Comparing Clines on Molecular and Phenotypic Traits in Hybrid Zones: A Window on Tension Zone Models

Crochet, Pierre‐André; Bell, Douglas A.; Lenormand, Thomas

doi:10.1111/j.1558-5646.2008.00491.x

Cited by 199 publications

(378 citation statements)

References 116 publications

(180 reference statements)

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“…In hybrid zones, there is good evidence for coincidence of barrier effects and its impact on the overall barrier to gene exchange from the observation of genome-wide stepped clines in some examples (e.g., Szymura andBarton 1986, 1991;Gay et al 2008), in contrast to scattered clines and a weak barrier to gene flow in others (e.g., Shuker et al 2005). However, where a strong barrier influences the whole genome (as in Bombina; Szymura and Barton 1991), it is hard to separate the underlying barrier effects and the loci responsible since all clines become stepped and concordant.…”

Section: Evidencing Patterns Of Coincidencementioning

confidence: 99%

Coupling, Reinforcement, and Speciation

Butlin

Smadja

2018

The American Naturalist

191

250

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During the process of speciation, populations may diverge for traits and at their underlying loci that contribute barriers to gene flow. These barrier traits and barrier loci underlie individual barrier effects, by which we mean the contribution that a barrier locus or trait-or some combination of barrier loci or traits-makes to overall isolation. The evolution of strong reproductive isolation typically requires the origin of multiple barrier effects. Critically, it also requires the coincidence of barrier effects; for example, two barrier effects, one due to assortative mating and the other due to hybrid inviability, create a stronger overall barrier to gene flow if they coincide than if they distinguish independent pairs of populations. Here, we define "coupling" as any process that generates coincidence of barrier effects, resulting in a stronger overall barrier to gene flow. We argue that speciation research, both empirical and theoretical, needs to consider both the origin of barrier effects and the ways in which they are coupled. Coincidence of barrier effects can occur either as a by-product of selection on individual barrier effects or of population processes, or as an adaptive response to indirect selection. Adaptive coupling may be accompanied by further evolution that enhances individual barrier effects. Reinforcement, classically viewed as the evolution of prezygotic barriers to gene flow in response to costs of hybridization, is an example of this type of process. However, we argue for an extended view of reinforcement that includes coupling processes involving enhancement of any type of additional barrier effect as a result of an existing barrier. This view of coupling and reinforcement may help to guide development of both theoretical and empirical research on the process of speciation.

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Section: Evidencing Patterns Of Coincidencementioning

confidence: 99%

Coupling, Reinforcement, and Speciation

Butlin

Smadja

2018

The American Naturalist

191

250

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“…In Drosophila, which has a worldwide distribution, significant morphometric wing variations were found in populations from different geographic regions, forming clusters or latitudinal clines ( Van'T Land et al 1999). Some studies report that variations in the wings may be related to intrapopulation genetic variations, life history [such as conditions during larval development (Swindell & Bouzat 2006)], the direction of selection throughout the population sources (Hansen & Houle 2008) and the fitness or possible targets of natural selection (Buggs 2007, Gay et al 2008. Other studies have related morphological differences to species divergence or ecological adaptations (James et al 1997).…”

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confidence: 99%

Genetic-morphometric variation in Culex quinquefasciatus from Brazil and La Plata, Argentina

