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Sex ratio of breeding Common toads (Bufo bufo) - influence of survival and skipped breeding

Loman, Jon LU and Madsen, Thomas LU (2010) In Amphibia-Reptilia 31(4). p.509-524
Abstract
Anuran sex ratio at breeding sites is typically male biased. Such sex ratios may be due to poor female survival, to females not breeding as frequently as males and/or to males becoming sexually mature earlier than females. In the present study, the first two factors are analyzed in a common toad (Bufo bufo) population in southern Sweden. Toads were captured, marked and recaptured at the breeding site during 5 years. Within season capture patterns were analyzed using the Jolly-Seber model and among-year captures using the Closed robust design model. Population estimates of males and females yielded an among year variation in breeding population sex ratio, ranging from 16% to 34% females. On average, 41% (proportion adult alive but not... (More)
Anuran sex ratio at breeding sites is typically male biased. Such sex ratios may be due to poor female survival, to females not breeding as frequently as males and/or to males becoming sexually mature earlier than females. In the present study, the first two factors are analyzed in a common toad (Bufo bufo) population in southern Sweden. Toads were captured, marked and recaptured at the breeding site during 5 years. Within season capture patterns were analyzed using the Jolly-Seber model and among-year captures using the Closed robust design model. Population estimates of males and females yielded an among year variation in breeding population sex ratio, ranging from 16% to 34% females. On average, 41% (proportion adult alive but not breeding) of the females skipped breeding seasons, whereas the corresponding estimate for males was less than 5%. Yearly survival averaged 42% for adult female and 63% for adult male toads. First year adult males and females had a lower survival rate than older toads. Our results demonstrate that both a female biased mortality rate and a higher proportion of skipped breeding in females contribute to the observed male biased sex ratio. However, a deterministic model suggests other factors may also be involved to obtain this degree of male biased sex ratio, the most likely being that females mature at a later age than male toads. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
MARK, life history, semelparous, breeding strategy, capture-recapture, temporary emigration
in
Amphibia-Reptilia
volume
31
issue
4
pages
509 - 524
publisher
Brill Academic Publishers
external identifiers
  • wos:000283924000008
  • scopus:78149315721
ISSN
0173-5373
DOI
10.1163/017353710X524705
language
English
LU publication?
yes
id
6171d339-7a17-4b52-9163-45d9decde443 (old id 1753489)
date added to LUP
2010-12-29 12:35:52
date last changed
2018-05-29 10:38:38
@article{6171d339-7a17-4b52-9163-45d9decde443,
  abstract     = {Anuran sex ratio at breeding sites is typically male biased. Such sex ratios may be due to poor female survival, to females not breeding as frequently as males and/or to males becoming sexually mature earlier than females. In the present study, the first two factors are analyzed in a common toad (Bufo bufo) population in southern Sweden. Toads were captured, marked and recaptured at the breeding site during 5 years. Within season capture patterns were analyzed using the Jolly-Seber model and among-year captures using the Closed robust design model. Population estimates of males and females yielded an among year variation in breeding population sex ratio, ranging from 16% to 34% females. On average, 41% (proportion adult alive but not breeding) of the females skipped breeding seasons, whereas the corresponding estimate for males was less than 5%. Yearly survival averaged 42% for adult female and 63% for adult male toads. First year adult males and females had a lower survival rate than older toads. Our results demonstrate that both a female biased mortality rate and a higher proportion of skipped breeding in females contribute to the observed male biased sex ratio. However, a deterministic model suggests other factors may also be involved to obtain this degree of male biased sex ratio, the most likely being that females mature at a later age than male toads.},
  author       = {Loman, Jon and Madsen, Thomas},
  issn         = {0173-5373},
  keyword      = {MARK,life history,semelparous,breeding strategy,capture-recapture,temporary emigration},
  language     = {eng},
  number       = {4},
  pages        = {509--524},
  publisher    = {Brill Academic Publishers},
  series       = {Amphibia-Reptilia},
  title        = {Sex ratio of breeding Common toads (Bufo bufo) - influence of survival and skipped breeding},
  url          = {http://dx.doi.org/10.1163/017353710X524705},
  volume       = {31},
  year         = {2010},
}