Tag Archives: evodevo

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

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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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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Junk DNA Mechanism That Prevents Two Species From Reproducing Discovered

Junk DNA Mechanism That Prevents Two Species From Reproducing Discovered.

“…The segment of DNA was found in the chromosome’s heterochromatin, a densely packed region of highly repetitive sequences of junk DNA near the chromosome’s center.
During the embryo’s initial divisions, the researchers found, a specific segment of heterochromatin gets “sticky” and halts the process, preventing the entire X chromosome from separating properly; the result is that the early embryo dies…”

I wonder whether this same mechanism was involved in hominin speciation events…May be some HERVs, considered junk DNA, were involved??

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The role of calcium in the Cambrian Explosion of Life

According to the Science Daily

“…the massive and sudden surge in the calcium concentration of the Cambrian seawater — that is believed to be the result of volcanically active midocean ridges — not only initiated the buildup of calcified shells, but was also mandatory for the aggregation and stabilisation of multicellular sponge structures. This allows, on the other hand, to formulate a novel theory where the geologically induced increase of marine calcium might be the key for understanding the Cambrian Explosion of Life…”

The original paper: Fernández-Busquets, X et al. Self-Recognition and Ca2 -Dependent Carbohydrate-Carbohydrate Cell Adhesion Provide Clues to the Cambrian Explosion. Molecular Biology and Evolution, 2009; 26 (11): 2551

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