scholarly journals The relationship between gene flow and population difference during secondary contact between butterfly sister species

2020 ◽  
Author(s):  
Erik D. Nelson ◽  
Qian Cong ◽  
Nick V. Grishin

AbstractClosely related species of butterfly sampled from southern suture zones in North America exhibit a continuous pattern of gene flow and population difference measures (index values) for autosomes, but not for the Z chromosome; When populations are compared through their Z chromosomes, index values obtained from samples of the same species are separated from those of closely related species by a gap of “missing” values, suggesting a discrete “on–off” criterion for species delimitation. Here, we explore the possibility that some, or all of the index data for suture zones reflects secondary contact between species formed in glacial refugia. We simulate fusion of butterfly populations limited by negative fitness interactions between genes in hybrids, assuming that interactions between autosomes and the Z chromosome are stronger than those among autosomes, and that hybrid fitness effects conform to Haldane’s rule. We find that weakly interbreeding populations trace out a path toward equilibrium consistent with the data for butterfly suture zones, in which index values for the Z chromosome lag behind those for autosomes, leading to a similar gap of missing values when species become indistinguishable through their autosomes, but no evidence of a sudden change in index values for the Z chromosome on longer timescales. As a result, we find that the gap can be explained by a process in which the pattern of index data for the Z chromosome is, ultimately, continuous.

2007 ◽  
Vol 3 (6) ◽  
pp. 660-663 ◽  
Author(s):  
Kanchon K Dasmahapatra ◽  
Armando Silva-Vásquez ◽  
Jae-Woo Chung ◽  
James Mallet

Interspecific hybridization occurs regularly in wild Heliconius butterflies, although hybrid individuals are usually very rare. However, hybridization generally occurs only between the most closely related species. We report a rare naturally occurring hybrid between non-sister species and carry out the first genetic analysis of such distant hybridization. Mitochondrial and nuclear genes indicate that the specimen is an F 1 hybrid between a female Heliconius ethilla and a male Heliconius melpomene , originating from a group of 13 species estimated to have diverged over 2.5 Myr ago. The presence of such distant natural hybrids, together with evidence for backcrossing, suggests that gene flow across species boundaries can take place long after speciation. Adaptive genes such as those involved in wing coloration could thus be widely shared among members of this highly mimetic genus.


2016 ◽  
Vol 6 (10) ◽  
pp. 3283-3295 ◽  
Author(s):  
Victor Borges Rezende ◽  
Carlos Congrains ◽  
André Luís A. Lima ◽  
Emeline Boni Campanini ◽  
Aline Minali Nakamura ◽  
...  

2014 ◽  
Vol 281 (1776) ◽  
pp. 20132733 ◽  
Author(s):  
Yasmin Latour ◽  
Marco Perriat-Sanguinet ◽  
Pierre Caminade ◽  
Pierre Boursot ◽  
Carole M. Smadja ◽  
...  

Sexual selection may hinder gene flow across contact zones when hybrid recognition signals are discriminated against. We tested this hypothesis in a unimodal hybrid zone between Mus musculus musculus and Mus musculus domesticus where a pattern of reinforcement was described and lower hybrid fitness documented. We presented mice from the border of the hybrid zone with a choice between opposite sex urine from the same subspecies versus hybrids sampled in different locations across the zone. While no preference was evidenced in domesticus mice, musculus males discriminated in favour of musculus signals and against hybrid signals. Remarkably, the pattern of hybrid unattractiveness did not vary across the hybrid zone. Moreover, allopatric populations tested in the same conditions did not discriminate against hybrid signals, indicating character displacement for signal perception or preference. Finally, habituation–discrimination tests assessing similarities between signals pointed out that hybrid signals differed from the parental ones. Overall, our results suggest that perception of hybrids as unattractive has evolved in border populations of musculus after the secondary contact with domesticus . We discuss the mechanisms involved in hybrid unattractiveness, and the potential impact of asymmetric sexual selection on the hybrid zone dynamics and gene flow between the two subspecies.


