scholarly journals Divergent natural selection drives the evolution of reproductive isolation in an Australian wildflower

Evolution ◽  
2016 ◽  
Vol 70 (9) ◽  
pp. 1993-2003 ◽  
Author(s):  
Thomas J. Richards ◽  
Greg M. Walter ◽  
Katrina McGuigan ◽  
Daniel Ortiz-Barrientos
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Divergent Natural Selection

scholarly journals Assortative flocking in crossbills and implications for ecological speciation

2012 ◽  
Vol 279 (1745) ◽  
pp. 4223-4229 ◽  
Author(s):  
Julie W. Smith ◽  
Stephanie M. Sjoberg ◽  
Matthew C. Mueller ◽  
Craig W. Benkman
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Ecological Speciation ◽  
Central Question ◽  
Loxia Curvirostra ◽  
Call Type ◽  
Divergent Natural Selection ◽  
Contact Calls ◽  
Red Crossbills

How reproductive isolation is related to divergent natural selection is a central question in speciation. Here, we focus on several ecologically specialized taxa or ‘call types’ of red crossbills ( Loxia curvirostra complex), one of the few groups of birds providing much evidence for ecological speciation. Call types differ in bill sizes and feeding capabilities, and also differ in vocalizations, such that contact calls provide information on crossbill phenotype. We found that two call types of red crossbills were more likely to approach playbacks of their own call type than those of heterotypics, and that their propensity to approach heterotypics decreased with increasing divergence in bill size. Although call similarity also decreased with increasing divergence in bill size, comparisons of responses to familiar versus unfamiliar call types indicate that the decrease in the propensity to approach heterotypics with increasing divergence in bill size was a learned response, and not a by-product of calls diverging pleiotropically as bill size diverged. Because crossbills choose mates while in flocks, assortative flocking could lead indirectly to assortative mating as a by-product. These patterns of association therefore provide a mechanism by which increasing divergent selection can lead to increasing reproductive isolation.

scholarly journals Rapid experimental evolution of reproductive isolation from a single natural population

2019 ◽  
Vol 116 (27) ◽  
pp. 13440-13445 ◽  
Author(s):  
Scott M. Villa ◽  
Juan C. Altuna ◽  
James S. Ruff ◽  
Andrew B. Beach ◽  
Lane I. Mulvey ◽  
...  
Keyword(s):  
Body Size ◽  
Natural Selection ◽  
Reproductive Isolation ◽  
Natural Population ◽  
Experimental Evolution ◽  
Natural Populations ◽  
Ecological Speciation ◽  
Phenotypic Trait ◽  
Divergent Natural Selection ◽  
Feather Lice

Ecological speciation occurs when local adaptation generates reproductive isolation as a by-product of natural selection. Although ecological speciation is a fundamental source of diversification, the mechanistic link between natural selection and reproductive isolation remains poorly understood, especially in natural populations. Here, we show that experimental evolution of parasite body size over 4 y (approximately 60 generations) leads to reproductive isolation in natural populations of feather lice on birds. When lice are transferred to pigeons of different sizes, they rapidly evolve differences in body size that are correlated with host size. These differences in size trigger mechanical mating isolation between lice that are locally adapted to the different sized hosts. Size differences among lice also influence the outcome of competition between males for access to females. Thus, body size directly mediates reproductive isolation through its influence on both intersexual compatibility and intrasexual competition. Our results confirm that divergent natural selection acting on a single phenotypic trait can cause reproductive isolation to emerge from a single natural population in real time.

scholarly journals Evidence for mutation-order speciation inSenecio lautus

2019 ◽  
Author(s):  
Maria C. Melo ◽  
Maddie E. James ◽  
Federico Roda ◽  
Diana Bernal-Franco ◽  
Melanie J. Wilkinson ◽  
...  
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Animal Species ◽  
Growth Habit ◽  
Sand Dunes ◽  
Ecological Speciation ◽  
Divergent Natural Selection ◽  
Genetic Complexity ◽  
Comprehensive Test ◽  
Prostrate Growth

