Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition
Estimates of the intensity and abundance of species provide essential data for ecological, evolutionary and epidemiological studies of gastrointestinal nematode communities. These estimates are typically derived from the species composition of adult males when only males have readily scorable specie...
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Cambridge University Press (CUP)
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crcambridgeupr:10.1017/s0031182004006298 2024-09-15T18:38:21+00:00 Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition STIEN, A. DALLIMER, M. IRVINE, R. J. HALVORSEN, O. LANGVATN, R. ALBON, S. D. DALLAS, J. F. 2004 http://dx.doi.org/10.1017/s0031182004006298 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0031182004006298 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Parasitology volume 130, issue 1, page 99-107 ISSN 0031-1820 1469-8161 journal-article 2004 crcambridgeupr https://doi.org/10.1017/s0031182004006298 2024-07-17T04:03:20Z Estimates of the intensity and abundance of species provide essential data for ecological, evolutionary and epidemiological studies of gastrointestinal nematode communities. These estimates are typically derived from the species composition of adult males when only males have readily scorable species-specific morphological traits. Such estimation assumes that all species in the community have the same adult sex ratio. We evaluated this assumption for the trichostrongyle nematodes Ostertagia gruehneri and Marshallagia marshalli in infracommunities in Svalbard reindeer by identifying to species adult females using a polymerase chain reaction assay. The proportion of males was found to be slightly higher in O. gruehneri than in M. marshalli . Evidence for seasonal variation and density dependence in the adult sex ratio was only found for O. gruehneri . Possible demographic mechanisms for such sex ratio variation are discussed, and stochastic models that generate density-dependent sex ratios proposed. Sex ratio variation caused substantial bias in some male-based estimates of intensity of infection, while substantial and consistent bias in estimates of abundances was only evident in late winter samples. Our results suggest that estimating sex ratios can be particularly important in individual host level studies of nematode species of low abundance. Article in Journal/Newspaper Svalbard svalbard reindeer Cambridge University Press Parasitology 130 1 99 107 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Estimates of the intensity and abundance of species provide essential data for ecological, evolutionary and epidemiological studies of gastrointestinal nematode communities. These estimates are typically derived from the species composition of adult males when only males have readily scorable species-specific morphological traits. Such estimation assumes that all species in the community have the same adult sex ratio. We evaluated this assumption for the trichostrongyle nematodes Ostertagia gruehneri and Marshallagia marshalli in infracommunities in Svalbard reindeer by identifying to species adult females using a polymerase chain reaction assay. The proportion of males was found to be slightly higher in O. gruehneri than in M. marshalli . Evidence for seasonal variation and density dependence in the adult sex ratio was only found for O. gruehneri . Possible demographic mechanisms for such sex ratio variation are discussed, and stochastic models that generate density-dependent sex ratios proposed. Sex ratio variation caused substantial bias in some male-based estimates of intensity of infection, while substantial and consistent bias in estimates of abundances was only evident in late winter samples. Our results suggest that estimating sex ratios can be particularly important in individual host level studies of nematode species of low abundance. |
format |
Article in Journal/Newspaper |
author |
STIEN, A. DALLIMER, M. IRVINE, R. J. HALVORSEN, O. LANGVATN, R. ALBON, S. D. DALLAS, J. F. |
spellingShingle |
STIEN, A. DALLIMER, M. IRVINE, R. J. HALVORSEN, O. LANGVATN, R. ALBON, S. D. DALLAS, J. F. Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition |
author_facet |
STIEN, A. DALLIMER, M. IRVINE, R. J. HALVORSEN, O. LANGVATN, R. ALBON, S. D. DALLAS, J. F. |
author_sort |
STIEN, A. |
title |
Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition |
title_short |
Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition |
title_full |
Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition |
title_fullStr |
Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition |
title_full_unstemmed |
Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition |
title_sort |
sex ratio variation in gastrointestinal nematodes of svalbard reindeer; density dependence and implications for estimates of species composition |
publisher |
Cambridge University Press (CUP) |
publishDate |
2004 |
url |
http://dx.doi.org/10.1017/s0031182004006298 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0031182004006298 |
genre |
Svalbard svalbard reindeer |
genre_facet |
Svalbard svalbard reindeer |
op_source |
Parasitology volume 130, issue 1, page 99-107 ISSN 0031-1820 1469-8161 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0031182004006298 |
container_title |
Parasitology |
container_volume |
130 |
container_issue |
1 |
container_start_page |
99 |
op_container_end_page |
107 |
_version_ |
1810482742574448640 |