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Munoz-Ramirez C.P.,University of Concepción | Munoz-Ramirez C.P.,University of Michigan | Habit E.,University of Concepción | Unmack P.J.,University of Canberra | And 3 more authors.
Zoological Studies | Year: 2016

Despite the fundamental importance of the family Diplomystidae for understanding catfish evolution, its species are poorly known and most of them endangered. Diplomystes camposensis, restricted to a single river basin in southern Chile, is perhaps the most vulnerable species due to its small geographic range and imminent habitat alterations by dam constructions. Using mitochondrial DNA sequences, we describe the genetic diversity across its entire distribution in the Valdivia basin and test hypotheses related to the impact of glacial cycles on the genetic diversity and structure. We found that Diplomystes camposensis has low genetic diversity and structure across the entire Valdivia basin along with a pattern of decreasing nucleotide and haplotype diversity from West to East. Demographic analyses showed evidence of population expansion in agreement with the glaciated history of the basin. Analyses of population structure showed no evidence of population subdivision. However, coalescent analyses indicated that very recent subdivision (in the last 50 years) cannot be ruled out. Low genetic diversity and genetic structure across the entire basin suggest that the species might be highly vulnerable to habitat fragmentation. Thus, the imminent construction of hydropower dams represents a serious threat to its conservation. Our results suggest that the low genetic diversity can be the product of the glaciated history of the basin, although the influence of species-specific biological traits may also add to this condition. Despite the overall low genetic diversity, higher diversity was found in the central portion of the basin suggesting high priority of conservation for this area as it might be used as a source population in case translocations are required among potential management plans. © 2016, Academia Sinica. All rights reserved.

Munoz-Ramirez C.P.,University of Concepción | Munoz-Ramirez C.P.,University of Michigan | Unmack P.J.,Brigham Young University | Habit E.,University of Concepción | And 5 more authors.
Molecular Phylogenetics and Evolution | Year: 2014

The catfish family Diplomystidae is one of the earliest branching lineages within the diverse order Siluriformes and shows a deep phylogenetic split from all other extant and extinct major catfish groups. Despite its relevance in the evolution of siluriforms, phylogenetic relationships within the Diplomystidae are poorly understood, and prior to this study, no phylogenetic hypotheses using molecular data had been published. By conducting a phylogeographic study across the entire distribution of the family, that encompasses river systems from Central-South Chile and Argentina, we provide the first molecular phylogenetic hypothesis among all known species of Diplomystidae, and in addition, investigate how their evolutionary history relates to major historical events that took place in southern South America. Our phylogenetic analyses show four main lineages and nine sub-lineages strongly structured geographically. All Pacific basin populations, with one exception (those found in the Baker basin) clustered within three of the four main lineages (clades I-III), while all populations from Atlantic basins and those from the Baker basin clustered in a single main clade (clade IV). There was a tendency for genetic diversity to decrease from north to south for Pacific basins consistent with an increasing north-south ice coverage during the last glacial maximum. However, we did not find a statistically significant correlation between genetic diversity and latitude. Analysis of molecular variance (AMOVA) showed that river basins and the barrier created by the Andes Mountains explained a high percentage of the genetic variation. Interestingly, most of the genetic variation among drainages was explained among Pacific basins. Molecular phylogenetic analyses agree only partially with current systematics. The geographical distribution of main lineages did not match species distribution and suggests a new taxonomic hypothesis with support for four species of Diplomystes, three species distributed allopatrically from the Rapel to the Valdivia basin, and only one species distributed in Baker and Atlantic basins. High genetic differentiation among river basins suggests that conservation efforts should focus on protecting populations in each basin in order to preserve the genetic diversity of one of the oldest groups of catfishes on the earth today. © 2014 Elsevier Inc.

Munoz-Ramirez C.P.,University of Michigan | Victoriano P.F.,University of Concepción | Victoriano P.F.,Research Center en Ecosistemas Patagonicos | Habit E.,Research Center en Ecosistemas Patagonicos | Habit E.,University of Concepción
Limnologica | Year: 2015

Biotic homogenization in freshwater ecosystems is a growing concern among conservation biologists. Recent phylogeographic data has shown low genetic structure between some basins from Central Chile, suggesting that either current dispersal through irrigation canals or incomplete lineage sorting due to recent divergence might explain the observed patterns. However, these hypotheses remain untested despite their potential implications for freshwater biodiversity and conservation. We used a statistical, model-based framework (approximate Bayesian computation) to investigate the relative support for each of these hypotheses in the freshwater catfish Diplomystes cf. camposensis, an endangered species from Central Chile. Our results show strong support for the model involving current migration between basins, and rejected the model of recent divergence without migration. These results strongly suggest that irrigation canals are facilitating the dispersal between basins, posing a serious threat to biodiversity in Central Chile, an area considered a biodiversity hotspot. Finally, these results highlight the utility of model-based approaches for determining demographic processes with potential conservation implications, even with the lack of extensive molecular data. © 2015 The Authors.

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