Phylogenetics of the Neotropical singing mice (Scotinomys)
J.L. Pino. 2012. Sistemática molecular de ratones cantadores (Scotinomys, Rodentia: Cricetidae) en Costa Rica y Panamá. XVI Congreso de la Sociedad Mesoamericana para la Biología y la Conservación. Panama, Panama. (citation pending)
ABSTRACT: La distribución geográfica de los ratones cantadores comprende las zonas montañosas con elevaciones mayores a los ~1000 metros en Mesoamérica, desde las montañas del sureste de México hasta la región occidental de Panamá. Con base en la última revisión taxonómica publicada hace cuarenta años, dos especies son tradicionalmente reconocidas S. teguina y S. xerampelinus, ambas especies presentes en Costa Rica y Panamá. Utilizando marcadores moleculares nucleares (intron-7 del gen beta fibrinógeno) y mitocondriales (citocromo B, y la región de control), se exploraron las relaciones filogenéticas de Scotinomys de Costa Rica y Panamá. La evidencia molecular encontrada muestra un alto grado de diferenciación entre las poblaciones de S. teguina de la región central-norte de Costa Rica y las poblaciones de la región sureste de Costa Rica y oeste de Panamá. S. xerampelinus muestra una señal filogeográfica similar a S. teguina. Los resultados de los análisis moleculares sugieren la consideración de más de dos especies de ratones cantantes en Panamá y Costa Rica, las cuales se están en el proceso de descripción. Conocer la identidad taxonómica de estas especies, al igual que otras especies, es fundamental para implementar cualquier iniciativa de conservación en la región; especialmente aquellas enfocadas a especies con distribución restringida a ambientes frágiles.
ABSTRACT: La distribución geográfica de los ratones cantadores comprende las zonas montañosas con elevaciones mayores a los ~1000 metros en Mesoamérica, desde las montañas del sureste de México hasta la región occidental de Panamá. Con base en la última revisión taxonómica publicada hace cuarenta años, dos especies son tradicionalmente reconocidas S. teguina y S. xerampelinus, ambas especies presentes en Costa Rica y Panamá. Utilizando marcadores moleculares nucleares (intron-7 del gen beta fibrinógeno) y mitocondriales (citocromo B, y la región de control), se exploraron las relaciones filogenéticas de Scotinomys de Costa Rica y Panamá. La evidencia molecular encontrada muestra un alto grado de diferenciación entre las poblaciones de S. teguina de la región central-norte de Costa Rica y las poblaciones de la región sureste de Costa Rica y oeste de Panamá. S. xerampelinus muestra una señal filogeográfica similar a S. teguina. Los resultados de los análisis moleculares sugieren la consideración de más de dos especies de ratones cantantes en Panamá y Costa Rica, las cuales se están en el proceso de descripción. Conocer la identidad taxonómica de estas especies, al igual que otras especies, es fundamental para implementar cualquier iniciativa de conservación en la región; especialmente aquellas enfocadas a especies con distribución restringida a ambientes frágiles.
Pino J.L.; Reed D. and Phelps S.M. 2011. Lineage divergence of singing mice (genus Scotinomys) in southern Central American highlands. 91st Meeting of the American Society of Mammalogists. Portland, USA.
ABSTRACT: Two lineages of Chiriqui brown singing mouse (Scotinomys xerampelinus) have been identified along their distribution in the mountains of Costa Rica and Panama based on mitochondrial cytochrome B. The greatest divergence within western lineage was 0.49% in localities separated by ~51km (Irazu–Cuerici); greatest divergence within eastern lineage was 0.26% in localities separated by ~57 km (Pittier–Volcan Baru). S. xerampelinus from the two inner localities (Cuerici–Pittier), separated by ~97 km, diverged 5.39%. This divergence was unexpected since Cuerici, Pittier and Volcan Baru are located in the continuous Talamanca ridge with no evident geographic depression that could prevent current gene flow between both eastern and western lineages. A greater divergence within the western lineage compared to within the eastern lineage was expected due a depression the between Irazu locality and the Talamancan ridge where the other three localities are found. The same pattern was found in the lower elevation species, Alton's brown singing mouse (S. teguina), where divergence within the western lineage was 0.32% (Irazu–Cerro Gomez); 1.08% within eastern lineage (Pittier– Volcan Baru); and 4.71% between both lineages in the inner localities (Cerro Gomez–Pittier). Relatively similar geographic distances apply for S. teguina localities. Current divergences between lineages in both species suggests that genetic isolation could be an important factor maintaining the signal of an ancient divergence in a continuous landscape, in which case elevating populations to species status must be considered for both S. teguina and S. xerampelinus. Ongoing research in this field includes testing hypotheses of divergence timing between eastern and western lineages, determining the directionality of recent distributions and accessing lineages past distribution during the last glacial maximum; these approaches will provide a better understanding of how past climatic or geological events have promoted current phylogeographic patterns in these species.
