Variation in the allometry of exaggerated rhinoceros beetle horns

McCullough, Erin L.; Ledger, Kimberly J.; O’Brien, Devin M.; Emlen, Douglas J.

doi:10.1016/j.anbehav.2015.08.013

Cited by 71 publications

(67 citation statements)

References 67 publications

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“…Many (probably most) weapons also function as threat signals; if selection on a given structure differs regarding its signal and weapon functions, the weapon function is likely to have more effect. If this argument is correct, then the long lists of positive allometries of "exaggerated" weapon/threat structures in some other studies (e.g., Kodric-Brown et al 2006;McCullough et al 2015) fit with the prediction here of a strong trend toward positive allometries in weapons.…”

Section: Allometry Of Tactile Signalssupporting

confidence: 67%

Sexual Selection and Static Allometry: The Importance of Function

Eberhard

Rodrı́guez

Huber

et al. 2018

The Quarterly Review of Biology

124

134

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Many spectacular cases of biological diversity are associated with sexual selection, and structures under sexual selection often show positive static allometry: they are disproportionately large for the size of the animal's body in larger individuals. Other sexually selected structures, however, show negative allometry or isometry. Theory fails to account for this variation and recent summaries do not agree regarding the frequency of positive allometry in sexually selected structures. We propose explanations for why sexually selected structures with different functions (courtship, threat signals, and weapons) should differ in allometry. Positive allometry is predicted for threat structures (including most weapons) because larger individuals tend to win fights and threat signals are used to avoid unwinnable fights with larger opponents, the reproductive payoffs for contests tend to be higher for larger males, and discriminating the sizes of relatively larger traits requires greater absolute differences due to Weber's Law of sensory physiology. Male courtship signals, in contrast, convey many types of information, much of which is not consistently related to male size, so positive allometry is expected less often. We tested these predictions empirically by comparing the allometries of male structures with relatively "pure" functions. Our predictions were confirmed, thus helping to explain differences in previous empirical surveys. 208Volume 93 THE QUARTERLY REVIEW OF BIOLOGY This content downloaded from 192.236.

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Section: Allometry Of Tactile Signalssupporting

confidence: 67%

Sexual Selection and Static Allometry: The Importance of Function

Eberhard

Rodrı́guez

Huber

et al. 2018

The Quarterly Review of Biology

124

134

View full text Add to dashboard Cite

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“…This nuanced view is perhaps more representative of the empirical evidence; although classically exaggerated sexual traits often exhibit positive allometries (e.g. Gould 1973;Petrie 1988;McLain et al 2003;McCullough et al 2015), other sexual traits are isometric or even negatively allometric (e.g. Eberhard et al 1998;Cuervo & Møller 2001;Eberhard 2002;Jennions & Kelly 2002).…”

Section: Introductionmentioning

confidence: 95%

Trait allometries generate super‐honesty in Anolis dewlaps and may underlie sexual dimorphism

Petelo

Swierk

2017

Integrative Zoology

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Whether or not sexually selected traits consistently exhibit positive allometry (i.e. are disproportionately large in larger individuals) is an ongoing debate. Multiple models and exceptions to this rule suggest that the underlying drivers of sexual trait allometry are nuanced. Here, we compare allometries of sexual and non-sexual traits of a species (Anolis aquaticus) within a well-studied lizard genus to test the competing hypotheses that sexual traits are, or are not, defined by positive allometry. We further consider the relationships of trait functions, which are relatively well understood in the genus Anolis, and allometry to identify potential drivers of allometric patterns. In particular, we explore how trait allometries interact to influence total organism function and generate sexual dimorphism. We quantified size (of targeted traits) and color of a sexual signal (the dewlap) in Anolis aquaticus in the field. The dewlap conveyed information relevant to intra-sexual combat and exhibited positive allometry. Overall, our results suggest that using single-trait allometries as indicators of past selection provides only an incomplete understanding of trait evolution. Although the function of positive allometry in some individual sexual signals (e.g. those conveying "super-honest" information) may be straightforward, we illustrate how scaling relationships interact synergistically to influence the function of phenotypes and propose avenues for future research.

