RESUMEN
The converse Bergmann's rule is a pattern of body size variation observed in many ectothermic organisms that contradicts the classic Bergmann's rule and suggests that individuals inhabiting warmer climates tend to exhibit larger body sizes compared to those inhabiting colder environments. Due to the thermoregulatory nature of Bergmann's rule, its application among ectotherms might prove to be more complicated, given that these organisms obtain heat by absorbing it from their habitat. The existence of this inverse pattern therefore challenges the prevailing notion that larger body size is universally advantageous in colder climates. Ceroglossus chilensis is a native Chilean beetle that has the largest latitudinal range of any species in the genus, from 34.3° S to 47.8° S. Within Chile, it continuously inhabits regions extending from Maule to Aysen, thriving on both native and non-native forest species. Beyond their remarkable color variation, populations of C. chilensis show minimal morphological disparity, noticeable only through advanced morphological techniques (geometric morphometrics). Based on both (1) the "temperature-size rule", which suggests that body size decreases with increasing temperature, and (2) the reduced resource availability in high-latitude environments that may lead to smaller body sizes, we predict that C. chilensis populations will follow the converse Bergmann's rule. Our results show a clear converse pattern to the normal Bergmann rule, where smaller centroid sizes were found to be measured in the specimens inhabiting the southern areas of Chile. Understanding the prevalence of the converse Bergmann's rule for ectotherm animals and how often this rule is broken is of utmost importance to understand the underlying mechanisms allowing organisms to adapt to different environments and the selective pressures they face.
RESUMEN
Diplomystidae is an early-diverged family of freshwater catfish endemic to southern South America. We have recently collected five juvenile specimens belonging to this family from the Bueno River Basin, a basin which the only previous record was a single juvenile specimen collected in 1996. This finding confirms the distribution of the family further South in northern Patagonia, but poses new questions about the origin of this population in an area with a strong glacial history. We used phylogenetic analyses to evaluate three different hypotheses that could explain the origin of this population in the basin. First, the population could have originated in Atlantic basins (East of the Andes) and dispersed to the Bueno Basin after the Last Glacial Maximum (LGM) via river reversals, as it has been proposed for other population of Diplomystes as well as for other freshwater species from Patagonia. Second, the population could have originated in the geographically close Valdivia Basin (West of the Andes) and dispersed south to its current location in the Bueno Basin. Third, regardless of its geographic origin (West or East of the Andes), the Bueno Basin population could have a longer history in the basin, surviving in situ through the LGM. In addition, we conducted species delimitation analyses using a recently developed method that uses a protracted model of speciation. Our goal was to test the species status of the Bueno Basin population along with another controversial population in Central Chile (Biobío Basin), which appeared highly divergent in previous studies with mtDNA. The phylogenetic analyses showed that the population from the Bueno Basin is more related to Atlantic than to Pacific lineages, although with a deep divergence that predated the LGM, supporting in situ survival rather than postglacial dispersal. In addition, these analyses also showed that the species D. nahuelbutaensis is polyphyletic, supporting the need for a taxonomic reevaluation. The species delimitation analyses supported two new species which are described using molecular diagnostic characters: Diplomystes arratiae sp. nov. from the Biobío, Carampangue, and Laraquete basins, maintaining D. nahuelbutaensis valid only for the Imperial Basin, and Diplomystes habitae sp. nov. from the Bueno Basin. This study greatly increases the number of species within both the family Diplomystidae and Patagonia, and contributes substantially to the knowledge of the evolution of southern South American freshwater biodiversity during its glacial history. Given the important contribution to the phylogenetic diversity of the family, we recommend a high conservation priority for both new species. Finally, this study highlights an exemplary scenario where species descriptions based only on DNA data are particularly valuable, bringing additional elements to the ongoing debate on DNA-based taxonomy.
