An evolutionary sampler
This week, I offer short summaries of several papers (and links to abstracts) rather than my usual longer analysis of one or two papers. Let me know if you see a nice blog summary of any of these, and I will add a link.
Note that this week's crop of evolution papers, from just three leading peer-reviewed journals (Nature, PNAS, and Proceedings of the Royal Society), equals the total number of peer-reviewed journal articles claimed by "intelligent design" (in the International Journal of Fuzzy Systems, etc.) over the entire history of this failed idea.
Reproductive skew in female common marmosets: what can proximate mechanisms tell us about ultimate causes?
Marmosets are monkeys; "proximate"="how does it work?" whereas "ultimate"="why did it evolve?" Subordinate females rarely ovulate and are less sexual because of past natural selection, imposed by infanticide against the offspring of subordinate females by dominant females.
Migration strategy and divergent sexual selection on bird song
Two components of sexual selection, female choice and male competition, can be hard to separate. Male blackcap birds sing differently to females, who prefer complex songs, and to other males, who are more intimidated by more repetitive songs. Comparing songs among populations suggests that female choice is more important in migratory populations and male competition is more important in nonmigratory populations. The latter should be particularly relevant to African swallows.
Hippocampal volumes and neuron numbers increase along a gradient of environmental harshness: a large-scale comparison
Chickadees living in colder climates had brain structure consistent with natural selection for ability to remember the location of cached food. [But could it be individual acclimation to cold climate or a maternal-environment effect rather than genetic evolution of populations?]
Selection and gene flow on a diminishing cline of melanic peppered moths
A favorite example of recent evolution was apparent in patterns over space as well as time and still is. Explaining the current pattern requires considering migration as well as natural selection.
An amino acid polymorphism in the couch potato gene forms the basis for climatic adaptation in Drosophila melanogaster
They found a gene for diapause (similar to hibernation) in fruit-flies, which shows the geographic pattern expected with natural selection imposed by winter weather.
Infrared radiation from hot cones on cool conifers attracts seed-feeding insects
Insects that feed on pine cones use infrared radiation to find them. [Trees may produce cones in batches too large for all the insects to eat, but maybe they should just chill.]
DNA variation and symbiotic associations in phenotypically diverse sea urchin Strongylocentrotus intermedius
Two visually-distinct forms of sea urchin aren't genetically different enough to be species, but they consistently harbor different symbiotic bacteria. Maybe adaptation to these different symbionts will eventually lead to speciation.
A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers
Who're you calling "bizarre?" Another fossil that should help us understand the evolution of birds from dinosaurs.
For more information, see the discussion by Carl Zimmer or this one by PZ Meyers.