Reproductive Isolation by Disruptive Selection: Did it Occur?

1971 ◽  
Vol 105 (941) ◽  
pp. 83-86 ◽  
Author(s):  
W. Scharloo
Keyword(s):  
Reproductive Isolation ◽  
Disruptive Selection

scholarly journals Speciation: more likely through a genetic or through a learned habitat preference?

2005 ◽  
Vol 272 (1571) ◽  
pp. 1455-1463 ◽  
Author(s):  
J.B Beltman ◽  
J.A.J Metz
Keyword(s):  
Reproductive Isolation ◽  
Habitat Preference ◽  
Sympatric Speciation ◽  
Genetic Mechanism ◽  
Dynamical Analysis ◽  
Disruptive Selection ◽  
Single Population ◽  
Preferred Habitat ◽  
Simultaneous Evolution ◽  
Evolution Proceeds

A problem in understanding sympatric speciation is establishing how reproductive isolation can arise when there is disruptive selection on an ecological trait. One of the solutions that has been proposed is that a habitat preference evolves, and that mates are chosen within the preferred habitat. We present a model where the habitat preference can evolve either by means of a genetic mechanism or by means of learning. Employing an adaptive-dynamical analysis, we show that evolution proceeds either to a single population of specialists with a genetic preference for their optimal habitat, or to a population of generalists without a habitat preference. The generalist population subsequently experiences disruptive selection. Learning promotes speciation because it increases the intensity of disruptive selection. An individual-based version of the model shows that, when loci are completely unlinked and learning confers little cost, the presence of disruptive selection most probably leads to speciation via the simultaneous evolution of a learned habitat preference. For high costs of learning, speciation is most likely to occur via the evolution of a genetic habitat preference. However, the latter only happens when the effect of mutations is large, or when there is linkage between genes coding for the different traits.

Evolutionary Branching in a Classical Model for Sympatric Speciation

2011 ◽  
Author(s):  
Michael Doebeli
Keyword(s):  
Reproductive Isolation ◽  
Adaptive Dynamics ◽  
Classical Model ◽  
Sympatric Speciation ◽  
Disruptive Selection ◽  
General Outcome ◽  
Wide Range ◽  
Genetic Mechanisms ◽  
Basic Concepts ◽  
Smith Model

This chapter begins by considering the Maynard Smith model. Much of this work concentrated on the genetic mechanisms for assortative mating and reproductive isolation, based on the assumption that the underlying niche ecology would generate disruptive selection. However, understanding the conditions under which disruptive selection arises in the first place is equally important, and indeed necessary for assessing whether diversification is a general outcome in the Maynard Smith model. The chapter then shows that disruptive selection and polymorphism are scenarios that occur generically, that is, for a wide range of parameters, in a classical and widely used speciation model. It also provides an introduction to some of the basic concepts of adaptive dynamics theory.

Adaptive Diversification Due to Resource Competition in Sexual Models

2011 ◽  
Author(s):  
Michael Doebeli
Keyword(s):  
Reproductive Isolation ◽  
Sexual Reproduction ◽  
Assortative Mating ◽  
Resource Competition ◽  
Disruptive Selection ◽  
Evolutionary Branching ◽  
Adaptive Diversification ◽  
Intermediate Phenotypes ◽  
Branching Point ◽  
Adaptive Speciation

This chapter examines evolutionary branching in sexual populations. As sexual populations converge to what would be a branching point in clonal models, splitting obviously becomes a problem, because mating between different marginal phenotypes generally creates intermediate phenotypes. Through segregation and recombination, sexual reproduction can prevent the establishment of diverging phenotypic clusters in randomly mating populations. To allow for a phenotypic split, mating needs to be assortative with respect to the ecological trait that is under disruptive selection. Thus, the question of evolutionary branching in sexual populations, that is, of adaptive speciation, is intimately tied to questions about the evolution of assortative mating. If evolutionary branching occurs in sexual populations due to the presence of assortative mating mechanisms, the diverging phenotypic clusters will show prezygotic reproductive isolation at least to some extent, and hence they can be viewed as representing incipient species.

scholarly journals Admixture between Ancient Lineages, Selection, and the Formation of Sympatric Stickleback Species-Pairs

2019 ◽  
Vol 36 (11) ◽  
pp. 2481-2497 ◽  
Author(s):  
Laura L Dean ◽  
Isabel S Magalhaes ◽  
Andrew Foote ◽  
Daniele D’Agostino ◽  
Suzanne McGowan ◽  
...  
Keyword(s):  
Reproductive Isolation ◽  
Gasterosteus Aculeatus ◽  
Ecological Speciation ◽  
Morphological Data ◽  
Secondary Contact ◽  
Disruptive Selection ◽  
Implicit Assumption ◽  
Hybridization Rate ◽  
Genome Wide ◽  
Species Pairs

Abstract Ecological speciation has become a popular model for the development and maintenance of reproductive isolation in closely related sympatric pairs of species or ecotypes. An implicit assumption has been that such pairs originate (possibly with gene flow) from a recent, genetically homogeneous ancestor. However, recent genomic data have revealed that currently sympatric taxa are often a result of secondary contact between ancestrally allopatric lineages. This has sparked an interest in the importance of initial hybridization upon secondary contact, with genomic reanalysis of classic examples of ecological speciation often implicating admixture in speciation. We describe a novel occurrence of unusually well-developed reproductive isolation in a model system for ecological speciation: the three-spined stickleback (Gasterosteus aculeatus), breeding sympatrically in multiple lagoons on the Scottish island of North Uist. Using morphological data, targeted genotyping, and genome-wide single-nucleotide polymorphism data, we show that lagoon resident and anadromous ecotypes are strongly reproductively isolated with an estimated hybridization rate of only ∼1%. We use palaeoecological and genetic data to test three hypotheses to explain the existence of these species-pairs. Our results suggest that recent, purely ecological speciation from a genetically homogeneous ancestor is probably not solely responsible for the evolution of species-pairs. Instead, we reveal a complex colonization history with multiple ancestral lineages contributing to the genetic composition of species-pairs, alongside strong disruptive selection. Our results imply a role for admixture upon secondary contact and are consistent with the recent suggestion that the genomic underpinning of ecological speciation often has an older, allopatric origin.

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