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Guldemond RAR, Louw CJ, Maré C, Nørgaard C, van Aarde RJ. Demographic responses of an insular elephant population to removal as a management intervention. CONSERVATION SCIENCE AND PRACTICE 2022. [DOI: 10.1111/csp2.12741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- Robert A. R. Guldemond
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
| | - Cornelius J. Louw
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
| | - Celesté Maré
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
| | - Camilla Nørgaard
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
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van Hooft P, Dougherty ER, Getz WM, Greyling BJ, Zwaan BJ, Bastos ADS. Genetic responsiveness of African buffalo to environmental stressors: A role for epigenetics in balancing autosomal and sex chromosome interactions? PLoS One 2018; 13:e0191481. [PMID: 29415077 PMCID: PMC5802885 DOI: 10.1371/journal.pone.0191481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 01/05/2018] [Indexed: 02/04/2023] Open
Abstract
In the African buffalo (Syncerus caffer) population of the Kruger National Park (South Africa) a primary sex-ratio distorter and a primary sex-ratio suppressor have been shown to occur on the Y chromosome. A subsequent autosomal microsatellite study indicated that two types of deleterious alleles with a negative effect on male body condition, but a positive effect on relative fitness when averaged across sexes and generations, occur genome-wide and at high frequencies in the same population. One type negatively affects body condition of both sexes, while the other acts antagonistically: it negatively affects male but positively affects female body condition. Here we show that high frequencies of male-deleterious alleles are attributable to Y-chromosomal distorter-suppressor pair activity and that these alleles are suppressed in individuals born after three dry pre-birth years, likely through epigenetic modification. Epigenetic suppression was indicated by statistical interactions between pre-birth rainfall, a proxy for parental body condition, and the phenotypic effect of homozygosity/heterozygosity status of microsatellites linked to male-deleterious alleles, while a role for the Y-chromosomal distorter-suppressor pair was indicated by between-sex genetic differences among pre-dispersal calves. We argue that suppression of male-deleterious alleles results in negative frequency-dependent selection of the Y distorter and suppressor; a prerequisite for a stable polymorphism of the Y distorter-suppressor pair. The Y distorter seems to be responsible for positive selection of male-deleterious alleles during resource-rich periods and the Y suppressor for positive selection of these alleles during resource-poor periods. Male-deleterious alleles were also associated with susceptibility to bovine tuberculosis, indicating that Kruger buffalo are sensitive to stressors such as diseases and droughts. We anticipate that future genetic studies on African buffalo will provide important new insights into gene fitness and epigenetic modification in the context of sex-ratio distortion and infectious disease dynamics.
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Affiliation(s)
- Pim van Hooft
- Resource Ecology Group, Wageningen University, Wageningen, The Netherlands
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Hatfield, South Africa
- * E-mail:
| | - Eric R. Dougherty
- Department of Environmental Science Policy & Management, University of California, Berkeley, California, United States of America
| | - Wayne M. Getz
- Department of Environmental Science Policy & Management, University of California, Berkeley, California, United States of America
- School of Mathematical Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Barend J. Greyling
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Hatfield, South Africa
- Agricultural Research Council, Irene, South Africa
| | - Bas J. Zwaan
- Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands
| | - Armanda D. S. Bastos
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Hatfield, South Africa
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Šárová R, Špinka M, Ceacero F. Higher dominance position does not result in higher reproductive success in female beef cattle. J Anim Sci 2018; 95:3301-3309. [PMID: 28805904 DOI: 10.2527/jas.2017.1415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to investigate whether beef cows that achieve higher dominance status than their age-mates have prolonged reproductive life, increased number of offspring born and weaned, and/or heavier BW of the offspring. We also assessed whether maternal dominance rank affects the offspring sex ratio. We recorded data on 309 potential deliveries of female beef cows with known dominance status in a seasonally pastured herd over a 14-yr period and linked them with yearly records of dominance status of the cows assessed around feeding. We did not find any effect of age-corrected dominance index on cow reproductive success measured as delivery or weaning success, calf birth weight or weaning weight, survival of the cow to the following reproductive season, or sex of the conceived calf (generalized linear models, > 0.05). In conclusion, the results indicate that in a typical situation of pastured beef cattle, there might be no selection for individual striving to achieve higher dominance status.
