scholarly journals Steep difference between ecotypes and intermediate phenotype depression for shell trait integration in a marine snail hybrid zone

2016 ◽  
Author(s):  
Carlos Garcia
Keyword(s):  
Gene Flow ◽  
Hybrid Zone ◽  
Intermediate Phenotype ◽  
Phenotypic Integration ◽  
Evolutionary Time ◽  
Marine Snail ◽  
Nw Iberia ◽  
Partial Correlations ◽  
Character Variation

AbstractMultivariate analyses of phenotypic integration for a set of characters provide information about biological systems that cannot be obtained in univariate studies of these characters. We studied phenotypic integration for seven shell measures across the phenotypic gradient in a hybrid zone of the marine snail Littorina saxatilis in Galicia, NW Iberia. We found clear differences in the degree of integration between the two ecotypes involved in the hybrid zone, likely related to differences in the strength of natural selection acting on the snails' shells in each ecotype's habitat. We found also evidence of a decrease in integration in the phenotypically intermediate, hybrid snails, consistent with hybridization resulting in a release of multivariate variation and increased evolvability. Across the phenotypic gradient, decreases in overall integration tended to be accompanied by increases in some measures of modularity, but the latter did nor reflect high correlation structure. The increases occurred only in a proportional sense, correlations among modules tending to decrease faster than within modules for low overall integration tiers. Integration analyses based on non partial and partial correlations tended to produce contrasting results, which suggested hierarchical sources of shell integration. Given that the two ecotypes could have differentiated in situ according to a parapatric model, our results would show that changes in integration can occur in a short evolutionary time and be maintained in the presence of gene flow, and also that this gene flow could result in the hybrid release of multi character variation.

Assessment of gene flow across a hybrid zone in red-tailed chipmunks (Tamias ruficaudus)

2009 ◽  
Vol 18 (14) ◽  
pp. 3097-3109 ◽  
Author(s):  
SARAH HIRD ◽  
JACK SULLIVAN
Keyword(s):  
Gene Flow ◽  
Hybrid Zone

Short-distance gene flow in Populus nigra L. accounts for small-scale spatial genetic structures: implications for in situ conservation measures

2009 ◽  
Vol 11 (4) ◽  
pp. 1327-1338 ◽  
Author(s):  
Georg Rathmacher ◽  
Marc Niggemann ◽  
Melanie Köhnen ◽  
Birgit Ziegenhagen ◽  
Ronald Bialozyt
Keyword(s):  
Gene Flow ◽  
Short Distance ◽  
In Situ Conservation ◽  
Populus Nigra ◽  
Small Scale ◽  
Conservation Measures ◽  
Genetic Structures

scholarly journals Morphometric Variation as an Indicator of Genetic Interactions Between Black-Capped and Carolina Chickadees at a Contact Zone in the Appalachian Mountains

The Auk ◽  
2000 ◽  
Vol 117 (2) ◽  
pp. 427-444 ◽  
Author(s):  
Gene D. Sattler ◽  
Michael J. Braun
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Markers ◽  
Hybrid Zone ◽  
Morphological Variation ◽  
Genetic Data ◽  
Mixed Ancestry ◽  
Morphometric Variation ◽  
Average Gene ◽  
Hybridization And Introgression

AbstractWe studied hybridization and introgression between Black-capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadees along two transects in the Appalachians using four genetic markers and multivariate analysis of morphology. Genetic data revealed that at least 58% of the birds in the center of each transect were of mixed ancestry and that recombinant genotypes predominated among hybrids, demonstrating that hybridization is frequent and that many hybrids are fertile. Genetic clines generally were steep and coincident in position, but introgression was evident well beyond the range interface. Introgression was higher at the one autosomal locus surveyed than in mitochondrial DNA or in two sex-linked markers, suggesting that the hybrid zone is a conduit for gene flow between the two forms at some loci. On a broad scale, morphometric variation was concordant with genetic variation. Clines in morphological variation based on principal components (PC) scores were steep and coincident with genetic clines. Also, a strong correlation within a population between PC scores and an individual's genetic makeup suggested that a large amount of morphological variation was genetically determined. However, morphological analysis indicated that hybrids were uncommon on one transect, whereas genetic data clearly showed that they were common on both. In addition, patterns of morphological variation were equivocal regarding introgression across the hybrid zone. Thus, genetic data provided a complementary and more detailed assessment of hybridization, largely due to the discrete nature of genetic variation. Genetic markers are useful in understanding hybridization and introgression, but diagnostic markers may underestimate average gene flow if selection against hybrids maintains steep clines at diagnostic loci. To gain a clearer picture of the genome-wide effects of hybridization, a much larger number of loci must be assayed, including non-diagnostic ones.

