Sex-based differences in Adélie Penguin (Pygoscelis adeliae) chick growth rates and diet

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dc.contributor.authorJennings, Scotten_ZA
dc.contributor.authorVarsani, Arvinden_ZA
dc.contributor.authorDugger, Katie Men_ZA
dc.contributor.authorBallard, Granten_ZA
dc.contributor.authorAinley, David Gen_ZA
dc.date.accessioned2016-03-08T10:55:34Z
dc.date.available2016-03-08T10:55:34Z
dc.date.issued2016en_ZA
dc.description.abstractSexually size-dimorphic species must show some difference between the sexes in growth rate and/or length of growing period. Such differences in growth parameters can cause the sexes to be impacted by environmental variability in different ways, and understanding these differences allows a better understanding of patterns in productivity between individuals and populations. We investigated differences in growth rate and diet between male and female Adélie Penguin ( Pygoscelis adeliae ) chicks during two breeding seasons at Cape Crozier, Ross Island, Antarctica. Adélie Penguins are a slightly dimorphic species, with adult males averaging larger than adult females in mass (~11%) as well as bill (~8%) and flipper length (~3%). We measured mass and length of flipper, bill, tibiotarsus, and foot at 5-day intervals for 45 male and 40 female individually-marked chicks. Chick sex was molecularly determined from feathers. We used linear mixed effects models to estimate daily growth rate as a function of chick sex, while controlling for hatching order, brood size, year, and potential variation in breeding quality between pairs of parents. Accounting for season and hatching order, male chicks gained mass an average of 15.6 g d -1 faster than females. Similarly, growth in bill length was faster for males, and the calculated bill size difference at fledging was similar to that observed in adults. There was no evidence for sex-based differences in growth of other morphological features. Adélie diet at Ross Island is composed almost entirely of two species--one krill ( Euphausia crystallorophias ) and one fish ( Pleuragramma antarctica ), with fish having a higher caloric value. Using isotopic analyses of feather samples, we also determined that male chicks were fed a higher proportion of fish than female chicks. The related differences in provisioning and growth rates of male and female offspring provides a greater understanding of the ways in which ecological factors may impact the two sexes differently.en_ZA
dc.identifier.apacitationJennings, S., Varsani, A., Dugger, K. M., Ballard, G., & Ainley, D. G. (2016). Sex-based differences in Adélie Penguin (Pygoscelis adeliae) chick growth rates and diet. <i>PLoS One</i>, http://hdl.handle.net/11427/17575en_ZA
dc.identifier.chicagocitationJennings, Scott, Arvind Varsani, Katie M Dugger, Grant Ballard, and David G Ainley "Sex-based differences in Adélie Penguin (Pygoscelis adeliae) chick growth rates and diet." <i>PLoS One</i> (2016) http://hdl.handle.net/11427/17575en_ZA
dc.identifier.citationJennings, S., Varsani, A., Dugger, K. M., Ballard, G., & Ainley, D. G. (2016). Sex-based differences in Adélie Penguin (Pygoscelis adeliae) chick growth rates and diet. PLOS ONE, 11(3), e0149090. doi:10.1371/journal.pone.0149090en_ZA
dc.identifier.ris TY - Journal Article AU - Jennings, Scott AU - Varsani, Arvind AU - Dugger, Katie M AU - Ballard, Grant AU - Ainley, David G AB - Sexually size-dimorphic species must show some difference between the sexes in growth rate and/or length of growing period. Such differences in growth parameters can cause the sexes to be impacted by environmental variability in different ways, and understanding these differences allows a better understanding of patterns in productivity between individuals and populations. We investigated differences in growth rate and diet between male and female Adélie Penguin ( Pygoscelis adeliae ) chicks during two breeding seasons at Cape Crozier, Ross Island, Antarctica. Adélie Penguins are a slightly dimorphic species, with adult males averaging larger than adult females in mass (~11%) as well as bill (~8%) and flipper length (~3%). We measured mass and length of flipper, bill, tibiotarsus, and foot at 5-day intervals for 45 male and 40 female individually-marked chicks. Chick sex was molecularly determined from feathers. We used linear mixed effects models to estimate daily growth rate as a function of chick sex, while controlling for hatching order, brood size, year, and potential variation in breeding quality between pairs of parents. Accounting for season and hatching order, male chicks gained mass an average of 15.6 g d -1 faster than females. Similarly, growth in bill length was faster for males, and the calculated bill size difference at fledging was similar to that observed in adults. There was no evidence for sex-based differences in growth of other morphological features. Adélie diet at Ross Island is composed almost entirely of two species--one krill ( Euphausia crystallorophias ) and one fish ( Pleuragramma antarctica ), with fish having a higher caloric value. Using isotopic analyses of feather samples, we also determined that male chicks were fed a higher proportion of fish than female chicks. The related differences in provisioning and growth rates of male and female offspring provides a greater understanding of the ways in which ecological factors may impact the two sexes differently. DA - 2016 DB - OpenUCT DO - 10.1371/journal.pone.0149090 DP - University of Cape Town J1 - PLoS One LK - https://open.uct.ac.za PB - University of Cape Town PY - 2016 T1 - Sex-based differences in Adélie Penguin (Pygoscelis adeliae) chick growth rates and diet TI - Sex-based differences in Adélie Penguin (Pygoscelis adeliae) chick growth rates and diet UR - http://hdl.handle.net/11427/17575 ER - en_ZA
dc.identifier.urihttp://dx.doi.org/10.1371/journal.pone.0149090en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17575
dc.identifier.vancouvercitationJennings S, Varsani A, Dugger KM, Ballard G, Ainley DG. Sex-based differences in Adélie Penguin (Pygoscelis adeliae) chick growth rates and diet. PLoS One. 2016; http://hdl.handle.net/11427/17575.en_ZA
dc.language.isoengen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.publisher.departmentDivision of Medical Biochemistryen_ZA
dc.publisher.facultyFaculty of Health Sciencesen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/4.0en_ZA
dc.sourcePLoS Oneen_ZA
dc.source.urihttp://journals.plos.org/plosoneen_ZA
dc.subject.otherPenguinsen_ZA
dc.subject.otherDieten_ZA
dc.subject.otherFeathersen_ZA
dc.subject.otherMarine fishen_ZA
dc.subject.otherAntarcticaen_ZA
dc.subject.otherForagingen_ZA
dc.subject.otherTrophic interactionsen_ZA
dc.subject.otherBirdsen_ZA
dc.titleSex-based differences in Adélie Penguin (Pygoscelis adeliae) chick growth rates and dieten_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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