Advanced

A blurring of life-history lines : Immune function, molt and reproduction in a highly stable environment

Merrill, Loren; González-Gómez, Paulina L.; Ellis, Vincenzo A. LU ; Levin, Iris I.; Vásquez, Rodrigo A. and Wingfield, John C (2015) In General and Comparative Endocrinology 213. p.65-73
Abstract

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... (More)

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.

(Less)
Please use this url to cite or link to this publication:
author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Bacteria-killing ability, Corticosterone, Hypothalamo-pituitary-adrenal axis, Rufous-collared sparrow, Trade-off, Zonotrichia
in
General and Comparative Endocrinology
volume
213
pages
9 pages
publisher
Elsevier
external identifiers
  • scopus:84925936371
ISSN
0016-6480
DOI
10.1016/j.ygcen.2015.02.010
language
English
LU publication?
no
id
c4acfa18-2171-4359-ad9b-7550534a0778
date added to LUP
2017-05-09 17:12:58
date last changed
2017-05-17 16:50:05
@article{c4acfa18-2171-4359-ad9b-7550534a0778,
  abstract     = {<p>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.</p>},
  author       = {Merrill, Loren and González-Gómez, Paulina L. and Ellis, Vincenzo A. and Levin, Iris I. and Vásquez, Rodrigo A. and Wingfield, John C},
  issn         = {0016-6480},
  keyword      = {Bacteria-killing ability,Corticosterone,Hypothalamo-pituitary-adrenal axis,Rufous-collared sparrow,Trade-off,Zonotrichia},
  language     = {eng},
  month        = {03},
  pages        = {65--73},
  publisher    = {Elsevier},
  series       = {General and Comparative Endocrinology},
  title        = {A blurring of life-history lines : Immune function, molt and reproduction in a highly stable environment},
  url          = {http://dx.doi.org/10.1016/j.ygcen.2015.02.010},
  volume       = {213},
  year         = {2015},
}