Asunto(s)
Bagres , Animales , Filogenia , Bagres/genética , Chile , ADN Mitocondrial/genética , Filogeografía , Variación GenéticaRESUMEN
The Western Antarctic Peninsula (WAP) is a hotspot for environmental change and has a strong environmental gradient from North to South. Here, for the first time we used adult individuals of the bivalve Aequiyoldia eightsii to evaluate large-scale spatial variation in the biochemical composition (measured as lipid, protein and fatty acids) and energy content, as a proxy for nutritional condition, of three populations along the WAP: O'Higgins Research Station in the north (63.3°S), Yelcho Research Station in mid-WAP (64.9°S) and Rothera Research Station further south (67.6°S). The results reveal significantly higher quantities of lipids (L), proteins (P), energy (E) and total fatty acids (FA) in the northern population (O'Higgins) (L: 8.33 ± 1.32%; P: 22.34 ± 3.16%; E: 171.53 ± 17.70 Joules; FA: 16.33 ± 0.98 mg g) than in the mid-WAP population (Yelcho) (L: 6.23 ± 0.84%; P: 18.63 ± 1.17%; E: 136.67 ± 7.08 Joules; FA: 10.93 ± 0.63 mg g) and southern population (Rothera) (L: 4.60 ± 0.51%; P: 13.11 ± 0.98%; E: 98.37 ± 5.67 Joules; FA: 7.58 ± 0.48 mg g). We hypothesize these differences in the nutritional condition could be related to a number of biological and environmental characteristics. Our results can be interpreted as a consequence of differences in phenology at each location; differences in somatic and gametogenic growth rhythms. Contrasting environmental conditions throughout the WAP such as seawater temperature, quantity and quality of food from both planktonic and sediment sources, likely have an effect on the metabolism and nutritional intake of this species.
RESUMEN
The Antarctic Circumpolar Current (ACC) dominates the open-ocean circulation of the Southern Ocean, and both isolates and connects the Southern Ocean biodiversity. However, the impact on biological processes of other Southern Ocean currents is less clear. Adjacent to the West Antarctic Peninsula (WAP), the ACC flows offshore in a northeastward direction, whereas the Antarctic Peninsula Coastal Current (APCC) follows a complex circulation pattern along the coast, with topographically influenced deflections depending on the area. Using genomic data, we estimated genetic structure and migration rates between populations of the benthic bivalve Aequiyoldia eightsii from the shallows of southern South America and the WAP to test the role of the ACC and the APCC in its dispersal. We found strong genetic structure across the ACC (between southern South America and Antarctica) and moderate structure between populations of the WAP. Migration rates along the WAP were consistent with the APCC being important for species dispersal. Along with supporting current knowledge about ocean circulation models at the WAP, migration from the tip of the Antarctic Peninsula to the Bellingshausen Sea highlights the complexities of Southern Ocean circulation. This study provides novel biological evidence of a role of the APCC as a driver of species dispersal and highlights the power of genomic data for aiding in the understanding of the influence of complex oceanographic processes in shaping the population structure of marine species.
RESUMEN
Due to climate change, numerous ice bodies have been lost in the West Antarctic Peninsula (WAP). As a consequence, deglaciation is expected to impact the marine environment and its biota at physiological and ecosystem levels. Nuculana inaequisculpta is a marine bivalve widely distributed around Antarctica that plays an important role for ecosystem functioning. Considering that N. inaequisculpta inhabits coastal areas under effect of glacial melt and retreat, impacts on its nutritional condition are expected due to alterations on its physiology and food availability. To test this hypothesis, biochemical composition (lipids, proteins, and fatty acids) and energy content were measured in individuals of N. inaequisculpta collected in a fjord at different distances to the retreating glacier in the WAP. Oceanographic parameters of the top and bottom-water layers (temperature, salinity, dissolved oxygen, and chlorophyll-a) were measured to investigate how the environment changes along the fjord. Results showed that surface oceanographic parameters displayed a lower temperature and dissolved oxygen, but a higher salinity and chlorophyll-a content at nearest compared to farthest sites to the glacier. In contrast, a lower temperature and chlorophyll-a, and a higher salinity and dissolved oxygen was measured in the bottom-water layer toward the glacier. N. inaequisculpta had a higher amount of lipids (17.42 ± 3.24 vs. 12.16 ± 3.46%), protein (24.34 ± 6.12 vs. 21.05 ± 2.46%) and energy content (50.57 ± 6.97 J vs. 39.14 ± 5.80 J) in the farthest compared to the nearest site to the glacier. No differences were found in total fatty acids among all sites. It seems likely that lower individual fitness related to proximity to the glacier would not be related to nutritional quality of sediment food, but rather to food quantity.
