Phylogeography of an Island Endemic, the Puerto Rican Freshwater Crab (Epilobocera sinuatifrons) (original) (raw)
Related papers
2011
Freshwater crabs constitute a common faunal component of tropical and subtropical river systems. They have a worldwide occurrence in these warmer regions, being represented by different taxonomic lineages on different continents or even within continents. Due to their mostly direct development and assumed dependency on fresh water, freshwater crabs are considered reliable model organisms to genetically reconstruct the hydrographical history of a region. However, very few studies have been carried out to directly document within-river dispersal or overland dispersal of these crabs. Thus the questions remain, in how far the restriction to river systems is comparable throughout the different taxa of freshwater crabs, and if all of the taxa can be used similarly well to reconstruct the history of watersheds, orogeny, island formation, and continental drift. In the current study, we analyze the phylogeographic structure of Epilobocera sinuatifrons (Decapoda: Brachyura: Pseudothelphusidae), a freshwater crab species endemic to the Caribbean island of Puerto Rico. Results show limited morphometric and genetic (mitochondrial and nuclear DNA) differentiation among metapopulations along a west-east gradient, paralleling the direction of the main mountain chain. The north-south comparison, in turn, does not show any differentiation, suggesting that the crabs must be able to migrate between headwaters of unconnected river systems. These results are compared to recently published ones on phylogeographic structure within species of Sesarma (Decapoda: Brachyura: Sesarmidae) from Jamaican rivers. The Jamaican freshwater crabs are endemic to a much smaller geographic area and show a pronounced genetic-geographical structure with restricted gene flow among many of the studied rivers systems. These results are unexpected, because the colonization of Jamaica occurred much more recently according to geological history and because the Jamaican crabs still have an abbreviated larval development (González-Gordillo et al. 2010) which should favor distribution within a drainage system and possibly among rivers, if able to survive in coastal areas. This comparison gives evidence for different distribution potential in freshwater crabs and cautions about the assumption that these crabs do not migrate between rivers and are thus infallible biogeographic model systems.
Shallow phylogeographic structure of Puerto Rico freshwater crabs
Crustacean Issues, 2011
Freshwater crabs constitute a common faunal component of tropical and subtropical river systems. They have a worldwide occurrence in these warmer regions, being represented by different taxonomic lineages on different continents or even within continents. Due to their mostly direct development and assumed dependency on fresh water, freshwater crabs are considered reliable model organisms to genetically reconstruct the hydrographical history of a region. However, very few studies have been carried out to directly document within-river dispersal or overland dispersal of these crabs. Thus the questions remain, in how far the restriction to river systems is comparable throughout the different taxa of freshwater crabs, and if all of the taxa can be used similarly well to reconstruct the history of watersheds, orogeny, island formation, and continental drift. In the current study, we analyze the phylogeographic structure of Epilobocera sinuatifrons (Decapoda: Brachyura: Pseudothelphusidae), a freshwater crab species endemic to the Caribbean island of Puerto Rico. Results show limited morphometric and genetic (mitochondrial and nuclear DNA) differentiation among metapopulations along a west-east gradient, paralleling the direction of the main mountain chain. The north-south comparison, in turn, does not show any differentiation, suggesting that the crabs must be able to migrate between headwaters of unconnected river systems. These results are compared to recently published ones on phylogeographic structure within species of Sesarma (Decapoda: Brachyura: Sesarmidae) from Jamaican rivers. The Jamaican freshwater crabs are endemic to a much smaller geographic area and show a pronounced genetic-geographical structure with restricted gene flow among many of the studied rivers systems. These results are unexpected, because the colonization of Jamaica occurred much more recently according to geological history and because the Jamaican crabs still have an abbreviated larval development (González-Gordillo et al. 2010) which should favor distribution within a drainage system and possibly among rivers, if able to survive in coastal areas. This comparison gives evidence for different distribution potential in freshwater crabs and cautions about the assumption that these crabs do not migrate between rivers and are thus infallible biogeographic model systems.
