Predation affects the evolution of sex-specific longevity.

Predation, a major cause of natural selection, is classically thought to target the weak and sick. However, predators can target animals with condition-dependent sexual traits, and therefore, high-quality individuals can also be the focus of predation. Thus, it is not always clear which individuals are the foci of predators or how this affects trait evolution.

Morphological and functional analyses for investigation of sexually selected legs in the frog legged beetle Sagra femorata (Coleoptera: Chrysomelidae).

Mate choice and male-male combat over successful mating often cause disproportionate exaggeration of male trait relative to body size. However, the exaggeration is often not the only trait involved with male-male combat and mate choice: suites of co-expressed traits may function together as a coordinated unit. When this occurs, dimorphism may be expected for these additional, non-exaggerated, structures.

Natural selection increases female fitness by reversing the exaggeration of a male sexually selected trait.

Theory shows how sexual selection can exaggerate male traits beyond naturally selected optima and also how natural selection can ultimately halt trait elaboration. Empirical evidence supports this theory, but to our knowledge, there have been no experimental evolution studies directly testing this logic, and little examination of possible associated effects on female fitness. Here we use experimental evolution of replicate populations of broad-horned flour beetles to test for effects of sex-specific predation on an exaggerated sexually selected male trait (the mandibles), while also testing for effects on female lifetime reproductive success.

Octopaminergic system orchestrates combat and mating behaviors: A potential regulator of alternative male mating tactics in an armed beetle.

Male-male combats over females and territories are widespread across animal taxa. The winner of a combat gains resources, while the loser suffers significant costs (e.g.

A specific type of insulin-like peptide regulates the conditional growth of a beetle weapon.

Evolutionarily conserved insulin/insulin-like growth factor (IGF) signaling (IIS) has been identified as a major physiological mechanism underlying the nutrient-dependent regulation of sexually selected weapon growth in animals. However, the molecular mechanisms that couple nutritional state with weapon growth remain largely unknown. Here, we show that one specific subtype of insulin-like peptide (ILP) responds to nutrient status and thereby regulates weapon size in the broad-horned flour beetle Gnatocerus cornutus.

Selection on an extreme weapon in the frog-legged leaf beetle (Sagra femorata).

Biologists have been fascinated with the extreme products of sexual selection for decades. However, relatively few studies have characterized patterns of selection acting on ornaments and weapons in the wild. Here, we measure selection on a wild population of weapon-bearing beetles (frog-legged leaf beetles: Sagra femorata) for two consecutive breeding seasons.

Sexual conflict over mating in Gnatocerus cornutus? Females prefer lovers not fighters.

Female mate choice and male-male competition are the typical mechanisms of sexual selection. However, these two mechanisms do not always favour the same males. Furthermore, it has recently become clear that female choice can sometimes benefit males that reduce female fitness.

Male courtship behavior and weapon trait as indicators of indirect benefit in the bean bug, Riptortus pedestris.

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.

Intralocus sexual conflict and offspring sex ratio.

Males and females frequently have different fitness optima for shared traits, and as a result, genotypes that are high fitness as males are low fitness as females, and vice versa. When this occurs, biasing of offspring sex-ratio to reduce the production of the lower-fitness sex would be advantageous, so that for example, broods produced by high-fitness females should contain fewer sons. We tested for offspring sex-ratio biasing consistent with these predictions in broad-horned flour beetles.

Effects of temperature on mating duration, sperm transfer and remating frequency in Callosobruchus chinensis.

Insect body temperature is usually determined by ambient temperature. Therefore, most biochemical and physiological processes underlying behavioural patterns are temperature dependent. Mating duration is also dependent on temperature, and therefore temperature should influence on sperm transfer and female remating frequency.