Asunto(s)
Bivalvos/fisiología , Cambio Climático , Cubierta de Hielo , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Regiones Antárticas , Bivalvos/química , Ecosistema , Estuarios , Ácidos Grasos/análisis , Cubierta de Hielo/química , Lípidos/análisis , Proteínas/análisisRESUMEN
The ancient catfish family Diplomystidae, with seven species endemic to rivers of southern South America, represents one of the oldest branches of the diverse order Siluriformes. With most species endangered, new reports of these species become extremely valuable for conservation. Currently, it is assumed that Diplomystes species inhabit only Andean (large) basins, and that they are extinct from coastal (small) basins from which their presence have not been recorded since 1919. Here, we document new records of the family Diplomystidae in the Laraquete and Carampangue basins, two coastal basins from the Nahuelbuta Coast Range, Chile, with no previous reports. This finding represents the rediscovery of the genus in coastal basins in more than a Century. Based on analysis of mitochondrial DNA sequences, the collected specimens were found to be closely related to Diplomystes nahuelbutaensis from the Andean Biobío Basin, but sufficiently differentiated to suggest that coastal basin populations are a different management unit. These populations are important because, contrary to previous thoughts, they prove these catfish can survive in small river networks, providing unique opportunities for research and conservation. The conservation category of Critically Endangered (CE) is recommended for the populations from the Laraquete and Carampangue basins.(AU)
La familia de bagres Diplomystidae, con siete especies endémicas de ríos del sur de Sudamérica, es uno de los linajes mas antiguos del diverso orden Siluriformes. Al estar la mayoría de las especies amenazadas, nuevos registros de éstas son extremadamente valiosos para su conservación. Actualmente, se ha asumido que los Diplomystidos se distribuyen solo en cuencas Andinas (más grandes), y que sus especies estarían extintas en cuencas de menor tamaño como las costeras, sin registros desde 1919. En este trabajo documentamos la familia Diplomistidae en las cuencas de Carampangue y Laraquete, dos cuencas costeras de la Cordillera de Nahuelbuta, Chile, lo que representa el primer registro de esta familia en estas cuencas costeras. Además, este hallazgo representa el re-descubrimiento de la familia en cuencas costeras después de un siglo. Sobre la base de análisis de ADN mitocondrial, los especímenes colectados se relacionaron más cercanamente con poblaciones de la especie Diplomystes nahuelbutaensis presente en la cuenca del Biobío. Sin embargo, existen diferencias genéticas suficientes entre las poblaciones costeras y las del Biobío para justificar su separación como unidad de manejo distinta. Estas poblaciones costeras son importantes porque demuestran que los Diplomístidos pueden sobrevivir en cuencas de pequeño tamaño, ofreciendo oportunidades únicas para su investigación y conservación. Se recomienda la categoría de conservación En Peligro Critico de Extinción (CR) para las poblaciones de las cuencas Laraquete y Carampangue.(AU)
Asunto(s)
Bagres/clasificación , Bagres/genética , ADN Mitocondrial/análisisRESUMEN
The ancient catfish family Diplomystidae, with seven species endemic to rivers of southern South America, represents one of the oldest branches of the diverse order Siluriformes. With most species endangered, new reports of these species become extremely valuable for conservation. Currently, it is assumed that Diplomystes species inhabit only Andean (large) basins, and that they are extinct from coastal (small) basins from which their presence have not been recorded since 1919. Here, we document new records of the family Diplomystidae in the Laraquete and Carampangue basins, two coastal basins from the Nahuelbuta Coast Range, Chile, with no previous reports. This finding represents the rediscovery of the genus in coastal basins in more than a Century. Based on analysis of mitochondrial DNA sequences, the collected specimens were found to be closely related to Diplomystes nahuelbutaensis from the Andean Biobío Basin, but sufficiently differentiated to suggest that coastal basin populations are a different management unit. These populations are important because, contrary to previous thoughts, they prove these catfish can survive in small river networks, providing unique opportunities for research and conservation. The conservation category of Critically Endangered (CE) is recommended for the populations from the Laraquete and Carampangue basins.(AU)
