Offspring sex ratio in domestic goats: Trivers-Willard out of natural selection
The Trivers-Willard hypothesis (TWH) predicts the ability of mothers to adaptively adjust offspring sex ratio through differential maternal investment based on their relative body condition. In the present study we have analyzed an extensive data set on the secondary sex ratio (SSR) including 59 335...
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Czech Academy of Agricultural Sciences
2015-05-01
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| Series: | Czech Journal of Animal Science |
| Subjects: | |
| Online Access: | https://cjas.agriculturejournals.cz/artkey/cjs-201505-0002_offspring-sex-ratio-in-domestic-goats-trivers-willard-out-of-natural-selection.php |
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| author | J. Polák V. Mareš R. Konrád D. Frynta |
| author_facet | J. Polák V. Mareš R. Konrád D. Frynta |
| author_sort | J. Polák |
| collection | DOAJ |
| description | The Trivers-Willard hypothesis (TWH) predicts the ability of mothers to adaptively adjust offspring sex ratio through differential maternal investment based on their relative body condition. In the present study we have analyzed an extensive data set on the secondary sex ratio (SSR) including 59 335 goat kids born in 30 633 litters to 11 644 mothers on farms all over the Czech Republic during the years 1992-2004. We found a male-biased SSR 0.568, which significantly deviates from the predicted balanced Fisherian equilibrium 1 : 1 (P < 0.0001). A generalized estimating equation model controlled for mother's identity revealed a significant effect of maternal age and season of conception (P < 0.001). Conversely, neither paternal age, gestation length, nor litter size were found to explain the sex ratio variation. We also failed to prove any effect of variables associated with maternal condition, particularly her body weight, breed, arbitrary ranking of genetic quality, and hornedness that were available in a data subset. Thus, unlike in some other ungulate species, our findings do not support the TWH in the domestic goat despite the tendency for male-biased litters and we discuss some alternative adaptive and proximate mechanism of the mammalian SSR. |
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| format | Article |
| id | doaj.art-9ba718fe855249c98fba56880d97ec8b |
| institution | Directory Open Access Journal |
| issn | 1212-1819 1805-9309 |
| language | English |
| last_indexed | 2024-04-10T08:26:22Z |
| publishDate | 2015-05-01 |
| publisher | Czech Academy of Agricultural Sciences |
| record_format | Article |
| series | Czech Journal of Animal Science |
| spelling | doaj.art-9ba718fe855249c98fba56880d97ec8b2023-02-23T03:33:18ZengCzech Academy of Agricultural SciencesCzech Journal of Animal Science1212-18191805-93092015-05-0160520821510.17221/8170-CJAScjs-201505-0002Offspring sex ratio in domestic goats: Trivers-Willard out of natural selectionJ. Polák0V. Mareš1R. Konrád2D. Frynta3Department of Zoology, Faculty of Science, Charles University in Prague, Prague, Czech RepublicUnion of Sheep and Goat Breeders, Brno, Czech RepublicUnion of Sheep and Goat Breeders, Brno, Czech RepublicDepartment of Zoology, Faculty of Science, Charles University in Prague, Prague, Czech RepublicThe Trivers-Willard hypothesis (TWH) predicts the ability of mothers to adaptively adjust offspring sex ratio through differential maternal investment based on their relative body condition. In the present study we have analyzed an extensive data set on the secondary sex ratio (SSR) including 59 335 goat kids born in 30 633 litters to 11 644 mothers on farms all over the Czech Republic during the years 1992-2004. We found a male-biased SSR 0.568, which significantly deviates from the predicted balanced Fisherian equilibrium 1 : 1 (P < 0.0001). A generalized estimating equation model controlled for mother's identity revealed a significant effect of maternal age and season of conception (P < 0.001). Conversely, neither paternal age, gestation length, nor litter size were found to explain the sex ratio variation. We also failed to prove any effect of variables associated with maternal condition, particularly her body weight, breed, arbitrary ranking of genetic quality, and hornedness that were available in a data subset. Thus, unlike in some other ungulate species, our findings do not support the TWH in the domestic goat despite the tendency for male-biased litters and we discuss some alternative adaptive and proximate mechanism of the mammalian SSR.https://cjas.agriculturejournals.cz/artkey/cjs-201505-0002_offspring-sex-ratio-in-domestic-goats-trivers-willard-out-of-natural-selection.phpmaternal ageparental investmentsex allocationsex ratio manipulationtrivers-willard hypothesisungulates |
| spellingShingle | J. Polák V. Mareš R. Konrád D. Frynta Offspring sex ratio in domestic goats: Trivers-Willard out of natural selection Czech Journal of Animal Science maternal age parental investment sex allocation sex ratio manipulation trivers-willard hypothesis ungulates |
| title | Offspring sex ratio in domestic goats: Trivers-Willard out of natural selection |
| title_full | Offspring sex ratio in domestic goats: Trivers-Willard out of natural selection |
| title_fullStr | Offspring sex ratio in domestic goats: Trivers-Willard out of natural selection |
| title_full_unstemmed | Offspring sex ratio in domestic goats: Trivers-Willard out of natural selection |
| title_short | Offspring sex ratio in domestic goats: Trivers-Willard out of natural selection |
| title_sort | offspring sex ratio in domestic goats trivers willard out of natural selection |
| topic | maternal age parental investment sex allocation sex ratio manipulation trivers-willard hypothesis ungulates |
| url | https://cjas.agriculturejournals.cz/artkey/cjs-201505-0002_offspring-sex-ratio-in-domestic-goats-trivers-willard-out-of-natural-selection.php |
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