Sociality of Octodontomys gliroides and other octodontid rodents reflects the influence of phylogeny

Multiple ecological factors are known to drive variation in social behavior. However, group-living in some species appears to be highly conserved, suggesting a phylogenetic influence. In this study, we evaluated both scenarios using intraspecific and interspecific comparisons across octodontid rodents. We first examined 2 different populations of Andean degu (Octodontomys gliroides), representing 2 extremes of a climate vegetation gradient across the Andes range. We evaluated how ecological variation in terms of abundance and distribution of food resources, predation risk, and burrowing costs predicted interpopulation variation in group size and range-area overlap (2 proxies of sociality). We estimated these measures of sociality from livetrapping and radiotelemetry. We then used phylogenetic methods to determine whether sociality exhibits a phylogenetic signal and reconstructed the ancestral state of sociality across the family Octodontidae. Overall activity of females and males of O. gliroides was greater during nighttime than daytime. Across populations we found significant differences in ecology, including abundance and distribution of food, predation risk, and burrowing costs. However, populations were similar in terms of group size and range-area overlap. The phylogenetic approach revealed a strong and significant phylogenetic signal associated with sociality, where this behavior was present early during the evolution of octodontid rodents. Together, these findings imply that sociality of O. gliroides is not linked to current population differences in ecology. La variación en la conducta social ha sido atribuida a múltiples factores ecológicos. Sin embargo, la vida en grupo en algunas especies es un rasgo altamente conservado, sugiriendo una influencia filogenética. En este estudio, se evaluó ambos escenarios usando comparaciones intraespecíficas e interespecíficas a través de roedores octodóntidos. En primer lugar se evaluaron 2 poblaciones de degu Andino (Octodontomys gliroides) que representan 2 extremos de un gradiente climático y de vegetación a través de la Cordillera de los Andes. Se evaluó como la variación en términos de abundancia y distribución de recursos alimenticios, riesgo de depredación, y costos asociados a cavar madrigueras podrían predecir la variación interpoblacional en tamaño de grupo y solapamiento del ámbito de hogar (2 medidas de sociabilidad). Estas medidas fueron estimadas con datos de trampeo y radiotelemetría. Además, se