scholarly journals Allopatric Divergence, Secondary Contact, and Genetic Isolation in Wild Yeast Populations

2007 ◽  
Vol 17 (5) ◽  
pp. 407-411 ◽  
Author(s):  
Heidi A. Kuehne ◽  
Helen A. Murphy ◽  
Chantal A. Francis ◽  
Paul D. Sniegowski
Keyword(s):  
Secondary Contact ◽  
Genetic Isolation ◽  
Wild Yeast ◽  
Allopatric Divergence

Phenotypic clines across an unstudied hybrid zone in Woodhouse’s Scrub-Jay (Aphelocoma woodhouseii)

The Auk ◽  
2019 ◽  
Vol 136 (2) ◽  
Author(s):  
Devon A DeRaad ◽  
James M Maley ◽  
Whitney L E Tsai ◽  
John E McCormack
Keyword(s):  
Body Size ◽  
Contact Zone ◽  
Mexico City ◽  
Rocky Mountains ◽  
Secondary Contact ◽  
Genetic Isolation ◽  
Southern Mexico ◽  
Phenotypic Differences ◽  
Northern Mexico ◽  
Group A

Abstract Woodhouse’s Scrub-Jay (Aphelocoma woodhouseii) comprises 7 subspecies, ranging from the Rocky Mountains to southern Mexico. We quantified the phenotype of specimens throughout Mexico and found support for significant phenotypic differences between “Sumichrast’s group” in southern Mexico (A. w. sumichrasti and A. w. remota) and the 2 subspecies in northern Mexico, or “Woodhouse’s group” (A. w. grisea and A. w. cyanotis). Despite significant differentiation in body size and mantle color, we found no clear geographic boundary between the groups, suggesting either a geographic cline or hybridization upon secondary contact. We tested for selection against hybridization by fitting models to geographic clines for both body size and back color, and found support for a stable contact zone centered near Mexico City, with selection against intermediate back color. Based on these results, we infer that Sumichrast’s and Woodhouse’s groups diverged during a period of geographic and genetic isolation. The phenotypic introgression between Sumichrast’s and Woodhouse’s groups near Mexico City likely represents a case of recent secondary contact, with selection against hybridization maintaining a geographically stable contact zone.

scholarly journals Speciation driven by hybridization and chromosomal plasticity in a wild yeast

2015 ◽  
Author(s):  
Jean-Baptiste Leducq ◽  
Lou Nielly-Thibault ◽  
Guillaume Charron ◽  
Chris Eberlein ◽  
Jukka-Pekka Verta ◽  
...  
Keyword(s):  
Rapid Evolution ◽  
Natural Populations ◽  
Secondary Contact ◽  
Hybrid Speciation ◽  
Hybrid Species ◽  
Chromosome Architecture ◽  
The North ◽  
Wild Yeast ◽  
Homoploid Hybrid ◽  
Powerful Mechanism

Hybridization is recognized as a powerful mechanism of speciation and a driving force in generating biodiversity. However, only few multicellular species, limited to a handful of plants and animals, have been shown to fulfill all the criteria of homoploid hybrid speciation. This lack of evidence could lead to the misconception that speciation by hybridization has a limited role in eukaryotes, particularly in single-celled organisms. Laboratory experiments have revealed that fungi such as budding yeasts can rapidly develop reproductive isolation and novel phenotypes through hybridization, showing that in principle homoploid speciation could occur in nature. Here we report a case of homoploid hybrid speciation in natural populations of the budding yeast Saccharomyces paradoxus inhabiting the North American forests. We show that the rapid evolution of chromosome architecture and an ecological context that led to secondary contact between nascent species drove the formation of an incipient hybrid species with a potentially unique ecological niche.

scholarly journals Implications of intraspecific behavioral interactions on the evolution of the mbuna cichlids of Lake Malawi and the effects of a small class intervention on a group of at-‐risk undergraduate students

