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Sex allocation in Savi’s Warblers Locustella luscinioides: multiple factors affect seasonal trends in brood sex ratios.

Neto, Julio LU ; Hansson, Bengt LU and Hasselquist, Dennis LU (2011) In Behavioural Ecology and Sociobiology 65(2). p.297-304
Abstract
Sex allocation theory predicts that whenever the relative fitness of sons and daughters differ, females should invest more in the sex with the greatest fitness return. In this study, we evaluated the influence of various ecological factors on the brood sex ratio (BSR) of Savi’s warblers (Locustella luscinioides) across several breeding seasons. There was a slight but significant female production bias at the population level, which is consistent with the ‘local resource competition’ hypothesis, as the breeding density is very high and females are more prone to disperse. We found that there was a significant decline in BSR during the breeding season, but no influence of male size, female size, social status nor extra-pair paternity were... (More)
Sex allocation theory predicts that whenever the relative fitness of sons and daughters differ, females should invest more in the sex with the greatest fitness return. In this study, we evaluated the influence of various ecological factors on the brood sex ratio (BSR) of Savi’s warblers (Locustella luscinioides) across several breeding seasons. There was a slight but significant female production bias at the population level, which is consistent with the ‘local resource competition’ hypothesis, as the breeding density is very high and females are more prone to disperse. We found that there was a significant decline in BSR during the breeding season, but no influence of male size, female size, social status nor extra-pair paternity were detected. The seasonal decline in BSR was further evaluated by assessing the within- and between-female effects, which indicated that multiple factors were operating simultaneously in our study population. First, there was a significant within- female decline in BSR, which was consistent with the decline in female condition due to the reproductive effort associated with multiple brooding (supporting the Trivers and Willard hypothesis). Second, a significant decline in BSR with the laying date of first clutches of different pairs indicated that male and/or female qualities are also associated with the seasonal variation in BSR. Finally, a comparison between the sex of the youngest nestling with the remaining ones did not suggest any bias, indicating that females do not compensate for the increased mortality of the last nestling (caused by asynchronous hatching) by producing a male from the last laid egg. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Brood sex ratio, Laying date, Laying order, Condition, Quality
in
Behavioural Ecology and Sociobiology
volume
65
issue
2
pages
297 - 304
publisher
Springer
external identifiers
  • WOS:000286322200018
  • Scopus:78751579093
DOI
10.1007/s00265-010-1046-5
language
English
LU publication?
yes
id
11e8c428-5c09-44c1-ab71-9c455fefe80d (old id 1837608)
date added to LUP
2011-03-09 13:04:35
date last changed
2016-10-13 04:40:02
@misc{11e8c428-5c09-44c1-ab71-9c455fefe80d,
  abstract     = {Sex allocation theory predicts that whenever the relative fitness of sons and daughters differ, females should invest more in the sex with the greatest fitness return. In this study, we evaluated the influence of various ecological factors on the brood sex ratio (BSR) of Savi’s warblers (Locustella luscinioides) across several breeding seasons. There was a slight but significant female production bias at the population level, which is consistent with the ‘local resource competition’ hypothesis, as the breeding density is very high and females are more prone to disperse. We found that there was a significant decline in BSR during the breeding season, but no influence of male size, female size, social status nor extra-pair paternity were detected. The seasonal decline in BSR was further evaluated by assessing the within- and between-female effects, which indicated that multiple factors were operating simultaneously in our study population. First, there was a significant within- female decline in BSR, which was consistent with the decline in female condition due to the reproductive effort associated with multiple brooding (supporting the Trivers and Willard hypothesis). Second, a significant decline in BSR with the laying date of first clutches of different pairs indicated that male and/or female qualities are also associated with the seasonal variation in BSR. Finally, a comparison between the sex of the youngest nestling with the remaining ones did not suggest any bias, indicating that females do not compensate for the increased mortality of the last nestling (caused by asynchronous hatching) by producing a male from the last laid egg.},
  author       = {Neto, Julio and Hansson, Bengt and Hasselquist, Dennis},
  keyword      = {Brood sex ratio,Laying date,Laying order,Condition,Quality},
  language     = {eng},
  number       = {2},
  pages        = {297--304},
  publisher    = {ARRAY(0x9a1b200)},
  series       = {Behavioural Ecology and Sociobiology},
  title        = {Sex allocation in Savi’s Warblers Locustella luscinioides: multiple factors affect seasonal trends in brood sex ratios.},
  url          = {http://dx.doi.org/10.1007/s00265-010-1046-5},
  volume       = {65},
  year         = {2011},
}