some tradeoff. In this case the authors propose that the Neanderthals suffered a reduction in their cognitive abilities. This was significant because it meant that your average Neanderthal could deal with fewer social partners than a comparable human.
The impacts of this in the authors’ words, “First, assuming similar densities, the area covered by the Neanderthals’ extended communities would have been smaller than those of [humans]. Consequently, the Neanderthals’ ability to trade for exotic resources and artefacts would have been reduced, as would their capacity to gain access to foraging areas sufficiently distant to be unaffected by local scarcity. Furthermore, their ability to acquire and conserve innovations may have been limited as a result, and they may have been more vulnerable to demographic fluctuations, causing local population extinctions.”
But this proposal hasn’t gone unchallenged. Anthropologist Trenton Holliday says that by ignoring the relatively larger faces of Neanderthals the inferred larger visual brain region is mistaken. Another criticism comes from Virginia Hughes over at the Only Human blog. She points out that brains aren’t perfectly modular. So by comparing these idealised modules across species isn’t 100% informative. Perhaps Neanderthal brains were set up in a different way to process social information.
I think the visual system-cognition trade-off is something that could be easily explored in extant fauna. Think of related species that differ in latitude et voila a confirmatory or dissenting paper awaits.
Last Wednesday a bunch of us (thanks to @nhcooper123 for organising) went to see Robin Ince@robinince perform his stand-up comedy science show The Importance of Being Interested at the Science Gallery. His shows are a unique blend of education and humour, combining a whistle-stop tour of the world of science with hilarious anecdotes, all the while vehemently challenging the doubters and the nay-sayers.
I found his show immensely inspiring, and I have to admit that I am normally bored by pop-sci outside of the relative academic safety of my office. I took so much from the show, but I think it boils down to these three points:
The world is big and wide, and fully of wonder. I kind of know this. Its pretty much the reason why I’m a scientist, but Robin has a wonderful charm and ability to find all the really cool stories and point out the best bits, even when showing you something you already know. Be in awe of the world around you.
Don’t sit back and swallow the crap. He would doggedly challenge the stance of anti-science types or the science ignorers. He took the anti-vaccine brigade to task, mocked homeopathy and challenged the religious devout. Recently, I have found myself sitting on my hands, and shoving food in my mouth at parties so as to avoid getting drawn in to discussions – well, arguments really about such matters. I have been taking a pacifist’s approach that in retrospect is cowardly and does a dis-service to science and the work of all my colleagues and my own. But no more. Bolshy grumpy argumentative Andrew is back (just ask my colleagues). I’m not sure my wife will thank @robinince but apparently he suffers from foot-in-mouth too. Be true to your convictions.
Don’t be shy. His style is mad, frenetic, at times all over the place, but always entertaining. Its all too easy to retreat into your shell when you present in public. People like Robin remind you that an entertaining style will hold your attention no matter how many beers you sank during the interval. Equally, you don’t be yourself when on stage. You can put on a show, be something different, whatever works to entertain. Lecturing is an act. Tell funny stories – why you will get poo on your finger if you stick it up your bum for instance. Swear at least occasionally (this is one of my tricks and usually gets a giggle and wakes up those in torpor). Be fun, be mad, be witty and be entertaining.
If at all you like science, one of his shows is a must see. Hopefully this inspiration lasts. If not, I will just have to go see his show again.
My post on the problem of consciousness troubled a few readers because I dared toy with the idea of dualism, something so offensive to scientists I’m wary to speak its name. But I’m going to continue to argue for dualism because it’s not clear to me that it is wrong even for all the flack it has received. I think a return to this topic is also warranted because of the controversy generated by Thomas Nagel’s latest book, ‘Mind and Cosmos’.
A charge made against my previous post was that dualism is a pernicious idea. Yet nihilism is a negative, and I would argue, damaging philosophy par excellence, but that has no bearing on its truth or falsity. Similarly, one commentator spoke about dualism being argued for because it speaks to a human desire to be something more than physical. But, again, that does not mean it’s wrong. This holds for any idea. We can only take people to task in arguing for something if the only reason they do so is because it comports with their views.
