A test of speciation via sexual selection on female preferences

Meffert, Lisa M.; Regan, Jennifer L.

doi:10.1006/anbe.2002.2020

Cited by 24 publications

(25 citation statements)

References 62 publications

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“…More importantly, we found the same kind of non-linear functions in an entirely different experiment (data unpublished). In particular, we selected for increased mating propensity in the same way as described here, while we were concomitantly selecting for divergent courtship repertoire (instead of selecting for increased assortative mating, see Meffert & Regan, 2002). Thus, we have confidence in our assertion that we had initial positive selection responses followed by long-term fitness declines, but also that the short-term responses for increased mating activity improved the flow of the protocol.…”

Section: Discussionmentioning

confidence: 65%

Reversed selection responses in small populations of the housefly (Musca domestica L.)

Meffert

Regan

2006

Genetica

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We compared the efficacy of artificial and natural selection processes in purging the genetic load of perpetually small populations. We subjected replicate lines of the housefly (Musca domestica L.), recently derived from the wild, to artificial selection for increased mating propensity (i.e., the proportion of male-female pairs initiating copulation within 30 min) in efforts to cull out the inbreeding depression effects of long-term small population size (as determined by a selection protocol for increased assortative mating). We also maintained parallel non-selection lines for assessing the spontaneous purge of genetic load due to inbreeding alone. We thus evaluated the fitness of artificially and 'naturally' purging populations held at census sizes of 40 individuals over the course of 18 generations. We found that the artificially selected lines had significant increases in mating propensity (up to 46% higher from the beginning of the protocol) followed by reversed selection responses back to the initial levels, resulting in non-significant heritabilities. Nevertheless, the 'naturally' selected lines had significantly lower fitness overall (a 28% reduction from the beginning of the protocol), although lower effective population sizes could have contributed to this effect. We conclude that artificial selection bolstered fitness, but only in the short-term, because the inadvertent fixation of extant genetic load later resulted in pleiotropic fitness declines. Still, the short-term advantage of the selection protocol likely contributed to the success of the speciation experiment since our recently-derived housefly populations are particularly vulnerable to inbreeding depression effects on mating behavior.

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Section: Discussionmentioning

confidence: 65%

Reversed selection responses in small populations of the housefly (Musca domestica L.)

Meffert

Regan

2006

Genetica

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“…These concordant responses for increased mating propensity were most likely due to our direct selection pressures for increased values of this fitness parameter. It is less likely that the selection protocols on the multivariate components of courtship performance would have directly caused the concordant increases in mating propensity because the lines did exhibit significant differences in courtship displays (Meffert and Regan 2002;data unpublished). The increased inbreeding pressure due to the selection protocols, however, could have contributed indirectly to the pleiotropic fitness declines (see Lande 1995;Lynch et al 1995;Whitlock 2000), most notable in Phase I of the experiment (Fig.…”

Section: Discussionmentioning

confidence: 96%

“…This design was intended to test whether a founder-flush event would alter selection responses for divergence in the ''shape'' of courtship (see Meffert and Regan 2002). We used the same base population from Phase 1 that had been maintained in the laboratory at the standard husbandry size of~1000 individuals for a total of 36 generations.…”

Section: Phase 2 Protocol Detailsmentioning

confidence: 99%

“…The first multifactorial trait represented the positive correlations among the five behaviors, and the second trait largely accounted for the antagonistic relationships within the suite of male displays. This principal component structure then served as the base-line reference point against which all subsequent courtships were mapped (Meffert and Regan 2002). In this way, the courtship of each male-female pair was assigned scores for each of these two multifactorial traits for determining which individuals would be selected as parents for the next generation (see below).…”

Section: General Experimental Designmentioning

confidence: 99%

“…These variables were expressed as a measure of the intensity of the individual's performance (i.e., the proportion of time spent in the display, see Meffert 1995;Meffert and Regan 2002). We used principal component analyses on the initial 160 courtships to reduce the five intercorrelated courtship behaviors to two multifactorial traits (Pimentel 1979).…”

Section: General Experimental Designmentioning

confidence: 99%

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Testing alternative methods for purging genetic load using the housefly (Musca domestica L.)

