No man is an island; the same could be said for the millions of life forms that populate our planet. Think of all the ways in which organisms interact with each other through predation, parasitism and the countless symbioses. Sometimes a pair of interacting partners can become inextricably linked such is their mutual dependence. Each one may provide the other with a resource it’s unable to obtain on its own.
A recent collaboration explored instances when these interactions lead to the loss of a trait and showed the fragility of this situation. One of the examples the authors use is an ant species that farms fungus. The fungus provides the ants with all the arginine (an amino acid) they need so they have lost the ability to synthesise it themselves. Thus anytime an ecological interaction involves some provision of a resource by one partner to another the evolutionary pressure is removed and the trait can be lost in the species receiving the goods. In other words we end up getting ‘compensated trait loss’ due to the ecological interaction. This can tighten a symbiosis from a facultative to an obligatory one.
But the fragility of compensated trait loss should be obvious now. In the ant example, were the fungus to go extinct the ant would disappear along with it. It’s like the ecological interaction is undermining all the good work done by natural selection in providing the ancestral ants with all the traits they need. The authors reckon that trait loss is “grossly underestimated” which puts many species in a precarious position in this age of mass extinction. Although there have been some instances where the trait was recovered, in flagrant disregard for Dollo’s law. Some of these law breakers include parasitic insects who regained their ability to synthesise lipids once the provision was lost.
A difficulty in studying these systems is how to detect when trait loss is taking place. A decreased expression of some gene in some members of a population would probably be reported as natural variation. But with ever improving molecular techniques we will be able to get a better estimate of the number of compensated trait loss interactions.
With the apocalypse come and gone we can still theorise about how our downfall will come about. E. O. Wilson wrote that ‘‘sex is an antisocial force in evolution’’. Charlie Cornwallis, his colleagues at Oxford and their promiscuous birds illustrated why this is so. As is so often the case in evolutionary theory the question centres on sociality, in this instance it takes the form of cooperative breeding. Why would an individual help someone else raise their young rather than having progeny of their own?
The authors ask us to consider the case in birds of a mother and her offspring. If the offspring remains at his natal site and his mother is monogamous he can help in rearing his siblings who are all as related to him as he would be to any of his own potential children. This makes evolutionary sense in terms of relatedness. However, if his mother is promiscuous his level of relatedness to the resultant other birds will be less than that of his own offspring. The sensible thing for him to do here is to disperse and start a family rather than helping out his half siblings.
The authors of the study collected data on almost 300 bird species recording levels of promiscuity and degree of cooperative breeding to test the monogamy hypothesis. This states that species with high levels of promiscuity will tend towards societies with low levels of cooperative breeding and vice versa.
They were able to show that highly promiscuous birds tend not to have cooperative breeding whereas species like the White-winged Chough, which are completely dependent on others for help in raising their young, are faithful.
But more than this their results demonstrated that, over evolutionary time, transitions to cooperative breeding were associated with low promiscuity. The reverse is also true and echoes Wilson’s statement, because highly promiscuous groups saw a breakdown in cooperation.
There are some exceptions to the rule in that birds can be promiscuous and still have a society of cooperative breeders but this is offset by kin discrimination which involves “directing aid preferentially towards relatives.” So there you have it, sex has the power to destroy societies.
NERD club, for the uninitiated, is a weekly meeting of the Networks in Ecology/Evolution Research Cluster Dynamic of the School of Natural Sciences, Trinity College Dublin. We present and discuss our research and also general aspects of academia such as science communication, job hunting and using twitter. The members include interns, PhD students, postdocs and both junior and senior faculty, so it’s always full of interesting research and heated debate! Essentially, it’s my favourite hour of the week, so as it’s the festive season and I’m in a festive mood, I decided to write a Christmas song for NERD club.
