Effect of weapon-supportive traits on fighting success in armed insects

Okada, Yasukazu; Suzaki, Yû; Miyatake, Takahisa; Okada, K.

doi:10.1016/j.anbehav.2012.01.021

Cited by 32 publications

(33 citation statements)

References 33 publications

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“…1). Weapon size is positively associated with competitive ability for mates [42], [43]. In this species, males establish their territories on soybean plants [41] and call over conspecific individuals irrespective of sexes by aggregation pheromone [72].…”

Section: Discussionmentioning

confidence: 99%

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Male Courtship Behavior and Weapon Trait as Indicators of Indirect Benefit in the Bean Bug, Riptortus pedestris

et al. 2013

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Females prefer male traits that are associated with direct and/or indirect benefits to themselves. Male–male competition also drives evolution of male traits that represent competitive ability. Because female choice and male–male competition rarely act independently, exploring how these two mechanisms interact is necessary for integrative understanding of the evolution of sexually selected traits. Here, we focused on direct and indirect benefits to females from male attractiveness, courtship, and weapon characters in the armed bug Riptortus pedestris. The males use their hind legs to fight other males over territory and perform courtship displays for successful copulation. Females of R. pedestris receive no direct benefit from mating with attractive males. On the other hand, we found that male attractiveness, courtship rate, and weapon size were significantly heritable and that male attractiveness had positive genetic covariances with both courtship rate and weapon traits. Thus, females obtain indirect benefits from mating with attractive males by producing sons with high courtship success rates and high competitive ability. Moreover, it is evident that courtship rate and hind leg length act as evaluative cues of female choice. Therefore, female mate choice and male–male competition may facilitate each other in R. pedestris. This is consistent with current basic concepts of sexual selection.

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Section: Discussionmentioning

confidence: 99%

“…Males of Riptortus pedestris usually fight for territories using their enlarged hind legs [41], and males with larger weapons tend to win the contest [42], [43]. In contrast, there is little information about male attractiveness and female preference in this species.…”

Section: Introductionmentioning

confidence: 99%

Male Courtship Behavior and Weapon Trait as Indicators of Indirect Benefit in the Bean Bug, Riptortus pedestris

et al. 2013

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“…Nontarget traits are sometimes enhanced to support or compensate for the primary target of exaggeration. For example, in male armed beetles and earwigs, the legs that are located close to weapon structures are also enlarged to support their primary targets (hereafter referred to as “supportive traits”: Tomkins et al ; Okada and Miyatake ; Okada et al ). In the case of ornaments, the wings of male barn swallows and stalk‐eyed flies are also enlarged to compensate for the cost of carrying their ornaments (compensatory traits: Hedenstrom and Møller ; Balmford et al ; Møller et al ; Husak et al ).…”

Section: Introductionmentioning

confidence: 99%

Juvenile hormone mediates developmental integration between exaggerated traits and supportive traits in the horned flour beetleGnatocerus cornutus

Okada

Gotoh

Miura

et al. 2012

Evolution and Development

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SUMMARY Sexually selected exaggerated traits are often coupled with modifications in other nontarget traits. In insects with weapons, enlargements of nontarget characters that functionally support the weapon often occur (i.e. supportive traits). The support of sexual traits requires developmental coordination among functionally related multiple traits—an explicit example of morphological integration. The genetic theory predicts that developmental integration among different body modules, for which development is regulated via different sets of genes, is likely to be coordinated by pleiotropic factors. However, the developmental backgrounds of morphological integrations are largely unknown. We tested the hypothesis that the juvenile hormone (JH), as a pleiotropic factor, mediates the integration between exaggerated and supportive traits in an armed beetle Gnatocerus cornutus. During combat, males of this beetle use exaggerated mandibles to lift up their opponents with the supportive traits, that is, the head and prothoracic body parts. Application of methoprene, a JH analog (JHA), during the larval to prepupal period, induced the formation of large mandibles relative to the body sizes in males. Morphometric examination of nontarget traits elucidated an increase in the relative sizes of supportive traits, including the head and prothoracic body parts. In addition, reductions in the hind wing area and elytra length, which correspond to flight and reproductive abilities, were detected. Our findings are consistent with the genetic theory and support the idea that JH is a key pleiotropic factor that coordinates the developmental integration of exaggerated traits and supportive characters, as well as resource allocation trade‐offs.

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“…For example, Okada et al. () found that legs closest to exaggerated weapons were also enlarged in the broad‐horned flour beetle, Gnatocerus cornutus , and the bean bug, Riptortus pedestris , and concluded that this enlargement was to support the primary target of selection and increase functionality. Likewise, Husak et al.…”

Section: Discussionmentioning

confidence: 99%

“…In other armed insects, combat success positively correlates with leg length, which is also correlated with weapon characteristics (Okada et al. ). Similarly, weapon size positively correlates with increases in fighting endurance, and weapon enlargement influences male body shape (Okada and Miyatake ).…”

Section: Discussionmentioning

confidence: 99%

Legs of male fiddler crabs evolved to compensate for claw exaggeration and enhance claw functionality during waving displays

et al. 2018

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Many exaggerated morphological traits evolve under sexual selection. However, the optimal level of exaggeration is dictated by a trade‐off between natural and sexual selection, representing a balance between its benefits and associated costs. Male fiddler crabs wave an enlarged major claw during behavioural displays that eliminates the need for direct combat, and determines courtship outcomes. The outcomes of these displays often depend on claw size, exposing males to selection for larger claws to improve mating and combat success. Applying phylogenetic comparative methods to 27 fiddler crab species, we examined the evolution of major claw morphologies, leg morphologies, and waving displays to determine whether these traits coevolved to optimise functioning of the exaggerated claw, or to mitigate potential metabolic or locomotor costs. We found legs to be sexually dimorphic, with males having longer legs than females. Legs were also longer in species that waved laterally rather than vertically, in species with larger major claws, and in species whose major claws were relatively elongate. These results suggest that leg morphology has coevolved with claw enlargement to enhance functionality of the major claw during waving displays, in addition to compensating for any negative effects of claw size.

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Effect of weapon-supportive traits on fighting success in armed insects

Cited by 32 publications

References 33 publications

Male Courtship Behavior and Weapon Trait as Indicators of Indirect Benefit in the Bean Bug, Riptortus pedestris

Male Courtship Behavior and Weapon Trait as Indicators of Indirect Benefit in the Bean Bug, Riptortus pedestris

Juvenile hormone mediates developmental integration between exaggerated traits and supportive traits in the horned flour beetleGnatocerus cornutus

Legs of male fiddler crabs evolved to compensate for claw exaggeration and enhance claw functionality during waving displays

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