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Xu S, Huynh TV, Snyman M. The transcriptomic signature of obligate parthenogenesis. Heredity (Edinb) 2022; 128:132-138. [PMID: 35039663 PMCID: PMC8814003 DOI: 10.1038/s41437-022-00498-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 01/04/2022] [Accepted: 01/04/2022] [Indexed: 02/03/2023] Open
Abstract
Investigating the origin of parthenogenesis through interspecific hybridization can provide insight into how meiosis may be altered by genetic incompatibilities, which is fundamental for our understanding of the formation of reproductive barriers. Yet the genetic mechanisms giving rise to obligate parthenogenesis in eukaryotes remain understudied. In the microcrustacean Daphnia pulex species complex, obligately parthenogenetic (OP) isolates emerged as backcrosses of two cyclically parthenogenetic (CP) parental species, D. pulex and D. pulicaria, two closely related but ecologically distinct species. We examine the genome-wide expression in OP females at the early resting egg production stage, a life-history stage distinguishing OP and CP reproductive strategies, in comparison to CP females of the same stage from the two parental species. Our analyses of the expression data reveal that underdominant and overdominant genes are abundant in OP isolates, suggesting widespread regulatory incompatibilities between the parental species. More importantly, underdominant genes (i.e., genes with expression lower than both parentals) in the OP isolates are enriched in meiosis and cell-cycle pathways, indicating an important role of underdominance in the origin of obligate parthenogenesis. Furthermore, metabolic and biosynthesis pathways enriched with overdominant genes (i.e., expression higher than both parentals) are another genomic signature of OP isolates.
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Affiliation(s)
- Sen Xu
- grid.267315.40000 0001 2181 9515Department of Biology, University of Texas at Arlington, Arlington, TX 76019 USA
| | - Trung V. Huynh
- grid.267315.40000 0001 2181 9515Department of Biology, University of Texas at Arlington, Arlington, TX 76019 USA
| | - Marelize Snyman
- grid.267315.40000 0001 2181 9515Department of Biology, University of Texas at Arlington, Arlington, TX 76019 USA
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Malec P, Weber J, Böhmer R, Fiebig M, Meinert D, Rein C, Reinisch R, Henrich M, Polyvas V, Pollmann M, von Berg L, König C, Steidle JLM. The emergence of ecotypes in a parasitoid wasp: a case of incipient sympatric speciation in Hymenoptera? BMC Ecol Evol 2021; 21:204. [PMID: 34781897 PMCID: PMC8591844 DOI: 10.1186/s12862-021-01938-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 11/08/2021] [Indexed: 11/24/2022] Open
Abstract
Background To understand which reproductive barriers initiate speciation is a major question in evolutionary research. Despite their high species numbers and specific biology, there are only few studies on speciation in Hymenoptera. This study aims to identify very early reproductive barriers in a local, sympatric population of Nasonia vitripennis (Walker 1836), a hymenopterous parasitoid of fly pupae. We studied ecological barriers, sexual barriers, and the reduction in F1-female offspring as a postmating barrier, as well as the population structure using microsatellites. Results We found considerable inbreeding within female strains and a population structure with either three or five subpopulation clusters defined by microsatellites. In addition, there are two ecotypes, one parasitizing fly pupae in bird nests and the other on carrion. The nest ecotype is mainly formed from one of the microsatellite clusters, the two or four remaining microsatellite clusters form the carrion ecotype. There was slight sexual isolation and a reduction in F1-female offspring between inbreeding strains from the same microsatellite clusters and the same ecotypes. Strains from different microsatellite clusters are separated by a reduction in F1-female offspring. Ecotypes are separated only by ecological barriers. Conclusions This is the first demonstration of very early reproductive barriers within a sympatric population of Hymenoptera. It demonstrates that sexual and premating barriers can precede ecological separation. This indicates the complexity of ecotype formation and highlights the general need for more studies within homogenous populations for the identification of the earliest barriers in the speciation process. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01938-y.
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Affiliation(s)
- Pawel Malec
- Naturpark Steigerwald E.V., 91443, Scheinfeld, Germany
| | - Justus Weber
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Robin Böhmer
- Natural History Museum Bern, 3005, Bern, Switzerland
| | - Marc Fiebig
- Untere Naturschutzbehörde, Landratsamt Kitzingen, 97318, Kitzingen, Germany
| | | | - Carolin Rein
- Apicultural State Institute, University of Hohenheim, 70593, Stuttgart, Germany
| | - Ronja Reinisch
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Maik Henrich
- Wildlife Ecology and Management, University of Freiburg, 79106, Freiburg, Germany
| | - Viktoria Polyvas
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Marie Pollmann
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Lea von Berg
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Christian König
- Akademie für Natur- und Umweltschutz Baden-Württemberg beim Ministerium für Umwelt, Klima und Energiewirtschaft, 70192, Stuttgart, Germany
| | - Johannes L M Steidle
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany.