In a number of animal species, divergent natural selection has repeatedly and independently driven the evolution of reproductive isolation between populations adapted to contrasting, but not to similar environments1. This process is known as parallel ecological speciation, and examples in plants are enigmatically rare2. Here, we perform a comprehensive test of the ecological speciation hypothesis in an Australian wildflower where parapatric populations found in coastal sand dunes (Dune ecotype) and headlands (Headland ecotype) have repeatedly and independently diverged in growth habit. Consistent with a role for divergent natural selection driving the evolution of reproductive isolation, we found that Dune populations with erect growth habit were easy to transplant across sand dunes, were largely interfertile despite half-a-million years of divergence, and were reproductively isolated from equally divergent Headland populations with prostrate growth habit. However, we unexpectedly discovered that both extrinsic and intrinsic reproductive isolation has evolved between prostrate Headland populations, suggesting that populations evolving convergent phenotypes can also rapidly become new species. Mutation-order speciation2, where the random accumulation of adaptive alleles create genetic incompatibilities between populations inhabiting similar habitats, provides a compelling explanation for these complex patterns of reproductive isolation. Our results suggest that natural selection can drive speciation effectively, but environmental and genetic complexity might make parallel ecological speciation uncommon in plants despite strong morphological convergence.

scholarly journals Assortative mating, sexual selection and their consequences for gene flow in Littorina

2020 ◽  
Author(s):  
Samuel Perini ◽  
Marina Rafajlović ◽  
Anja M. Westram ◽  
Kerstin Johannesson ◽  
Roger K. Butlin
Keyword(s):  
Sexual Selection ◽  
Gene Flow ◽  
Natural Selection ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Small Male ◽  
Mating Pattern ◽  
Barrier Effects ◽  
Divergent Natural Selection ◽  
Coastal Marine

AbstractWhen divergent populations are connected by gene flow, the establishment of complete reproductive isolation usually requires the joint action of multiple barrier effects. One example where multiple barrier effects are coupled consists of a single trait that is under divergent natural selection and also mediates assortative mating. Such multiple-effect traits can strongly reduce gene flow. However, there are few cases where patterns of assortative mating have been described quantitatively and their impact on gene flow has been determined. Two ecotypes of the coastal marine snail, Littorina saxatilis, occur in North Atlantic rocky-shore habitats dominated by either crab predation or wave action. There is evidence for divergent natural selection acting on size, and size-assortative mating has previously been documented. Here, we analyze the mating pattern in L. saxatilis with respect to size in intensively-sampled transects across boundaries between the habitats. We show that the mating pattern is mostly conserved between ecotypes and that it generates both assortment and directional sexual selection for small male size. Using simulations, we show that the mating pattern can contribute to reproductive isolation between ecotypes but the barrier to gene flow is likely strengthened more by sexual selection than by assortment.

scholarly journals Ecological Divergence and the Origins of Intrinsic Postmating Isolation with Gene Flow

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Aneil F. Agrawal ◽  
Jeffrey L. Feder ◽  
Patrik Nosil
Keyword(s):  
Linkage Disequilibrium ◽  
Gene Flow ◽  
Natural Selection ◽  
Theoretical Models ◽  
Ecological Speciation ◽  
Divergent Selection ◽  
Postmating Isolation ◽  
Divergent Natural Selection ◽  
Mathematical Exploration ◽  
Neutral Gene

The evolution of intrinsic postmating isolation has received much attention, both historically and in recent studies of speciation genes. Intrinsic isolation often stems from between-locus genetic incompatibilities, where alleles that function well within species are incompatible with one another when brought together in the genome of a hybrid. It can be difficult for such incompatibilities to originate when populations diverge with gene flow, because deleterious genotypic combinations will be created and then purged by selection. However, it has been argued that if genes underlying incompatibilities are themselves subject to divergent selection, then they might overcome gene flow to diverge between populations, resulting in the origin of incompatibilities. Nonetheless, there has been little explicit mathematical exploration of such scenarios for the origin of intrinsic incompatibilities during ecological speciation with gene flow. Here we explore theoretical models for the origin of intrinsic isolation where genes subject to divergent natural selection also affect intrinsic isolation, either directly or via linkage disequilibrium with other loci. Such genes indeed overcome gene flow, diverge between populations, and thus result in the evolution of intrinsic isolation. We also examine barriers to neutral gene flow. Surprisingly, we find that intrinsic isolation sometimes weakens this barrier, by impeding differentiation via ecologically based divergent selection.

