Category: Research Blog Page 3 of 7

This paper shows that the Scr protein binds DNA as a homodimer in at least some contexts.  One interesting question is whether this prediction can be used to search for candidate Scr binding sites in enhancer sequences?

A quick overview in Nature Methods.

Pavlicev and Wagner have a new paper in TREE where they “discuss evidence for variation in pleiotropy and propose the selection, pleiotropy and compensation model (SPC) for adaptive evolution. [This model] predicts that adaptive change in one character is associated with deleterious pleiotropy in others and subsequent selection to compensate for these pleiotropic effects.”  They talk about the implications of this model for the genetic basis of evolutionary change and many other things including sexual dimorphism  Take a look – this is well worth reading.

Here is a paper in Evolution looking at the evolution of sex-specific color patterns in dragon lizards.  Using phylogenetic analysis, the authors conclude that there are “clear sex differences in colour pattern complexity, which were positively correlated with both sexual dichromatism and sexual size dimorphism, consistent with the idea that sexual selection plays a significant role in the evolution of colour pattern complexity”.

This is just for fun.  Such complex genetic architecture is typical of most complex traits in humans and other organisms – recall Matt Rockman’s review that Judy presented a while ago.  So their conclusions may elicit a “duh” reaction from us evolutionary biologists, but from the social science point of view it’s enjoyable.

Here is a new paper that looks at the evolution of gene expression on the W chromosome in chicken breeds that were selected for either female-specific or male-specific traits.  The results are not unexpected, but still quite interesting – take a look.  If you are interested in sexual conflict or the evolution of sex determination and sex chromosomes in general, look up other papers by Judith Mank – lots of good stuff.

A brief history and update on nanopore sequencing in Science.

Take a look at this paper from the last issue of Nature.   From the abstract:

“Here we confirm, using species-level molecular phylogenies for five families of non-passerine birds, that colour polymorphism is associated with accelerated speciation rates in the three groups in which polymorphism is most prevalent. In all five groups, colour polymorphism is lost at a significantly greater rate than it is gained. Thus, the general rarity and phylogenetic dispersion of colour polymorphism is accounted for by a combination of higher speciation rate and higher transition rate from polymorphism to monomorphism”.

It would be interesting to hear Brian Moore’s perspective on the phylogenetic analysis.  And of course I wonder whether the same pattern would hold outside of birds.

Here’s a nice experimental analysis of the role that genital bristles play in sexual selection.  The authors used laser surgery to ablate specialized bristles on the male genitalia of D. ananassae (these bristles are actually located on the anal plates (A10 segment) rather than the genitalia (A9), but let’s not quibble – they are still part of the mating apparatus).  The males’ competitiveness and ability to mate were greatly reduced.  These “genital spines” have evolved independently in many Drosophila species, but of course there are many more species that get along just fine without them.  Now if we could also understand the female side of this interaction…

Cell type–specific chromatin immunoprecipitation from multicellular complex samples using BiTS-ChIP

This is based on FACS sorting of cells from formaldehyde-fixed tissues.  Not easily applicable to a lot of our questions, but there are cases where it may be useful.