Morais

Moratore

Suesdek

et al. 2010

Mem. Inst. Oswaldo Cruz

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Variation among natural populations of Culex (Culex) Key words: Culex pipiens complex -Culex quinquefasciatus -clines -molecular identification -wing morphologyThe Culex (Culex) pipiens complex in the Americas is composed of two main species, Culex (Culex) quinquefasciatus Say, which is adapted to tropical zones and Cx. pipiens L., which is found in temperate zones. In intermediate areas, these two members can mate yielding hybrids and intermediate forms (Barr 1957), through the processes of gene flow and introgression (Humeres et al. 1998, McAbee et al. 2008, Kothera et al. 2009). Mosquitoes of the Cx. pipiens complex are potential vectors of filarid worms in tropical and subtropical areas (Bockarie et al. 2009) and diverse arboviruses, including West Nile virus (Apperson et al. 2004, Cook et al. 2006.Adult females and immature stages of the Cx. pipiens complex are morphologically similar. The differentiation of adult males can be made by analysis of genitalia, which includes measuring the DV/D ratio of the dorsal arms of the aedeagus in the phallosome, as reported by Sundararaman (1949). Because members of the Cx. pipiens complex have a broad geographical distribution, other phenotypical differences beyond those of the male genitalia can be found. For example, some wing characters can also been used for morphologic identification of mosquito species.Financial support: FAPESP (05/50225-2, 06/02622-5) SAM and CM contributed equally to this work (FAPESP 06/57272-9 and 07/1665-5, respectively The taxonomic keys compiled by Forattini (2002) compared wing morphology of adult females. In that report, the subcosta vein (Sc) was reported to bind with the costa vein (C) before the bifurcation of the radial 2+3 vein (R 2+3 ) in Cx. quinquefasciatus, whereas in Cx. pipiens, the Sc vein binds to vein C at the same point or beyond the R 2+3 bifurcation. To our knowledge, these findings have not been investigated in other geographically distant populations. Linam and Nielsen (1962) reported that Bekku (1956), in Northern Japan, also attempted to use wing characteristics [the length of radial cell R 2 (second marginal cell) divided by the length of vein R 3 ] to distinguish adults of the pipiens group. The results of Bekku (1956) were inconclusive, which was later explained when Kamura (1958) found that these particular wing measurements varied with the temperature of the environment. Nielsen and Rees (1961) and Linam and Nielsen (1962) reported that the most reliable method of separating females of Cx. pipiens and Cx. quinquefasciatus was by a wing measurement value obtained by dividing the length of the cell R 2 by the length of the vein R 2+3 (R 2 /R 2+3 ratio). These authors reported the value of this ratio to be about 5.0 in Cx. pipiens and 3.0 or less in Cx. quinquefasciatus, with intermediate values present in the hybrids. However, these studies did not evaluate morphometric data among mosquito populations and climatic/geographic gradients.In insects, the phenotypic variations among members of species complexes have...

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“…Using the program CFIT Version 0.6 (Gay et al, 2008), we estimated the best-fit shape parameters for the allele and haplotypic frequencies (f(x)) as a function of geographic distance (x). Clines were fitted for our 11 microsatellite markers and cyt b haplotypes, wherein each locus was reduced to a simple twoallele system using lineage-specific (either Eastern or Interior) compound alleles (Gay et al, 2008) based on the first axis coordinates of a Multiple Correspondence Analysis implemented in GENETIX (Version 4.05; http:// kimura.univ-montp2.fr/genetix/). We identified some private alleles across loci and found most alleles to be distinct between lineages.…”

Section: Clinal Variation and Quantifying Hybridizationmentioning

confidence: 99%

“…We identified some private alleles across loci and found most alleles to be distinct between lineages. In instances where alleles are shared or incorrectly assigned, cline shape is typically flattened, and thus tests for the presence of clines are conservative (Gay et al, 2008). We fitted the centre and width parameters of a logit cline for each microsatellite marker and the mtDNA, and then used Akaike information criteria to compare patterns of gene flow.…”

Section: Clinal Variation and Quantifying Hybridizationmentioning

confidence: 99%

“…We assessed four models: (1) unconstrained clines (difference in cline centres and widths), (2) cline centres coincident (geographic centres constrained), (3) cline widths concordant (widths constrained) and (4) cline centres coincident and widths concordant. All tests used a maximum centre value of 580 km (maximum transect distance) and used 1000 repetitions for 100 000 iterations (Gay et al, 2008). Convergence was assessed by comparing the results of all models (replicated 10 times) with different random seeds.…”

Section: Clinal Variation and Quantifying Hybridizationmentioning

confidence: 99%

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Contact zone dynamics during early stages of speciation in a chorus frog (Pseudacris crucifer)

et al. 2015

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Characterizing the genetic and behavioural consequences of contact between previously geographically isolated lineages provides insights into the mechanisms underlying diversification and ultimately speciation. The spring peeper (Pseudacris crucifer) is a widespread Nearctic chorus frog with six divergent mitochondrial DNA (mtDNA) lineages, many of which came into secondary contact during the Holocene. We examined genetics, morphology, advertisement calls and female preference for two lineages that began diverging in allopatry in the Pliocene and now overlap in southwestern Ontario, Canada. We found non-coincident clines in mtDNA and nuclear DNA, mirroring directionality of premating isolation barriers. We also found divergence in a range of traits between these two lineages, displacement in male call attributes and female preference for calls of their natal lineage in sympatry. Hybrids were morphologically distinct from both parental lineages, but hybrid male calls were acoustically intermediate. Female hybrids showed asymmetrical preference for Eastern male calls. These results considered together provide evidence of either unidirectional hybridization or selection against hybrids, potentially implying reproductive character displacement. Our work demonstrates the utility of integrated, multi-character approaches to understanding the processes of divergence and the nature of speciation.

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Comparing Clines on Molecular and Phenotypic Traits in Hybrid Zones: A Window on Tension Zone Models

Cited by 199 publications

References 116 publications

Coupling, Reinforcement, and Speciation

Coupling, Reinforcement, and Speciation

Genetic-morphometric variation in Culex quinquefasciatus from Brazil and La Plata, Argentina

Contact zone dynamics during early stages of speciation in a chorus frog (Pseudacris crucifer)

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