Females can solve the problem of low signal reliability by assessing multiple male traits

Male signals that provide information to females about mating benefits are often of low reliability. It is thus not clear why females often express strong signal preferences. We tested the hypothesis that females can distinguish between males with preferred signals that provide lower and higher quality direct benefits. In the field cricket, Gryllus lineaticeps , females usually prefer higher male chirp rates, but chirp rate is positively correlated with the fecundity benefits females will receive from males only for males that have experienced low quality diets. We paired females with muted males that were maintained on low or high nutrition diets, during the interactions we broadcast a replacement high chirp rate, and we observed whether females mated with the assigned male. Females were more likely to mate when paired with low nutrition males. These results suggest that females have evolved assessment mechanisms that allow them distinguish between males with preferred signals that provide high quality benefits (low nutrition males with high chirp rates) and males with preferred signals that provide low quality benefits (high nutrition males with high chirp rates).

Tradeoffs limit the evolution of male traits that are attractive to females

Tradeoffs occur between a variety of traits in a diversity of organisms, and these tradeoffs can have major effects on ecological and evolutionary processes. Far less is known, however, about tradeoffs between male traits that affect mate attraction than about tradeoffs between other types of traits. Previous results indicate that females of the variable field cricket, Gryllus lineaticeps , prefer male songs with higher chirp rates and longer chirp durations. In the current study, we tested the hypothesis that a tradeoff between these traits affects the evolution of male song. The two traits were negatively correlated among full-sibling families, consistent with a genetically based tradeoff, and the tradeoff was stronger when nutrients were limiting. In addition, for males from 12 populations reared in a common environment, the traits were negatively correlated within populations, the strength of the tradeoff was largely invariant across populations, and the within-population tradeoff predicted how the traits have evolved among populations. A widespread tradeoff thus affects male trait evolution. Finally, for males from four populations assayed in the field, the traits were negatively correlated within and among populations. The tradeoff is thus robust to the presence of environmental factors that might mask its effects. Together, our results indicate there is a fundamental tradeoff between male traits that: (i) limits the ability of males to produce multiple attractive traits; (ii) limits how male traits evolve; and (iii) might favour plasticity in female mating preferences.

Seasonal dynamics and overwintering strategy of the tachinid fly (Diptera: Tachinidae), Ormia ochracea (Bigot) in southern California

We present the first data on the seasonal abundance of an acoustically orienting parasitoid fly, Ormia ochracea (Bigot), in southern California. Peak population abundance of the parasitoid lags peak population abundance of its primary local host species the field cricket Gryllus lineaticeps Stål, by about six weeks. We also examined pupal diapause as a potential overwintering mechanism. Taken together our results suggest (1) that O. ochracea lacks a highly effective pupal diapause, (2) that spring adult field cricket species are safe from the fly, and (3) that most of the late fall flies die without reproducing.

False promises: females spurn cheating males in a field cricket

Females commonly prefer to mate with males that provide greater material benefits, which they often select using correlated male signals. When females select higher-benefit males based on correlated signals, however, males can potentially deceive females by producing exaggerated signals of benefit quality. The handicap mechanism can prevent lower-quality males from producing exaggerated signals, but cannot prevent cheating by higher-quality males that choose to withhold the benefit, and this poses a major problem for the evolution of female choice based on direct benefits. In a field cricket, Gryllus lineaticeps , females receive seminal fluid products from males with preferred songs that increase their fecundity and lifespan. We tested the hypothesis that female behaviour penalizes males that provide lower-quality benefits. When females were paired with males that varied in benefit quality but had experimentally imposed average songs, they were less likely to re-mate with males that provided lower-quality benefits in the initial mating. This type of conditional female re-mating may be a widespread mechanism that penalizes males that cheat on direct benefits.