2017 ◽  
Author(s):  
David Thomas Mellor
Keyword(s):  
At Risk ◽  
Reproductive Success ◽  
Female Choice ◽  
Female Preference ◽  
Lake Malawi ◽  
Secondary Contact ◽  
Small Scale ◽  
Male Reproductive Success ◽  
Allopatric Divergence ◽  
Male Contests

The rock-dwelling cichlids of Lake Malawi, the mbuna, are a model system of rapid, sympatric diversification of vertebrates. Though sexual selection has often been invoked to explain their radiation, the best evidence to date suggests that female choice and male-male interactions act to reinforce incipient, allopatric divergence upon secondary contact. First, I expand on the evidence previously gathered on male-male interactions at the inter-population level, by examining within-population behavioral patterns that could explain the diversification of this lineage. Specifically, I measure female preference for conspecific males who are in social isolation and those who are in groups of interacting males. I found that females show preference for males who score higher in male-male contests. In chapter two, I measure the effect of these male-male interactions on female choice and show that these interactions do affect female preference. By controlling the outcome of each male-male interaction, I show that female preference is affected by the male-male contests themselves. In chapter three, I measure the reflectance of brightly colored, territorial males and look for a correlation between color-similarity and level of aggression between two males. Males show more aggression towards similarly colored conspecific rivals than they do towards rivals who are more differently colored. In chapter four, I measure male reproductive success and the chromatic, behavioral, and territorial traits that affect it. Male color does predict reproductive success. Given my desire to integrate scholarship into every aspect of my academic career, I undertake an investigation on students who are at risk for leaving college because of low academic performance. I describe the social and psychological issues affecting the high rate of college attrition and the effects of a small scale class intervention on student retention, GPA, locus of control, and academic self-efficacy.

scholarly journals Maintenance of Fungal Pathogen Species That Are Specialized to Different Hosts: Allopatric Divergence and Introgression through Secondary Contact

2010 ◽  
Vol 28 (1) ◽  
pp. 459-471 ◽  
Author(s):  
P. Gladieux ◽  
E. Vercken ◽  
M. C. Fontaine ◽  
M. E. Hood ◽  
O. Jonot ◽  
...  
Keyword(s):  
Fungal Pathogen ◽  
Secondary Contact ◽  
Allopatric Divergence

DNA barcoding and species delimitation: the Stylodrilus heringianus case (Annelida : Clitellata : Lumbriculidae)

2013 ◽  
Vol 27 (1) ◽  
pp. 118 ◽  
Author(s):  
Ainara Achurra ◽  
Christer Erséus
Keyword(s):  
Nuclear Genes ◽  
Pairwise Distance ◽  
Taxonomic Resolution ◽  
Secondary Contact ◽  
Internal Transcribed Spacer Region ◽  
Distance Method ◽  
Network Analyses ◽  
Histone 3 ◽  
Allopatric Divergence ◽  
Phylogeographic History

Individuals of the aquatic oligochaete species Stylodrilus heringianus Claparède, 1862 were collected across a part of this species’ distribution range in Sweden, Estonia, Great Britain and Spain to test whether they represent a single metapopulation or several separately evolving lineages. Using sequences of the barcoding gene cytochrome c oxidase subunit I (COI) and two nuclear genes (internal transcribed spacer region and histone 3), three different approaches were conducted: pairwise distance-method, Bayesian inference and network analysis. Both the COI phylogeny and network analyses were concordant in recovering six haplotype clusters, which showed a maximum genetic distance of 7.7% (K2P) among each other. Nevertheless, nuclear genes failed to confirm any lineage separation, and we conclude that the sampled specimens all belong to the same species. A phylogeographic history with allopatric divergence and secondary contact is suggested to explain this intraspecific pattern of mitochondrial divergence and nuclear non-divergence. The study shows that a mitochondrial single-locus approach can be problematic for the accurate delimitation of species, and we emphasise the need for nuclear genes as supplementary markers, when taxonomic resolution is assessed with COI barcodes.

