Modeling Selection on Conditional Strategies in Stochastic Environments

Hazel, Wade N.; Smock, Richard

doi:10.1007/978-3-642-51483-8_8

Cited by 11 publications

(13 citation statements)

References 19 publications

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“…Consequently, as a population's mean phenotype changes, so does a given male's competitive status, even though his absolute phenotype may remain constant (Dominey, 1984;Hazel and Smock, 1993;Hazel et al, 1990;Gross, 1996;Gross and Repka, 1998). This view also allows for a better understanding of another important aspect of alternative reproductive phenotypes: the switch point, or threshold, that typically separates alternative morphs.…”

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“…An important implication of this perspective is that a given male's competitive status is, by definition, a relative measure and a function of its own phenotype relative to the mean phenotype in the population within which it competes (Hazel and Smock, 1993). Consequently, as a population's mean phenotype changes, so does a given male's competitive status, even though his absolute phenotype may remain constant (Dominey, 1984;Hazel and Smock, 1993;Hazel et al, 1990;Gross, 1996;Gross and Repka, 1998).…”

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“…Here, differences in the social environment experienced by different males are thought to be crucial for the origin and maintenance of alternative male phenotypes (Travis, 1994;West-Eberhard, 1989. Such differences may arrise from differences in the competitive status of males, which in many taxa can be a direct consequence of the animal's own phenotype such as its body size (Dominey, 1984;Hazel and Smock, 1993;Hazel et al, 1990;Gross, 1996;Gross and Repka, 1998). For example, relatively small or large males, by virtue of their different competitive status, often experience very different social conditions and hence selective environments.…”

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The behavioral ecology of threshold evolution in a polyphenic beetle

Moczek¹

2003

Behavioral Ecology

121

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Facultative expression of alternative male morphologies is thought to allow individual males to select the phenotype with the highest fitness gain given their competitive status relative to other males with which they compete for females. Choice of, or switching between, morphs commonly relies on developmental threshold responses. Evolutionary changes in developmental threshold responses are thought to provide an important avenue for phenotypic diversification and the evolution of morphological and behavioral novelties. However, the extent to which alternative male phenotypes and their underlying threshold responses actually evolve in natural populations is unclear. Likewise, the ecological factors that shape the evolution of threshold responses in natural populations are unexplored for most organisms, as are the consequences of such modifications for patterns of morphological diversity. I examined the ecological basis of rapid threshold evolution in exotic populations of the horn-polyphenic dung beetle Onthophagus taurus. Male O. taurus vary continuously in body size as a function of larval feeding conditions. Only males that exceed a critical threshold body size develop a pair of long horns on their heads, whereas males below this threshold remain hornless. Populations in two exotic ranges of this species, the eastern United States and western Australia, have diverged in the mean threshold body size, which has resulted in the evolution of highly divergent and novel horn length-body size allometries in these populations. Populations in a third and previously unstudied exotic range of O. taurus in eastern Australia exhibit threshold body sizes roughly intermediate between the eastern U.S. and western Australian populations. I tested three hypothesis to explain how differences in ecological and demographic factors can drive allometric divergences between populations, using data derived from comparative, standardized sampling of a large number of populations in each exotic range. Results suggest that differences in the intensity of both intra-and interspecific competition have contributed to the evolution of divergent thresholds in these populations. My results do not support the hypothesis that shifts in threshold body sizes to larger body sizes are a consequence of increases in the mean body size of competing males. I discuss my results in the context of Onthophagus mating systems and the evolutionary implications of threshold evolution.

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The behavioral ecology of threshold evolution in a polyphenic beetle

Moczek¹

2003

Behavioral Ecology

121

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“…Hazel et al (1990) in a paper entitled &&A polygenic model for the evolution and maintenance of conditional strategies,'' showed, using standard quantitative genetic methods, that &&conditional strategies will evolve to their evolutionary optimum and be maintained by stabilizing selection'', (p. 181). Moreover, Hazel & Smock (1993) show that this optimum is a stable equilibrium. Neither of these papers is cited by Gross & Repka, who again take credit for a result that was published well before their own.…”

Section: Inheritance In the Conditional Strategy Revisitedmentioning

confidence: 96%

Inheritance in the Conditional Strategy Revisited

Hazel

Smock

2000

Journal of Theoretical Biology

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“…Hazel et al [2,5] used a quantitative genetic model (the Environmental Threshold model or ET) to examine the ecological conditions leading to the evolution and maintenance of conditional strategies [2,3,5]. The ET model differs from the ESS model in that the ET postulates genetic differences in sensitivity (response threshold) to the environmental cue that influences which tactic of the conditional strategy is exercised.…”

Section: The Environmental Threshold Model (Et)mentioning

confidence: 99%

Using evolutionary computation methods to support analytical models for the evolution and maintenance of conditional strategies in chthamalus anisopoma

Townsend

Hazel

Smock

2005

Proceedings of the 7th Annual Conference on Genetic and Evolutionary Computation

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Biologists have developed models to explain why different environmentally induced morphs of the same organism exist over time. Such conditional strategies are a common form of adaptation to variable environments, whereby an environmental cue allows some individuals to respond to the cue and develop into a morph that is different from the morph of individuals that do not receive the cue. Recently, these efforts have resulted in two different analytical models that give somewhat different predictions. Here we apply evolutionary computation methods to test the two analytical models. The results bear a remarkable similarity to the results of one of the two analytical models. The paper that follows presents the details of a biological application involving snails and barnacles (that occur naturally in two different morphs), moving then to an explanation of two competing mathematical models of the application. Finally, the interdisciplinary paper, which coordinates three separate research projects of a biologist, a mathematician and a computer scientist, describes the evolutionary computation methods used to support one of the two competing analytical models.

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Modeling Selection on Conditional Strategies in Stochastic Environments

Cited by 11 publications

References 19 publications

The behavioral ecology of threshold evolution in a polyphenic beetle

The behavioral ecology of threshold evolution in a polyphenic beetle

Inheritance in the Conditional Strategy Revisited

Using evolutionary computation methods to support analytical models for the evolution and maintenance of conditional strategies in chthamalus anisopoma

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