Microsatellite genetic differentiation among populations of the Trinidadian guppy

Abstract

Insight into the processes of evolutionary change can be obtained by studying the distribution of genetic diversity among populations. Such diversity can be shaped by historical colonization events, population connectivity and adaptation to local selection pressures. Here we examine genetic differentiation of Trinidadian guppies, Poecilia reticulata, by genotyping 373 individuals from 15 populations located in three drainages (northern coast, Caroni and Oropouche) with 7 microsatellite loci. Our data provide little evidence to support previous claims of two major genetic lineages of guppies in northern Trinidad but instead suggest a more complex pattern of gene flow among populations from different drainages. First, some of the populations in the Caroni drainage show genetic signatures similar to those in the Oropouche drainage. Second, the populations in the northern coast are all highly differentiated from those in either the Caroni or Oropouche drainages. Despite differing selection regimes owing to predation pressure, populations from upstream and downstream locales typically cluster together, albeit upstream populations consistently have less genetic variability than the corresponding downstream population. There is, however, no overall pattern of isolation by distance. We also find evidence that an artificially transplanted population from the Caroni drainage is successfully invading into other populations within the Oropouche system. Our analysis details the genetic and phylogeographic structure of Trinidadian guppies in the northern range and provides insight into evolutionary processes at different timescales that have shaped genetic heterogeneity in this fish.

Testing for local host–parasite adaptation: an experiment with Gyrodactylus ectoparasites and guppy hosts

“…These two rivers represent different guppy lineages (and probably separate colonisation events) as genetic distances between them are very large (see Suk and Neff, 2009;Willing et al, 2010). The Gyrodactylus populations in these different drainages are probably also distinct (given their host specificity for guppies), but this has not yet been confirmed.…”

“…Another possibility is that genetic differentiation between HP and LP populations in a given drainage is relatively low -thus making Gyrodactylus adaptation to particular genotypes easier. Indeed, low microsatellite genetic differentiation between predation environments has been shown for both Marianne River and Aripo River drainages (Suk and Neff, 2009), but is still unknown for genes of the immune system (e.g., MHC). Irrespective of the particular mechanisms by which evolutionary history could affect the evolution of host resistance and parasite infectivity, our study indicates that these effects Table 3 Statistical analyses of guppy performance when infected with sympatric versus allopatric Gyrodactylus.…”

Annotated list and key to the stream fishes of Trinidad & Tobago

“…They provided evidence of two sources of colonisation of R. hartii. The following year, Suk & Neff (2009) refuted claims of genetic divergence of the Oropuche populations. Later in the same year, Schories et al (2009) declared the guppies of the northern Oropuche River to be a new species, Poecilia (Acanthophacelus) obscura (= Poecilia reticulata), based on new molecular evidence.…”

Characterization and pilot application of 14 microsatellite loci from the Korean shiner (Coreoleuciscus splendidus)

“…By studying the variation of microsatellites among populations, inferences can be made about population structures, genetic drift, fragmentation-interaction dynamics of different populations, and even the date of a last common ancestor (e.g. Domínguez-Domínguez et al 2008;Suk and Neff 2009). Microsatellites can also be used for the identification of new and incipient populations (Kashi et al 1997;Li et al 2002;Remya et al 2010).…”