scholarly journals Divergence in the face of gene flow in two Charadrius plovers along the Chinese coast

2018 ◽  
Author(s):  
Xuejing Wang ◽  
Pinjia Que ◽  
Gerald Heckel ◽  
Junhua Hu ◽  
Xuecong Zhang ◽  
...  
Keyword(s):  
Gene Flow ◽  
Southern China ◽  
Character Displacement ◽  
Niche Differentiation ◽  
Secondary Contact ◽  
Sea Level Changes ◽  
Charadrius Alexandrinus ◽  
Chinese Coast ◽  
The Face ◽  
Underlying Mechanisms

AbstractSpeciation with gene flow is an alternative to the nascence of new taxa in strict allopatric separation. Indeed, many taxa have parapatric distributions at present. It is often unclear if these are secondary contacts, e.g. caused by past glaciation cycles or the manifestation of speciation with gene flow, which hampers our understanding of how different forces drive diversification. Here we studied genetic, phenotypic and ecological aspects of divergence in a pair of incipient species, the Kentish (Charadrius alexandrinus) and the white-faced Plovers (C. dealbatus), shorebirds with parapatric breeding ranges along the Chinese coast. We assessed divergence based on molecular markers with different modes of inheritance and quantified phenotypic and ecological divergence in aspects of morphometric, dietary and climatic niches. These analyses revealed small to moderate levels of genetic and phenotypic distinctiveness with symmetric gene flow across the contact area at the Chinese coast. The two species diverged approximately half a million years ago in dynamical isolation and secondary contact due to cycling sea level changes between the Eastern and Southern China Sea in the mid-late Pleistocene. We found evidence of character displacement and ecological niche differentiation between the two species, invoking the role of selection in facilitating divergence despite gene flow. These findings imply that the ecology can indeed counter gene flow through divergent selection and thus contribute to incipient speciation in these plovers. Furthermore, our study highlights the importance of using integrative datasets to reveal the evolutionary history and underlying mechanisms of speciation.

Asymmetric acoustic signal recognition led to asymmetric gene flow between two parapatric frogs

2020 ◽  
Author(s):  
Yu-Wei Hsiao ◽  
Hui-Yun Tseng ◽  
Hung Ngoc Nguyen ◽  
Si-Min Lin
Keyword(s):  
Gene Flow ◽  
Contact Region ◽  
Character Displacement ◽  
Secondary Contact ◽  
Genetic Introgression ◽  
Genetic Integrity ◽  
Signal Recognition ◽  
Reproductive Character Displacement ◽  
Reproductive Character ◽  
Behavioural Experiments

Abstract Correct discrimination between courtship signals could help to maintain genetic integrity between closely related species. However, asymmetric usage of signals might cause asymmetric gene flow across the contact zone. Buergeria choui and B. otai are sibling-species with a parapatric distribution pattern in Taiwan, having two narrow contact zones on the east and west sides of the island. Combining behavioural experiments with genome-wide RAD-seq analyses, we test whether the ability of signal recognition influences genetic introgression across their species boundary. The playback experiments show that all B. choui populations respond strongest to their own ‘cricket’ trills, while the western population of B. otai have evolved a strong level of reproductive character displacement by showing the inclusive usage of the unique ‘chicken’ signals. In contrast, the eastern B. otai population uses both ‘chicken’ and ‘cricket’ trills, and has a stronger preference for the latter. The weak reproductive character displacement in the eastern population has led to asymmetry genetic introgression from B. choui toward B. otai. Our results support the prediction that a more specialized signal-user, compared to its sibling, generalized signal-user, might have a higher probability of maintaining their genetic integrity in the secondary contact region.

scholarly journals Sexual selection against natural hybrids may contribute to reinforcement in a house mouse hybrid zone

2014 ◽  
Vol 281 (1776) ◽  
pp. 20132733 ◽  
Author(s):  
Yasmin Latour ◽  
Marco Perriat-Sanguinet ◽  
Pierre Caminade ◽  
Pierre Boursot ◽  
Carole M. Smadja ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Gene Flow ◽  
Hybrid Zone ◽  
Mus Musculus ◽  
Character Displacement ◽  
Secondary Contact ◽  
Lower Hybrid ◽  
Mus Musculus Domesticus ◽  
Hybrid Fitness ◽  
Signal Perception

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.

scholarly journals Genomic impacts of chromosomal inversions in parapatric Drosophila species

2012 ◽  
Vol 367 (1587) ◽  
pp. 422-429 ◽  
Author(s):  
Suzanne E. McGaugh ◽  
Mohamed A. F. Noor
Keyword(s):  
Gene Flow ◽  
Secondary Contact ◽  
Chromosome 2 ◽  
Chromosomal Inversions ◽  
The Face ◽  
Flow Through ◽  
Drosophila Persimilis ◽  
Suppressed Recombination ◽  
Or Gene ◽  
Double Crossovers

Chromosomal inversions impact genetic variation and facilitate speciation in part by reducing recombination in heterokaryotypes. We generated multiple whole-genome shotgun sequences of the parapatric species pair Drosophila pseudoobscura and Drosophila persimilis and their sympatric outgroup ( Drosophila miranda ) and compared the average pairwise differences for neutral sites within, just outside and far outside of the three large inversions. Divergence between D. pseudoobscura and D. persimilis is high inside the inversions and in the suppressed recombination regions extending 2.5 Mb outside of inversions, but significantly lower in collinear regions further from the inversions. We observe little evidence of decreased divergence predicted to exist in the centre of inversions, suggesting that gene flow through double crossovers or gene conversion is limited within the inversion, or selection is acting within the inversion to maintain divergence in the face of gene flow. In combination with past studies, we provide evidence that inversions in this system maintain areas of high divergence in the face of hybridization, and have done so for a substantial period of time. The left arm of the X chromosome and chromosome 2 inversions appear to have arisen in the lineage leading to D. persimilis approximately 2 Ma, near the time of the split of D. persimilis–D. pseudoobscura–D. miranda , but likely fixed within D. persimilis much more recently, as diversity within D. persimilis is substantially reduced inside and near these two inversions. We also hypothesize that the inversions in D. persimilis may provide an empirical example of the ‘mixed geographical mode’ theory of inversion origin and fixation, whereby allopatry and secondary contact both play a role.