Allopatric divergence and secondary contact with gene flow: a recurring theme in rattlesnake speciation

2019 ◽  
Vol 128 (1) ◽  
pp. 149-169 ◽  
Author(s):  
Drew R Schield ◽  
Blair W Perry ◽  
Richard H Adams ◽  
Daren C Card ◽  
Tereza Jezkova ◽  
...  
Keyword(s):  
Gene Flow ◽  
Demographic History ◽  
Secondary Contact ◽  
Tree Model ◽  
Crotalus Viridis ◽  
Species Complexes ◽  
Isolating Mechanisms ◽  
Allopatric Divergence ◽  
History Of ◽  
Study Population

Abstract The study of recently diverged lineages whose geographical ranges come into contact can provide insight into the early stages of speciation and the potential roles of reproductive isolation in generating and maintaining species. Such insight can also be important for understanding the strategies and challenges for delimiting species within recently diverged species complexes. Here, we use mitochondrial and nuclear genetic data to study population structure, gene flow and demographic history across a geographically widespread rattlesnake clade, the western rattlesnake species complex (Crotalus cerberus, Crotalus viridis, Crotalus oreganus and relatives), which contains multiple lineages with ranges that overlap geographically or contact one another. We find evidence that the evolutionary history of this group does not conform to a bifurcating tree model and that pervasive gene flow has broadly influenced patterns of present-day genetic diversity. Our results suggest that lineage diversity has been shaped largely by drift and divergent selection in isolation, followed by secondary contact, in which reproductive isolating mechanisms appear weak and insufficient to prevent introgression, even between anciently diverged lineages. The complexity of divergence and secondary contact with gene flow among lineages also provides new context for why delimiting species within this complex has been difficult and contentious historically.

Ecogeography of Plumage Pigmentation In Great Horned Owls

2021 ◽  
Author(s):  
Peter M. Mattison ◽  
Christopher C. Witt
Keyword(s):  
Geographic Variation ◽  
Local Adaptation ◽  
Linear Models ◽  
Environmental Gradients ◽  
Bimodal Distribution ◽  
Secondary Contact ◽  
Cold Environments ◽  
Allopatric Divergence ◽  
Gloger’S Rule

ABSTRACT Plumage pigmentation is fundamental to a bird's phenotype, with pigment deposition causing relative crypsis or conspicuousness, depending on the environmental context. Geographic variation in plumage melanin tends to be predictable, suggesting that aspects of climate cause local matching of plumage to environment via genetic adaptation. Ecogeographic rules describe this predictability: Gloger's rule predicts that populations in wetter and warmer environments will be more pigmented; Bogert's Rule predicts more pigmentation in cold environments. The Great Horned Owl (Bubo virginianus) exhibits extensive geographic variation in the degree of melanin-based pigmentation. We examined fine-scale spatial variation in owl plumage melanism along environmental gradients in southwestern North America. We tested whether variation is explained by either of two non-mutually exclusive hypotheses: (1) a history of allopatric divergence between subspecies or (2) in situ local adaptation consistent with ecogeographic rules. The allopatric divergence hypothesis predicts a bimodal distribution of plumage melanism, with a geographic cline across a zone of secondary contact, whereas the local adaptation hypothesis predicts that climate explains variation independently of geography. Using a colorimeter, we measured coloration in 101 museum specimens of breeding-season Great Horned Owls that had been obtained from variable environments and elevations. Specimens previously identified as separate subspecies were distinguishable by colorimetry. Plumage lightness, however, was continuously distributed, rather than bimodal. While accounting for males having reduced pigmentation relative to females, linear models revealed that lighter plumage was associated with low latitude, low elevation, high temperature, and low precipitation. These findings suggest that variation in Great Horned Owl plumage pigmentation is best understood as continuous ecogeographic variation, consistent with ecogeographic predictions, and currently maintained in situ along multiple environmental gradients that characterize the “sky island” topography of the southwestern USA.

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