Caribbean damselfish with varying territory quality: correlated behaviors but not a syndrome
The behavioral syndrome hypothesis suggests that individuals within a population behave differently due to specific behavioral types and these should be consistent in a variety of contexts. In contrast, for territorial animals that live in stochastic environments, natural selection should favor animals that show behavioral flexibility and can modulate behavior in relation to current territory quality. We examined the territorial behavior of a natural population of male beaugregory damselfish by enhancing territory quality using artificial breeding sites and comparing their behavior to males on lower quality natural sites. When male fish were defending high quality artificial territories, they had higher levels of aggression toward male conspecifics and courtship toward females than when on low quality natural territories. We also found that aggression and courtship behaviors were correlated on natural sites, but not artificial. Behaviors were not correlated when males switched from natural to artificial territories or from artificial to natural territories. These results indicate that males assess their current territories and adjust behaviors accordingly and that courtship and aggression behaviors are not linked within a permanent behavioral syndrome.
Differences in territory quality and subsequent behavioral changes of male beaugregory damselfish, Stegastes leucostictus
When territory quality can vary over time, natural selection should have favored animals with behavioral flexibility in order to modulate the cost of defense in accordance with territory quality. This requires assessment of the territory followed by appropriate types and intensities of behavior. We examined this hypothesis using male beaugregory damselfish by enhancing territory quality using artificial breeding sites and comparing their behavior to males on natural sites. Males on artificial sites reproduce at higher levels than males on natural sites. In Experiment 1, our aim was to determine if a behavioral syndrome existed between courtship and aggressive behaviors across different quality sites. We found that behaviors were correlated on natural sites, but not artificial. When changes in territory quality occurred, courtship and aggression were not correlated and males had high levels of behaviors on high quality (artificial) territories. These results indicate that males assess their current territories and adjust behaviors accordingly. In Experiment 2, the value of reproduction was explored by giving males a choice between courting a female (potential reproduction) or attacking an egg predator (potential loss of eggs). A significant interaction was seen between the territory type and the stimuli: males on natural sites spent more time courting females and less time defending, while males on artificial sites behaved oppositely. Thus, males defending low quality territories invest in courtship while devaluing the relative importance of an egg predator while males defending high quality sites invest more in repelling the egg predator than attracting the female.
Aggression & Courtship Behaviors of Beaugregory Damselfish on Different Quality Territories: Correlated Behaviors, But Not a Syndrome
Personalities, temperaments, or behavioral types have long been the interest of scientists and have been studied in more than 60 species, from ants to zebrafish. The behavioral syndrome hypothesis suggests that individual animals within a population behave differently because of their specific behavioral type or temperament and these behavioral types should be consistent across behaviors or in different situations. In contrast, when animals live within an environment in which territory quality can change over time, natural selection should have favored animals that show behavioral flexibility and modulate the cost of defense of the area in relation to territory quality. This would require assessment of the territory followed by displays of appropriate types and intensities of behavior. We examined the territorial behavior of male beaugregory damselfish by enhancing territory quality using artificial breeding sites and comparing their behavior to males on natural sites. Males on artificial sites reproduce at a higher level than males on natural sites. We found that when male fish were defending high quality artificial territories, they had higher levels of aggression toward male conspecifics and courtship toward females than when on low quality natural territories. We also found that behaviors were correlated on natural sites, but not artificial. Behaviors were not correlated when males switched from natural to artificial territories or from artificial to natural territories. These results indicate that males assess their current territories and adjust behaviors accordingly.
An Examination of Biparental Care by Convict Cichlids: Sex Differences in the Retrieval of Offspring
Parents do not always share offspring care equally and each parent often has a specialized role. The most commonly observed sex-typical roles are defense by males and direct care of the offspring by females. In our study of convict cichlids (*Archocentrus nigrofasciatus*) we examined the behaviors of each parent when non-swimming young were displaced from the nest. Parental care was measured using retrieval of offspring and agonistic behaviors toward potential offspring predators. We found that males were more likely to retrieve young displaced far from the nest, while females retrieved young at closer distances. Additionally, although we found that both parents do attack the potential predator (a conspecific individual), retrieval behaviors did not change for either parent. We also examined retrieval behavior when one parent was removed and found that the remaining male or female parent was able to perform all behaviors associated with parental care. These preliminary studies suggest that while there is plasticity in parental behavior of convict cichlids, when together, parents often assume sex-typical roles.
Causes and consequences of population decline in an endangered pupfish, Cyprinodon bovinus
When intrasexual interactions influence reproductive success, declines in population size may alter individual reproductive success as well as the breeding system of the species. The endangered Leon Springs pupfish, Cyprinodon bovinus, has a breeding system where large males defend territories around female oviposition sites, while smaller males show satellite or sneaker tactics to gain matings. In related species, absence of territorial males results in satellites taking over territorial vacancies. However, despite a decline in number of territorial males, we observed an altered breeding system with satellites not becoming territorial. Territorial males with neighbors have few heterospecific intruders and we hypothesize territoriality is no longer beneficial to satellites due to the lack of interaction with territorial neighbors. We examine the costs of both strategies in number of intruders present at spawning and benefits in number of spawnings. In addition, large numbers of a pupfish egg predator, the endangered Gambusia nobilis, may be contributing to the decline of C. bovinus. We discuss management implications when one endangered species threatens another.