The data from this field study provided evidence that biparental convict cichlid Archocentrus nigrofasciatus pairs with large males had fewer intruders near their offspring compared to pairs with small males. This suggested that large males were more capable of defending their young against predators.
We examined how male size and fighting ability influence a female's mate assessment process and her eventual mate choice in the monogamous convict cichlid, Amatitlania nigrofasciata. Females always chose the larger of two males when they were allowed to see a larger male next to a smaller one and when a larger male defeated a smaller one in a fight. They did not differentiate between large and small males when they did not see the two males together nor did they choose a dominant over a subordinate male when both were the same size. We suggest that females select on the basis of male size because it is a better predictor of both direct and indirect benefits (i.e., future competitive interactions and foraging ability) than dominance behavior only. Despite selecting one male over the other early in the courtship period, females continued to visit both males until spawning. Our evidence suggests that this assessment behavior more closely resembles a bethedging tactic rather than the female's indecision as to which male will be her mate.
Dominant individuals have access to higherquality resource; thus, reversing their dominance status would be important for subordinate individuals. Using the convict cichlid fish (Amatitlania nigrofasciata), this study examines whether forming a pair bond can reverse dominance status. Furthermore, I hypothesize that female convict cichlids will incur more dominance reversals from pair-bond formation than males. Dyadic, same-sex contests were conducted to determine dominant and subordinate individuals. Forced pairing of these individuals based on status was followed by polyadic, between-pair contests.The results indicate that individual dominance status does carry over into between-pair competition. Furthermore, dominance reversals do occur in convict cichlids and occur more frequently in females than in males. In addition, dominant males assist their mates during aggressive encounters, and these assists may account for subordinate females winning against dominant females during polyadic contests.
Fight theory predicts that asymmetries between contestants can be used to predict the winners and losers in fights. Using the monogamous convict cichlid (Amatitlania nigrofasciata), we examined whether being in a pair bond has an advantage in defeating a single same-sex individual. We hypothesize that the male and female members of a pair bond would defeat a same-sex single intruder because it is beneficial to form a pair bond prior to competing for mutual resources, such as a breeding site. To test our hypotheses, we allowed paired males to engage in contests with single males with and without the interaction of their mate. In addition, we allowed paired females to engage in contests with single females with and without the interaction of their mate. Our results indicate that the paired male gained no advantage in being paired; however, paired females seem to have an advantage over single females because they typically defeated them. To reduce the influence of the other pair member on the fight, we restrained one member and allowed the other pair member to confront the same-sex individual. The paired male was frequently defeated while the paired female typically won. These results suggest that forming a pair bond gives females, but not males an advantage in fights with same-sex competitors.
Despite an abundance of studies documenting antipredator and defensive behaviors of gartersnakes (genus Thamnophis), few have quantitatively examined musking, a widely utilized antipredator tactic. In this study we quantify musking behaviors in the Terrestrial Gartersnake (Thamnophis elegans) and the Plains Gartersnake (T. radix) when hand-captured at four sites in and near Denver, Colorado, USA. Overall, Plains Gartersnakes musked significantly more often than Terrestrial Gartersnakes. Female Terrestrial Gartersnakes musked more frequently than males, a pattern not evident in the Plains Gartersnake. Additionally, we observed a positive correlation in body condition and musking propensity in Terrestrial Gartersnakes, suggesting resource-dependent behavior in this species. Musking behavior was consistent across variations in predation pressure, environmental conditions, and snake body size, all factors shown to influence other gartersnake defensive behaviors. These results corroborate other research which demonstrates that snake antipredator behaviors are determined by complex interactions of abiotic and biotic factors.
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