scholarly journals Combining microsatellites, growth, and adaptive traits for managing in situ genetic resources of Eucalyptus urophylla

2007 ◽  
Vol 37 (4) ◽  
pp. 773-785 ◽  
Author(s):  
Vincent Tripiana ◽  
Michaël Bourgeois ◽  
Daniel Verhaegen ◽  
Philippe Vigneron ◽  
Jean-Marc Bouvet
Keyword(s):  
Gene Flow ◽  
Genetic Resources ◽  
Quantitative Traits ◽  
Negative Relationship ◽  
Seed Source ◽  
Ex Situ ◽  
Clinal Variation ◽  
Eucalyptus Urophylla ◽  
Genetic Diversity And Structure

Genetic diversity and structure of 17 populations representative of the natural range of Eucalyptus urophylla S.T. Blake in Indonesia were analysed with 10 microsatellite markers. Two provenance and progeny trials, using the same populations, were established in the Republic of the Congo and analysed for growth and survival at 37 months. Observed microsatellite heterozygosity (Ho) was moderate to high within populations (Ho = 0.51–0.72). The index of fixation (FIS) was significantly different from zero for all populations (FIS = 0.13–0.31) and possibly resulted from a Wahlund effect. The differentiation parameter was low (FST = 0.04) and not significantly different from zero, which can be explained by effective gene flow via pollen. The genetic variances within and among provenances for survival and growth traits were significantly different from zero, representing 13%–23% and 14%–50% of the total variation, respectively. The differentiation between populations based on quantitative traits was marked (QST = 0.07–0.33). A negative relationship between altitude of the seed source and its performance in the Congo was observed (R2 = 0.59–0.67) and could be explained by the effect of natural selection along the altitudinal gradient. This marked differentiation for quantitative traits despite high apparent gene flow results in a clinal variation, which suggests the use of altitude of seed source as an important principle for in situ or ex situ management of E. urophylla genetic resources.

Cytonuclear Theory for Haplodiploid Species and X-Linked Genes. II. Stepping-Stone Models of Gene Flow and Application to a Fire Ant Hybrid Zone

Evolution ◽  
1998 ◽  
Vol 52 (5) ◽  
pp. 1423 ◽  
Author(s):  
Michael A. D. Goodisman ◽  
D. DeWayne Shoemaker ◽  
Marjorie A. Asmussen
Keyword(s):  
Gene Flow ◽  
Hybrid Zone ◽  
Fire Ant ◽  
Stepping Stone ◽  
Stepping Stone Models

scholarly journals The role of hybridization during ecological divergence of southwestern white pine (Pinus strobiformis) and limber pine (P. flexilis)

2017 ◽  
Author(s):  
Mitra Menon ◽  
Justin C. Bagley ◽  
Christopher Friedline ◽  
Amy V. Whipple ◽  
Anna W. Schoettle ◽  
...  
Keyword(s):  
Gene Flow ◽  
Hybrid Zone ◽  
Ecological Niche Modeling ◽  
Life History Strategies ◽  
Species Boundaries ◽  
Disruptive Selection ◽  
Hybrid Index ◽  
Extrinsic Factors ◽  
Intrinsic Factors ◽  
Demographic Modeling

AbstractInteractions between extrinsic factors, such as disruptive selection, and intrinsic factors, such as genetic incompatibilities among loci, can contribute to the maintenance of species boundaries. The relative roles of these factors in the establishment of reproductive isolation can be examined using species pairs characterized by gene flow throughout their divergence history. We investigated the process of speciation and the maintenance of species boundaries between Pinus strobiformis and P.flexilis. Utilizing ecological niche modeling, demographic modeling, and genomic cline analyses, we illustrated a history of divergence with continuous gene flow between these species. We found an abundance of advanced generation hybrids and a lack of loci exhibiting large allele frequency differences across the hybrid zone. Additionally, we found evidence for climate-associated variation in the hybrid index and niche divergence between parental species and the hybrid zone. Our results are consistent with extrinsic factors, such as climate, being an important isolating mechanism for these species. A buildup of intrinsic incompatibilities and of co-adapted gene complexes is also apparent in our results, although these appear to be in the earliest stages of development. This supports previous work in coniferous species demonstrating the importance of extrinsic factors in creating and enforcing species boundaries. Overall, we lend support to the hypothesis that varying strengths and directions of selection pressures across the long lifespans of conifers, in combination with their life history strategies, delay the evolution of strong intrinsic incompatibilities.

Sign in / Sign up

Export Citation Format

Share Document