To each his own: no evidence of gyrodactylid parasite host switches from invasive poeciliid fishes to Goodea atripinnis, the most dominant endemic freshwater goodeid fish in the Mexican Highlands

Background: Goodeid topminnows are live-bearing fishes endemic to the Mexican Highlands (Mesa Central, MC). Unfortunately, in the MC, environmental degradation and introduced species have pushed several goodeid species to the brink of extinction. Invasive fishes can introduce exotic parasites, and the most abundant goodeid, blackfin goodea Goodea atripinnis Jordan, is parasitised by six exotic helminths. Poeciliids are widely dispersed invasive fishes, which exert negative ecological effects on goodeids. Poeciliids host several species of the monogenean genus Gyrodactylus von Nordmann, 1832, including pathogenic, invasive parasites. Here, we looked for evidence of Gyrodactylus species switching hosts from poeciliids to goodeids.  Methods: Fish were collected in rivers draining the MC into both sides of the continental divide. Hosts were screened for gyrodactylid parasites in localities where G. atripinnis and poeciliids occurred sympatrically. Gyrodactylus specimens were characterised morphologically (attachment apparatus) and molecularly (internal transcribed spacer region, ITS). A Bayesian phylogenetic tree using ITS sequences established relationships between gyrodactylids collected from goodeid fishes and those from parasites infecting poeciliids.  Results: Gyrodactylids were collected from G. atripinnis in six localities on both sides of the watershed where exotic poeciliids occurred sympatrically. Morphological and molecular analyses indicated the presence of four undescribed species of Gyrodactylus infecting this goodeid host. Gyrodactylus tomahuac n. sp., the most abundant and geographically widespread species, is described here. The other three Gyrodactylus spp. are not described, but their ITS sequences are used as molecular data presented here, are the only available for gyrodactylids infecting goodeid fishes. Morphological and molecular data suggest that two distinct groups of gyrodactylids infect goodeids, one of which shares a common ancestor with gyrodactylids parasitizing poeciliids.  Conclusions: No evidence was found of gyrodactylids switching hosts from invasive poeciliids to endemic goodeids, nor vice versa. Moreover, considering that G. atripinnis is known to host both Gyrodactylus lamothei Mendoza-Palmero, Sereno-Uribe & Salgado-Maldonado, 2009 and Gyrodactylus mexicanus Mendoza-Palmero, Sereno-Uribe & Salgado-Maldonado, 2009, with the addition of G. tomahuac n. sp. and the three undescribed Gyrodactylus spp. reported, at least six gyrodactylids may infect this host. This would make monogeneans the second most abundant parasite group infecting G. atripinnis, which to date is known to harbour 22 helminth species: nine digeneans, five nematodes, four cestodes, three monogeneans and one acanthocephalan

Genetic Evidence for Multiple Sources of the Non-Native Fish Cichlasoma urophthalmus (Günther; Mayan Cichlids) in Southern Florida

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid). Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. The mismatch between mitochondrial and nuclear genomes suggests admixture of a female lineage from Guatemala, where all individuals were fixed for the mitochondrial haplotype found in the introduced population, and a more diverse but also relatively small number of individuals from Belize. The Florida cytochrome b haplotype appears to be absent from Belize (0 out of 136 fish screened from Belize had this haplotype). Genetic structure within the Florida population was minimal, indicating a panmictic population, while Mexican and Central American samples displayed more genetic subdivision. Individuals from the Upper Yucatán Peninsula and the Petén region of Guatemala were more genetically similar to each other than to fish from nearby sites and movement of Mayan Cichlids between these regions occurred thousands of generations ago, suggestive of pre-Columbian human transportation of Mayan Cichlids through this region. Mayan Cichlids present a rare example of cytonuclear disequilibrium and reduced genetic diversity in the introduced population that persists more than 30 years (at least 7–8 generations) after introduction. We suggest that hybridization occurred in ornamental fish farms in Florida and may contribute their establishment in the novel habitat. Hybridization prior to release may contribute to other successful invasions

Genetic Evidence for Multiple Sources of the Non-Native Fish \u3ci\u3eCichlasoma urophtalmus\u3c/i\u3e (Günther; Mayan Cichlids) in Southern Florida

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid). Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. The mismatch between mitochondrial and nuclear genomes suggests admixture of a female lineage from Guatemala, where all individuals were fixed for the mitochondrial haplotype found in the introduced population, and a more diverse but also relatively small number of individuals from Belize. The Florida cytochrome b haplotype appears to be absent from Belize (0 out of 136 fish screened from Belize had this haplotype). Genetic structure within the Florida population was minimal, indicating a panmictic population, while Mexican and Central American samples displayed more genetic subdivision. Individuals from the Upper Yucatán Peninsula and the Petén region of Guatemala were more genetically similar to each other than to fish from nearby sites and movement of Mayan Cichlids between these regions occurred thousands of generations ago, suggestive of pre-Columbian human transportation of Mayan Cichlids through this region. Mayan Cichlids present a rare example of cytonuclear disequilibrium and reduced genetic diversity in the introduced population that persists more than 30 years (at least 7–8 generations) after introduction. We suggest that hybridization occurred in ornamental fish farms in Florida and may contribute their establishment in the novel habitat. Hybridization prior to release may contribute to other successful invasions

Median estimates of parameters from group 1, scenario 10 and from group 2, scenario 4.

<p>For parameters, N = effective population size, Nf = number of founders in each population, t = time of events in generations, and db = duration of bottleneck in generations.</p><p>The parameter values correspond to those in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104173#pone-0104173-g005" target="_blank">Figure 5B and 5E</a>.</p><p>NA denotes parameter that were absent in the model.</p><p>Median estimates of parameters from group 1, scenario 10 and from group 2, scenario 4.</p

Most supported models and posterior probabilities from groups 1 and 2.

<p>Model (A), scenario (B), and logistic regression of posterior probabilities for scenario 10 (C) from group 1, and model (D), scenario (E) and logistic regression of posterior probabilities for scenario 4 from group 2. Population numbers are indicated with the population names in the flow chart. YP refers to Yucatán Peninsula.</p

Summary statistics calculated for microsatellite markers.

<p>CA denotes Central America; YP denotes the Yucatán Peninsula. # and % represent “number” and “percentage” respectively. H^o and H^e represent observed and expected heterozygosities.</p><p>Summary statistics calculated for microsatellite markers.</p

Map of sampling sites for Mayan Cichlids in Mexico and Central America (A) and Florida (B).

<p>Numbers on the map correspond to site numbers in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104173#pone.0104173.s002" target="_blank">Table S1</a>. Light grey shading in box A indicates the range of Mayan Cichlids (Miller 1966) in the native range. “Mexico” denotes samples from Mexico that are not within the Yucatán Peninsula (states of Yucatán, Campeche and Quintana Roo). YP = Yucatán Peninsula; FL = Florida.</p

Prior distribution of parameters used in ABC analyses.

<p>The time of events in generations are labelled backwards in time and the conditions were as follows: t1</p><p>Prior distribution of parameters used in ABC analyses.</p

Haplotype network of cytochrome b in Mexico, Central America and Florida.

<p>Circles represent different haplotypes; sizes of partitions within circles are proportional to the number of specimens per haplotype. Colors correspond to localities as indicated. Line lengths signify the number of bases separating each haplotype; the short lines symbolize one base and the long line denotes six bases.</p