Chad D. Hoefler

The costs of male courtship and potential benefits of male choice for large mates in Phidippus clarus (Araneae, Salticidae)

Abstract Despite a wealth of research on the benefits of mate choice, empirical evidence for the costs of courtship is scarce. Understanding the interplay between the costs and benefits of reproductive behaviors is critical to our understanding of sexual selection. I present a study designed to explore the potential reproductive benefits of male choosiness for large mates as well as the costs of courtship in the jumping spider Phidippus clarus (Keyserling 1885). My findings suggest that a positive relationship between female tibia length and the number of emerging spiderlings may underlie male choice for large females. However, this benefit may be mitigated by the longevity costs of courtship. Further investigation of the potential trade-offs between the benefits of male preferences for large females and the costs of courtship in this species is required.

Male courtship repeatability and potential indirect genetic benefits in a wolf spider

Indirect benefits derived by females that mate with males that express preferred traits are important to our understanding of ‘good genes’ models of sexual selection. However, few studies have explored male courtship behaviours with potential indirect benefits conferred to females in order to ascertain whether these behaviours serve as honest indicators of male quality. Using a common species of wolf spider, Pardosa milvina, we addressed the honesty of male courtship behaviours in two laboratory experiments. In our first experiment, we quantified the repeatability of courtship rate in adult males that were manipulated to be in high or low condition and were sequentially presented with adult virgin females that similarly differed in body condition. In our second experiment, we explored the effect of male courtship rate on several measures of fitness: number of offspring produced, days until offspring emerged and offspring viability measured as offspring survival. Our experiments show that male courtship rate is statistically significantly repeatable except when males in high condition have repeated encounters with females in low condition. Our results also reveal that females have the potential to gain indirect genetic benefits by mating with males that naturally court at high rates: females produced more offspring that emerged from eggsacs sooner and survived starvation better compared to females that mated with males that naturally courted at low rates. Our study provides additional support that male courtship rate is an honest indicator of quality, and it makes the novel finding that the repeatability of courtship rate is context sensitive.

CHEMOSENSORY RESPONSE TO PREY IN PHIDIPPUS AUDAX (ARANEAE, SALTICIDAE) AND PARDOSA MILVINA (ARANEAE, LYCOSIDAE)

Abstract Many predators exploit the chemical signatures of prey when foraging. We present a comparative study designed to test if the foraging behavior of Phidippus audax (Hentz 1845) is manipulated by substrate-borne chemicals left by prey. Our findings suggest that foraging P. audax do not use chemical cues left by prey, while the wolf spider Pardosa milvina (Hentz 1844) in the same experimental setup does respond to chemical cues. However, further examination into the role of chemical cues on prey detection in salticids is required.

The Effect of Experience on Male Courtship and Mating Behaviors in a Cellar Spider

Abstract Experience effects on mating have been implicated as important factors that can account for some of the variability in responses by prospective mates. Previous studies have demonstrated that sexual experience and learning can play significant roles in female choice; however, few studies have concentrated on experience effects in males. Using a partially sex-role reversed cellar spider, Pholcus phalangioides, in two laboratory experiments, we addressed the importance of male experience with (1) nonvirgin female cues associated with silk and (2) virgin females on a suite of male behaviors associated with mating. We discovered that males experienced with female silk and associated cues courted nonvirgin females for a longer duration than inexperienced males. Courtship latency and courtship duration had significant effects on mating success in trials involving inexperienced, but not experienced males. Female leg length affected the mating success of experienced, but not inexperienced males. Interestingly, no males mated twice when sequentially presented with two virgin females over a 24 h period, and most mated males (92%) failed to court the second female. Our findings suggest that male experience affects mating behaviors with both mated and virgin females and that males may be sperm limited.

Sex differences in early instar behavior in Pholcus phalangioides (Araneae: Pholcidae)

Abstract Intersexual differences in juvenile behavior in invertebrates are poorly understood despite the recognition that they may be widespread. We present a study designed to explore sex differences in behavior in early instar long-bodied cellar spiders Pholcus phalangioides (Fuesslin 1775). Our findings reveal that sex differences in activity and feeding are present early in P. phalangioides, which may have important implications for studies of behavior that involve juveniles. Further investigation of the factors that underlie the early emergence of sex differences in behavior is needed.

Learning to be Winners and Losers

Publisher Summary Most investigations of agonistic behavior in crustaceans have focused on crayfish, which are especially easy to maintain in the laboratory. Animals that have recently won aggressive interactions may often be more likely to win against new opponents that have not had recent winning experience; that is, winners keep winning. This phenomenon has been found in a variety of taxa, including juncos, chickens, paradise fish, red deer, and spiders. Crustaceans have been widely used in agonistic behavioral investigations and are excellent candidates for a test of this hypothesis. Many species are relatively large and easy to observe and measure, have well-described aggressive behaviors, are hardy, and readily interact with conspecifics. Agonistic behavior in crustaceans have examined species-specific ritualized displays inter- and intrasexual agonistic interactions and how fighting behavior is influenced by predation risk and time of day. Similarly, crabs have been used in studies considering the energetic costs of fighting the influence of relative and absolute body size on strategic decision making during agonistic encounters and the behaviors associated with the initiation and resolution of aggressive disputes.