We report Anopheles darlingi in Darien Province in eastern Panama. Polymerase chain reaction-restriction fragment length polymorphism profiles of the single copy nuclear white gene and sequence ...comparisons confirmed the presence of 66 specimens of the northern lineage of An. darlingi. The parsimony network depicted 5 CO1 haplotypes in 40 specimens of An. darlingi, which connected through 7-8 mutational steps with sequences from Central and South America. Furthermore, the presence of haplotypes in Biroquera, Darien Province identical to those previously published from northern Colombia suggests that Panamanian samples originated in Colombia. Results of neutrality tests (R(2) and Fu's F(S)) were not significant and the mismatch distribution was multimodal and did not fit the model of sudden population growth. These findings may indicate a long and stable presence of An. darlingi in eastern Panama.
Free-ranging ticks are widely known to be restricted to the ground level of vegetation. Here, we document the capture of the tick species
Amblyomma tapirellum in light traps placed in the forest ...canopy of Barro Colorado Island, central Panama. A total of forty eight adults and three nymphs were removed from carbon dioxide-octenol baited CDC light traps suspended 20 meters above the ground during surveys for forest canopy mosquitoes. To our knowledge, this represents the first report of questing ticks from the canopy of tropical forests. Our finding suggests a novel ecological relationship between
A. tapirellum and arboreal mammals, perhaps monkeys that come to the ground to drink or to feed on fallen fruits.
We have investigated the phylogenetic relationships among six wild and six domesticated taxa of Cucurbita using as a marker an intron region from the mitochondrial nad1 gene. Our study represents one ...of the first successful uses of a mtDNA gene in resolving inter- and intraspecific taxonomic relationships in Angiosperms and yields several important insights into the origins of domesticated Cucurbita.
Fish of the genus Poeciliopsis provide an exceptional model for ecological and evolutionary questions. Study of these fish has contributed to the understanding of the origin and evolution of ...unisexuality, ecology of sexual and hybrid populations, cancer biology, and maintenance of sex in higher organisms. The present dissertation assessed three questions regarding molecular systematics and evolutionary issues in sexual and asexual Poeciliopsis taxa. In Chapter 1, I used allozyme and mitochondrial genetic markers to test a morphologically-based hypothesis and to infer phylogenetic relationships among species of the genus Poeciliopsis. Both genetic markers placed P. occidentalis and P. lucida as sister taxa, and P. infans in a basal position. Phylogeographic considerations revealed a stepwise, south to north pattern of anagenesis. The present data are consistent with a southern origin for these species and a progressive stepwise dispersal to northern environments. In Chapter 2, mitochondrial cytochrome b sequence data were used to estimate the evolutionary age of one of the asexual lineages of P. monacha-occidentalis (MO). The estimated age for the MO lineage was 142,000 years, an estimate well within the range of values (60,000 to 150,000) obtained by a previous RFLP study (Quattro et al. 1992a). Tests for rate heterogeneity showed no significant differences in rates of substitution between sexual and asexual lineages. The present results, combined with evidence from previous studies, suggest that one of the P. monacha-occidentalis lineages is very recent in evolutionary time. In Chapter 3, I used sequence data from the mitochondrial Cytb and the nuclear tyrosine kinase src genes to test the "asexual breakdown" (AB) hypothesis for the origin of a sexually reproducing species in the genus Poeciliopsis (Schenk 1991; Vrijenhoek 1989). This hypothesis proposes that the new species (P. n. sp.) was the product of breakdown of hybridogenesis in P. monacha-occidentalis. Mitochondrial Cytb sequence data placed P. n. sp. basal to P. occidentalis, P. lucida, and P. prolifica, refuting the hypothesis that P. monacha-occidentalis was the maternal ancestor. Analyses of the src gene placed P. n. sp. outside the P. occidentalis/P. lucida/P. prolifica/P. infans clade. A test for recombination revealed a potential recombination breakpoint in the src sequence. Analysis of the src sequence up-stream from the recombination point placed P. n. sp. between the monacha/viriosa and occidentalis/lucida/prolifica/infans clades. Analysis of the src sequence down-stream from the recombination point placed P. n. sp. firmly within the occidentalis/lucida/prolifica/infans clade. Results from this study indicate that the AB hypothesis is too simplistic and that further studies are necessary.
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