La familia de bagres Diplomystidae, con siete especies endémicas de ríos del sur de Sudamérica, es uno de los linajes mas antiguos del diverso orden Siluriformes. Al estar la mayoría de las especies amenazadas, nuevos registros de éstas son extremadamente valiosos para su conservación. Actualmente, se ha asumido que los Diplomystidos se distribuyen solo en cuencas Andinas (más grandes), y que sus especies estarían extintas en cuencas de menor tamaño como las costeras, sin registros desde 1919. En este trabajo documentamos la familia Diplomistidae en las cuencas de Carampangue y Laraquete, dos cuencas costeras de la Cordillera de Nahuelbuta, Chile, lo que representa el primer registro de esta familia en estas cuencas costeras. Además, este hallazgo representa el re-descubrimiento de la familia en cuencas costeras después de un siglo. Sobre la base de análisis de ADN mitocondrial, los especímenes colectados se relacionaron más cercanamente con poblaciones de la especie Diplomystes nahuelbutaensis presente en la cuenca del Biobío. Sin embargo, existen diferencias genéticas suficientes entre las poblaciones costeras y las del Biobío para justificar su separación como unidad de manejo distinta. Estas poblaciones costeras son importantes porque demuestran que los Diplomístidos pueden sobrevivir en cuencas de pequeño tamaño, ofreciendo oportunidades únicas para su investigación y conservación. Se recomienda la categoría de conservación En Peligro Critico de Extinción (CR) para las poblaciones de las cuencas Laraquete y Carampangue.(AU)
Asunto(s)
Bagres/clasificación , Bagres/genética , ADN Mitocondrial/análisisRESUMEN
Grasslands in southern South America are extensive ecosystems which harbor a unique biodiversity; however, studies on the evolution of their taxa are scarce. Here we studied the phylogeography and population history of the Correndera Pipit (Anthus correndera), a grassland specialist bird with a large breeding distribution in southern South America, with the goals of investigating its phylogeographic history and relate it to the historical development of South American grasslands. The mitochondrial NADH dehydrogenase subunit II gene (ND2) was sequenced in 66 individuals from 19 localities and the intron 9 of the sex-linked gene for aconitase (ACOI9) was sequenced from a subset of those individuals, including all five subspecies of A. correndera, as well as the closely related A. antarcticus. Phylogenetic analysis revealed two distinct lineages within the complex: the first (A) corresponding to Andean subspecies A. c. calcaratus and A. c. catamarcae and the second (B) including birds traditionally assigned to A. c. correndera, A. c. chilensis, A. c. grayi and some individuals of A. c. catamarcae. A. antarcticus is nested within this second lineage. These results were also supported by evidence of niche divergence for variables associated with precipitation. The oldest split between clade A and B was estimated at c. 0.37 Mya, during the middle Pleistocene. Species distribution models for the present and the Last Glacial Maximum (LGM) suggest that grassland areas in southern South America remained relatively stable, in contrast to the general view of a reduction in grassland cover in South America since the LGM. Recent divergences and low phylogeographic structure (for lowland vs. highland geographic groups, intra-population genetic variance was greater than inter-groups; e.g., for ACOI9: 95.47% and ND2: 51.51% respectively), suggest widespread gene flow between lowland populations.
RESUMEN
We document movement patterns and home range of Diplomystes camposensis, an endemic and threatened freshwater catfish from Chile. We tracked the movements of seven individuals of different body size (13.5 to 19 cm SL) using portable radio telemetry equipment to investigate movement patterns in relation to day/night activity and habitat use in the San Pedro River (Valdivia Basin). Tracked movements and model-based analyses revealed that D. camposensis has a large home range and high mobility. The average home range was 0.068163 ± 0.033313 km2, and the average area of higher activity was 0.005646 ± 0.011386 km2. The mean linear home range was 387.4 m. The results also showed that movements were longer during the night, supporting nocturnal habits. Movements tended to be in an upstream direction for some individuals, although these differences were not significant when data was pooled. Large home range and movements suggest that the species may require large river areas to meet ecological demands, an aspect that could be severely affected by fragmentation. These results, along with previously published genetic data, suggest that the conservation of D. camposensis would be seriously threatened by hydromorphological alterations (e.g. lack of connectivity), such as those resulting from dam building.(AU)
En este trabajo documentamos patrones de movimiento y estimación de ámbito de hogar de Diplomystes camposensis, un siluriforme endémico y amenazado del Sur de Chile. Por medio de radio telemetría, se monitorearon 7 individuos con un rango de tamaño entre 13.5 y 19 cm de longitud estándar, para evaluar patrones de movimiento con respecto al uso de hábitat y tiempo de actividad (dia/noche) en la zona del Río San Pedro, Cuenca del Río Valdivia. Los resultados muestran que D. camposensis tiene un ámbito de hogar grande y una alta movilidad. El ámbito de hogar fue de 0.068163 ± 0.033313 km2 con un área promedio de mayor actividad de 0.005646 ± 0.011386 km2. El ámbito de hogar lineal medio fue de 387.4 m. Los resultados también mostraron que la especie presenta una mayor actividad por la noche y una tendencia hacia un mayor flujo de movimiento en dirección aguas arriba, aunque esto último no fue significativo. Un ámbito de hogar grande y su alta movilidad sugieren que la especie podría requerir de amplias zonas del río para satisfacer sus demandas ecológicas. Al igual que estudos previos con datos genéticos, estos resultados sugieren que la especie D. camposensis se vería perjudicada por alteraciones en la hidromorfología del cauce (e.g. falta de conectividad) tales como aquellas que resulten de la construcción de represas.(AU)
