TY - JOUR
T1 - A blurring of life-history lines: Immune function, molt and reproduction in a highly stable environment
AU - Merrill, Loren
AU - González-Gómez, Paulina L.
AU - Ellis, Vincenzo A.
AU - Levin, Iris I.
AU - Vásquez, Rodrigo A.
AU - Wingfield, John C.
N1 - Funding Information:
We thank Jennifer Grindstaff for use of lab space to run the BKA, and we thank Pedro Gallo who kindly allowed us to work on his property. Javiera Pantoja and Cristobal Venegas were instrumental in the data collection. The population genetics work was supported by an HHMI Undergraduate Science Education award to Grinnell College. A large proportion of the genotyping was done by I. Levin’s Bio240 Animal Behavior students: Marta Andelson, Julia Daniels, Moira Donovan, Evan Griffith, Haley Hajic, Sun Han, Seth Howard, Amanda Hodo, Edith March, Sarah McManis, Natalia Nakaidze, Elle Silverman, Loren Ulloa, and Ian Windham. Funded by the Institute of Ecology and Biodiversity ( ICM-P05-002 , and PFB-23-CONICYT ), and Grants FONDECYT 1090794 , and FONDECYT 1140548 to R.A.V. J.C.W. is grateful for support from the National Science Foundation (Grant No. IOS-0750540 ) and the Endowed Chair in Physiology, University of California , Davis.
Publisher Copyright:
© 2015 Elsevier Inc.
PY - 2015/3/1
Y1 - 2015/3/1
N2 - Rufous-collared sparrows (Zonotrichia capensis peruviensis) from valleys in the Atacama Desert of Chile, live in an extremely stable environment, and exhibit overlap in molt and reproduction, with valley-specific differences in the proportion of birds engaged in both. To better understand the mechanistic pathways underlying the timing of life-history transitions, we examined the relationships among baseline and stress-induced levels of corticosterone (CORT), testosterone, and bacteria-killing ability of the blood plasma (BKA), as well as haemosporidian parasite infections and the genetic structure of two groups of sparrows from separate valleys over the course of a year. Birds neither molting nor breeding had the lowest BKA, but there were no differences among the other three categories of molt-reproductive stage. BKA varied over the year, with birds in May/June exhibiting significantly lower levels of BKA than the rest of the year. We also documented differences in the direction of the relationship between CORT and BKA at different times during the year. The direction of these relationships coincides with some trends in molt and reproductive stage, but differs enough to indicate that these birds exhibit individual-level plasticity, or population-level variability, in coordinating hypothalamo–pituitary–adrenal axis activity with life-history stage. We found weak preliminary evidence for genetic differentiation between the two populations, but not enough to indicate genetic isolation. No birds were infected with haemosporidia, which may be indicative of reduced parasite pressure in deserts. The data suggest that these birds may not trade off among different life-history components, but rather are able to invest in multiple life-history components based on their condition.
AB - Rufous-collared sparrows (Zonotrichia capensis peruviensis) from valleys in the Atacama Desert of Chile, live in an extremely stable environment, and exhibit overlap in molt and reproduction, with valley-specific differences in the proportion of birds engaged in both. To better understand the mechanistic pathways underlying the timing of life-history transitions, we examined the relationships among baseline and stress-induced levels of corticosterone (CORT), testosterone, and bacteria-killing ability of the blood plasma (BKA), as well as haemosporidian parasite infections and the genetic structure of two groups of sparrows from separate valleys over the course of a year. Birds neither molting nor breeding had the lowest BKA, but there were no differences among the other three categories of molt-reproductive stage. BKA varied over the year, with birds in May/June exhibiting significantly lower levels of BKA than the rest of the year. We also documented differences in the direction of the relationship between CORT and BKA at different times during the year. The direction of these relationships coincides with some trends in molt and reproductive stage, but differs enough to indicate that these birds exhibit individual-level plasticity, or population-level variability, in coordinating hypothalamo–pituitary–adrenal axis activity with life-history stage. We found weak preliminary evidence for genetic differentiation between the two populations, but not enough to indicate genetic isolation. No birds were infected with haemosporidia, which may be indicative of reduced parasite pressure in deserts. The data suggest that these birds may not trade off among different life-history components, but rather are able to invest in multiple life-history components based on their condition.
KW - INHS
KW - Rufous-collared sparrow
KW - Corticosterone
KW - Hypothalamo-pituitary-adrenal axis
KW - Trade-off
KW - Zonotrichia
KW - Bacteria-killing ability
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U2 - 10.1016/j.ygcen.2015.02.010
DO - 10.1016/j.ygcen.2015.02.010
M3 - Article
C2 - 25712433
SN - 0016-6480
VL - 213
SP - 65
EP - 73
JO - General and Comparative Endocrinology
JF - General and Comparative Endocrinology
IS - 3/1
ER -