It’s to the tune of the 12 Days of Christmas. It’s also not very good, but I had time to fill on the train…
“On the 1st day of Christmas the NERD club gave to me…
parasites in a fractal stomach
On the 2nd day of Christmas the NERD club gave to me…
and parasites in a fractal stomach
On the 3rd day of Christmas the NERD club gave to me…
debates about twitter
and parasites in a fractal stomach
[And so on until]
On the 12th day of Christmas the NERD club gave to me…
a million chocolate fingers
mixed effects models
test tubes full of glitter
bats living longer
news on seminars
debates about twitter
and parasites in a fractal stomach!”
Merry Christmas everyone! See you in the New Year (provided I survive the hippos – see Keith’s hippo-critical post last week).
What will happen today on the last day of the world (21st)? Will some giant asteroid hit the Earth? Will massive tsunamis ravage all the coast lines? Will climate suddenly be way to warm for life? Will methane bubble out of the oceans and asphyxiate everybody? Or are aliens going to take over our planet?
We could spend a long time discussing the causes (or not !) of the end of the world. However people usually ignore the timing of this type of inevitable (or not !!) catastrophe. We all have in mind the asteroid that Alvarez and his fellows discovered – the one that wiped out in a blink of an eye the ferocious Mr. T-Rex. But what people tend to ignore/forget is the timing of such events…
When studying the history of life, the timing and the scale of the timing is always very important! Did the asteroid wiped out the dinosaurs? If we could watch the impact of this asteroid, would we see a herd of Triceratops peacefully grazing on the ground and then, in a blink of an eye… Nothing ?! Same for the even more massive end-Permian event, would we have seen the trilobites bubbling in the sea and then the day after a desolated planet? No.
As this biological crisis appears really swift and savage in the fossil record, it does not mean that they were quick in reality. The fossil record is a random and imperfect record of time. What might look as quick as a blink of an eye could also be something as smooth and long as several million years !
As a French guy, I’m not putting the Catastrophism vs. Uniformitarianism debate back on the table. Obviously these crises were real, loads of species disappeared and in a small amount of time. But a small amount of time relative to the fossil record, not according to the Mayan calendar !
So I’ll say no worries, if the Mayans were right we still will have time to enjoy Christmas turkey as well as the next couple of million years to go !
We all know that cigarettes and smoking are bad for you. However, a recent Biology Letters paper which was featured on BBC Nature suggests that the discarded remains of cigarette butts may help to maintain the health of some urban birds.
Researchers from the National Autonomous University of Mexico found that smoked cigarette butts incorporated into house sparrow and house finch nests may act as parasite repellents. Nests which included high numbers of cigarette butts had fewer parasites. A further experiment involving heat traps to attract parasites indicated that the anti-parasitic properties of the cigarettes seemed to be related to their nicotine content which is only released after the cigarettes have been smoked. This doesn’t necessarily mean that the birds use cigarette butts as an adaptive anti-parasite strategy. Cellulose in the butts is an effective thermal insulator so any anti-parasite effects may be a fortuitous coincidence. The authors suggest that future behavioural choice tests could be used to determine whether birds can distinguish and preferentially include smoked cigarette butts in their constructions.
The paper is an interesting contribution to the growing fields of urban ecological and wildlife research. More than half of the world’s population now lives in urban areas so it is increasingly important to understand the ecological effects of this changing environment. Wildlife and urban areas are not always a happy mix – we have all seen the squished remains of a hedgehog’s attempt to cross a busy road. However, as this paper shows, sometimes urban animals can adopt novel behaviours which appear to have positive consequences.
Hippopotami have been the talk of the Trinity College Zoology department’s tea room recently. Mainly because a number of staff are about to embark on a field trip to Kenya with some undergraduate students and hippos have featured highly on the list of possible animals which an encounter with might result in death or injury, I therefore decided to investigate, partly to allay fears but mainly to stir them.
