Genetic mechanisms preventing the fusion of ecotypes even in the face of gene flow

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.

Download Full-text

Population Genomic Evidence Reveals Subtle Patterns of Differentiation in the Trophically Polymorphic Cuatro Ciénegas Cichlid, Herichthys minckleyi

Journal of Heredity ◽

10.1093/jhered/esz004 ◽

2019 ◽

Vol 110 (3) ◽

pp. 361-369 ◽

Cited By ~ 1

Author(s):

Katherine L Bell ◽

Chris C Nice ◽

Darrin Hulsey

Keyword(s):

Gene Flow ◽

Biological Diversity ◽

Molecular Genetic ◽

Molecular Ecology ◽

Cichlid Fish ◽

Genome Wide ◽

A Genome ◽

The Face ◽

Or Gene ◽

Herichthys Minckleyi

Abstract In recent decades, an increased understanding of molecular ecology has led to a reinterpretation of the role of gene flow during the evolution of reproductive isolation and biological novelty. For example, even in the face of ongoing gene flow strong selection may maintain divergent polymorphisms, or gene flow may introduce novel biological diversity via hybridization and introgression from a divergent species. Herein, we elucidate the evolutionary history and genomic basis of a trophically polymorphic trait in a species of cichlid fish, Herichthys minckleyi. We explored genetic variation at 3 hierarchical levels; between H. minckleyi (n = 69) and a closely related species Herichthys cyanoguttatus (n = 10), between H. minckleyi individuals from 2 geographic locations, and finally between individuals with alternate morphotypes at both a genome-wide and locus-specific scale. We found limited support for the hypothesis that the H. minckleyi polymorphism is the result of ongoing hybridization between the 2 species. Within H. minckleyi we found evidence of geographic genetic structure, and using traditional population genetic analyses found that individuals of alternate morphotypes within a pool appear to be panmictic. However, when we used a locus-specific approach to examine the relationship between multi-locus genotype, tooth size, and geographic sampling, we found the first evidence for molecular genetic differences between the H. minckleyi morphotypes.

Download Full-text

The genomic landscape underlying phenotypic integrity in the face of gene flow in crows

Science ◽

10.1126/science.1253226 ◽

2014 ◽

Vol 344 (6190) ◽

pp. 1410-1414 ◽

Cited By ~ 332

Author(s):

J. W. Poelstra ◽

N. Vijay ◽

C. M. Bossu ◽

H. Lantz ◽

B. Ryll ◽

...

Keyword(s):

Gene Flow ◽

Genomic Landscape ◽

The Face

Download Full-text

Lineage isolation in the face of active gene flow in the coastal plant wild radish is reinforced by differentiated vernalisation responses

BMC Evolutionary Biology ◽

10.1186/s12862-016-0655-7 ◽

2016 ◽

Vol 16 (1) ◽

Cited By ~ 6

Author(s):

Qingxiang Han ◽

Hiroyuki Higashi ◽

Yuki Mitsui ◽

Hiroaki Setoguchi

Keyword(s):

Gene Flow ◽

Wild Radish ◽

Active Gene ◽

The Face ◽

Coastal Plant

Download Full-text

Understanding specialism when the jack of all trades can be the master of all

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2012.1990 ◽

2012 ◽

Vol 279 (1749) ◽

pp. 4861-4869 ◽

Cited By ~ 69

Author(s):

Susanna Remold

Keyword(s):

Habitat Use ◽

Recent Work ◽

Habitat Change ◽

Directional Selection ◽

Antagonistic Pleiotropy ◽

Disease Emergence ◽

Evolutionary Genetic ◽

The Face ◽

Genetic Mechanisms ◽

Selection For

Specialism is widespread in nature, generating and maintaining diversity, but recent work has demonstrated that generalists can be equally fit as specialists in some shared environments. This no-cost generalism challenges the maxim that ‘the jack of all trades is the master of none’, and requires evolutionary genetic mechanisms explaining the existence of specialism and no-cost generalism, and the persistence of specialism in the face of selection for generalism. Examining three well-described mechanisms with respect to epistasis and pleiotropy indicates that sign (or antagonistic) pleiotropy without epistasis cannot explain no-cost generalism and that magnitude pleiotropy without epistasis (including directional selection and mutation accumulation) cannot explain the persistence of specialism. However, pleiotropy with epistasis can explain all. Furthermore, epistatic pleiotropy may allow past habitat use to influence future use of novel environments, thereby affecting disease emergence and populations' responses to habitat change.

Download Full-text

Adaptive signal coloration maintained in the face of gene flow in a Hispaniolan Anolis Lizard

BMC Evolutionary Biology ◽

10.1186/s12862-016-0763-4 ◽

2016 ◽

Vol 16 (1) ◽

Cited By ~ 7

Author(s):

Julienne Ng ◽

Alison G. Ossip-Klein ◽

Richard E. Glor

Keyword(s):

Gene Flow ◽

Anolis Lizard ◽

The Face ◽

Adaptive Signal

Download Full-text

Altitudinal gradients, plant hybrid zones and evolutionary novelty

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2013.0346 ◽

2014 ◽

Vol 369 (1648) ◽

pp. 20130346 ◽

Cited By ~ 48

Author(s):

Richard J. Abbott ◽

Adrian C. Brennan

Keyword(s):

Gene Flow ◽

Mount Etna ◽

Hybrid Zones ◽

Evolutionary Novelty ◽

Altitudinal Gradients ◽

Interspecific Gene Flow ◽

Adaptive Introgression ◽

Local Environments ◽

The Face ◽

Plant Hybrid

Altitudinal gradients are characterized by steep changes of the physical and biotic environment that present challenges to plant adaptation throughout large parts of the world. Hybrid zones may form where related species inhabit different neighbouring altitudes and can facilitate interspecific gene flow and potentially the breakdown of species barriers. Studies of such hybrid zones can reveal much about the genetic basis of adaptation to environmental differences stemming from changes in altitude and the maintenance of species divergence in the face of gene flow. Furthermore, owing to recombination and transgressive effects, such hybrid zones can be sources of evolutionary novelty. We document plant hybrid zones associated with altitudinal gradients and emphasize similarities and differences in their structure. We then focus on recent studies of a hybrid zone between two Senecio species that occur at high and low altitude on Mount Etna, Sicily, showing how adaptation to local environments and intrinsic selection against hybrids act to maintain it. Finally, we consider the potential of altitudinal hybrid zones for generating evolutionary novelty through adaptive introgression and hybrid speciation. Examples of homoploid hybrid species of Senecio and Pinus that originated from altitudinal hybrid zones are discussed.

Download Full-text