In a variety of animals, these carotenoids can have potent free-radical-quenching and immune-boosting activity. "Whether the stud birds are acquiring more carotenoids from food or having to use less to keep their bodies healthy, they're clearly successful at keeping levels high while out-reproducing their competitors."
While several other studies have examined how carotenoid levels in animals are linked to health and other aspects of fitness at single points in time, the new study is the first to consider how an individual's temporal change in carotenoid levels is associated with its evolutionary fitness.
Conventional wisdom, McGraw explained, is that vigorous activities such as migrating thousands of miles, courtship, nesting and reproduction should deteriorate the physiological state of animals like swallows.
"Among a variety of animals, reproduction can compromise health and decreased health can inhibit reproduction," McGraw said. "But here we show that, among the best barn swallows, they're able to both keep carotenoid levels high and breed the most. Thus, we don't find clear support for a health/reproduction trade-off among wild animals."
CU's Safran and her team, which included dozens of CU students and volunteers, trapped scores of barn swallows with mist nets in rural sites around Boulder County, Colo., measuring and weighing them and taking blood and feather samples before releasing them back into the wild. Each bird was sampled between two and four times over the breeding season. Blood analysis work was done in McGraw's lab at ASU.
Three carotenoids were measured by McGraw lutein, zeaxanthin, and beta-cryptoxanthin all of which are sold in health food stores around the world. The swallows acquire caroten
|Contact: Skip Derra|
Arizona State University