(On a side note I reckon the implications of a physicalist universe are far more terrifying than a dualist one. They are best spelled out by the atheist philosopher Alexander Rosenberg in his essay ‘The Disenchanted Naturalist’s Guide to Reality’.)
Previously I used David Chalmers’ zombie argument to question if the world as we conceive it can account for the presence of consciousness. Chalmers summarises the message of his original zombie argument as “If any account of physical processes would apply equally well to a zombie world, it is hard to see how such an account can explain the existence of consciousness in our world.” Arguments from logical possibility are contentious but let’s not lose sight of what Chalmers is saying.
The subtitle of Nagel’s book is likely to grab the attention of biologists – ‘Why the Materialist Neo-Darwinian Conception of Nature is Almost Certainly False’. But you should hold your cries of “Creationist!” because they’re misplaced. I really need to stress that this debate should not be framed as being between science and religion or science and pseudoscience but rather physicalism and dualism. Indeed some of the more prominent defenders of the latter position, Nagel and Chalmers included, are card carrying atheists.
I haven’t read Nagel’s book yet (I hope to do so) but you can get a sense of the themes he develops from the following description, “The modern materialist approach to life has conspicuously failed to explain such central mind-related features of our world as consciousness, intentionality, meaning, and value.” He argues that there is something more needed to get us from physical matter to conscious thoughts, not even evolution by natural selection can get us there with a purely material world to manipulate. There is a difference of kind rather than degree here.
Some of the criticisms of his latest work argue that he leaves a lot unsaid and many of his arguments have been criticised as vague. But Nagel is most famously known for a famous 1974 essay he wrote on ‘What Is it Like to Be a Bat?’ He says that although bats are conscious they experience the world in an entirely different way to us i.e. there is something like it is to be a bat. If we imagine ourselves as being bats it’s actually through our human minds, i.e. we’re imagining what it would be like for us to have echolocation, which is entirely different. If instead we record all the sensory data that a bat experiences we’re still left wondering about how he/she experiences the world from its own point of view. The normal physicalist approach leaves us guessing.
Previously we were asked to have a prior commitment to physicalism but there are a number of properties of consciousness that should cause us to at least re-evaluate our priors. Neurons, physical entities that they are, do not seem to have the tools to do what is being asked of them. When it comes to physicalism, past performance is no guarantee of future success.
I would like to say that the talk presented a range of evidence for intelligent design and carefully countered the usual arguments against it. I would like to say this, but I can’t. The talk, which lasted over one hour, spent much of the time quoting non-scientists and misquoting scientists, painting ID proponents as martyrs to the cause and science as tautologically incapable of addressing questions of design. The religious beliefs of ID proponents were constantly referred to, despite supposedly being completely irrelevant, which was an indication that this was, after all, a religious proposition not a scientific one.
It would be easy to question the credentials of Dr Alistair Noble (PhD in chemistry) and ask how someone who has been outside of scientific academia longer than I have been alive can claim to have found fundamental flaws that no working biologist has been able to find, but I won’t. Instead, I have tried to focus on the claims of Dr Noble and see if they can be answered (see my last blog post).
There is much more that I could have said. The case for evolution is so strong that I could go on for hours about the evidence from multiple disciplines that support it. It seems that the same cannot be said for intelligent design. Dr Noble spent about 15 minutes of his (more than) one hour talk providing evidence which can be easily refuted by anyone who has even a basic understanding of evolutionary theory. His ‘evidence’ ultimately boiled down to an Argument from Incredulity with a side helping of the Argument from Authority.
I was disappointed by the lack of scientific rigor Dr Noble exhibited. Not one journal article was presented, not a single claim that hasn’t been refuted multiple times before. I had hoped for an intellectually stimulating talk that would force me to question my understanding of evolutionary theory but instead I was confronted with the same, tired claims that have been presented by ID proponents for years now. It is a shame that Dr Noble could not have used his clearly considerable intellect to study the actual science and see that evolutionary theory is not a threat to his faith but is an amazingly simple yet profound explanation into how the diversity of life arose.
