Savanna habitat drives birds, and perhaps others, to cooperativ...(gram at the Cornell Laboratory of Ornith...)

Date:8/16/2007

gram at the Cornell Laboratory of Ornithology in Ithaca, New York, constructed a family tree of the African starlings using DNA from samples they captured on expeditions to Africa, from birds housed in zoos and from museum specimens. They used this evolutionary tree to determine whether specific lineages were associated with savanna or non-savanna habitats.

"What's important here is how many times behavior changed," said Lovette. "If you find the same pattern consistently repeated, you can be confident of cause and effect. In this case, we found cooperative breeding evolved when different starling species moved from forests to savannas."

The researchers found that more than one-third of the African starlings are cooperative breeders, and all live in savanna environments - semi-arid grasslands characterized by unpredictable rainfall patterns. In contrast, they found that most of the non-cooperative species live in forests, which are much more predictable and stable environments.

"If we saw just a single evolutionary origin of the behavior and a single switch in habitat, it would be very weak evidence of a relationship between these factors. But we found that cooperative breeding and habitat changed repeatedly in the same direction at the same points in the tree, so we can make a much more powerful statistical argument that the factors are related," Rubenstein said.

Using long-term rainfall data from the National Oceanic and Atmospheric Administration collected from over 2,000 sites across Africa and going back nearly 150 years at some locations, the researchers showed that African savannas are not only highly seasonal environments, but that rainfall is unpredictable and varies greatly from year-to-year. Statistical analyses and the researchers' evolutionary tree helped them isolate the specific environmental characteristic of savannas that might be responsible for this pattern: temporal, or year-to-year, variability in rainfall.'/>"/>

Contact: Robert Sanders rsanders@berkeley.edu 510-643-6998 University of California - Berkeley Source:Eurekalert

0 GOOD

Page: 1 2 3 4
Related biology news :

1. Habitat use by North Pacific right whales, Eubalaena japonica, in the Bering Sea and Gulf of Alaska
2. Could better mangrove habitats have spared lives in the 2004 tsunami?
3. Bird song changes sound alarm over habitat fragmentation
4. Habitat microstructure drives salamander metamorphosis
5. New tiger report release: Tiger habitat down from just a decade ago
6. Invasive species alter habitat to their benefit
7. Palaus coral reefs show differential habitat recovery following the 1998 bleaching event
8. Unchecked DNA replication drives earliest steps toward cancer
9. Climate change drives widespread amphibian extinctions
10. Mindless autopilot drives people to underestimate food decisions
11. Buildup of damaged DNA in cells drives aging