Exaggerated sexually selected weapons maintained with disproportionately low metabolic costs in a single species with extreme size variation

Somjee, Ummat; Powell, Erin C.; Hickey, Anthony J. R.; Harrison, Jon F.; Painting, Christina J.

doi:10.1111/1365-2435.13888

Cited by 16 publications

(9 citation statements)

References 81 publications

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“…These structures are likely honest signals of ghting quality since the cost of cheating would be too risky if a stronger rival engaged them in combat (Simmons et al 2007;Emlen et al 2012). In most cases, these sexually selected traits evolutionarily scale positively allometrically with body size (Gould 1974;Kodric-Brown et al 2006;Somjee et al 2021), and our ndings for solely antlered species produce similar results (Table 5,6; Fig. 8).…”

Section: Intraspeci C Static Allometric Relationshipssupporting

confidence: 72%

“…Sexual weapons are used in physical combat to secure mating opportunities; victorious males typically have larger body size and larger sexual weapons as a direct result of intrasexual selection (Geist 1999;Emlen 2008;McCullough et al 2016;Sol et al 2020). Structures that serve as intrasexual signals and weapons (e.g., ungulate antlers and horns) typically exhibit positive allometry in both developmental growth and evolution: As individuals grow and species evolve larger body sizes, they grow and evolve disproportionately larger ornaments than smaller individuals and species (Gould 1974;McCullough et al 2015; Rico-Guevara and Hurme 2018; Somjee et al 2021).…”

Section: Introductionmentioning

confidence: 99%

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Sizing Up Swords: Correlated Evolution of Antlers and Tusks in Ungulates

Lopez

Stankowich

2021

Preprint

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Most sexual weapons in sexual combat and visual displays of dominance (e.g., antlers, horns) show positively allometry with body size for both growth during development and evolution across species, but allometry in species with more than one sexual weapon is unstudied. We examined the allometric relationships between body size and tusks (pure combat weapons) and/or antlers (both a visual signal and combat weapon) from forty-three artiodactyl species including the muntjaks (Muntiacinae), which uniquely have both antlers and tusks. We found that in Muntiacinae antler length scales positively allometrically with skull length, whereas tusk size scales isometrically suggesting greater energy investment in antlers as signals over tusks as combative weapons when both are present. Interspecifically, we found that species who possess only one weapon (either solely tusked or solely antlered) scaled positively allometrically with body mass, and the latter relationship levels off at larger body sizes. In our tusk analysis, when we included Muntiacinae species the positive allometric trend was not conserved resulting in an isometric relationship suggesting the possession of antlers negatively affect the energy investment in tusks as weapons. Overall, our findings show that species that possess dual weapons unproportionally invest energy in the development and maintenance of their multiple weapons.

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Section: Intraspeci C Static Allometric Relationshipssupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Sizing Up Swords: Correlated Evolution of Antlers and Tusks in Ungulates

Lopez

Stankowich

2021

Preprint

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“…A ubiquitous pattern across nature is that most measurable traits of an organism scale with body size (West et al, 1997). Allometry has been important for unravelling evolutionary processes such as speciation and the origin of novel phenotypes (Chatterji et al, 2022;Marcy et al, 2020;Tokita et al, 2017), as well as understanding allometry's connection with species' development (Emlen et al, 2012), physiology (Dudley & Srygley, 1994;Somjee et al, 2021;West et al, 2002), and behaviour (Dial et al, 2008;Eberhard et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…A ubiquitous pattern across nature is that most measurable traits of an organism scale with body size (West et al., 1997). Allometry has been important for unravelling evolutionary processes such as speciation and the origin of novel phenotypes (Chatterji et al., 2022; Marcy et al., 2020; Tokita et al., 2017), as well as understanding allometry's connection with species' development (Emlen et al., 2012), physiology (Dudley & Srygley, 1994; Somjee et al., 2021; West et al., 2002), and behaviour (Dial et al., 2008; Eberhard et al., 2018). Given this, understanding how these scaling relationships are characterised among groups of different species (“evolutionary allometry”), among individuals throughout development (“ontogenetic allometry”), and among individuals at the same life stage (“static allometry”) is a major focus of biology (Gould, 1966; Huxley, 1932; Sherratt et al., 2022).…”

