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: Achoerodus viridis (Pisces : Labridae) was sampled over two years at Little Bay, NSW, Australia, and comparative material was taken from a site 4.5 km away at Cape Solander. Population structure and gonadal structure showed that A. viridis was protogynous and monandric (i.e. no primary males were found). Histological sections of male gonads showed a gonadal lumen, general ovarian lamellar form and multiple sperm ducts running longitudinally through the gonad wall. Males dominated the larger size and age classes, whereas females predominated in the smaller size and age classes. The sex ratio of mature fish and the whole population was biased in favour of females. Individuals at both sites matured as females at 1+-2+ years. Fish at Little Bay functioned as females at ages ranging from 8+ to 18+ years before changing sex at a size between 480 and 580 mm SL. Fish at Cape Solander may function as females for up to 18+' years and change sex between 500 and 520 mm SL. Spawning occurred between July and October (1991-93).Marine and Freshwater Research - MAR FRESHWATER RES. 01/1995; 46(7).
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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 160(4). · 2.39 Impact Factor