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Oor Unlikely Next of Kin
The colugo, a foot-long nocturnal glider from Southeast Asia, is the closest living relative of primates. Researchers from Texas A&M University and elsewhere compared genes from colugos, tree shrews and 30 other mammals with genes from primates such as macaques and humans. They found rare genetic changes suggesting that colugos' and primates' evolutionary paths diverged about 86 million years ago, during the reign of the dinosaurs.
Fate of the Flower
The American bellflower can live for either one year or two. Which strategy does a seed adopt? It takes a cue from its parent. Scientists from Virginia and Minnesota say bellflowers grown in sunny spots produce seeds that are likely to become annuals, which thrive in full sun; shaded bellflowers yield seeds more likely to become shade-loving biennials.
Observed
Name: Zonotrichia leucophrys gambelii, or the white-crowned sparrow.
Summers In: Alaska.
Winters In: Mexico and the southwestern United States.
Navigates By: Map.
Map? Yes. And they create it themselves.
How Can You Tell? Researchers captured 15 adult and 15 juvenile sparrows in Washington State in September, flew them to New Jersey, placed radio transmitters on their backs and let them go. The adults headed southwest, toward their known wintering grounds. The juveniles—making their first migration—flew straight south, and would have missed their goal.
That's Some Map: The key, say the researchers, is that the birds automatically fly south on their first migration, and only then build a mental map of their wintering grounds that lets them return via a different route.
Nowhere to Hide
Orcas are even more cunning than their nickname—killer whales—suggests. A new analysis of field observations in Antarctica made over nearly 30 years shows that orcas, which are dolphins rather than true whales, can hunt down seals and penguins seemingly out of reach on an ice floe. Working alone or in a group, orcas create waves that dislodge a floe, break it up and wash the stranded prey into open water. The skill is probably learned: baby orcas watch the wave-making frenzy.
Mating in Desperation
In the Southwest, spadefoot toads start life in desert ponds that can dry out while they're still tadpoles. Now Karin Pfennig of the University of North Carolina has discovered an unusual strategy in a species called the plains spadefoot. In especially shallow ponds, females mate with males of another species, the Mexican spadefoot, whose tadpoles develop about three days sooner. The resulting hybrid matures more quickly than a purebred plains spadefoot, boosting survival, but it is less fertile—a trade-off.
Additional Sources
"Molecular and Genomic Data Identify the Closest Living Relative of Primates," by Jane E. Janecka et al., Science, November 2, 2007
"Evidence for a navigational map stretching across the continental U.S. in a migratory songbird," by Kasper Thorup et al., Proceedings of the National Academy of Sciences, November 13, 2007
"Facultative Mate Choice Drives Adaptive Hybridization," by Karin S. Pfennig, Science, November 9, 2007
"Transgenerational Plasticity Is Adaptive in the Wild," by Laura F. Galloway and Julie R. Etterson, Science, November 16, 2007
Comments
Is there some way to get photos that are in the magazine - in my case for educational use? My present goal was to get the photo of the colugo for my lecture on primates (as an introduction to human evolution). Also, what is the best way to find out the publication about the genetics of colugos compared to primates?
Posted by Robert E. Johnston on January 20,2008 | 05:56AM