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Pluháček J, Steck BL. Different Sex Allocations in Two Related Species: The Case of the Extant Hippopotamus. Ethology 2015. [DOI: 10.1111/eth.12357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Jan Pluháček
- Department of Ethology; Institute of Animal Science; Praha - Uhříněves Czech Republic
- Ostrava Zoo; Ostrava Czech Republic
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van Hooft P, Greyling BJ, Getz WM, van Helden PD, Zwaan BJ, Bastos ADS. Positive selection of deleterious alleles through interaction with a sex-ratio suppressor gene in African Buffalo: a plausible new mechanism for a high frequency anomaly. PLoS One 2014; 9:e111778. [PMID: 25372610 PMCID: PMC4221135 DOI: 10.1371/journal.pone.0111778] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/23/2014] [Indexed: 11/18/2022] Open
Abstract
Although generally rare, deleterious alleles can become common through genetic drift, hitchhiking or reductions in selective constraints. Here we present a possible new mechanism that explains the attainment of high frequencies of deleterious alleles in the African buffalo (Syncerus caffer) population of Kruger National Park, through positive selection of these alleles that is ultimately driven by a sex-ratio suppressor. We have previously shown that one in four Kruger buffalo has a Y-chromosome profile that, despite being associated with low body condition, appears to impart a relative reproductive advantage, and which is stably maintained through a sex-ratio suppressor. Apparently, this sex-ratio suppressor prevents fertility reduction that generally accompanies sex-ratio distortion. We hypothesize that this body-condition-associated reproductive advantage increases the fitness of alleles that negatively affect male body condition, causing genome-wide positive selection of these alleles. To investigate this we genotyped 459 buffalo using 17 autosomal microsatellites. By correlating heterozygosity with body condition (heterozygosity-fitness correlations), we found that most microsatellites were associated with one of two gene types: one with elevated frequencies of deleterious alleles that have a negative effect on body condition, irrespective of sex; the other with elevated frequencies of sexually antagonistic alleles that are negative for male body condition but positive for female body condition. Positive selection and a direct association with a Y-chromosomal sex-ratio suppressor are indicated, respectively, by allele clines and by relatively high numbers of homozygous deleterious alleles among sex-ratio suppressor carriers. This study, which employs novel statistical techniques to analyse heterozygosity-fitness correlations, is the first to demonstrate the abundance of sexually-antagonistic genes in a natural mammal population. It also has important implications for our understanding not only of the evolutionary and ecological dynamics of sex-ratio distorters and suppressors, but also of the functioning of deleterious and sexually-antagonistic alleles, and their impact on population viability.
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Affiliation(s)
- Pim van Hooft
- Resource Ecology Group, Wageningen University, Wageningen, The Netherlands
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Hatfield, South Africa
- * E-mail:
| | - Ben J. Greyling
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Hatfield, South Africa
- Agricultural Research Council, Irene, South Africa
| | - Wayne M. Getz
- Department of Environmental Science Policy & Management, University of California, Berkeley, California, United States of America
- School of Mathematical Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Paul D. van Helden
- DST/NRF Centre of Excellence for Biomedical TB Research, US/MRC Centre for TB Research, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Bas J. Zwaan
- Laboratory of Genetics, Wageningen University, Droevendaalsesteeg 1, Wageningen, The Netherlands
| | - Armanda D. S. Bastos
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Hatfield, South Africa
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Law PR, Fike B, Lent PC. Birth sex in an expanding black rhinoceros (Diceros bicornis minor) population. J Mammal 2014. [DOI: 10.1644/13-mamm-a-175] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Megaze A, Belay G, Balakrishnan M. Population structure and ecology of the African buffalo (Syncerus cafferSparrman, 1779) in Chebera Churchura National Park, Ethiopia. Afr J Ecol 2012. [DOI: 10.1111/aje.12049] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Aberham Megaze
- Department of Zoological Sciences; College of Natural Sciences; Addis Ababa University; PO Box 1176; Addis Ababa; Ethiopia
| | - Gurja Belay
- Department of Zoological Sciences; College of Natural Sciences; Addis Ababa University; PO Box 1176; Addis Ababa; Ethiopia
| | - Mundanthra Balakrishnan