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“…Because large species usually grow for long period of time, steep ontogenetic allometry would produce particularly large horns that may be too costly to carry (Vander Linden & Dumont, 2019). Although Gould (1966) suggested this hypothesis for both ontogenetic and static allometry, it has never been tested for ontogenetic allometry, and evidence for a change in static allometry with body size is inconclusive (Emlen & Nijhout, 2000; Gould, 1966; Knell, Pomfret, & Tomkins, 2004; McCullough et al, 2015; Voje et al, 2014). Yet, as an illustration of this hypothesis, we calculated the size of the horns that S. caffer males (max body mass = 718 kg) would carry if they had an ontogenetic allometry similar to C. ibex males (max body mass = 109 kg).…”

Section: Discussionmentioning

confidence: 99%

“…Ontogenetic allometry is often nonlinear (Deacon, 1990; Pélabon et al, 2013) and can be described by various models such as quadratic or segmented regressions (i.e., threshold models) or standard asymptotic growth models (e.g., monomolecular, Gompertz, logistic, or von Bertalanffy, France, Dijkstra, & Dhanoa, 1996). Segmented regressions are seldom used in allometric studies (but see Huxley, 1932; Knell, 2008; Lemaître, Vanpe, Plard, & Gaillard, 2014; McCullough, Ledger, O'Brien, & Emlen, 2015). Segmented regressions are described by four parameters: the intercept ( α ), the slope before the threshold ( β 1 ), the position of the threshold on the x ‐axis at which the slope shifts ( T BM , in natural log), and the slope after the threshold ( β 2 ).…”

Section: Methodsmentioning

confidence: 99%

Variation in the ontogenetic allometry of horn length in bovids along a body mass continuum

Tidière

Gaillard

Garel³

et al. 2020

Ecology and Evolution

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Allometric relationships describe patterns of proportional covariation between morphological, physiological, or life-history traits and the size of the organisms among populations or species (evolutionary allometry), or within population, among individuals measured at similar (static allometry), or different (ontogenetic allometry) age or developmental stages. When expressed on a log-log scale, allometric relationships are often described by a linear regression: log(y) = a + b log(x) where y is the trait size; x the body size; and a and b the allometric intercept and slope, respectively (Huxley, 1932). Because population and species mean trait size and body size used to estimate evolutionary allometry result from the proportional growth of both traits, patterns of evolutionary allometry emerge from variation in ontogenetic allometry (Abstract Allometric relationships describe the proportional covariation between morphological, physiological, or life-history traits and the size of the organisms. Evolutionary allometries estimated among species are expected to result from species differences in ontogenetic allometry, but it remains uncertain whether ontogenetic allometric parameters and particularly the ontogenetic slope can evolve. In bovids, the nonlinear evolutionary allometry between horn length and body mass in males suggests systematic changes in ontogenetic allometry with increasing species body mass. To test this hypothesis, we estimated ontogenetic allometry between horn length and body mass in males and females of 19 bovid species ranging from ca. 5 to 700 kg.Ontogenetic allometry changed systematically with species body mass from steep ontogenetic allometries over a short period of horn growth in small species to shallow allometry with the growth period of horns matching the period of body mass increase in the largest species. Intermediate species displayed steep allometry over long period of horn growth. Females tended to display shallower ontogenetic allometry with longer horn growth compared to males, but these differences were weak and highly variable. These findings show that ontogenetic allometric slope evolved across species possibly as a response to size-related changes in the selection pressures acting on horn length and body mass. K E Y W O R D S comparative analysis, development, ornament, sexual selection, ungulates, weapons | 4105 TIDIÈRE ET al.

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Variation in the allometry of exaggerated rhinoceros beetle horns

Cited by 71 publications

References 67 publications

Sexual Selection and Static Allometry: The Importance of Function

Sexual Selection and Static Allometry: The Importance of Function

Trait allometries generate super‐honesty in Anolis dewlaps and may underlie sexual dimorphism

Variation in the ontogenetic allometry of horn length in bovids along a body mass continuum

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