Inferences From a Rapidly Moving Hybrid Zone

Dasmahapatra, Kanchon K.; Blum, Michael J.; Aiello, Annette; Hackwell, Stuart; Davies, Neil; Bermingham, Eldredge; Mallet, James

doi:10.1111/j.0014-3820.2002.tb01385.x

Cited by 136 publications

(146 citation statements)

References 55 publications

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“…In the gradient contact zone, the respective mechanism is unknown since Gligor et al [30] did not detect recent purebred immigrants in either direction. They discussed cyto-nuclear incompatibility [58,59] versus environmental selection, potentially on cyto-nuclear gene complexes (e.g. [60]), as possible causes for asymmetric introgression.…”

Section: Discussionmentioning

confidence: 99%

Hybridization of mouse lemurs: different patterns under different ecological conditions

et al. 2011

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BackgroundSeveral mechanistic models aim to explain the diversification of the multitude of endemic species on Madagascar. The island's biogeographic history probably offered numerous opportunities for secondary contact and subsequent hybridization. Existing diversification models do not consider a possible role of these processes. One key question for a better understanding of their potential importance is how they are influenced by different environmental settings. Here, we characterized a contact zone between two species of mouse lemurs, Microcebus griseorufus and M. murinus, in dry spiny bush and mesic gallery forest that border each other sharply without intermediate habitats between them. We performed population genetic analyses based on mtDNA sequences and nine nuclear microsatellites and compared the results to a known hybrid zone of the same species in a nearby wide gradient from dry spiny bush over transitional forest to humid littoral forest.ResultsIn the spiny-gallery system, Microcebus griseorufus is restricted to the spiny bush; Microcebus murinus occurs in gallery forest and locally invades the dryer habitat of its congener. We found evidence for bidirectional introgressive hybridization, which is closely linked to increased spatial overlap within the spiny bush. Within 159 individuals, we observed 18 hybrids with mitochondrial haplotypes of both species. Analyses of simulated microsatellite data indicate that we identified hybrids with great accuracy and that we probably underestimated their true number. We discuss short-term climatic fluctuations as potential trigger for the dynamic of invasion and subsequent hybridization. In the gradient hybrid zone in turn, long-term aridification could have favored unidirectional nuclear introgression from Microcebus griseorufus into M. murinus in transitional forest.ConclusionsMadagascar's southeastern transitional zone harbors two very different hybrid zones of mouse lemurs in different environmental settings. This sheds light on the multitude of opportunities for the formation of hybrid zones and indicates an important influence of environmental factors on secondary contact and hybridization. Our findings suggest that hybridization could enhance the adaptability of mouse lemurs without necessarily leading to a loss of distinctiveness. They point to a potential role of hybridization in Madagascar's diversification history that requires further investigation.

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Section: Discussionmentioning

confidence: 99%

Hybridization of mouse lemurs: different patterns under different ecological conditions

et al. 2011

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“…Determining if a hybrid zone is moving can be accomplished using distributional data in combination with phenotypic and/or genetic data (e.g., [66]). Direct measurements of hybrid zone movement require long-term sampling of any of these data types (e.g., [67-69]).…”

Section: Monitoring Changes In Geographic Distributions Using Hybrid mentioning

confidence: 99%

“…When available, diagnostic (or nearly diagnostic) differences between species allow us to be confident that alleles that are shared in the hybrid zone are the result of hybridization and introgression, as opposed to shared ancestral polymorphism (see Box 1). In a similar way, we can use distribution data and records of hybrid individuals, or of the overlap between parental species, to determine hybrid zone locations through time (e.g., [66]). This approach can be problematic when identification of hybrids in the field is difficult, or when the parental species have similar morphology.…”

Section: Monitoring Changes In Geographic Distributions Using Hybrid mentioning

confidence: 99%

Hybrid zones: windows on climate change

Taylor

Larson

Harrison

2015

Trends in Ecology & Evolution

183

210

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Defining the impacts of anthropogenic climate change on biodiversity and species distributions is currently a high priority. Niche models focus primarily on predicted changes in abiotic factors; however, species interactions and adaptive evolution will impact the ability of species to persist in the face of changing climate. Our review focuses on the use of hybrid zones to monitor species' responses to contemporary climate change. Monitoring hybrid zones provides insight into how range boundaries shift in response to climate change by illuminating the combined effects of species interactions and physiological sensitivity. At the same time, the semi-permeable nature of species boundaries allows us to document adaptive introgression of alleles associated with response to climate change.

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“…In some cases it has proved possible to detect the actual movement of hybrid zones by repeated surveys or reviewing museum collections e.g. [45],[46]. In other cases the movement would be too slow, or held back by barriers to gene flow or gradients in population density [47].…”

Section: Discussionmentioning

confidence: 99%

The Inexorable Spread of a Newly Arisen Neo-Y Chromosome

2008

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A newly arisen Y-chromosome can become established in one part of a species range by genetic drift or through the effects of selection on sexually antagonistic alleles. However, it is difficult to explain why it should then spread throughout the species range after this initial episode. As it spreads into new populations, it will actually enter females. It would then be expected to perform poorly since it will have been shaped by the selective regime of the male-only environment from which it came. We address this problem using computer models of hybrid zone dynamics where a neo-XY chromosomal race meets the ancestral karyotype. Our models consider that the neo-Y was established by the fusion of an autosome with the ancestral X-chromosome (thereby creating the Y and the ‘fused X’). Our principal finding is that sexually antagonistic effects of the Y induce indirect selection in favour of the fused X-chromosomes, causing their spread. The Y-chromosome can then spread, protected behind the advancing shield of the fused X distribution. This mode of spread provides a robust explanation of how newly arisen Y-chromosomes can spread. A Y-chromosome would be expected to accumulate mutations that would cause it to be selected against when it is a rare newly arrived migrant. The Y can spread, nevertheless, because of the indirect selection induced by gene flow (which can only be observed in models comprising multiple populations). These results suggest a fundamental re-evaluation of sex-chromosome hybrid zones. The well-understood evolutionary events that initiate the Y-chromosome's degeneration will actually fuel its range expansion.

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Inferences From a Rapidly Moving Hybrid Zone

Cited by 136 publications

References 55 publications

Hybridization of mouse lemurs: different patterns under different ecological conditions

Hybridization of mouse lemurs: different patterns under different ecological conditions

Hybrid zones: windows on climate change

The Inexorable Spread of a Newly Arisen Neo-Y Chromosome

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