Section: Introductionmentioning

confidence: 99%

The evolution of positive allometry and exaggerated traits in a diverse beetle clade

Painting,

Symonds,

Holwell

2024

Functional Ecology

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Understanding variation in trait allometry and the drivers of variation in sexually selected traits is a major theme in evolutionary biology. The static allometries of sexually selected traits are often positive due to disproportional investment by large individuals into trait size. Comparative studies of weapon allometry are rare, and typically focus on variation along a single dimension (e.g. length), despite weapons often diverging dramatically in shape. Furthermore, studies predominantly focus on groups where weapons have evolved as novel structures (e.g. horns), despite most weapons arising from modifications of existing structures. We test the hypothesis that sexual selection drives variation in static allometry using a phylogenetic comparative approach with 59 brentine weevil species showing remarkable variation in trait exaggeration and sexual size dimorphism (SSD). Contrasting two dimensions of head size exaggeration (a sexually selected trait) and elytron length (a nonsexual trait), positive static allometry was common across both measures of male head size, but not females, and there was positive covariance between male head static allometry and SSD across species. Positive static allometry for male elytron length was less common, but did show positive covariance with SSD, possibly due to the function of wings as compensatory structures for bearing large weapons. Our findings support the hypothesis that sexual selection drives the evolution of allometries both within and among species, and that the modification of existing structures to be used as weapons does not limit the potential for positive static allometry. Read the free Plain Language Summary for this article on the Journal blog.

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“…For example, contrary to expectations, weapons did not impair movement, incur aerodynamic costs or increase energetic costs in rhinoceros beetles ( Trypoxylus dichotomus ) [13,14] or fiddler crabs ( Uca pugilator ) [15]. Furthermore, compensatory morphology and behaviour is often detected that mitigates the costs of bearing weapons [16–18] and possibly explain why the costs of weapons do not necessarily result in the loss of the trait or population extinction. Thus, there is contradicting empirical support that weapons negatively impact functional activities.…”

Section: Introductionmentioning

confidence: 99%

Exaggerated mandibles are correlated with enhanced foraging efficacy in male Auckland tree wētā

Farnworth,

Purdie,

Wehi

et al. 2023

Biol. Lett.

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Sexual selection has driven the evolution of weaponry for males to fight rivals to gain access to females. Although weapons are predicted to increase males' reproductive success, they are also expected to incur costs and may impair functional activities, including foraging. Using feeding assays, we tested whether the enlarged mandibles of Auckland tree wētā ( Hemideina thoracica ) impact feeding activity (the total volume of biomass consumed, bite rate, and number of foraging visits) and foraging behaviour (time spent moving, feeding, or stationary). We predicted that increased head capsule size in male wētā would hinder their foraging efficacy. However, we found that wētā with longer heads fed at a faster rate and spent less time foraging than wētā with smaller heads, regardless of sex. Contrary to expectations that weapons impede functional activities, our results demonstrate that exaggerated traits can improve feeding performance and may offer benefits other than increased mating success.

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Exaggerated sexually selected weapons maintained with disproportionately low metabolic costs in a single species with extreme size variation

Abstract: 1. Larger individuals typically have lower mass-specific metabolic rates compared to small ones (hypometric scaling). This trend is most evident across species where body size differences can be extreme. Yet, within-species studies are critical to | 2283Functional Ecology SOMJEE Et al.

Cited by 16 publications

References 81 publications

Sizing Up Swords: Correlated Evolution of Antlers and Tusks in Ungulates

Sizing Up Swords: Correlated Evolution of Antlers and Tusks in Ungulates

The evolution of positive allometry and exaggerated traits in a diverse beetle clade

Exaggerated mandibles are correlated with enhanced foraging efficacy in male Auckland tree wētā

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