Tag Archives: wonders of evolution

Evolutionary marvels: Biodiversity in animals

Evolutionary marvels: Biodiversity in animals

The Guardian has a dozen #amazing pictures of remarkable animals that inhabit land and the deep seas. “A very worthwhile diversion,” says the New York Times’ Jennifer Kingson.

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09.19. 2013 · 9:45 am

GFP stained Drosophila larva

Please also view Dosophila embryogenesis video

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Bonobo toolmaking hints glimpses of “cutting edge” stone age technology

This is really cool as human ancestors, many millions of years ago, my have started making tools in very similar fashion. Here is the Roffman et al. PNAS paper that describes the findings in detail.

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Origin of species: through gene regulation?

“How does evolution occur?” This has been a central question in biology. Does evolution occur because a new mutation results in a new protein or because the same gene is regulated differently? How do new morphological structures evolve? How does speciation occur? A recent paper in Science ties principles in evolutionary biology, development biology, and molecular biology to answer these exact questions.

Distalless protein (dll), which is highly conserved across many genera, seems to have EVOLVED A NOVEL FUNCTION in a particular species of insect (Rheumatobates rileyi) to generate male specific antennal appendages. Males possessing these appendages have increased chances of reproducing therefore, have higher fitness (see video below). There could be two reasons for the development of these antennal appendages: first, dll in this particular species is shorter than all other species and second, dll is differentially regulated in this species. Although dll in R. rileyi appears to be shortened,  I feel that its differential expression may be more important in creating this morphology. dll is an important protein in development and therefore, it is pleiotrophic (see figure on the right below). Thus, it is likely that any alteration of the original function by the shortened protein would result in death. One scenario could be that a cis-mediated regulatory change in dll expression causes it to be expressed at a novel developmental stage in a novel tissue where some other male-specific proteins are also expressed. Interactions between dll and such male-specific protein(s) results in the formation of antennal appandages.

So, what does this study tell us about how evolution occurs? Well, one way evolution by natural selection occurs is not through new mutations that alters the function of existing proteins but through mutations that result in modifications in regulation of existing proteins to acquire novel function. Existing proteins may acquire novel functions if they are ectopically expressed, i.e, in developmental stages or tissues where they are normally not expressed. Most of the times ectopic expression may either provide no benefit to the individuals or even be detrimental but sometimes, ectopic expression may allow these proteins to interact with other proteins expressed in that tissue at that developmental stage to perform new functions. This new function may confer some reproductive advantage to that individual, therefore enhancing what population geneticists/evolutionary biologists call ‘fitness’. Over time, these individuals will take over in the population. If this population remains isolated from the ancestral population for a long period of time, it may give rise to a novel species (not this study but can be imagined).

This is a cool example of how integrating many areas of biology (evolutionary, developmental, molecular, and entomology) can elucidate novel genetic mechanisms underlying phenotypic diversity.

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Visualizing biology: from conception to birth, cell division, and more

Visualization helps in learning anything. In biology visualization has traditionally been done using pictures or posters (right).
From conception to birth. But that is so 1970s. In the technocratic future, where lullabies are delivered via iPod and iPads are norm in kindergarten, figures or posters wond do any good. Kids would hate to learn from static images….they need videos! And if you are making videos, you might as well use real data…and Alexander Tsiaras does exactly that. Using advanced technology on real pregnant women he captures images of life from conception to birth. Mes merizing!

Okay, let’s take it to a molecular level now. Let us look at structure of DNA, cell division, and molecular machinery of cell division:

Cant have enough? Visit Drew Berry’s page.

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Another example of ERV’s role in evolution

To end a royal dynasty, one has to eliminate its generals: this was the lesson of a Chinese movie I once watched in Netflix. Similar strategy is adopted by ERVs.
In a recent Plos Biology article (click here for a good summary for general audience) the authors identify MAVS, a protein produced by mitochondria (the general) that ignites immune response to protect the human cell (the Royalty) from Hepatitis-C virus (HCV). Three unrelated primates have the exact same non-synonymous mutation in the MAVS gene that  potentially alters the protein’s structure making it untouchable by the HCV particles. Unfortunately, humans, the primary host of HCV, do not have that mutation thus are relatively easily conquered by HCV. Sucks!
VERY INTERESTING is the presence of that same mutation in three different species: the authors apparently conclude it is a convergent evolution. However, this finding is in stark contrast with studies in yeast where convergence occurred at genic and network level but not at SNP level. Also, population genetics theories also find it very unlikely. Think about it, what is the probability that exactly same mutation would occur in three species branch AND SNP gets selected in all three branches? MINISCULE.
Could it be more plausible that the particular mutation existed in low frequencies in the common ancestor of all the primates and was readily available in all three branches at the time HCV like virus was active and quickly got fixed in the population? That particular virus probably did not infect humans (and other primates that do not have them) so they lost the mutaiton due to drift. Just a thought…

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How Life Started 4 BILLION Years Ago:Experimental Demonstration


This was one of the most interesting TED talks in science in a while. Many of us are familiar with the Miller-Urey experiment (1952) that showed organic compounds can be formed from inorganic chemicals. Hanczyc takes it one step further by actually demonstrating tar-like chemicals can come together to form little pockets of life like creatures that are able to eat and replicate!

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