It's that time where I feel I have not been educational enough, or haven't written enough, so I force myself to seek out interesting news, usually resulting in me raiding ScienceDaily and giving snippets of insight into what's going on in the science world. This time I have gone a little bit further and have found a wider range of stories, from other sites too. Some are up to date (ish) whereas the odd one might be a few weeks old. Ah well, here goes:
One of the most important innovations in evolutionary history was the evolution of segmentation, allowing for evolution to become more creative. Many segmented organisms have repeating segments which are identical (think of a centipede or millipede for example) and this allows evolution to co-opt these segments for other purposes, allowing differentiation whilst not disrupting the original function, as one segment continues its job whilst the other alters (this occurs at genetic levels with the duplication of genes and gene complexes too). Increases in differentiation lead to specialisation and the result is often a highly complex structure. Dawkins termed the evolution of segmentation a watershed event in evolution, opening up the door for incredible diversification (see The Ancestor's Tale for details). Organisms such as arthropods and annelid worms are obviously segmented, but so are we and the rest of the chordates. Our segmentation is slightly more obvious when we look at the vertebral column, though keep in mind that segments can fuse and merge together.
A question that has been looming in the minds of scientists is whether or not segmentation evolved once, in a common ancestor of the three aforementioned groups, or whether it is a convergent feature. The three groups are not closely related, so a segmented common ancestor would be back in the Precambrian, around 600 million years ago. If it evolved multiple times, then it may have appeared close to the Cambrian explosion, but then an explanation is needed in order to explain why it evolved in three separate lineages at the same time. A recent study looking at the genes involved in segmentation has found that they are remarkably similar in the separate segmented phyla, suggesting that we all did evolve from a segmented common ancestor and that segmentation evolved only once. See here for more details.
Necks: An Important Evolutionary Innovation
here for more.
Stress and Lampreys
here for more.
Belly Flopping Frogs
here. It saddens me that frog diversity is really struggling right now, especially in a time when we are discovering some very interesting adaptations among them (who can forget the frog which walks on water; the Pinocchio-nosed frog; the frogs which breathe through their skin; or the elaborate behavioural patterns of some frogs?) who knows what we will never discover?
The "basic machinery" for sex appears to have been present in eukaryotes from very early on, whereas the evolution of meiosis from mitosis would suggest a long period where there was no meiosis. The key to the problem appears to be stress; prokaryotes tend to favour transformation in conditions where stress is common and damage to DNA occurs. Similarly, in eukaryotes which reproduce by both mitosis and meiosis, such as yeast, stressful conditions tend to favour meiosis over mitosis. Both transformation and meiosis are utilised during stressful conditions as they combat DNA damage. The researchers have suggested that this gives great insight into how meiosis evolved from transformation. See here for more on this fascinating story.
Red Blood and More Lampreys
here for more.
here for more on the whale olfaction discovery and see here for my own previous discussion of whales and evolution.
here for more on this story. Although it would likely be very difficult, the idea of underwater palaeontology is quite appealing as we normally look for fossils on land, even though most of the planet is underwater. It is almost as appealing as extra-terrestrial palaeontology, which is the subject of another post maybe...
New Species and Novel Fundraising
here for some beautiful pictures of the fossils and here for the university's public article.
Ducks: More Obsessed With Penis Size Than We Are
here for the article. Also, with the mention of birds, check out this article about sex chromosomes in mammals and birds, it turns out we took opposite paths.
That's all for now, but not quite all I have to talk about. Some of the news I found was worthy of its own post, due later (or tomorrow). That's not to say that these others aren't as interesting, they simply caused less tangents.