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Nick Santangelo and M. Itzkowitz

Abstract

It is understood that mate choice, competition, and sex differences produced by sexual selection underlie behavior, but few studies focus on their interactions within a system to understand how they shape behavior. Here, using the monogamous convict cichlid, Archocentrus nigrofasciatus, we examined the mate choice process of males and females in the presence of intrasexual competition. We compared and contrasted patterns reported in a previous study exploring this process in the absence of competition by using the same methodological paradigm. Specifically, two individuals (i.e., the competitors) were presented with a choice of two alternative, visually and tactilely isolated, mates and observed until one competitor (i.e., the primary competitor) spawned with one of the potential mates (i.e., the accepted mate). This was done for males and females separately. Both sexes spent more time with their mates while attacking and inhibiting the courtship of the other competitor (i.e., the secondary competitor). Only females expressed this time preference in the absence of competition (Santangelo & Itzkowtiz, 2004), but both sexes visited accepted mates more in the presence of competition. These results suggest competition causes the adoption of a mate guarding tactic. Males exhibited more differences than females with the addition of competition suggesting that male mate choice patterns are more labile than females. We attribute this to the ability of males to be bigamous and the adoption of different strategies based on the level of male-male competition. Courtship was not affected by competition for either sex, however the courtship of secondary individuals did appear to be influenced by primary individuals. Competition did not eliminate a searcher's continuous assessment of potential mates, yet it was conducted to a lesser degree. Thus, mate guarding is an important strategy that must be balanced with an individual's inclination to continuously assess based on present competition levels.

Itzkowitz and Nick Santangelo

Abstract

Compared to polygynous species, monogamous males and females are considered more similar in their mate choosiness, yet few studies have explored the mate selection process between the sexes. Here, we examined this mate selection process in the monogamous convict cichlid, Archocentrus nigrofasciatus. We presented an individual (i.e. the selector) of each sex with a choice of two alternative, visually and tactilely isolated, mates. Tanks were video taped each day until the selector fish spawned with one of the potential mates (i.e. the accepted mate). The number of visits, length of visits, and courtship interactions were recorded. Selecting females spent significantly more time with accepted versus rejected males (i.e. females expressed a time-based preference for their chosen males), but there was no significant difference in the number of visits made to either male. Selecting females did not court accepted and rejected males differently, but rejected males courted at a significantly higher rate than did accepted males. Although selecting females expressed a time-based preference for accepted males, they continued to visit and court rejected males throughout the mate choice process; thus females did not terminate their selection process until they spawned. In contrast to selecting females, selecting males did not spend a significantly different amount of time with accepted and rejected females while visiting both females equally. Furthermore, selecting males courted accepted females significantly more than they courted rejected females. Thus, males expressed their mate preferences through courtship whereas females expressed them through time spent. Males also courted more than females. Many of these sex differences curiously resemble those of a polygynous social system, which we suggest perhaps indicates polygynous ancestral origins.