et al. 2006

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When a population faces long-term inbreeding, artificial selection, in principle, can enhance natural selection processes for purging the exposed genetic load. However, strong purge pressures might actually decrease fitness through the inadvertent fixation of deleterious alleles and allelic combinations. We tested lines of the housefly (Musca domestica L.) for the effectiveness of artificial selection to promote the adaptation to small population size. Specifically, replicate populations were held at average census sizes of 54 for nine generations or 30 for 14 generations while being subjected to artificial selection pressure for increased fitness in overall mating propensity (i.e., the proportion of virgin male-female pairs initiating copulation within 30 min), while also undergoing selection to create differences among lines in multivariate components of courtship performance. In the 14-generation experiment, a subset of the lines were derived from a founder-flush population (i.e., derived from three male-female pairs). In both experiments, we also maintained parallel non-selection lines to assess the potential for natural purging through serial inbreeding alone. Sub-populations derived from a stock newly derived from the wild responded to artificial selection for increased mating propensity, but only in the short-term, with eventual rebounds back to the original levels. Serial inbreeding in these lines simply reduced mating propensity. In sub-populations derived from the same base population, but 36 generations later, both artificial selection and serial inbreeding increased mating propensity, but mainly to restore the level found upon establishment in the laboratory. Founder-flush lines responded as well as the non-bottlenecked controls, so we base our major conclusions on the comparisons between fresh-caught and long-term laboratory stocks. We suggest that the effectiveness of the alternative purge protocols depended upon the amount of genetic load already exposed, such that prolonged periods of relaxed or altered selection pressures of the laboratory rendered a population more responsive to purging protocols.

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The evolution of dynamic and flexible courtship displays that reveal individual quality

Hollon

García-Ruiz

Veen

et al. 2023

Behav Ecol Sociobiol

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Sexual selection is a major force shaping morphological and behavioral diversity. Existing theory focuses on courtship display traits such as morphological ornaments whose costs and benefits are assumed be to fixed across individuals’ lifetimes. In contrast, empirically observed displays are often inherently dynamic, as vividly illustrated by the acrobatic dances, loud vocalizations, and vigorous motor displays involved in courtship behavior across a broad range of taxa. One empirically observed form of display flexibility occurs when signalers adjust their courtship investment based on the number of rival signalers. The predictions of established sexual selection theory cannot readily be extended to such displays because display expression varies between courtship events, such that any given display may not reliably reflect signaler quality. We thus lack an understanding of how dynamic displays coevolve with sexual preferences and how signalers should tactically adjust their display investment across multiple courtship opportunities. To address these questions, we extended an established model of the coevolution of a female sexual preference and a male display trait to allow for flexible, dynamic displays. We find that such a display can coevolve with a sexual preference away from their naturally selected optima, though display intensity is a weaker signal of male quality than for non-flexible displays. Furthermore, we find that males evolve to decrease their display investment when displaying alongside more rivals. This research represents a first step towards generalizing the findings of sexual selection theory to account for the ubiquitous dynamism of animal courtship. Significance statement Animal courtship displays are typically costly for survival: songs attract predators; dances are exhausting; extravagant plumage is cumbersome. Because of the trade-off between mating benefits and survival costs, displaying individuals often vary their displays across time, courting more intensely when the potential benefit is higher or the cost is lower. Despite the ubiquity of such adjustment in nature, existing theory cannot account for how this flexibility might affect the coevolution of displays with sexual preferences, nor for the patterns of tactical display adjustment that might result, because those models treat displays as static, with fixed costs and benefits. Generalizing a well-studied model of sexual selection, we find that a static display and a flexible display can evolve under similar conditions. Our model predicts that courtship should be less intense when more competitors are present.

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A test of speciation via sexual selection on female preferences

Cited by 24 publications

References 62 publications

Reversed selection responses in small populations of the housefly (Musca domestica L.)

Reversed selection responses in small populations of the housefly (Musca domestica L.)

Testing alternative methods for purging genetic load using the housefly (Musca domestica L.)

The evolution of dynamic and flexible courtship displays that reveal individual quality

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