Findings

Science  18 Jan 2013:
Vol. 339, Issue 6117, pp. 258
  1. Building a Better Burrow

    Dig in.

    Genetics drives this oldfield mouse to build a two-tunnel burrow.

    CREDIT: J. B. MILLER, FLORIDA PARK SERVICE

    Genetically speaking, it might not take much to evolve some new complex behaviors—such as how a wild mouse expands its burrow. Burrowing behavior varies between species: Deer mice make simple, one-tunnel burrows, whereas a close relative, the oldfield mouse, goes for a long, two-tunnel design that includes an escape passage. To assess the genetic basis of burrow building, Harvard University evolutionary biologist Hopi Hoekstra and her colleagues bred oldfield mice with deer mice, mated the offspring again with deer mice, and then assessed tunnel characteristics in both generations. Different genes control different components of burrow building, Hoekstra and her colleagues reported this week in Nature. Three gene regions underlie tunnel length, but just one determines whether escape tunnels are made. That region could contain only one gene—suggesting that very little genetic change is needed to evolve the two-tunnel burrow (a dominant trait). "The paper provides a nice empirical example of how a complex behavior evolves on a genetic level," says Catherine Peichel, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle, Washington. http://scim.ag/burrowers

  2. Rethinking Barnacle Reproduction

    Long shot.

    P. polymerus shoots sperm into the water via its long penis (top, above feeding legs).

    CREDIT: M. BARAZANDEH ET AL., PROCEEDINGS OF THE ROYAL SOCIETY B, 2 (ADVANCED ONLINE) © THE ROYAL SOCIETY 2013

    Scientists continue to marvel at the length of the barnacle's penis—up to eight times its body length in some species. That endowment has long been thought to explain how the immobile creatures manage to reproduce (barring a few self-fertilizing species). But a study published this week in the Proceedings of the Royal Society B suggests that at least one species, Pollicipes polymerus, has a different approach—possibly a compensation for its relatively short penis. P. polymerus delivers sperm through copulation when close enough to reach its neighbor, but it also casts sperm out into the water column, trusting that distant mates will capture them. Apparently, the scattershot approach works: The researchers found that most fertilized barnacle eggs contained DNA from distant barnacles. But the finding may make some scientists cringe, says Joseph Pawlik, a marine biologist at the University of North Carolina, Wilmington, who was not involved in the study. Previous studies have assumed that barnacles reproduce only with their near neighbors, he says—so "I suspect that some people will need to go back and look at the studies they've been doing." http://scim.ag/barnre

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