Phylogeographic and diversification patterns of the white-nosed coati (Nasua narica): Evidence for south-to-north colonization of North America.

White-nosed coatis (Nasua narica) are widely distributed throughout North, Central, and South America, but the patterns of temporal and spatial diversification that have contributed to this distribution are unknown. In addition, the biogeographic history of procyonid species in the Americas remains contentious. Using sequences from three mitochondrial loci (Cytochrome b, NAHD5 and 16S rRNA; 2201 bp) and genotypes from 11 microsatellite loci, we analyzed genetic diversity to determine phylogeographic patterns, genetic structure, divergence times, and gene flow among Nasua narica populations throughout the majority of the species' range. We also estimated the ancestral geographic range of N. narica and other procyonid species. We found a high degree of genetic structure and divergence among populations that conform to five evolutionarily significant units. The most southerly distributed population (Panama) branched off much earlier (∼3.8 million years ago) than the northern populations (<1.2 million years ago). Estimated gene flow among populations was low and mostly northwards and westwards. The phylogeographic patterns within N. narica are associated with geographic barriers and habitat shifts likely caused by Pliocene-Pleistocene climate oscillations. Significantly, our findings suggest the dispersal of N. narica was south-to-north beginning in the Pliocene, not in the opposite direction during the Pleistocene as suggested by the fossil record, and that the most recent common ancestor for coati species was most likely distributed in South or Central America six million years ago. Our study implies the possibility that the diversification of Nasua species, and other extant procyonid lineages, may have occurred in South America.

Reproductive seasonality of the female Florida gar, Lepisosteus platyrhincus.

Our objective was to characterize the reproductive seasonality of a wild population of female Florida gar, Lepisosteus platyrhincus. We measured the gonadosomatic index, plasma estradiol, testosterone, and vitellogenin concentrations, and follicle diameters of fish collected from Orange Lake, Florida (USA). Additionally, the reproductive stage of the ovary was resolved histologically. We observed a seasonal pattern in reproduction. Following a quiescent period in the summer, there was an increase in sex steroid hormones during the fall, associated with the onset of vitellogenesis and active oogenesis. During the February collection, we directly observed ovulation in several females. This observation was supported by a sharp decrease in the gonadosomatic index between February and March as well as a decline in plasma hormones to basal levels during the summer months. Our data suggest the Florida gar has a group-synchronous ovary and the majority of females spawned during the early spring, followed by a general decrease in reproductive parameters to summer levels. While hormone and vitellogenin peaks may vary annually and variations in these reproductive patterns are expected for different collection sites, this study is important as it is the first characterization of the seasonal morphological and endocrinological reproductive pattern in a female holostean species. Moreover, it increases our understanding of basic reproductive biology of semitropical fishes in general, and nonteleost, bony fishes in particular.

Reproductive seasonality of the male Florida gar, Lepisosteus platyrhincus.

The objective of this study was to characterize the reproductive seasonality of a wild population of male Florida gar, Lepisosteus platyrhincus. We measured the gonadosomatic index, reproductive stage of the testes, seminiferous tubule area, and plasma concentrations of testosterone and 11-ketotestosterone for each fish. A seasonal pattern was observed in the reproduction of male gar. Following a quiescent period in the summer, there was an increase in plasma testosterone concentration during the fall, which was associated with the onset of active spermatogenesis as indicated by an increase in seminiferous tubule area and gonadosomatic index. Plasma concentrations of 11-ketotestosterone remained basal during the summer and winter and then increased during the early spring. These data, taken together with data from female gar collected in a parallel study by our lab, suggest that spawning occurred during the early spring (February-March), followed by a general decrease in reproductive parameters to summer levels. Recognizing that peaks of hormone concentrations and spawning period could vary with annual seasonal variation, this study is important because it is the first characterization of the seasonal morphological and endocrinological reproductive pattern in a holostean species. Furthermore, it increases our understanding of the reproductive biology of semitropical fishes.