TY - JOUR
T1 - Context dependency of baseline glucocorticoids as indicators of individual quality in a capital breeder
AU - Jaatinen, Kim
AU - Seltmann, Martin W.
AU - Hollmén, Tuula
AU - Atkinson, Shannon
AU - Mashburn, Kendall
AU - Öst, Markus
PY - 2013/9/15
Y1 - 2013/9/15
N2 - Identifying markers of individual quality is a central goal of life-history theory and conservation biology. The 'corticosterone (CORT)-fitness hypothesis' postulates that low fitness signals impaired ability to cope with the environment, resulting in elevated baseline CORT levels. CORT can, however, be negatively, positively or neutrally related to fitness, depending on the context. In order to clarify this controversial issue, we elucidate the utility of using baseline CORT as a correlate of individual fitness in incubating female eiders across variable environments. An increase in serum CORT with decreasing body condition was evident in older, more experienced breeders, while increased clutch mass was associated with elevated serum CORT in females breeding late in the season. For faecal CORT, the expected negative association with body condition was observed only in early breeders. We found a strong increase in faecal CORT with increasing baseline body temperature, indicating the utility of body temperature as a complementary stress indicator. Females in good body condition had a lower baseline body temperature, but this effect was only observed on open islands, a harsher breeding habitat less buffered against weather variability. Females with higher reproductive investment also maintained a lower baseline body temperature. Nest success strongly decreased with increasing serum and faecal CORT concentrations, and individual stress hormone and body temperature profiles were repeatable over years. Although our data support the tenet that baseline CORT is negatively related to fitness, the complex context-dependent effects call for cautious interpretation of relationships between stress physiology and phenotypic quality.
AB - Identifying markers of individual quality is a central goal of life-history theory and conservation biology. The 'corticosterone (CORT)-fitness hypothesis' postulates that low fitness signals impaired ability to cope with the environment, resulting in elevated baseline CORT levels. CORT can, however, be negatively, positively or neutrally related to fitness, depending on the context. In order to clarify this controversial issue, we elucidate the utility of using baseline CORT as a correlate of individual fitness in incubating female eiders across variable environments. An increase in serum CORT with decreasing body condition was evident in older, more experienced breeders, while increased clutch mass was associated with elevated serum CORT in females breeding late in the season. For faecal CORT, the expected negative association with body condition was observed only in early breeders. We found a strong increase in faecal CORT with increasing baseline body temperature, indicating the utility of body temperature as a complementary stress indicator. Females in good body condition had a lower baseline body temperature, but this effect was only observed on open islands, a harsher breeding habitat less buffered against weather variability. Females with higher reproductive investment also maintained a lower baseline body temperature. Nest success strongly decreased with increasing serum and faecal CORT concentrations, and individual stress hormone and body temperature profiles were repeatable over years. Although our data support the tenet that baseline CORT is negatively related to fitness, the complex context-dependent effects call for cautious interpretation of relationships between stress physiology and phenotypic quality.
KW - Baseline CORT
KW - Body temperature
KW - CORT-fitness hypothesis
KW - Context-dependent CORT response
KW - Individual quality
KW - Somateria mollissima
UR - http://www.scopus.com/inward/record.url?scp=84880994563&partnerID=8YFLogxK
U2 - 10.1016/j.ygcen.2013.06.022
DO - 10.1016/j.ygcen.2013.06.022
M3 - Article
SN - 0016-6480
VL - 191
SP - 231
EP - 238
JO - General and Comparative Endocrinology
JF - General and Comparative Endocrinology
ER -