Tracking Pacific walrus, impacts of early-life stress, and plant traits matter more than origin

Monitoring Pacific Walrus: With the end of summer fast approaching, US Geological Survey (USGS) researchers are once again gearing up to radio-tag walruses on Alaska’s northwestern coast as part of the agency’s ongoing study of how the marine mammals are coping with declining sea ice. “Sea ice is an important component in the life cycle of walruses.  These tracking studies will help us to better understand how top consumers in the arctic ecosystem may be affected by changes in sea ice habitats,” said USGS Alaska Science Center research ecologist Chad Jay in yesterday’s USGS press release. Walruses, which can dive hundreds of feet in search of food, rely on sea ice to rest between dives.  When sea ice is not available, the animals haul out on beaches, something they have been doing more frequently as the extent of sea ice has decreased in recent summers.  Read more at www.usgs.gov/blogs/features/ Far-reaching impact of stress: A new study published in the Proceedings of the Royal Society B. shows that when zebra finches (Taeniopygia guttata) are briefly exposed to stress early in life, the jolt of stress hormones reduced not only their own lifespan, but that of their breeding partner as well.  Pat Monaghan (University of Glasgow) and co-authors report that “only 5 percent of control birds with control partners had died after 3 years, compared with over 40 percent in early stress pairs. Interestingly, a pair’s reproductive success did not seem to be compromised by the early-life exposure to stress. Traits trump plant origins: Nonnative plants often get a bad rap as being a potential threat to wildlife habitat and many state agencies spend time and energy getting rid of them.  An In Press study with Ecological Applications suggests that might be a misplaced effort in some cases.  Jillian Cohen (Cornell University) and colleagues compared the impacts of native and nonnative wetland plants on three species of native larval amphibians.  They found no difference in metamorphosis rates and length of larval period between habitats dominated by native and nonnative plants.  Say the authors: “We suggest that to improve habitats for native fauna managers should focus on assembling a plant community with desirable traits rather than only focusing on plant origin.” Rising sources of nitrate to Gulf of Mexico:  The results of a new study by the US Geological Survey (USGS) published in Environmental Science and Technology found that in spite of decreases along some portions of the Mississippi River Basin, overall efforts to curb this nutrient have been unsuccessful.   Excessive nitrate contributes to the Gulf of Mexico’s dead zones—areas unable to support marine life because of minimal oxygen.  The USGS study...

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Zebra finches practice singing for the ladies

The male zebra finch (Taeniopygia guttata) learns to sing in private before performing for a female audience, according to Satoshi Kojima and Allison J. Doupe from the University of California, San Francisco. In addition, juvenile male finches seem to step up the quality of their singing, despite their immaturity, when in the presence of potential mates. As described in the blog Talking Science, part of National Public Radio’s Science Friday Initiative, “Male finches, by the time they are sexually mature, typically know two different forms of song: undirected, which is performed in isolation, and directed, which is performed for a female audience. Young males learn undirected song first, which characteristically sounds immature and is of variable quality. As adults, they become experts in directed song, a talent they refine specifically for the purpose of courting females.” As the researchers reported in the Proceedings of the National Academy of Sciences study, the juveniles, when performing for females, seemed to focus on the best parts of the songs that they practiced in private. Kara Rogers wrote in Talking Science, “The discovery reveals that the undirected song of young male finches disguises the actual extent of the birds’ song-learning capabilities…” In other words, despite their inexperience, immature male finches were able to sing at the level of mature finches in the appropriate social conditions: When there was a chance to  mate. Read about the zebra finch genome in Nature or take the songbird call challenge at enature.com. Photo Credit: Patricia van...

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Genome reveals olfactory communication in the zebra finch

In an article published earlier this week in Nature, researchers revealed the complete genome of the zebra finch and focused on the intricacies of their vocal communication. The zebra finch, the males of which are known to learn and repeat the same song generation after generation, show 800 active genes involved in vocalization. One group of researchers, however, found more hidden in the code. Doron Lancet and Tsviya Olender of the Weizmann Institute’s Molecular Genetics Department co-authored the study, but they honed in on the olfactory system of the zebra finch. They discovered that, of the approximately 500 genes encoding smell receptors, 200 of the finch’s genes can potentially produce functional smell receptors. Compared to the chicken genome, which is known to produce around 70 active proteins of the 500 genes, this shows a key role for smell, say the researchers. Given the importance of communication in the zebra finch, they suggest that smell is also playing an important part in communication. Lancet and Olender compared the finch’s sequence to other bird species and found that 95% of the receptors in the finch appeared to belong to families unique to them. That is, the gene sequence for olfaction in one finch could be distinct from another finch, suggesting the smell receptors are just as individual as the song a particular bird produces. As Lancet described in a press release, “this finding suggests that smells may be involved in the unique communications among individuals within the species, on top of the messages they send through their songs.” Read more on the implications for vocal communication in finches and humans at “From a Songbird, New Insights Into the Brain.” Warren, W., et al. (2010). The genome of a songbird Nature, 464 (7289), 757-762 DOI: 10.1038/nature08819 Photo credit: marj k on...

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