- Department of Zoological Sciences; College of Natural Sciences; Addis Ababa University; PO Box 1176; Addis Ababa; Ethiopia
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Hohenbrink S, Meinecke-Tillmann S. Influence of social dominance on the secondary sex ratio and factors affecting hierarchy in Holstein dairy cows. J Dairy Sci 2012; 95:5694-701. [PMID: 22921625 DOI: 10.3168/jds.2011-5281] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 06/28/2012] [Indexed: 11/19/2022]
Abstract
In several studies of different species, the proportions of male and female offspring did not match the statistical assumption of 50:50. Aside from environmental and genetic factors, biological parameters were found to influence the sex ratio. Three hypotheses (Trivers-Willard, advantaged daughter, and the local resource competition hypothesis) have been proposed, stating that the sex of progeny might be influenced by sex-biased maternal investment in the raising of offspring. The results of existing studies are still conflicting, even within studies on the same species. The aim of the present study was to investigate whether the dominance status of cows influences the secondary sex ratio. A herd of lactating cows was observed directly for 126 h, and a dominance index (DI) was established for 71 individuals (aged between 2.6 and 9.8 yr) for which at least 8 encounters had been observed to categorize individuals as subordinate, intermediate, or dominant. Furthermore, the number and sex of calves were assessed, and further individual characteristics of the animals (e.g., age, milk yield, body condition, and lameness scores) were analyzed for interrelationships with dominance status as well as the influence of the DI on the secondary sex ratio. The results indicated that the DI was independent of age, but a negative correlation was found between DI and lameness, whereas a positive correlation was shown for DI and body condition score. In general, more dominant animals had lower lameness scores and better body conditions. No sex ratio bias was found for primi- or for pluriparous animals and no seasonal influences were detected. The proportion of male offspring was significantly correlated with the DI of lactating cows, where animals with a higher social rank produced a lower proportion of male progeny. The pairwise comparison between dominant and subordinate lactating cows revealed a significant difference in the sex ratios of progeny, with subordinate animals having more male calves. These results indicate that the maternal dominance rank was associated with the secondary sex ratio in cattle. These observations are generally in agreement with the advantaged daughter hypothesis.
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Affiliation(s)
- S Hohenbrink
- Institute for Reproductive Biology, University of Veterinary Medicine Hannover, 30559 Hanover, Germany
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Marealle WN, Fossøy F, Holmern T, Stokke BG, Røskaft E. Does illegal hunting skew Serengeti wildlife sex ratios? WILDLIFE BIOLOGY 2010. [DOI: 10.2981/10-035] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Bercovitch FB, Loomis CP, Rieches RG. Age-Specific Changes in Reproductive Effort and Terminal Investment in Female Nile Lechwe. J Mammal 2009. [DOI: 10.1644/08-mamm-a-124.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Selection at the Y chromosome of the African buffalo driven by rainfall. PLoS One 2007; 2:e1086. [PMID: 17971851 PMCID: PMC2034602 DOI: 10.1371/journal.pone.0001086] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Accepted: 10/08/2007] [Indexed: 11/19/2022] Open
Abstract
Selection coefficients at the mammalian Y chromosome typically do not deviate strongly from neutrality. Here we show that strong balancing selection, maintaining intermediate frequencies of DNA sequence variants, acts on the Y chromosome in two populations of African buffalo (Syncerus caffer). Significant correlations exist between sequence variant frequencies and annual rainfall in the years before conception, with five- to eightfold frequency changes over short time periods. Annual rainfall variation drives the balancing of sequence variant frequencies, probably by affecting parental condition. We conclude that sequence variants confer improved male reproductive success after either dry or wet years, making the population composition and dynamics very sensitive to climate change. The mammalian Y chromosome, interacting with ecological processes, may affect male reproductive success much more strongly than previously thought.
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Tobey JR, Andrus CH, Doyle L, Thompson VD, Bercovitch FB. Maternal effort and joey growth in koalas (Phascolarctos cinereus). J Zool (1987) 2006. [DOI: 10.1111/j.1469-7998.2005.00041.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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