Fisher vs. the Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms that Produce Them
Parker, Baker, and Smith provided the first robust theory explaining why anisogamy evolves in parallel in multicellular organisms. Anisogamy sets the stage for the emergence of separate sexes, and for another phenomenon with which Parker is associated: sperm competition. In outcrossing taxa with sep...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-07-01
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| Series: | Cells |
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| Online Access: | https://www.mdpi.com/2073-4409/10/7/1793 |
| _version_ | 1797527405617741824 |
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| author | Justin Van Goor Diane C. Shakes Eric S. Haag |
| author_facet | Justin Van Goor Diane C. Shakes Eric S. Haag |
| author_sort | Justin Van Goor |
| collection | DOAJ |
| description | Parker, Baker, and Smith provided the first robust theory explaining why anisogamy evolves in parallel in multicellular organisms. Anisogamy sets the stage for the emergence of separate sexes, and for another phenomenon with which Parker is associated: sperm competition. In outcrossing taxa with separate sexes, Fisher proposed that the sex ratio will tend towards unity in large, randomly mating populations due to a fitness advantage that accrues in individuals of the rarer sex. This creates a vast excess of sperm over that required to fertilize all available eggs, and intense competition as a result. However, small, inbred populations can experience selection for skewed sex ratios. This is widely appreciated in haplodiploid organisms, in which females can control the sex ratio behaviorally. In this review, we discuss recent research in nematodes that has characterized the mechanisms underlying highly skewed sex ratios in fully diploid systems. These include self-fertile hermaphroditism and the adaptive elimination of sperm competition factors, facultative parthenogenesis, non-Mendelian meiotic oddities involving the sex chromosomes, and environmental sex determination. By connecting sex ratio evolution and sperm biology in surprising ways, these phenomena link two “seminal” contributions of G. A. Parker. |
| first_indexed | 2024-03-10T09:43:24Z |
| format | Article |
| id | doaj.art-b86371a2b84e45be9f6c18ff2d537aee |
| institution | Directory Open Access Journal |
| issn | 2073-4409 |
| language | English |
| last_indexed | 2024-03-10T09:43:24Z |
| publishDate | 2021-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Cells |
| spelling | doaj.art-b86371a2b84e45be9f6c18ff2d537aee2023-11-22T03:30:12ZengMDPI AGCells2073-44092021-07-01107179310.3390/cells10071793Fisher vs. the Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms that Produce ThemJustin Van Goor0Diane C. Shakes1Eric S. Haag2Department of Biology, University of Maryland, College Park, MD 20742, USADepartment of Biology, William and Mary, Williamsburg, VA 23187, USADepartment of Biology, University of Maryland, College Park, MD 20742, USAParker, Baker, and Smith provided the first robust theory explaining why anisogamy evolves in parallel in multicellular organisms. Anisogamy sets the stage for the emergence of separate sexes, and for another phenomenon with which Parker is associated: sperm competition. In outcrossing taxa with separate sexes, Fisher proposed that the sex ratio will tend towards unity in large, randomly mating populations due to a fitness advantage that accrues in individuals of the rarer sex. This creates a vast excess of sperm over that required to fertilize all available eggs, and intense competition as a result. However, small, inbred populations can experience selection for skewed sex ratios. This is widely appreciated in haplodiploid organisms, in which females can control the sex ratio behaviorally. In this review, we discuss recent research in nematodes that has characterized the mechanisms underlying highly skewed sex ratios in fully diploid systems. These include self-fertile hermaphroditism and the adaptive elimination of sperm competition factors, facultative parthenogenesis, non-Mendelian meiotic oddities involving the sex chromosomes, and environmental sex determination. By connecting sex ratio evolution and sperm biology in surprising ways, these phenomena link two “seminal” contributions of G. A. Parker.https://www.mdpi.com/2073-4409/10/7/1793sex ratiosperm competitionmeiosislocal mate competitionnematodes |
| spellingShingle | Justin Van Goor Diane C. Shakes Eric S. Haag Fisher vs. the Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms that Produce Them Cells sex ratio sperm competition meiosis local mate competition nematodes |
| title | Fisher vs. the Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms that Produce Them |
| title_full | Fisher vs. the Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms that Produce Them |
| title_fullStr | Fisher vs. the Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms that Produce Them |
| title_full_unstemmed | Fisher vs. the Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms that Produce Them |
| title_short | Fisher vs. the Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms that Produce Them |
| title_sort | fisher vs the worms extraordinary sex ratios in nematodes and the mechanisms that produce them |
| topic | sex ratio sperm competition meiosis local mate competition nematodes |
| url | https://www.mdpi.com/2073-4409/10/7/1793 |
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