2017 ◽  
Vol 13 (7) ◽  
pp. 20170208 ◽  
Author(s):  
P. Anders Nilsson ◽  
Kaj Hulthén ◽  
Ben B. Chapman ◽  
Lars-Anders Hansson ◽  
Jakob Brodersen ◽  
...  

Species integrity can be challenged, and even eroded, if closely related species can hybridize and produce fertile offspring of comparable fitness to that of parental species. The maintenance of newly diverged or closely related species therefore hinges on the establishment and effectiveness of pre- and/or post-zygotic reproductive barriers. Ecological selection, including predation, is often presumed to contribute to reduced hybrid fitness, but field evidence for a predation cost to hybridization remains elusive. Here we provide proof-of-concept for predation on hybrids being a postzygotic barrier to gene flow in the wild. Cyprinid fishes commonly produce fertile, viable hybrid offspring and therefore make excellent study organisms to investigate ecological costs to hybrids. We electronically tagged two freshwater cyprinid fish species (roach Rutilus rutilus and bream Abramis brama ) and their hybrids in 2005. Tagged fish were returned to their lake of origin, exposing them to natural predation risk from apex avian predators (great cormorant, Phalacrocorax carbo ). Scanning for regurgitated tags under cormorant roosts 3–4 years later identified cormorant-killed individual fish and allowed us to directly test for a predation cost to hybrids in the wild. Hybrid individuals were found significantly more susceptible to cormorant predation than individuals from either parental species. Such ecological selection against hybrids contributes to species integrity, and can enhance species diversification.


2022 ◽  
Author(s):  
Leeban Yusuf ◽  
Venera Tyukmaeva ◽  
Anneli Hoikkala ◽  
Michael G Ritchie

Speciation with gene flow is now widely regarded as common. However, the frequency of introgression between recently diverged species and the evolutionary consequences of gene flow are still poorly understood. The virilis group of Drosophila contains around a dozen species that are geographically widespread and show varying levels of pre-zygotic and post-zygotic isolation. Here, we utilize de novo genome assemblies and whole-genome sequencing data to resolve phylogenetic relationships and describe patterns of introgression and divergence across the group. We suggest that the virilis group consists of three, rather than the traditional two, subgroups. We found evidence of pervasive phylogenetic discordance caused by ancient introgression events between distant lineages within the group, and much more recent gene flow between closely-related species. When assessing patterns of genome-wide divergence in species pairs across the group, we found no consistent genomic evidence of a disproportionate role for the X chromosome. Some genes undergoing rapid sequence divergence across the group were involved in chemical communication and may be related to the evolution of sexual isolation. We suggest that gene flow between closely-related species has potentially had an impact on lineage-specific adaptation and the evolution of reproductive barriers. Our results show how ancient and recent introgression confuse phylogenetic reconstruction, and suggest that shared variation can facilitate adaptation and speciation.


2021 ◽  
Vol 12 ◽  
Author(s):  
Zeyu Zheng ◽  
Ying Li ◽  
Minjie Li ◽  
Guiting Li ◽  
Xin Du ◽  
...  

Speciation is the key evolutionary process for generating biological diversity and has a central place in evolutionary and ecological research. How species diverge and adapt to different habitats is one of the most exciting areas in speciation studies. Here, we sequenced 55 individuals from three closely related species in the genus Carpinus: Carpinus tibetana, Carpinus monbeigiana, and Carpinus mollicoma to understand the strength and direction of gene flow and selection during the speciation process. We found low genetic diversity in C. tibetana, which reflects its extremely small effective population size. The speciation analysis between C. monbeigiana and C. mollicoma revealed that both species diverged ∼1.2 Mya with bidirectional gene flow. A total of 291 highly diverged genes, 223 copy number variants genes, and 269 positive selected genes were recovered from the two species. Genes associated with the diverged and positively selected regions were mainly involved in thermoregulation, plant development, and response to stress, which included adaptations to their habitats. We also found a great population decline and a low genetic divergence of C. tibetana, which suggests that this species is extremely vulnerable. We believe that the current diversification and adaption study and the important genomic resource sequenced herein will facilitate the speciation studies and serve as an important methodological reference for future research.