In a recent study by Dunham et al. (2010) they investigated human-wildlife conflicts which have resulted in death or injury. The fact that Hippos are one of the most dangerous animals in Africa is common knowledge (in our tea room anyway), but the good news is that crocodiles are far more dangerous. Oh and lions, lions are really dangerous, but mostly crocodiles. In Mozambique crocodiles have killed more people than all other animals combined. More good news for our would-be travellers, only 55% of hippo attacks resulted in death, whereas the figure is close to 80% for crocodiles and alarmingly even higher for elephants. Though chillingly there have been reports of Hippos abandoning herbivory for a more carnivorous lifestyle.
Overall it is good news, hippos are not in fact that dangerous as long as you can manage to keep away from the water. So our intrepid explorers can relax in their campsite in their tents on the shores of lake Naivasha just remember hippos come onto land at night to feed, so perhaps pitch your tent away from the juicy grass.
If you were given a resource that could guarantee revenue of $30 million every year, with almost triple that amount additionally coming through ancillary spending, would you ignore it? If this resource then had the power to lift some of the most marginalised people on the planet out of poverty, you would even think twice? Gorilla tourism in Rwanda is this valuable and the people living around Volcanoes National Park (one of the few remaining islands for this species) are some of the poorest in Africa. My research into interactions between the national park and local farmers has revealed that control of land is one of the key factors in creating conflict between the ideals of national park management and those of subsistence farmers. When people have little control over what they grow in this highly fertile region, either through government land use consolidation initiatives or private agro-industry, the impact of buffalos raiding potato fields or gorillas decimating eucalyptus plantations is exacerbated. The catch is, cultural values and hierarchies in Rwanda mean that leadership will be followed, as changes are effected unquestioningly. One solution is to increase the proportion of tourism revenue shared with local communities, instilling a feeling of ownership, and responsibility for, their forest. But this can only come with livelihood autonomy.
As the festive season draws upon us, Pope Benedict XVI is attracting increasing attention in the international press. Today (12th December) is scheduled to see the first tweet issued by the pontiff, a message which is predicted to reach at least 1 million followers; a remarkable number which fades in comparison to the 32 million people following Lady Gaga – what does that say about modern society?
Aside from his increasing social media presence, Pope Benedict has also been at the centre of a media storm which accused him of “banning Christmas”. The article was in response to the pontiff’s latest book, “The Infancy Narratives-Jesus of Nazareth” in which he re-evaluates evidence for aspects of the Christmas story. He commented that there was no historical record of angels singing carols and also no account of animals being present in the manger, statements which were easy fodder for attention-grabbing headlines. However, these sensationalist accounts were gross misrepresentations of what the Pope actually said and prompted a Christian news blog to release a re-assuring statement that the pontiff did not ban Christmas!
Aside from the worrying evidence of just how easily “news” can be fabricated and misconstrued, what attracted me to this story was the importance of animals in the Christmas tradition. The idea that seemed to upset people the most was the suggestion that a donkey and an ox might be removed from nativity scenes for ever more (which would undoubtedly alleviate some of the stresses associated with home-made nativity costumes!). This outcry is a reminder of our need to feel connected with animals and the natural world in general; E.O Wilson’s concept of biophilia. The presence of animals in the manger seems to be associated with some of the comforting qualities which contribute to the ever-expanding success of animal assisted therapies. Positive effects of human-animal interactions permeate all aspects of our society, from religious traditions to promoting a general sense of health and well-being in our daily lives. Some evidence even suggests that pet ownership may be correlated with longer life spans!
Rest-assured, therefore, the Pope did not in fact “ban Christmas” and both a donkey and an ox feature in the nativity scene in St. Peter’s Square. I guess this means that there will be more proud parents of “donkey number 1” swelling the audience ranks of nativity plays for many years to come!
Mr Garrison taught South Park Elementary children (season 10, episode 12) the good old fashion way of seeing evolution; “we are the retarded children of some retarded frog-fish-squirrel…”. This is the gradualist way of seeing evolutionary processes; leading from uninteresting jelly fishes to the mighty Arnold Shwarzenegger.
