No abstract

We examined the role of several earth history events on the phylogeographic distribution of the catfish Trichomycterus areolatus in Chile using the cytochrome b gene. We explored three biogeographic hypotheses: that sea level changes have resulted in the isolation of populations by drainages; that glaciation has impacted genetic diversity; and that ichthyological subprovince boundaries correspond to phylogeographic breaks in our focal species. We found seven well-supported clades within T. areolatus with high levels of genetic divergence. The strongest signal in our data was for an important role of sea level changes structuring populations. Five of the seven clades mapped cleanly to the geographic landscape and breaks corresponded closely to areas of narrowest continental shelf. In addition, few haplotypes were shared between rivers within clades, suggesting that only limited local movement of individuals has occurred. There was no relationship between the levels of genetic diversity and the proportion of individual drainages covered by glaciers during the last glacial maximum. Two phylogeographic breaks within T. areolatus did match the two previously identified faunal boundaries, but we found three additional breaks, which suggests that faunal breaks have only limited utility in explaining phylogeographic patterns. These results imply that the narrow continental shelf coupled with sea level changes had a strong influence on the obligate freshwater fishes in Chile.

In this study, we used a recently developed supertrees method to test for shared phylogeographical signal in partially overlapping geographical ranges of lizards of the genus Liolaemus from the Andean Range in south-central Chile. We reconstruct mtDNA gene trees for three partially codistributed species (Liolaemus tenuis, L. lemniscatus and L. pictus), and our sampling effort is sufficient to allow statistical tests of shared signal between the combinations L. tenuis-L. pictus, and L. tenuis-L. lemniscatus. For both combinations, standardized maximum agreement subtrees scores showed statistically significant signal for shared pattern in regions of overlap, as evaluated by randomization tests (P < 0.001 and < 0.05, respectively). The matrix representation with parsimony tree obtained from the combination of the three different gene trees revealed concordant phylogeographical associations of all species, and was consistent with the geographical association of intraspecific haploclades with three Chilean bioclimatic zones. A multidimensional scaling analysis of several climate variables showed highly significant differences among these zones, which further suggests that they may have contributed to similar patterns of intraspecific divergence across all three species. In the mesomorphic zone in Central Chile, the species L. tenuis and L. lemniscatus may have codiverged in response to shared orogenic vicariant events, which likely predominated over climatic events associated with cycles of glacial advance and retreat. In the hygromorphic zone in southern Chile, however, glacial cycles likely predominated in structuring the phylogeographical histories of L. tenuis and L. pictus, although important ecological differences between these two caution against broad generalizations at this point.

Historical climate changes and orogenesis are two important factors that have shaped intraspecific biodiversity patterns worldwide. Although southern South America has experienced such complex events, there is a paucity of studies examining the effects on intraspecific diversification in this part of the world. Liolaemus pictus is the southernmost distributed lizard in the Chilean temperate forest, whose genetic structure has likely been influenced by Pleistocene glaciations. We conducted a phylogeographic study of L. pictus in Chile and Argentina based on one mitochondrial and two nuclear genes recovering two strongly divergent groups, Northern and Southern clades. The first group is distributed from the northernmost limit of the species to the Araucanía region while the second group is distributed throughout the Andes and the Chiloé archipelago in Southern Chile. Our results suggest that L. pictus originated 751 Kya, with divergence between the two clades occurring in the late Pleistocene. Demographic reconstructions for the Northern and Southern clades indicate a decrease in effective population sizes likely associated with Pleistocene glaciations. Surprisingly, patterns of genetic variation, clades age and historical gene flow in populations distributed within the limits of the Last Glacial Maximum (LGM) are not explained by recent colonization. We propose an “intra-Andean multiple refuge” hypothesis, along with the classical refuge hypothesis previously proposed for the biota of the Chilean Coastal range and Eastern Andean Cordillera. Our hypothesis is supported by niche modelling analysis suggesting the persistence of fragments of suitable habitat for the species within the limits of the LGM ice shield. This type of refuge hypothesis is proposed for the first time for an ectothermic species.

No abstract

River environments are characterized by extreme spatial and temporal variation in the physical environment. The relationship of Wsh assemblages to environmental variation is poorly understood in many systems. In Chile zonation patterns of Wsh assemblages have been documented in several Andean river drainages. Coastal river drainages are comparatively small, but inordinately important because of their highly endemic Xora and fauna and their proximity to major human populations. For conservation purposes it is important to understand what environmental factors aVect assemblage structure of Wshes especially in the comparatively high diversity coastal drainages. We studied patterns of Wsh distribution and abundance in three rivers of the coastal, Andalien drainage near Concepción, Chile. We used multi-dimensional scaling analyses to compare patterns among zones (rithron, transition and potamon) and high and low Xow seasons. Species assemblages diVered by zone, but not with season. Assemblages consisted of nested subsets of species characterized by their range of distribution among zones. One species group was composed of widespread species that occurred in all three zones, another species group consisted of species found only in transitional and potamal zones, and a Wnal group was comprised of species found only in the potamal zone. The potamal zone contained the most diverse and abundant Wsh assemblage. Fish assemblages were related to both water quality and habitat E. Habit (Biodivers Conserv (2007) 16:3179-3191 1 C structure variables. This study suggests that the key to conserving the diversity of native Wsh communities in coastal Chilean rivers is in the conservation of potamal regions. Unfortunately, most protected areas in Chile are in the depauperate headwaters of drainages. Protection of only headwaters is clearly inadequate and will not contribute to the conservation of this unique freshwater Wsh fauna.

No abstract

Here we present a multi-taxa inventory of naturalized alien species recorded on continental Chile and adjacent marine habitats, including eight taxonomic groups. We identified 1,122 species. These comprise 790 vascular plants (terrestrial and aquatic); 31 nonvascular plants [Bryophyta (mosses), Marchantiophyta (liverworts) and Anthocerotophyta (hornworts)]; 18 marine and freshwater macro and micro algae; 71 fungi; 39 terrestrial vertebrates (amphibians, reptiles, mammals and birds); 108 insects; 37 marine and freshwater invertebrates and vertebrates (6 polychaetes, 3 mollusks and 28 Pisces); and 28 terrestrial gastropods. For all taxonomic groups, naturalized species were found to mainly be distributed in regions with Mediterranean and temperate climates, with few at either extreme of the country. The invasion curves show that naturalized species first underwent a positive increment, followed by an apparent plateau phase, mainly in vascular plants, insects and vertebrates. In fungi, marine and freshwater macro and microalgae, vertebrates and invertebrates, the cumulative number of naturalized species increased sharply starting in the early 20th century; the lack of collections before 1900 is also evident. When considering naturalized species as a whole, this inventory highlights that the rate of new naturalizations consistently increased after 1950, especially for some taxonomic groups such as insects, fungi, and vascular plants. This multi-taxa inventory of naturalized species provides a platform for national reporting on biodiversity indicators and highlights areas where Chile must invest resources to manage biological invasions.