Journal of the North American Benthological Society, 2009
Various components of island stream faunas, including caridean shrimps, fish, and gastropods, undertake obligate amphidromous migration, whereby larvae are released in upstream freshwater reaches, drift downstream to estuaries or marine waters, then migrate upstream as postlarvae to freshwater adult habitats. Longitudinal migration from estuaries to headwaters is well documented for many amphidromous species, but the degree of among-river marine dispersal is poorly known for most species. We need better understanding of the potential for marine dispersal in population processes of amphidromous species, particularly recolonization and population recovery in impacted lotic systems, such as those on Puerto Rico, because some theories of dispersal for species with marine larvae predict high rates of self-recruitment. We tested population genetic predictions for widespread marine larval dispersal and self-recruitment to the natal river for 11 amphidromous species, including shrimps, fish, and a gastropod, in Puerto Rico. Population genetic analysis of mitochondrial DNA data showed high rates of gene flow among rivers and indicated that marine dispersal determines the population genetic structure of all 11 species. Difficulty in recruiting to oceanic currents promotes closed population structures in some marine species, but larvae of amphidromous species entrained in downstream river flow might be delivered more readily to ocean currents. Population recovery processes occurred at the island scale rather than at the river scale, but further studies are needed to identify whether population recovery processes are likely at larger spatial scales (e.g., among islands). River management strategies should maintain environmental flows that allow larval export, maintain longitudinal dispersal pathways over dam spillways and via subterranean passages, and maintain open and healthy estuaries.
Molecular Ecology, 2012
Quaternary climatic oscillations caused changes in sea level that altered the size, number and degree of isolation of islands, particularly in land-bridge archipelagoes. Elucidating the demographic effects of these oscillations increases our understanding of the role of climate change in shaping evolutionary processes in archipelagoes. The Puerto Rican Bank (PRB) (Puerto Rico and the Eastern Islands, which comprise Vieques, Culebra, the Virgin Islands and associated islets) in the eastern Caribbean Sea periodically coalesced during glaciations and fragmented during interglacial periods of the quaternary. To explore population-level consequences of sea level changes, we studied the phylogeography of the frog Eleutherodactylus antillensis across the archipelago. We tested hypotheses encompassing vicariance and dispersal narratives by sequencing mtDNA (c. 552 bp) of 285 individuals from 58 localities, and four nuDNA introns (totalling c. 1633 bp) from 173 of these individuals. We found low support for a hypothesis of divergence of the Eastern Islands populations prior to the start of the penultimate interglacial c. 250 kya, and higher support for a hypothesis of colonization of the Eastern Islands from sources in eastern Puerto Rico during the penultimate and last glacial period, when a land bridge united the PRB. The Río Grande de Loíza Basin in eastern Puerto Rico delineates a phylogeographic break. Haplotypes shared between the PRB and St. Croix (an island c. 105 km south-east of this archipelago) likely represent human-mediated introductions. Our findings illustrate how varying degrees of connectivity and isolation influence the evolution of tropical island organisms.
Journal of Biogeography, 2011
Aim Hypotheses proposed for lineage diversification of tropical montane species have rarely been tested within oceanic islands. Our goal was to understand how basin barriers and Pleistocene climatic fluctuations shaped the distribution of diversity in Eleutherodactylus portoricensis (Eleutherodactylidae), a frog endemic to the montane rain forests of Puerto Rico. Location The northeastern (Luquillo) and southeastern (Cayey) mountains of Puerto Rico. Methods We generated mitochondrial DNA (mtDNA) control region sequences (c. 565 bp) from 144 individuals of E. portoricensis representing 16 localities, and sequenced 646 bp of cytochrome b and 596 bp of nuclear DNA (nDNA) rhodopsin exon and intron 1 from a subset of individuals. We conducted a phylogenetic analysis on the mtDNA sequence data and explored population substructure with maximum parsimony networks, a spatial analysis of molecular variance, and pairwise F ST analysis. Coalescent simulations were performed to test alternative models of population divergence in response to late Pleistocene interglacial periods. Historical demography was assessed through coalescent analyses and Bayesian skyline plots. Results We found: (1) two highly divergent groups associated with the disjunct Luquillo and Cayey Mountains, respectively; (2) a shallow mtDNA genetic discontinuity across the La Plata Basin within the Cayey Mountains; (3) phylogeographic congruence between nDNA and mtDNA markers; (4) divergence dates for both mtDNA and nDNA pre-dating the Holocene interglacial (c. 10 ka), and nDNA suggesting divergence in the penultimate interglacial (c. 245 ka); and (5) historical demographic stability in both lineages. Main conclusions The low-elevation Caguas Basin is a long-term barrier to gene flow between the two montane frog populations. Measures of genetic diversity for mtDNA were similar in both lineages, but lower nDNA diversity in the Luquillo Mountains lineage suggests infrequent dispersal between the two mountain ranges and colonization by a low-diversity founder population. Population divergence began prior to the Holocene interglacial. Stable population sizes over time indicate a lack of demonstrable demographic response to climatic changes during the last glacial period. This study highlights the importance of topographic complexity in promoting within-island vicariant speciation in the Greater Antilles, and indicates long-term persistence and lineage diversification despite late Pleistocene climatic oscillations.
