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Ecology, 86(8), 2005, pp. 20402046 2005 by the Ecological Society of America
 

Summary: 2040
Reports
Ecology, 86(8), 2005, pp. 20402046
2005 by the Ecological Society of America
TREE SWALLOWS TRADE OFF IMMUNE FUNCTION AND
REPRODUCTIVE EFFORT DIFFERENTLY ACROSS THEIR RANGE
DANIEL R. ARDIA1
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853 USA
Abstract. Latitudinal differences in life histories are believed to be underlain by dif-
ferences in trade-offs between current and future reproduction. I report differences in trade-
offs between parent and offspring across the range of a widespread avian species, the Tree
Swallow (Tachycineta bicolor). I manipulated parental effort and found that in Alaska,
where yearly adult return rates are low, breeding females increase their reproductive in-
vestment to maintain offspring quality, whereas in Tennessee, where yearly adult return
rates are high, breeding females are either unable or unwilling to increase reproductive
investment and, consequently, raise offspring of lower quality. I further investigated a
critical mechanism of self-maintenance that may underlie differences in survival among
sites: immunocompetence. Females breeding in Alaska mounted weaker immune responses
when raising enlarged broods, whereas females in Tennessee did not, further suggesting a
strategy in Alaskan females to incur costs (i.e., reduce future reproduction) in order to

  

Source: Ardia, Dan - Department of Biology, Franklin and Marshall College

 

Collections: Biology and Medicine