ABSTRACT: Two lineages of Chiriqui brown singing mouse (Scotinomys xerampelinus) have been identified along their distribution in the mountains of Costa Rica and Panama based on mitochondrial cytochrome B. The greatest divergence within western lineage was 0.49% in localities separated by ~51km (Irazu–Cuerici); greatest divergence within eastern lineage was 0.26% in localities separated by ~57 km (Pittier–Volcan Baru). S. xerampelinus from the two inner localities (Cuerici–Pittier), separated by ~97 km, diverged 5.39%. This divergence was unexpected since Cuerici, Pittier and Volcan Baru are located in the continuous Talamanca ridge with no evident geographic depression that could prevent current gene flow between both eastern and western lineages. A greater divergence within the western lineage compared to within the eastern lineage was expected due a depression the between Irazu locality and the Talamancan ridge where the other three localities are found. The same pattern was found in the lower elevation species, Alton's brown singing mouse (S. teguina), where divergence within the western lineage was 0.32% (Irazu–Cerro Gomez); 1.08% within eastern lineage (Pittier– Volcan Baru); and 4.71% between both lineages in the inner localities (Cerro Gomez–Pittier). Relatively similar geographic distances apply for S. teguina localities. Current divergences between lineages in both species suggests that genetic isolation could be an important factor maintaining the signal of an ancient divergence in a continuous landscape, in which case elevating populations to species status must be considered for both S. teguina and S. xerampelinus. Ongoing research in this field includes testing hypotheses of divergence timing between eastern and western lineages, determining the directionality of recent distributions and accessing lineages past distribution during the last glacial maximum; these approaches will provide a better understanding of how past climatic or geological events have promoted current phylogeographic patterns in these species.
Pino J.L.; Campbell, P.; Pasch, B.; Reed, D. and Phelps S.M. 2009. Insights into the evolutionary history of singing mice, Genus Scotinomys. International Mammalogical Meeting. Mendoza, Argentina.
ABSTRACT: The genus Scotinomys is restricted to the Mesoamerican mountains at elevations above 1000m. Two species, Scotinomys teguina and S. xerampelinus, are formally recognized based on the last revision of the genus published more than 35 years ago (Hooper 1972). According to the literature, S. teguina is distributed from south-western Mexico to western Panama with a major population disjunction due to the Nicaraguan Lake depression lowlands, and S. xerampelinus occurs only south of the Nicaraguan Lake, both species end their distribution in western Panama. In the southern part of their range they segregate elevationally with S. xerampelinus found at higher elevations (above 2100m) with a few documented zones of sympatry at the lower distributional range of S. xerampelinus. This research examined the relationships of populations of both species throughout their distributional range by analyzing mitochondrial DNA sequences. Samples were provided by museum and field collections. Our analyses confirm haplotypes of what was thought to be S. teguina in populations to the north and south of the Nicaraguan Lake, showing geographic structure among populations. Results suggest an interesting demographic history with evidence of a bottleneck in the southernmost populations of S. teguina and a recent expansion in northern populations. Haplotypes of former S. xerampelinus (Costa Rica-Panama) were present in populations to the north of Lake Nicaragua, suggesting the possible presence of disjunct populations that would greatly expand the previously suggested distributional range. The mtDNA tree generated suggests other species level relationships, but nuclear data must be added to the existing dataset to test this prediction thoroughly.
ABSTRACT: The genus Scotinomys is restricted to the Mesoamerican mountains at elevations above 1000m. Two species, Scotinomys teguina and S. xerampelinus, are formally recognized based on the last revision of the genus published more than 35 years ago (Hooper 1972). According to the literature, S. teguina is distributed from south-western Mexico to western Panama with a major population disjunction due to the Nicaraguan Lake depression lowlands, and S. xerampelinus occurs only south of the Nicaraguan Lake, both species end their distribution in western Panama. In the southern part of their range they segregate elevationally with S. xerampelinus found at higher elevations (above 2100m) with a few documented zones of sympatry at the lower distributional range of S. xerampelinus. This research examined the relationships of populations of both species throughout their distributional range by analyzing mitochondrial DNA sequences. Samples were provided by museum and field collections. Our analyses confirm haplotypes of what was thought to be S. teguina in populations to the north and south of the Nicaraguan Lake, showing geographic structure among populations. Results suggest an interesting demographic history with evidence of a bottleneck in the southernmost populations of S. teguina and a recent expansion in northern populations. Haplotypes of former S. xerampelinus (Costa Rica-Panama) were present in populations to the north of Lake Nicaragua, suggesting the possible presence of disjunct populations that would greatly expand the previously suggested distributional range. The mtDNA tree generated suggests other species level relationships, but nuclear data must be added to the existing dataset to test this prediction thoroughly.