Population genetics of the speckled peacock bass (Cichla temensis), South America’s most important inland sport fishery

Abstract

The Neotropics harbor the world's most diverse freshwater fish fauna, with many of these species supporting major commercial, subsistence, or sport fisheries. Knowledge of population genetic structure is available for very few Neotropical fishes, thereby restricting management. To address this need, we examined population genetic variation in mtDNA control region sequences and twelve microsatellite loci in the speckled or barred peacock bass, Cichla temensis. Moderate and statistically significant genetic divergence among localities indicates that migration is low in this species, implying that populations inhabiting tributaries or even smaller spatial units should constitute management units. Analysis of molecular variance of mtDNA sequences identified six areas with largely exclusive haplotype clades, and a seventh area of high admixture, but major drainage basins harbored nonmonophyletic haplotype groups. On the other hand, molecular variation in the microsatellite data was best explained by drainage basin and, subsequently, by the seven areas. Populations in these seven areas could be considered evolutionarily significant units (ESUs), and, therefore, we tested hypotheses explaining the discordant signal of mtDNA and microsatellite data using approximate Bayesian computation. This analysis indicated that the divergence of mtDNA clades preceded the divergence of contemporary ESUs across basins, with subsequent lineage sorting among ESUs due to reduced gene flow. Available genetic and ecological information indicates that C. temensis populations of major tributary rivers should be managed as separate stocks that likely are adapted to local environmental conditions.

Bayesian analyses detect a history of both vicariance and geodispersal in Neotropical freshwater fishes

“…ABC is a flexible class of Monte Carlo algorithms that bypass the calculation of exact likelihoods using summary statistics and simulation. Its use has increased in population genetics and phylogeographical studies, allowing a quantitative evaluation of the demographic and evolutionary history by strictly contrasting realistic models defined a priori and estimating relevant parameters (Inoue, Lang, & Berg, ; Vanhaecke et al., ; Willis et al., ).…”

“…(). Following other phylogeographical studies of South American freshwater systems (Ramirez, Birindelli, & Galetti, ; Tagliacollo et al., ; Willis et al., ), we used our trees to estimate divergence times among lineages, and tentatively associated them with geological events known to have changed the hydrologic landscape (thus potentially flagging relevant processes in the group diversification). Going beyond that, however, we employed an ABC statistical framework to specifically identify which biogeographical scenario (palaeogeographical or hydrogeological hypotheses) better explains the genetic structure observed within our focus group.…”

A review of potential factors promoting fish movement in inter‐basin water transfers, with emergent patterns from a trait‐based risk analysis for a large‐scale project in china

“…There is a clear shift in habitat conditions along this connection from more whitewater systems in the Orinoco to more blackwater systems in the Amazon, and this strong ecological gradient has restricted inter-basin movement for specialised species, while allowing passage for generalist species (Escobar, Andrade-López, Farias, & Hrbek, 2015;Olivares, Hrbek, Escobar, & Caballero, 2013;Willis et al, 2010Willis et al, , 2015Winemiller et al, 2008). Conversely, as habitat conditions in donor and recipient systems converge (weak ecological gradient), there might logically be comparatively increased inter-basin movement rates for more specialised species (generalist species should not be affected), but this pattern has yet to be tested or documented.…”

One species or four? Yes!...and, no. Or, arbitrary assignment of lineages to species obscures the diversification processes of Neotropical fishes

“…The analysis here used haplotypes from the control region (CR), as well as ATPase 8,6 gene (ATP) sequences from a subset of individuals (121 of 324 CR haplotypes). To calibrate coalescence times, a mutation rate was applied that was derived from comparison with cytochrome b data for these species [ 30 , 36 ], and is consistent with the long term mutation rate (>1mya) in African cichlids [ 37 ].…”

“…To test the degree to which the demes (groups of individuals with approximately random mating, here taken to be localities; see [ 37 ]) of Cichla pinima sensu lato form a single population and provide an estimate of the pattern and magnitude of gene exchange among them, two F ST analogs were calculated. The first, an AMOVA-based F ST , considered only the identity of alleles, calculated in Arlequin 3.5 [ 40 ].…”