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Moy I, Green M, Pham TP, Luu D, Xu S. The life-history fitness of F 1 hybrids of the microcrustacean Daphnia pulex and D. pulicaria (Crustacea, Anomopoda). INVERTEBRATE BIOLOGY : A QUARTERLY JOURNAL OF THE AMERICAN MICROSCOPICAL SOCIETY AND THE DIVISION OF INVERTEBRATE ZOOLOGY/ASZ 2021; 140:e12333. [PMID: 34366655 PMCID: PMC8341403 DOI: 10.1111/ivb.12333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Negative interaction between alleles that arise independently in diverging populations (i.e., Dobzhansky-Muller incompatibilities) can cause reduction of fitness in their hybrids. However, heterosis in hybrids can emerge if hybridization breaks down detrimental epistatic interaction within parental lineages. In this study, we examined the life-history fitness of the inter-specific F1s of two recently diverged microcrustacean species Daphnia pulex and D. pulicaria as well as intra-specific crosses of D. pulex. We identified heterosis in two out of five life-history traits in the inter-specific F1s. According to theories that heterosis can transiently emerge in early speciation, the observation of heterosis in these life-history traits suggests that there are no major genetic incompatibilities between these two species affecting these traits and that D. pulex and D. pulicaria are at an early stage of speciation.
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Affiliation(s)
| | | | | | | | - Sen Xu
- Correspondence: 501 S. Nedderman Dr, Arlington, TX, 76019.
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Chin TA, Cristescu ME. Speciation in Daphnia. Mol Ecol 2021; 30:1398-1418. [PMID: 33522056 DOI: 10.1111/mec.15824] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/11/2021] [Accepted: 01/20/2021] [Indexed: 11/26/2022]
Abstract
The microcrustacean Daphnia is arguably one of the most studied zooplankton species, having a well understood ecology, life history, and a relatively well studied evolutionary history. Despite this wealth of knowledge, species boundaries within closely related species in this genus often remain elusive and the major evolutionary forces driving the diversity of daphniids remain controversial. This genus contains more than 80 species with multiple cryptic species complexes, with many closely related species able to hybridize. Here, we review speciation research in Daphnia within the framework of current speciation theory. We evaluate the role of geography, ecology, and biology in restricting gene flow and promoting diversification. Of the 253 speciation studies on Daphnia, the majority of studies examine geographic barriers (55%). While evidence shows that geographic barriers play a role in species divergence, ecological barriers are also probably prominent in Daphnia speciation. We assess the contribution of ecological and nonecological reproductive isolating barriers between closely related species of Daphnia and found that none of the reproductive isolating barriers are restricting gene flow completely. Research on reproductive isolating barriers has disproportionally focused on two species complexes, the Daphnia pulex and Daphnia longispina species complexes. Finally, we identify areas of research that remain relatively unexplored and discuss future research directions that build our understanding of speciation in daphniids.
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Affiliation(s)
- Tiffany A Chin
- Department of Biology, McGill University, Montreal, QC, Canada
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Millette KL, Gonzalez A, Cristescu ME. Breaking ecological barriers: Anthropogenic disturbance leads to habitat transitions, hybridization, and high genetic diversity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 740:140046. [PMID: 32563876 DOI: 10.1016/j.scitotenv.2020.140046] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 06/01/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
Genetic diversity is expected to erode in disturbed habitats through strong selection, local extinctions, and recolonization associated with genetic bottlenecks and restricted gene flow. Despite this general prediction and over three decades of population genetics studies, our understanding of the long-term effect of environmental disturbance on local and regional genetic diversity remains limited. We conducted a population genetic survey of the microcrustacean Daphnia across a landscape subject to anthropogenic stressors from a century of industrial mining. At the local scale we found moderate genetic diversity (i.e., low clonal diversity), characteristic of habitat-specific selective sweeps and local extinctions, but high diversity and strong genetic structure at the regional scale despite the shared watershed of many lakes and exceptional dispersal ability of daphniids. Many habitats experienced changes in species assemblages, with the obligate asexual Daphnia pulex lineages-known only to inhabit ponds-dominating disrupted urban lakes. This habitat transition (pond to lake) was likely facilitated by the disruption of ecological barriers maintaining the genomic separation of these young species. Thus, disrupted habitats can exhibit complex and unexpected genetic patterns of local extinctions and recolonizations, followed by habitat transitions, hybridization and potential speciation events that are difficult to predict and should not be underestimated.
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Affiliation(s)
- Katie L Millette
- Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada; Quebec Centre for Biodiversity Science, Canada.
| | - Andrew Gonzalez
- Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada; Quebec Centre for Biodiversity Science, Canada
| | - Melania E Cristescu
- Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada; Quebec Centre for Biodiversity Science, Canada
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