scholarly journals Genomic signatures of isolation, hybridization, and selection during speciation of island finches

2022 ◽  
Author(s):  
Martin Stervander ◽  
Martim Melo ◽  
Peter Jones ◽  
Bengt Hansson
Keyword(s):  
Gene Flow ◽  
Introgressive Hybridization ◽  
Sister Species ◽  
Secondary Contact ◽  
Gulf Of Guinea ◽  
Island Endemic ◽  
Genomic Signatures ◽  
The Face ◽  
Bill Morphology ◽  
Divergence With Gene Flow

Sister species occurring sympatrically on islands are rare and offer unique opportunities to understand how speciation can proceed in the face of gene flow. The São Tomé grosbeak is a massive-billed, 'giant' finch endemic to the island of São Tomé in the Gulf of Guinea, where it has diverged from its co-occurring sister species the Príncipe seedeater, an average-sized finch that also inhabits two neighbouring islands. Here, we show that the grosbeak carries a large number of unique alleles different from all three Príncipe seedeater populations, but also shares many alleles with the sympatric São Tomé population of the seedeater, a genomic signature signifying divergence in isolation as well as subsequent introgressive hybridization. Furthermore, genomic segments that remain unique to the grosbeak are situated close to genes, including genes that determine bill morphology, suggesting the preservation of adaptive variation through natural selection during divergence with gene flow. This study reveals a complex speciation process whereby genetic drift, introgression, and selection during periods of isolation and secondary contact all have shaped the diverging genomes of these sympatric island endemic finches.

Shallow genetic divergence and distinct phenotypic differences between two Andean hummingbirds: Speciation with gene flow?

The Auk ◽  
2019 ◽  
Vol 136 (4) ◽  
Author(s):  
Catalina Palacios ◽  
Silvana García-R ◽  
Juan Luis Parra ◽  
Andrés M Cuervo ◽  
F Gary Stiles ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Incomplete Lineage Sorting ◽  
Lineage Sorting ◽  
Phenotypic Differences ◽  
Adaptive Mechanisms ◽  
The Face ◽  
Gloger’S Rule ◽  
Divergence With Gene Flow ◽  
Neutral Markers

Abstract Ecological speciation can proceed despite genetic interchange when selection counteracts the homogenizing effects of migration. We tested predictions of this divergence-with-gene-flow model in Coeligena helianthea and C. bonapartei, 2 parapatric Andean hummingbirds with marked plumage divergence. We sequenced putatively neutral markers (mitochondrial DNA [mtDNA] and nuclear ultraconserved elements [UCEs]) to examine genetic structure and gene flow, and a candidate gene (MC1R) to assess its role underlying divergence in coloration. We also tested the prediction of Gloger’s rule that darker forms occur in more humid environments, and examined morphological variation to assess adaptive mechanisms potentially promoting divergence. Genetic differentiation between species was low in both ND2 and UCEs. Coalescent estimates of migration were consistent with divergence with gene flow, but we cannot reject incomplete lineage sorting reflecting recent speciation as an explanation for patterns of genetic variation. MC1R variation was unrelated to phenotypic differences. Species did not differ in macroclimatic niches but were distinct in morphology. Although we reject adaptation to variation in macroclimatic conditions as a cause of divergence, speciation may have occurred in the face of gene flow driven by other ecological pressures or by sexual selection. Marked phenotypic divergence with no neutral genetic differentiation is remarkable for Neotropical birds, and makes C. helianthea and C. bonapartei an appropriate system in which to search for the genetic basis of species differences employing genomics.

scholarly journals The effect of intrinsic physiological traits on diapause survival and their underlying mechanisms in an annual bee species Bombus impatiens

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Erin Treanore ◽  
Etya Amsalem
Keyword(s):  
Oxidative Stress ◽  
Life Stage ◽  
Mass Gain ◽  
Nutrient Acquisition ◽  
Bombus Impatiens ◽  
Factors Affecting ◽  
Age Related ◽  
The Face ◽  
Underlying Mechanisms ◽  
Age Range

Abstract In the face of insect declines, identifying phases of the life cycle when insects are particularly vulnerable to mortality is critical to conservation efforts. For numerous annual insect groups, diapause is both a key adaptation that allows survival of inhospitable conditions and a physiologically demanding life stage that can result in high rates of mortality. As bees continue to garner attention as a group experiencing high rates of decline, improving our understanding of how annual bees prepare for diapause and identifying factors that reduce survival is imperative. Here, we studied factors affecting diapause survival length and their underlying mechanisms using an economically and ecologically important annual bee species, Bombus impatiens. We examined how age and mass upon diapause onset correlate with diapause survival length, and the mechanistic role of nutrient acquisition and oxidative stress post pupal eclosion in mediating these effects. Our findings show that both age and mass were strong predictors of diapause survival length. Heavier queens or queens in the age range of ~6–17 days survived longer in diapause. Mass gain was attributed to increases in lipid, protein and glycerol amounts following pupal eclosion, and the ability to deal with oxidative stress was significantly compromised in older pre-diapause queens. Our results demonstrate that age-related shifts in bee physiology and timing of nutrient acquisition may both be critical factors driving diapause survival.

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