Frequency-Dependent Selection, Disruptive Selection, and the Evolution of Reproductive Isolation

Udovic, Daniel

doi:10.1086/283654

Cited by 130 publications

(102 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, it is implicitly assumed that loss through reduced fitness of heterozygotes cannot be compensated by increased fitness of homozygotes since the fitness of homozygotes is assumed to be fixed at its maximum. However, this assumption is relaxed if some form of frequency dependence is required to maintain polymorphism with heterozygote disadvantage (of the form pioneered by Udovic 1980), meaning that an allele contributing to an incompatibility can increase when rare, even though it reduces heterozygote fitness at equilibrium. To make this concrete, consider a phytophagous insect feeding on two host plants.…”

Section: Examples Of Processes That Might Be Considered Adaptivementioning

confidence: 99%

“…A new allele, A, that enhances fitness on one host when homozygous may not spread because the fitness of the heterozygote, Aa, is reduced on both plants. Frequency dependence due to competition may make the spread of A more likely (Udovic 1980;Wilson and Turelli 1986). A prezygotic barrier between populations on the two hosts, due to habitat choice, would also make the spread of A more likely by increasing the proportion of AA homozygotes and their chances of being on the host where they have high fitness.…”

Section: Examples Of Processes That Might Be Considered Adaptivementioning

confidence: 99%

See 1 more Smart Citation

Coupling, Reinforcement, and Speciation

Butlin

Smadja

2018

The American Naturalist

184

250

View full text Add to dashboard Cite

During the process of speciation, populations may diverge for traits and at their underlying loci that contribute barriers to gene flow. These barrier traits and barrier loci underlie individual barrier effects, by which we mean the contribution that a barrier locus or trait-or some combination of barrier loci or traits-makes to overall isolation. The evolution of strong reproductive isolation typically requires the origin of multiple barrier effects. Critically, it also requires the coincidence of barrier effects; for example, two barrier effects, one due to assortative mating and the other due to hybrid inviability, create a stronger overall barrier to gene flow if they coincide than if they distinguish independent pairs of populations. Here, we define "coupling" as any process that generates coincidence of barrier effects, resulting in a stronger overall barrier to gene flow. We argue that speciation research, both empirical and theoretical, needs to consider both the origin of barrier effects and the ways in which they are coupled. Coincidence of barrier effects can occur either as a by-product of selection on individual barrier effects or of population processes, or as an adaptive response to indirect selection. Adaptive coupling may be accompanied by further evolution that enhances individual barrier effects. Reinforcement, classically viewed as the evolution of prezygotic barriers to gene flow in response to costs of hybridization, is an example of this type of process. However, we argue for an extended view of reinforcement that includes coupling processes involving enhancement of any type of additional barrier effect as a result of an existing barrier. This view of coupling and reinforcement may help to guide development of both theoretical and empirical research on the process of speciation.

show abstract

Section: Examples Of Processes That Might Be Considered Adaptivementioning

confidence: 99%

Section: Examples Of Processes That Might Be Considered Adaptivementioning

confidence: 99%

Coupling, Reinforcement, and Speciation

Butlin

Smadja

2018

The American Naturalist

184

250

View full text Add to dashboard Cite

show abstract

“…The first model, developed by Udovic (1980) describes a diploid population with alleles A and a and the first locus and alleles B and b at the second locus. There are two common indices measuring the progress toward sympatric speciation in models of this kind.…”

Section: Sympatric Speciationmentioning

confidence: 99%

“…Figure 8 illustrates the effects of parameters on the possibility of sympatric speciation and the degree of resulting genetic differentiation. Close linkage (i.e., small r) and strong selection are known to both make sympatric speciation easier and result in stronger genetic differentiation (Dickinson and Antonovics 1973;Udovic 1980;Felsenstein 1981). The inequality (9) and Figure 8 provide a quantitative description of these effects.…”

Section: The Udovic Modelmentioning

confidence: 99%

Perspective: Models of Speciation: What Have We Learned in 40 Years?

2003

View full text Add to dashboard Cite

Abstract. Theoretical studies of speciation have been dominated by numerical simulations aiming to demonstrate that speciation in a certain scenario may occur. What is needed now is a shift in focus to identifying more general rules and patterns in the dynamics of speciation. The crucial step in achieving this goal is the development of simple and general dynamical models that can be studied not only numerically but analytically as well. I review some of the existing analytical results on speciation. I first show why the classical theories of speciation by peak shifts across adaptive valleys driven by random genetic drift run into trouble (and into what kind of trouble). Then I describe the Bateson-Dobzhansky-Muller (BDM) model of speciation that does not require overcoming selection. I describe exactly how the probability of speciation, the average waiting time to speciation, and the average duration of speciation depend on the mutation and migration rates, population size, and selection for local adaptation. The BDM model postulates a rather specific genetic architecture of reproductive isolation. I then show exactly why the genetic architecture required by the BDM model should be common in general. Next I consider the multilocus generalizations of the BDM model again concentrating on the qualitative characteristics of speciation such as the average waiting time to speciation and the average duration of speciation. Finally, I consider two models of sympatric speciation in which the conditions for sympatric speciation were found analytically. A number of important conclusions have emerged from analytical studies. Unless the population size is small and the adaptive valley is shallow, the waiting time to a stochastic transition between the adaptive peaks is extremely long. However, if transition does happen, it is very quick. Speciation can occur by mutation and random drift alone with no contribution from selection as different populations accumulate incompatible genes. The importance of mutations and drift in speciation is augmented by the general structure of adaptive landscapes. Speciation can be understood as the divergence along nearly neutral networks and holey adaptive landscapes (driven by mutation, drift, and selection for adaptation to a local biotic and/or abiotic environment) accompanied by the accumulation of reproductive isolation as a by-product. The waiting time to speciation driven by mutation and drift is typically very long. Selection for local adaptation (either acting directly on the loci underlying reproductive isolation via their pleiotropic effects or acting indirectly via establishing a genetic barrier to gene flow) can significantly decrease the waiting time to speciation. In the parapatric case the average actual duration of speciation is much shorter than the average waiting time to speciation. Speciation is expected to be triggered by changes in the environment. Once genetic changes underlying speciation start, they go to completion very rapidly. Sympatric speciation is possible if ...

show abstract

“…Many specific models have been proposed to explain sympatric speciation (e.g., Rosenzweig 1977;Udovic 1980;van Doorn et al 1998;Gavrilets and Waxman 2002). A typical scenario is one where competition causes disruptive selection on an ecological trait (Christiansen and Loeschke 1980;Dieckmann and Doebeli 1999).…”

Section: A Scenario For Competition-driven Sympatric Speciationmentioning

confidence: 99%