2020 ◽  
Vol 287 (1924) ◽  
pp. 20200270
Author(s):  
Anna F. Feller ◽  
Marcel P. Haesler ◽  
Catherine L. Peichel ◽  
Ole Seehausen

One hallmark of the East African cichlid radiations is the rapid evolution of reproductive isolation that is robust to full sympatry of many closely related species. Theory predicts that species persistence and speciation in sympatry with gene flow are facilitated if loci of large effect or physical linkage (or pleiotropy) underlie traits involved in reproductive isolation. Here, we investigate the genetic architecture of a key trait involved in behavioural isolation, male nuptial coloration, by crossing two sister species pairs of Lake Victoria cichlids of the genus Pundamilia and mapping nuptial coloration in the F2 hybrids. One is a young sympatric species pair, representative of an axis of colour motif differentiation, red-dorsum versus blue, that is highly recurrent in closely related sympatric species. The other is a species pair representative of colour motifs, red-chest versus blue, that are common in allopatric but uncommon in sympatric closely related species. We find significant quantitative trait loci (QTLs) with moderate to large effects (some overlapping) for red and yellow in the sympatric red-dorsum × blue cross, whereas we find no significant QTLs in the non-sympatric red-chest × blue cross. These findings are consistent with theory predicting that large effect loci or linkage/pleiotropy underlying mating trait differentiation could facilitate speciation and species persistence with gene flow in sympatry.


2021 ◽  
Author(s):  
Darren Irwin ◽  
Dolph Schluter

It is thought that two species can coexist if they use different resources present in the environment, yet this assumes that species are completely reproductively isolated. Closely related species often interbreed, raising the question of how this might affect coexistence. We model coexistence outcomes for two sympatric species that are ecologically differentiated but have incomplete reproductive isolation. Results show that the consequences of interbreeding depend crucially on hybrid fitness. When hybrid fitness is high, just a small rate of hybridization can lead to collapse of two species into one. Low hybrid fitness can cause population declines, making extinction of one or both species likely. The intrinsic growth rate of the population has an important influence on the outcome. High intrinsic growth rates result in higher reproductive rates when populations are below carrying capacity, reducing the probability of extinction and increasing the likelihood of stable coexistence at moderate levels of assortative mating and hybrid fitness. Very strong but incomplete assortative mating can induce low hybrid fitness via a mating disadvantage to rare genotypes, and this can stabilize coexistence of two species at high but incomplete levels of assortative mating. Given these results and evidence that it may take many millions of years of divergence before related species become sympatric, we postulate that coexistence of closely-related species is more often limited by insufficient assortative mating than by insufficient ecological differentiation.


Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 965 ◽  
Author(s):  
Dang ◽  
Yue ◽  
Zhang ◽  
Zhao ◽  
Zhao

Gene introgression usually results from natural hybridization occurring among closely related species in sympatric populations. In this study, we discussed two rare and frequent gene flow phenomena between three species of Juglans plants and analyzed the possible causes for the difference. We collected 656 individuals from 40 populations of Persian walnut (Juglans regia L.), Chinese walnut (J. cathayensis Dode), and Iron walnut (J. sigillata Dode) that were genotyped at 17 expressed sequence tag simple sequence repeat (EST-SSR) loci to analyze the introgressions between J. regia and J. cathayensis, and J. regia and J. sigillata. Our study compared the spatial patterns of expected heterozygosity (HE), allelic richness (Rs), and private allele richness (PAR) so as to vividly infer the biogeographic history of related species of Juglans in the two regions. The results of the PCoA, UPGMA, and STRUCTURE analyses showed that all J. regia and J. sigillata populations clustered into one group, and the J. cathayensis populations clustered into the other group. The results of the historical gene flow analysis indicated that J. regia and J. sigillata have no genetic barriers, and the directional gene flow is mainly from J. regia to J. sigillata. For the three species of Juglans, all the above results indicated that gene flow was common among the same group of Juglans, and only rare and low-level gene flow appeared in distinct groups. Therefore, our study revealed multiple phenomena of gene flow and introgression among closely related species in sympatric populations, thereby providing a theoretical basis for the genetic evolution of the genus Juglans.


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