ALBERT

Description: Females often prefer males with bright, showy, or large secondary sexual characters. However, social experience can result in variation in female preferences, with evidence of sexual imprinting in some taxa. In the brush-legged wolf spider, Schizocosa ocreata , asynchrony of maturation provides a time period in which imprinting may occur. We tested whether adult females demonstrated plasticity in their visual preferences for male leg tuft size after experience with digitally courting males during their penultimate stage. Penultimate instar females were presented visual courtship signals from males with small, average, or large tufts; a mixture of tuft sizes; or no males at all. During Week 2 of adulthood, each female was presented playback of digital courting small- and/or large-tufted males in both no-choice and two-choice presentations. Adult female preferences varied significantly with prior experience. Females exposed to only large-tufted males or males with a mixture of tuft sizes demonstrated more receptivity displays to large-tufted males than small-tufted males. Females exposed to only small-tufted males demonstrated more receptivity displays toward small-tufted males than large-tufted males. Because results suggested the possibility of sexual imprinting, we tested for reversibility. A subset of females was retested for selectivity in two-choice trials, revealing a positive correlation between Week 2 and Week 5 female selectivity. Females previously exposed to small-tufted males, however, no longer maintained their preference for small-tufted males in Week 5. This study demonstrates the effects of an individual’s social environment on mating preferences, and the importance of age and timing when studying sexual imprinting.

Description: During annual migrations between breeding and nonbreeding grounds, billions of land birds encounter migratory barriers en route . Although birds are thought to be more selective (i.e., cross under favorable wind conditions) and spend more time refueling at stopover sites when confronted with these barriers, there is no direct evidence to support these hypotheses. Using 2 automated radio-telemetry arrays at stopover sites situated before (south of) and after (north of) a large ecological barrier (Lake Erie), we tracked departure decisions of American redstarts Setophaga ruticilla and yellow-rumped (myrtle) warblers Setophaga coronata coronata during spring migration. We found evidence that condition, age, and tailwind assistance were all positively correlated with the likelihood of departure. Interestingly, these patterns did not differ between species, with presumably differing migratory tactics, nor across sites, suggesting that during spring migration, migratory songbirds may follow general rules for departure from stopover sites, despite varying ecological and life-history contexts.

Description: The immunocompetence handicap hypothesis postulates that higher-quality males may be able to balance potential conflicts between resource-demanding activities, such as courtship behavior and immune responses, whereas lower-quality males suffer from immunosuppression or lower reproductive output. In this study, we examined the immune response of the brush-legged wolf spider Schizocosa ocreata to infection with pathogenic bacteria as juveniles (penultimate), and its impact on development of adult male secondary sexual signaling traits. After oral ingestion of a bacterial pathogen, active bacteria were found in the hemolymph for up to 5h. We found that immune activation (ingestion of bacteria) at the juvenile stage resulted in higher immune response as an adult than control individuals, but also led to lower body condition index values and a higher degree of asymmetry in secondary sexual signaling traits (foreleg tufts). Infected males also had relatively smaller tufts than control males when penultimate body condition was added as a covariate and tuft size was appropriately scaled. Additionally, males infected as juveniles had significantly lower mating success than control males, although this difference was not due to courtship vigor. These results suggest that during development, juvenile males may be allocating more resources into immune function during infection, potentially at the cost of reduced sexual signaling and mating success as adults, and that there is the potential for complex trade-offs between immunity and sexual signaling in this species.

Description: Eavesdropping by conspecific males that are competing for mates has been demonstrated across a variety of taxa. However, few studies have investigated how eavesdropping may actually impact female mating decisions. Specifically, females may change their mating preferences based on whether the eavesdropping male varies in its phenotype (e.g., expression of condition-indicating secondary sexual characters or courtship vigor) relative to the male that initiated courtship. We examined variation in female preferences in the context of eavesdropping in the brush-legged wolf spider, Schizocosa ocreata . Female S. ocreata typically prefer males with large tufts and males that court at higher rates. In live mating trials, however, females preferentially mated with the males that courted first. It has yet to be investigated whether female preferences change when males of varying phenotypes are encountered sequentially, as might be expected in an eavesdropping context. We used video playback experiments to introduce females to a virtual courting male (initial male), followed by a second virtual courting male thirty seconds later (interloper male). We separately manipulated 2 aspects of male courtship (tuft size and courtship vigor) to measure female responses to an interloper male of lower, higher, or equal phenotypic expression. For both traits, females had an overall preference for the initial males. However, when the interloper male had large tufts or had high courtship vigor, female S. ocreata shifted the relative number of their receptivity displays. These results suggest that eavesdropping could be beneficial for interloper males, but the benefits may vary depending on the male’s phenotype.