Molecular Ecology, 2008
Taxon cycling, i.e. sequential phases of expansions and contractions in species' distributions associated with ecological or morphological shifts, are postulated to characterize dynamic biogeographic histories in various island faunas. The Caribbean freshwater shrimp assemblage is mostly widespread and sympatric throughout the region, although one species (Atyidae: Atya lanipes) is geographically restricted and ecologically and morphologically differentiated from other Atya species. Using patterns of nucleotide variation at the COI mtDNA gene in five species of freshwater shrimp (A. lanipes, A. scabra, A. innocuous; Xiphocarididae: Xiphocaris elongata; Palaemonidae: Macrobrachium faustinum) from Puerto Rico, we expected to detect a signature of sequential colonization in these shrimp, consistent with the concept of taxon cycling, and expected that A. lanipes would be at a different taxon stage (i.e. an early stage species) to all other species. We also examined patterns of genetic population structure in each species expected with poor, intermediate and well-developed abilities for among-river dispersal. Population expansions were detected in all species, although the relative timing of the expansions varied among them. Assuming that population expansions followed colonization of Puerto Rico by freshwater shrimp, results bear the hallmarks of sequential colonization and taxon cycling in this fauna. A. lanipes had a star phylogeny, low mean pairwise nucleotide differences and recent (Holocene) estimates for an in situ population expansion in Puerto Rico, and it was inferred as an early stage species in the taxon cycle undergoing a secondary phase of expansion. All other species were inferred as late stage species undergoing regional population expansions, as their mean pairwise nucleotide differences were relatively high and phylogenetic patterns were more complex than A. lanipes. High rates of gene flow without isolation by distance among rivers were detected in all species, although results should be treated cautiously as some populations are unlikely to be in mutation-drift equilibrium. Nested clade analysis produced inconsistent results among species that all have high rates of gene flow and expanding populations.
Journal of the North American Benthological Society, 2010
Whether active or passive, dispersal accompanied by gene flow shapes the genetic makeup of populations and ultimately the evolutionary divergence of species. Our objective was to determine if 2 very different aquatic invertebrates with overlapping distributions show similar dispersal histories in their phylogeographic patterns and genetic uniqueness. Two spring-dwelling invertebrates, Hyalella azteca and Callibaetis americanus, were collected from 6 adjacent closed basins in the Great Basin of western North America. Cytochrome c oxidase subunit I (COI) and the 28S ribosomal subunit were used as genetic markers in Hyalella, and COI with the 16S ribosomal subunit of the mitochondrial genome were examined in Callibaetis. Maximum parsimony (MP) and likelihood (ML) analyses, F ST values, analysis of molecular variance (AMOVA), Mantel tests, and nested clade phylogeographical analysis (NCPA) were used to evaluate geographical associations. Hyalella azteca appears to have been in the adjacent basins much longer than has Callibaetis. F ST values in H. azteca reached near fixation. Callibaetis americanus F ST values were lower suggesting greater gene flow and, consequently, higher dispersal rates. Mantel tests did not detect significant isolation by distance for either species, but NCPA on smaller networks of closely related haplotypes found the genetic structure in C. americanus dominated by restricted gene flow with isolation by distance. Hyalella azteca was characterized more by gradual range expansion followed by fragmentation. These results suggest that these isolated freshwater communities are amalgams of species that entered at different times, with weak dispersers having greater constraints on movement and, thus, reflecting an older geographical story than do species with stronger dispersal capabilities.
Scientific Reports
Parastacus is a genus of South American freshwater crayfishes disjunctively distributed in southern Chile, Northern Argentina, Uruguay and Southeastern Brazil. Parastacus pugnax is a Chilean endemic distributed along 700 km of latitude in central-southern Chile from the Pacific coast to the Andean piedmont, which is intensively captured for consumption for local communities. Considering the habitat (wet meadows) and natural history (primary burrower, non-migrant) of the species, we tested a hypothesis of highly structured genetic diversity using mtDNA of 465 specimens gathered at 56 localities across the species range. The crown age of P. pugnax was estimated at 38 Ma, predating the main Andean uplift. The genetic variation of P. pugnax is large and geographically structured. In some cases, genetic groups do not match basin limits, suggesting a previous to current dynamic of basin evolution. The uncovered intraspecific main lineages have different demographic histories. A latitudina...