Biogeography of the livebearing fish Poecilia gillii in Costa Rica: are phylogeographical breaks congruent with fish community boundaries?

One of the original goals of phylogeography was to use genetic data to identify historical events that might contribute to breaks among communities. In this study, we examine the phylogeography of a common livebearing fish (Poecilia gillii) from Costa Rica. Our goal was to determine if phylogeographical breaks in this species were congruent with previously defined boundaries among four fish community provinces. We hypothesized that if abiotic factors influence both community boundaries and genetic structuring in P. gillii then we might find four clades within our focal species that were geographically separated along community boundary lines. Similarly, we expected to find most of the genetic variation in P. gillii partitioned among these four geographical regions. We generated DNA sequence data (mitochondrial cytochrome b and nuclear S7 small ribosomal subunit) for 260 individuals from 42 populations distributed across Costa Rica. We analysed these data using phylogenetic (parsimony and likelihood) and coalescent approaches to estimate phylogenetic relationships among haplotypes, patterns of gene flow and effective population size. Contrary to our expectations, we did not find four monophyletic groups that mapped cleanly to our geographical community provinces. However, one of our clades was restricted to a single province, suggesting that common earth history events could be responsible for both genetic structuring in P. gillii and fish community composition in this area. However, our results show a complex pattern of gene flow throughout other regions in Costa Rica where genetic structuring is not predicted by community province boundaries.

Eleven microsatellites in an emerging invader, Phytolacca americana (Phytolaccaceae), from its native and introduced ranges.

PREMISE OF THE STUDY: To facilitate population genetic analyses, microsatellite markers were developed for pokeweed (Phytolacca americana), a large, weedy, perennial herb native to eastern North America that is emerging as a significant invasive species in China. METHODS AND RESULTS: We mined 1,100,538 Illumina MiSeq reads from genomic DNA for microsatellites and identified 58 primer pairs. We screened these primers for polymorphism in two native and two invasive populations. We identified 11 loci that amplified consistently. The number of alleles per locus ranged from two to six, and observed heterozygosity ranged from 0.00 to 1.00. All loci were largely monomorphic within populations but different among populations. The primers were of very limited use in the congener P. acinosa. CONCLUSIONS: These loci will provide a valuable resource to study the population genetics and invasion history of P. americana.