Asunto(s)
Animales , Bagres/crecimiento & desarrollo , Especies en Peligro de Extinción/tendencias , Telemetría/veterinaria , EcosistemaRESUMEN
We document movement patterns and home range of Diplomystes camposensis, an endemic and threatened freshwater catfish from Chile. We tracked the movements of seven individuals of different body size (13.5 to 19 cm SL) using portable radio telemetry equipment to investigate movement patterns in relation to day/night activity and habitat use in the San Pedro River (Valdivia Basin). Tracked movements and model-based analyses revealed that D. camposensis has a large home range and high mobility. The average home range was 0.068163 ± 0.033313 km2, and the average area of higher activity was 0.005646 ± 0.011386 km2. The mean linear home range was 387.4 m. The results also showed that movements were longer during the night, supporting nocturnal habits. Movements tended to be in an upstream direction for some individuals, although these differences were not significant when data was pooled. Large home range and movements suggest that the species may require large river areas to meet ecological demands, an aspect that could be severely affected by fragmentation. These results, along with previously published genetic data, suggest that the conservation of D. camposensis would be seriously threatened by hydromorphological alterations (e.g. lack of connectivity), such as those resulting from dam building.(AU)
En este trabajo documentamos patrones de movimiento y estimación de ámbito de hogar de Diplomystes camposensis, un siluriforme endémico y amenazado del Sur de Chile. Por medio de radio telemetría, se monitorearon 7 individuos con un rango de tamaño entre 13.5 y 19 cm de longitud estándar, para evaluar patrones de movimiento con respecto al uso de hábitat y tiempo de actividad (dia/noche) en la zona del Río San Pedro, Cuenca del Río Valdivia. Los resultados muestran que D. camposensis tiene un ámbito de hogar grande y una alta movilidad. El ámbito de hogar fue de 0.068163 ± 0.033313 km2 con un área promedio de mayor actividad de 0.005646 ± 0.011386 km2. El ámbito de hogar lineal medio fue de 387.4 m. Los resultados también mostraron que la especie presenta una mayor actividad por la noche y una tendencia hacia un mayor flujo de movimiento en dirección aguas arriba, aunque esto último no fue significativo. Un ámbito de hogar grande y su alta movilidad sugieren que la especie podría requerir de amplias zonas del río para satisfacer sus demandas ecológicas. Al igual que estudos previos con datos genéticos, estos resultados sugieren que la especie D. camposensis se vería perjudicada por alteraciones en la hidromorfología del cauce (e.g. falta de conectividad) tales como aquellas que resulten de la construcción de represas.(AU)
Asunto(s)
Animales , Bagres/crecimiento & desarrollo , Especies en Peligro de Extinción/tendencias , Telemetría/veterinaria , EcosistemaRESUMEN
Carlos P. Muñoz-Ramírez, Evelyn Habit, Peter J. Unmack, Jerald B. Johnson, and Pedro F. Victoriano (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.
RESUMEN
The Andean Altiplano has served as a complex setting throughout its history, driving dynamic processes of diversification in several taxa. We investigated phylogeographic processes in the Telmatobius marmoratus species complex occurring in this region by studying the geographic patterns of genetic variability, genealogies, and historical migration, using the cytochrome b (cyt-b) gene as a marker. DNA sequences from Telmatobius gigas and Telmatobius culeus, Bolivian species with an uncertain taxonomic status, were also included. Additionally, we evaluated the phylogenetic diversity (PD) represented within Chilean protected areas and the complementary contribution from unprotected populations. Phylogenetic reconstructions from 148 cyt-b sequences revealed 4 main clades, one of which corresponded to T. culeus. T. gigas was part of T. marmoratus clade indicating paraphyletic relationships. Haplotypes from Chilean and Bolivian sites were not reciprocally monophyletic. Geographic distribution of lineages, spatial Bayesian analysis, and migration patterns indicated that T. marmoratus displays a weaker geographic structure than expected based on habitat distribution and physiological requirements. Demographic and statistical phylogeography analyses pointed out to a scenario of recent population expansion and high connectivity events of a more recent age than the post Last Glacial Maximum, probably associated to more humid events in Altiplano. PD of T. marmoratus populations within protected areas represents 55.6% of the total estimated PD. The unprotected populations that would contribute the most to PD are Caquena and Quebe (21%). Recent evolutionary processes and paleoclimatic changes, potentially driving shifts in habitat connectivity levels and population sizes, could explain the phylogeographic patterns recovered herein.