Isolation by distance and Pleistocene expansion of the lowland populations of the white piranha Serrasalmus rhombeus

Abstract

The genetic variability and distribution of Amazonian fish species have likely been influenced by major disturbance events in recent geological times. Alternatively, the great diversity of aquatic habitat in the Amazon is likely to shape ongoing gene flow and genetic diversity. In this context, complex patterns of genetic structure originating from a joint influence of historical and contemporary gene flow are to be expected. We explored the relative influence of Pleistocene climatic fluctuations and current water chemistry on the genetic structure of a piranha, Serrasalmus rhombeus, in the Upper Amazon by the simultaneous analysis of intron length polymorphism and mitochondrial DNA sequences. The Madeira river is well suited for that purpose as it is characterized by a great diversity of water types, the presence of one of the largest floodplain of the Amazon and the potential occurrence of two Pleistocene refuges. We found evidence of genetic structure even at a small geographical scale (less than 10 km), indicating that the floodplain is not a homogenizing factor promoting interdrainage dispersal in S. rhombeus. Likewise, the hierarchical genetic structure inferred was correlated to geographical distance instead of habitat characteristic. Our results also support the hypothesis that the area underwent population expansion during the last 800,000 years. In addition, a higher level of genetic diversity was found in the samples from the putative Aripuanã refuge. The present findings suggest that Pleistocene refuges contributed significantly to the colonization of the lowlands in the Upper Amazon valley during the Pleistocene.

Continuous Miocene, Pliocene and Pleistocene Influences on Mitochondrial Diversification of the Capybara (Hydrochoerus Hydrochoeris; Hydrochoeridae, Rodentia): Incapacity to Determine Exclusive Hypotheses on the Origins of the Amazon and Orinoco Diversity for This Species

“…This coincides with the Napo and the Inambari Refugia stated by the RH [162,163]. The Napo and Inambari Refugia have been determined to be of importance for butterflies [137,164], characiform fishes [111], amphibians and lizards [163] and birds [165][166][167]. Eight aquatic freshwater refuges have also been detected for characiform fishes [111].…”

“…Many phylogenetic studies of Amazon organisms emphasize that populations and species from the lowlands of the Upper Amazon Basin originated more recently than other organisms in the Brazilian and Guyana shields [116][117][118][119][137][138][139]. This finding was attributed to the Miocene-Pliocene marine incursion that occurred around 5 MYA and provided considerable species range contractions for terrestrial and freshwater biota [8,140,141].…”

“…Second, each species (or genome) has a different capacity and adaptability to colonize new areas because the additive effects of the natural selection is different for each taxon. Many researchers have searched for shared phylogeographic (or phylogenetic) relationships among taxa that would suggest a common mechanism of biological diversification [137,[223][224][225]. Nevertheless this is not an easy task to generate global identical hypotheses to explain the high levels of genetic variability found in the many Amazon taxa.…”

Phylogeography of Schizothorax o’connori (Cyprinidae: Schizothoracinae) in the Yarlung Tsangpo River, Tibet

“…In others, geographic patterns of genetic structure may be more a product of current environments, involving restricted gene flow, demographic processes (e.g., bottlenecks or founder events), or selection (Templeton et al, 1995). Consequently, assessing the relative influence of these historical and contemporary factors on extant genetic structure has clear implications for questions related to evolutionary change and has become an important consideration in terms of conservation (Costello et al, 2003;Crispo et al, 2006;Hubert et al, 2007).…”

Effects of slope and riparian habitat connectivity on gene flow in an endangered Panamanian frog, Atelopus varius

“…2). white piranha: Hubert et al, 2007) as well as a host of temperate taxa (e.g. However, it is also possible that climatic heterogeneity does influence gene flow, but that the species distribution model used to quantify relative climatic suitability failed to capture its effect.…”