Many scientists reject this gradualist view in favour of Darwin’s idea that “there is no innate tendency leading to progress in evolution”. But do they really gave up this idea? A few gradualistic events in the history of life remains firmly accepted such as how the vertebrates went out of the water. . This theory refers to fossil evidence from the Late Devonian period (that’s about 350 million years ago), suggesting that early tetrapods used their legs to go out of the water and conquer the brave new terrestrial world.
However, during this last decade, many paleontologists (yes, they don’t just look for dinos) pointed out some disturbing facts: the early tetrapods, such as the iconic Ichthyostega, were in fact not able to walk out of the water at all ! So why the hell did they develop legs?
This question is an example of my favourite part of macroevolution: exaptations (when the function of a trait shifts during evolution). The French palaeontologist, S. Steyer, pointed out that early legs may have been used in many way before being useful to Usain Bolt: for swimming, for hunting (used to hold onto the seabed) or even… for sex ! S. Steyer suggested that legs could have been used to grab the female during sexy time as frogs do today.
Other interesting aspects of this gradual transition from water to land are the timing and the possible reasons why early tetrapods left the water to go conquer the new terrestrial world – which was not new at all by the way; arthropods had ventured out of the water since the early Devonian. Recent tracks discovered in Poland suggest that a 50cm long “retarded fish-frog” walked on the beach in the Early-Middle Devonian, that’s 20 million years before Mr. Ichthyostega was groping his lovely wife. Niedzwiedzki and his team interpreted these tracks (and some other “younger” ones like the Irish Valentia Island trackway) as belonging to some tetrapods that eventually went out of the sea to scavenge on the beach on low tide.
So was there really a graduale evolution from water to land in vertebrates? Who really made these tracks if it wasn’t Ichthyostega who actually just “walked ” like a walrus? Even though legs probably didn’t evolve for walking, some tetrapods may have thought that it would be fun to go on the beach for a walk and get yummy carcasses. Were their other tetrapod colleagues using their legs for less adventurous but still cool purposes such as the possibilities listed above? As an answer to these questions, let’s just say that it’s complicated and it takes more than one big step on the shore to go from the “retarded fish-frogs”…
Early ecological research relied on adventurous naturalists striking forth into unknown territory and expanding our knowledge of the natural world. This exploratory work is far from complete and many species new to science are still being identified. However, in order to study and investigate the remaining unexplored frontiers, knowing where they are is a fundamental necessity.
Finding our way around has never been so easy. GPS trackers are readily available; Google maps takes the stress out of navigating unfamiliar cities and Google Earth allows us to look down from above on some of the most remote regions of the world. The works of early cartographers with approximations of coastlines and vague “beyond here there are monsters” warnings can be relegated to historical archives. However, a recent discovery by the research vessel Southern Surveyor during its surveys of the seabed off Australia reminds us not to be so trusting of our highfalutin technology.
Sandy Island featured on weather maps and was depicted on Google Earth as lying halfway between Australia and New Caledonia. However, the 24 by 5 kilometre island was not marked on navigation charts. When the Southern Surveyor diverted its course to investigate the supposed island, they found only empty ocean with a depth of about 1.5km. Records of the phantom island seem to trace back to cartographic errors reported by the whaling ship, Velocity, in 1876. The island has now been removed from Google Maps.
From a biodiversity perspective, the non-existent island could have been home to a whole host of unusual and endemic species. The surrounding islands in this region of the South West Pacific are the remaining splinters of Australia’s separation from the ancient super-continent, Gondwana. They have high percentages of endemic species with New Caledonia recognised as one of the 25 global biodiversity hotspots. However, human colonisation of the Pacific islands caused significant biodiversity loss which continues today. If Sandy Island had existed, we can only speculate about the number of weird and wonderful creatures which, in the absence of human threats, could have called the island home.
Inaccurate maps from the 19th Century aren’t that surprising but it is pretty incredible that in our technologically savvy age an island the size of Manhattan just doesn’t exist! One expedition member commented that the mistake “raises all kinds of conspiracy theories” especially when the CIA is one of the contributing sources to the world coastline database.
I guess this is just a reminder that Google is not omnipotent after all!