Movements and behavior of 56 stream-spawning smallmouth bass and rock bass from Lake Ontario were examined in spring and summer 1985 and 1986. Fish were captured by electrofishing near spawning areas in two tributaries 60 km apart, fitted with temperature-sensing radiotransmitters and released in their "home" tributaries or displaced to the lake 3-10 km from these tributaries. Twenty-six percent of displaced smallmouth bass and 42% of rock bass returned to their original sites of capture in tributaries. Non-homing fish general1 dispersed along the lake shore and eventually established sma Y l residence areas in the lake, often near home or other tributaries. No differences were observed in movement rates, temperatures occupied or die1 activity patterns between years or tributary stocks, but differences were found between species and between lake and tributary habitats for smallmouth bass. Smallmouth bass homing to, or released in, tributaries generally established home ranges downstream from spawning areas and often occupied tributaries all summer, but rock bass did not. Both species occupied temperatures between 20-22 C in lake and tributar habitats when available. Smallmouth bass were most active in May, r east active in July and generally more active in the lake than in tributaries. Rock bass activity did not appear to vary by season or habitat. Both species were most active in Lake Ontario at mid-day; differences in tributaries were less pronounced.

Since its introduction, Anolis sagrei (Sauria: Polychrotidae) has been replacing native A. carolinensis in Florida and native A. conspersus in Grand Cayman Island as the common anole of urban environments and other open habitats. To assess the likelihood that predation of juvenile native anoles by A. sagrei adults is an important interaction in this process, the propensities for intraguild predation and cannibalism were assessed for A. sagrei and A. carolinensis in Florida and for A. sagrei and A. conspersus in Grand Cayman. Predation experiments were conducted in cages, using freshly captured lizards, in which adult males of each species were presented with conspecific and heterospecific juveniles. Adult A. sagrei were (1) significantly more likely to eat juveniles than were adult A. carolinensis or A. conspersus, and (2) significantly more likely to eat heterospecific than conspecific juveniles, whereas adult A. carolinensis and A. conspersus were not. Thus, the propensity for intraguild predation is asymmetrical in favor of introduced A. sagrei in Florida and Grand Cayman. Further study is needed, however, to determine the importance of intraguild predation under field conditions.

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Iguana delicatissima is an endangered endemic of the Lesser Antilles in the Caribbean. Phylogeographic analyses for many terrestrial vertebrate species in the Caribbean, particularly lizards, suggest ancient divergence times. Often, the closest relatives of species are found on the same island, indicating that colonization rates are so low that speciation on islands is often more likely to generate biodiversity than subsequent colonization events. Mitochondrial sequence analysis of the region spanning ND4 was performed on I. delicatissima individuals from islands across the species' range to estimate genetic divergence among geographically isolated populations. Five unique haplotypes were recovered from 46 individuals. The majority of animals carry a single common haplotype. Two of the haplotypes were only present in individuals classified as hybrids from Îles des Saintes. The final 2 haplotypes, single nucleotide substitutions, were present in animals from Îlet Chancel of Martinique and Saint Barthélemy, respectively. Despite the great distances between islands and habitat heterogeneity within islands, this species is characterized by low haplotype diversity. The low mtDNA variation of I. delicatissima suggests a single colonization coupled with rapid range expansion, potentially hastened by human-mediated dispersal.