Evidence for divergent natural selection of a Lake Tanganyika cichlid inferred from repeated radiations in body size

2009 ◽  
Vol 18 (14) ◽  
pp. 3110-3119 ◽  
Author(s):  
T. TAKAHASHI ◽  
K. WATANABE ◽  
H. MUNEHARA ◽  
L. RÜBER ◽  
M. HORI
Keyword(s):  
Body Size ◽  
Natural Selection ◽  
Lake Tanganyika ◽  
Divergent Natural Selection ◽  
Selection Of

scholarly journals Genetic Architecture of a Reinforced, Postmating, Reproductive Isolation Barrier between Neurospora Species Indicates Evolution via Natural Selection

PLoS Genetics ◽  
2011 ◽  
Vol 7 (8) ◽  
pp. e1002204 ◽  
Author(s):  
Elizabeth Turner ◽  
David J. Jacobson ◽  
John W. Taylor
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Genetic Architecture

Natural Selection for the Origin of Reproductive Isolation

1971 ◽  
Vol 105 (945) ◽  
pp. 479-483 ◽  
Author(s):  
Lee Ehrman
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Selection For

scholarly journals Host races in plant–feeding insects and their importance in sympatric speciation

2002 ◽  
Vol 357 (1420) ◽  
pp. 471-492 ◽  
Author(s):  
Michele Drès ◽  
James Mallet
Keyword(s):  
Linkage Disequilibrium ◽  
Gene Flow ◽  
Natural Selection ◽  
Reproductive Isolation ◽  
Sympatric Speciation ◽  
Accurate Information ◽  
Sympatric Populations ◽  
New Host ◽  
Host Races ◽  
Plant Feeding

The existence of a continuous array of sympatric biotypes—from polymorphisms, through ecological or host races with increasing reproductive isolation, to good species—can provide strong evidence for a continuous route to sympatric speciation via natural selection. Host races in plant–feeding insects, in particular, have often been used as evidence for the probability of sympatric speciation. Here, we provide verifiable criteria to distinguish host races from other biotypes: in brief, host races are genetically differentiated, sympatric populations of parasites that use different hosts and between which there is appreciable gene flow. We recognize host races as kinds of species that regularly exchange genes with other species at a rate of more than ca . 1% per generation, rather than as fundamentally distinct taxa. Host races provide a convenient, although admittedly somewhat arbitrary intermediate stage along the speciation continuum. They are a heuristic device to aid in evaluating the probability of speciation by natural selection, particularly in sympatry. Speciation is thereby envisaged as having two phases: (i) the evolution of host races from within polymorphic, panmictic populations; and (ii) further reduction of gene flow between host races until the diverging populations can become generally accepted as species. We apply this criterion to 21 putative host race systems. Of these, only three are unambiguously classified as host races, but a further eight are strong candidates that merely lack accurate information on rates of hybridization or gene flow. Thus, over one–half of the cases that we review are probably or certainly host races, under our definition. Our review of the data favours the idea of sympatric speciation via host shift for three major reasons: (i) the evolution of assortative mating as a pleiotropic by–product of adaptation to a new host seems likely, even in cases where mating occurs away from the host; (ii) stable genetic differences in half of the cases attest to the power of natural selection to maintain multilocus polymorphisms with substantial linkage disequilibrium, in spite of probable gene flow; and (iii) this linkage disequilibrium should permit additional host adaptation, leading to further reproductive isolation via pleiotropy, and also provides conditions suitable for adaptive evolution of mate choice (reinforcement) to cause still further reductions in gene flow. Current data are too sparse to rule out a cryptic discontinuity in the apparently stable sympatric route from host–associated polymorphism to host–associated species, but such a hiatus seems unlikely on present evidence. Finally, we discuss applications of an understanding of host races in conservation and in managing adaptation by pests to control strategies, including those involving biological control or transgenic parasite–resistant plants.

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