No abstract

Divergence in mating signals is a primary factor leading to reproductive isolation, and thus, speciation. However, the genetic changes underlying such divergence are poorly understood, especially in vertebrates. We used two species of poeciliid fishes, Poecilia velifera and P. mexicana, to explore the link between genes and mating behaviors that has resulted in pre‐mating reproductive isolation between these species. Using backcross hybrids created from the F1 male offspring of reciprocal interspecific crosses between a sailfin molly (P. velifera) and a shortfin molly (P. mexicana), we examined the effects of Y‐linkage and autosomal contributions on the expression of two male mating behaviors: courtship displays and gonopodial thrusts. The F1 hybrid males displayed a strong influence of sire on courtship display rates, with F1 males sired by the sailfin species showing courtship display rates that were up to three times higher than the rates of displays performed by F1 males sired by the shortfin species. These results suggest a Y‐linked genetic effect on the expression of courtship display behavior. Comparisons between backcross hybrid males with sailfin Y‐chromosomes or shortfin Y‐chromosomes suggested that the interaction of autosomal genes also influences the inheritance of courtship display rates. Sailfin autosomal genes significantly increased the probability of performing courtship displays for hybrid males, and increased display rate for males from the sailfin Y‐chromosome line. Autosomal genes had less of an impact on gonopodial thrusting behavior, however, thrust rates did significantly decrease with an increasing proportion of sailfin autosomes in males from the shortfin Y‐chromosome line. These results suggest that the inheritance of species differences in mating signals between shortfin and sailfin mollies involves both genes found on the Y‐chromosome and autosomal gene influences on their expression.

Head and lateral line erosion syndrome (HLLES) is a common but very poorly understood disease of marine aquarium fish. One suspected etiology is the use of granulated activated carbon (GAC) to filter the water. Seventy-two ocean surgeons Acanthurus bahianus were distributed among three carbon-negative control systems and three GAC-treated systems such that each tank contained approximately the same total body mass. Each replicate system was made up of two 250-L circular tanks with a common filtration system (6 fish per tank, 12 fish per replicate system). The GAC-treated tanks were exposed to full-stream, extruded coconut shell activated carbon, which produced a mean total organic carbon content of 0.4 mg/L. The results of this study indicate that extruded coconut shell activated carbon filtering at full-stream rates can cause HLLES-type lesions in ocean surgeons. The HLLES developed exponentially over 15 d, beginning in the chin region. This was followed by pitting in the cheek region, which expanded until erosions coalesced. Once the carbon was discontinued, the processes reversed in a mean time of 49 d. As the lesions healed, they reverted from the coalesced to the pitted stage and then darkened before returning to normal.

Goliath groupers (Epinephelus itajara) are large charismatic species, which are often residents in public aquaria. This study reports a novel approach to feeding techniques for three resident goliath groupers. Because of the size and depth of their exhibit, the groupers were conditioned to hand feed from aquarists. Daily food logs were recorded including the type and number of species, how often the groupers were fed, and how often they accepted the offered food. Mackerel, herring, and sardine represented the highest percentage of the diet, whereas capelin, squid, and shrimp were the lowest percentage. Over a one-year period, records showed that grouper 1 and grouper 3 ate fairly consistently throughout the year. Grouper 2 had a higher degree of variation in his monthly feeding average with a decrease from May to September and an increase through April. Grouper 1 and grouper 3 took food from the aquarists most consistently with a monthly average of 88.8+/-10.8 and 89.7+/-6.15% of the time, respectively. Grouper 2 was not as consistent, hand feeding at only 74.5+/-16.2% of the time offered. Diet management and behavioral conditioning with the goliath groupers have established consistent husbandry records and therefore better monitoring of the individual fish's long-term health status. Zoo Biol 27:414-419, 2008. (c) 2008 Wiley-Liss, Inc.