Gonadal structure and population characteristics of the protogynous goby Coryphopterus glaucofraenum
ABSTRACT Protogynous hermaphroditism has been reported in two gobiid species within the genus Coryphopterus, including C. nicholsi from the temperate northeastern Pacific and C. personatus from the Caribbean. In a third species from the Caribbean, C. glaucofraenum, experimental groups were established and gonad structure of experimental individuals (collected off the southwest coast of Puerto Rico between February 1985 and June 1987) was subsequently examined histologically to determine the sexual pattern. Protogyny was confirmed in C. glaucofraenum. Sex change was either initiated or completed, typically by the largest female, in all-female groups held for 10 to 40 d. Ovarian, transitional, and testis structure were similar to that of C. nicholsi and C. personatus. No preformed testicular tissue was evident in the ovary proper and ovarian features were not retained in the sex-changed testis beyond the newly transformed stage. Secretory accessory gonadal structures associated with the testis and which develop at the time of sex change arose from precursive tissue masses associated with the ventral portion of the ovarian wall in the region of the common genital sinus. The rapid development and onset of function in these structures, generally preceding that of the associated developing testis, suggest that they may play an important role in sex change events and in advertising new male status. Based on observed similarities of ovarian, transitional and secondary testis structure in three protogynous Coryphopterus species, including one species isolated since the last closing of the American landbridge, it is probable that protogyny is an ancestral condition in this genus.
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ABSTRACT: Understanding prey response to predators and their utilization of sensory cues to assess local predation risk is crucial in determining how predator avoidance strategies affect population demographics. This study examined the antipredator behaviors of two ecologically similar species of Caribbean coral reef fish, Coryphopterus glaucofraenum and Gnatholepis thompsoni, and characterized their responses to different reef predators. In laboratory assays, the two species of gobies were exposed to predator visual cues (native Nassau grouper predator vs. invasive lionfish predator), damage-released chemical cues from gobies, and combinations of these, along with appropriate controls. Behavioral responses indicate that the two prey species differ in their utilization of visual and chemical cues. Visual cues from predators were decisive for both species’ responses, demonstrating their relative importance in the sensory hierarchy, whereas damage-released cues were a source of information only for C. glaucofraenum. Both prey species could distinguish between native and invasive predators and subsequently altered their antipredator responses.Marine Biology 04/2013; 160(4). DOI:10.1007/s00227-012-2156-6 · 2.39 Impact Factor
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ABSTRACT: An active debate has focused on whether patterns in the abundance of reef fishes are primarily determined by the supply of larvae or by subsequent interactions occurring on the reef. By manipulating the presence of predators and the density of older conspecifics on small standardized reefs, we tested the influences of these 2 factors - and interactions between them - on recruitment of reef fishes. To assess the generality of our findings, we conducted similar experiments on 2 closely related species in 2 different systems: 1 tropical and 1 temperate. At Santa Catalina Island (a temperate site in southern California, USA) we worked with the blackeye qoby Coryphopterus nicholsii and at Lee Stocking Island (a tropical site in the Bahamas) we studied the bridled goby Coryphopterus glaucofraenum. Predators reduced recruitment of blackeye gobies, but in contrast, in one experiment, recruitment of bridled gobies was positively affected by 1 class of predators (reef residents) and unaffected by transient predators. In another experiment, recruitment of bridled gobies was unaffected by either class of predators; however, there was little statistical power to detect a similar positive effect of predators. Older conspecifics (adults and subadults) did not significantly influence recruitment of blackeye gobies, but recruitment of bridled gobies was negatively related to density of adult conspecifics. For both species, the presence of predators did not influence the relationship between recruitment and the density of older conspecifics. Our results suggest that patterns of abundance among local populations of reef fishes can be decoupled from patterns of larval supply by reef-based biotic processes (namely predation and intraspecific interactions). However, the influences of older conspecifics and predators varied widely between the 2 quite similar species that we studied. This underscores the need to understand the specific reasons for such differences in order to make predictions regarding the relative importance of these processes in novel circumstances.Marine Ecology Progress Series 01/1998; 172:115-125. DOI:10.3354/meps172115 · 2.64 Impact Factor