December 2008 - Biology Issues

Biology Issues

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Biology Issues - December 2008

Advances in our knowledge of genetics

December 17th 2008 05:04

Genetics is currently undergoing a revolution, not only in terms of the techniques and technologies employed to allow us to see more clearly and quickly the hereditary basis for much of the variation in humans and nature, but also in terms of understanding how the genome was put together through evolution. There have been some notable surprises, some of which are presented in an excellent bunch of articles from New Scientist.

How does a genome increase in size? How does it get more complex? To what extent has horizontal gene transfer been integral to both? Are new genes predominantly the result of duplications and modifications of preexisting genes, or are a substantial proportion of them built up de novo? How much of a genome's so-called "junk DNA" actually carries out important functions? Is variability in gene number as important in terms of phenotypic effect as heterozygosity? Can relaxed selection be regarded as a creative evolutionary process in its own right that contributes to complexification? These sorts of questions form the crux of much current research in genetics, and while we are making some notable advances in coming up with likely answers to them, we clearly still have most of the work cut out for us

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Living fossils

December 10th 2008 05:45

Wired magazine has listed 12 "living fossils" for your edification. A living fossil is a species that appears to have changed very little over geological time right up to the present day. The iconic living fossil is the Coelacanth, a sarcopterygian that was discovered alive in 1938 off the coast of South Africa (and has been found subsequently in other places). The term living fossil is actually somewhat misleading. It implies that these species haven't changed at all, but since we have only fossil data, we can't tell to what extent these lineages have changed at the molecular level, or whether non-fossilised parts of their morphology have changed. Indeed, these may well have changed. Another thing to keep in mind is that these species, while they may bear a striking resemblance to their kin in the fossil record, are not necessarily any less efficient than other species that show more derived character states. Clearly, if they have survived to the present day, they must have had what it took to get here, either because of the aforementioned non-fossilised aspects of their make-up, or because their ancestral biological design has sufficed in the environments in which they live. It is possible that these designs are in fact so efficient that stablilising selection has kept them there. Finally, some people are apt to see these species as "proof" that evolution is a fraud, because, to their minds, evolutionary theory necessitates that all species must evolve; finding species that seem to have stayed the same for a long time therefore means that evolution cannot account for them. This is wrong on two counts. Firstly, evolutionary theory doesn't necessitate that a species must evolve. There are factors that could see a species remaining the same indefinitely, for the reasons I stated above, or perhaps because of some homeostasis that prevails in the species' genetic or developmental architecture. Secondly, evolution is clearly visible in the fossil record, so finding evidence of lineages that have undergone little or no evolution simply presents us with another problem: why haven't these lineages evolved?

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Posted By: LuisC - Category: No Category

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Olivia Judson's evolution blog

December 9th 2008 07:29

In case anyone's interest, the biologist Olivia Judson has a highly entertaining and fascinating blog on the New York Times website, called The Wild Side. She provides regular stories about issues in evolution, including genetics and disease control, human psychology, natural history and sexual selection, and lots more. She is also the author of the wonderfully hilarious and informative Dr Tatiana's Sex Advice to all Creation.

Here is an excerpt from her blog, where she talks about the latest efforts to bring dengue fever under control by genetically engineering its vector, the mosquito species Aedes aegypti:
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Posted By: LuisC - Category: No Category

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The wonder of evolution

December 8th 2008 13:28

There is an underlying, deep and haunting wonder about biology that all biologists (whether professional or aspiring) are familiar with. In biology, one is dealing with systems that work according to a type of logic but that nevertheless lacks a conscious logician directing it all. It is a sort of emergent logic that arises from the interplay of entities that exhibit a few simple features but that, once these features are actualised, end up producing entities that are stranger and more awe-inspiring than even our most advanced technology. Biological machines - organisms, organs, cells, ribosomes, enzymes - can, like human-made machines, be said to function in the furtherance of a purpose. The purpose of a bat's echolocation is to allow it find its prey; the purpose of a pheromone is to attract a mate. The truly wonderful thing about all this is that the rationality, as one might call it, that we see in these entities is the result of natural processes that are themselves unconscious and blind but extremely powerful. They are so powerful that they produce things of incredible complexity that have baffled us for centuries but that are only now being understood in any significant detail. The imperative behind all biological machinery is the propagation of DNA (or RNA, in the case of many viruses). That is the utility function of the complex pieces of apparatus that make up the living world.

Understanding how this actually happens is one of the greatest joys available to the human psyche. A species has come of age when it understands the forces that have produced it - that is, how its existence is tied in with the rest of nature, and how nature has, through countless eons, produced creatures capable of asking questions like "What's it all about?" Evolution, perhaps the most stunning discovery ever made, is that process. It is a process of change - fortuitous, gradual, episodic, uneven, but with a regularity called "natural selection". It is also a story - the grandest story we know of, spanning three and a half billion years, comprising countless lost dynasties, false starts and dead ends, close calls and great flowerings, eternal partnerships and eternal rivalries, shaky alliances and squabbling companions. It is a story often times punctuated by cataclysm, often times by enduring stasis, of repetition and reinvention, and novelty and opportunism. It's rich beyond measure, fascinating like nothing else, and important enough to deserve no less than a fully naturalistic explanation. I have spoken about evolution as though it were poetry, and in a way it is. Certainly, it is haunting and mind-expanding enough to warrant the very finest that poetry can deliver, and its telling must be available to every person on the planet so that they can share in its wonder

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