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Maternal androgens in the pied flycatcher; timing of breeding and within-female consistency

Tobler, Michael LU ; Granbom, Martin and Sandell, Maria LU (2007) In Oecologia 151(4). p.731-740
Abstract
Maternal hormones can have substantial phenotypic effects in the progeny of many vertebrates. It has been proposed that mothers adaptively adjust hormone levels experienced by particular young to optimize their reproductive output. In birds, systematic variation in egg hormone levels has been related to different female reproductive strategies. Because in many bird species prospects of the offspring change seasonally and with brood number, strategic adjustment of yolk androgen levels would be expected. To test this idea, we induced pied flycatcher (Ficedula hypoleuca) females to nest twice during the same season by removing their first clutches shortly after clutch completion. We collected eggs of first and replacement clutches to measure... (More)
Maternal hormones can have substantial phenotypic effects in the progeny of many vertebrates. It has been proposed that mothers adaptively adjust hormone levels experienced by particular young to optimize their reproductive output. In birds, systematic variation in egg hormone levels has been related to different female reproductive strategies. Because in many bird species prospects of the offspring change seasonally and with brood number, strategic adjustment of yolk androgen levels would be expected. To test this idea, we induced pied flycatcher (Ficedula hypoleuca) females to nest twice during the same season by removing their first clutches shortly after clutch completion. We collected eggs of first and replacement clutches to measure yolk concentrations of androstenedione (A4) and testosterone (T) and captured the females that laid these clutches for phenotypic measurements. Although average egg androgen levels were remarkably consistent within females, hormone patterns differed considerably between first and replacement clutches. Eggs of replacement clutches were heavier with larger yolks compared to first clutches, but they contained on average lower levels of androgens. Within clutches, androgen concentration increased over the laying sequence in the first clutch, but decreased or remained more constant over the laying sequence in the replacement clutch. Mean yolk T, but not A4 levels, were negatively associated with laying date for both breeding attempts. Moreover, females in good body condition produced eggs containing lower levels of androgens than females in poor condition. Our results are consistent with the idea that differences in yolk androgen levels may be one mechanism underlying seasonal variation in reproductive success and it is possible that changes in egg androgen patterns may reflect a change in female reproductive strategy. High within-female consistency also highlights the possibility that there may be some underlying genetic variation in yolk androgen levels (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Maternal effects - Reproductive investment - Seasonal adjustment - Laying order - Clutch number
in
Oecologia
volume
151
issue
4
pages
731 - 740
publisher
Springer
external identifiers
  • wos:000246261800016
  • scopus:33947393069
ISSN
1432-1939
DOI
10.1007/s00442-006-0610-1
language
English
LU publication?
yes
id
082549a9-e7e2-430c-9ce4-9d4e9c3b1c44 (old id 629329)
date added to LUP
2007-11-28 12:50:03
date last changed
2017-01-01 04:36:58
@article{082549a9-e7e2-430c-9ce4-9d4e9c3b1c44,
  abstract     = {Maternal hormones can have substantial phenotypic effects in the progeny of many vertebrates. It has been proposed that mothers adaptively adjust hormone levels experienced by particular young to optimize their reproductive output. In birds, systematic variation in egg hormone levels has been related to different female reproductive strategies. Because in many bird species prospects of the offspring change seasonally and with brood number, strategic adjustment of yolk androgen levels would be expected. To test this idea, we induced pied flycatcher (Ficedula hypoleuca) females to nest twice during the same season by removing their first clutches shortly after clutch completion. We collected eggs of first and replacement clutches to measure yolk concentrations of androstenedione (A4) and testosterone (T) and captured the females that laid these clutches for phenotypic measurements. Although average egg androgen levels were remarkably consistent within females, hormone patterns differed considerably between first and replacement clutches. Eggs of replacement clutches were heavier with larger yolks compared to first clutches, but they contained on average lower levels of androgens. Within clutches, androgen concentration increased over the laying sequence in the first clutch, but decreased or remained more constant over the laying sequence in the replacement clutch. Mean yolk T, but not A4 levels, were negatively associated with laying date for both breeding attempts. Moreover, females in good body condition produced eggs containing lower levels of androgens than females in poor condition. Our results are consistent with the idea that differences in yolk androgen levels may be one mechanism underlying seasonal variation in reproductive success and it is possible that changes in egg androgen patterns may reflect a change in female reproductive strategy. High within-female consistency also highlights the possibility that there may be some underlying genetic variation in yolk androgen levels},
  author       = {Tobler, Michael and Granbom, Martin and Sandell, Maria},
  issn         = {1432-1939},
  keyword      = {Maternal effects - Reproductive investment - Seasonal adjustment - Laying order - Clutch number},
  language     = {eng},
  number       = {4},
  pages        = {731--740},
  publisher    = {Springer},
  series       = {Oecologia},
  title        = {Maternal androgens in the pied flycatcher; timing of breeding and within-female consistency},
  url          = {http://dx.doi.org/10.1007/s00442-006-0610-1},
  volume       = {151},
  year         = {2007},
}