Cannibalism in Microlophus Lizards
Cannibalism involves killing and consuming an individual of the same species. Different factors modulate cannibalism, and here we explored whether the diet diversity would mediate the cannibalism propensity in Microlophus lizards. We compiled the available information on diet and cannibalism of the 22 Microlophus species. We found that there is a relatively high incidence of cannibalism within Microlophus, as 41% of the species exhibited this behavior. There are, however, few reports of cannibalism by each species. Cannibalism propensity showed a positive association with diet diversity, which suggests that a generalist diet might provide room for cannibalism in Microlophus lizards. We also found that only adults, mostly males, consume juveniles. Conspecific predation pressure may explain the habitat segregation among age classes reported in some Microlophus species that exhibit cannibalism. Finally, cannibalism appears to be an ancestral condition in Microlophus, as it occurs in the two main clades of this genus. Moreover, Tropidurus, the sister taxon of Microlophus, also includes species that exhibit cannibalism, and the ancestor of these genera may have exhibited cannibalism. El canibalismo implica matar y consumir a un individuo de la misma especie. Diferentes factores modulan esta conducta, y aquí exploramos si la diversidad de la dieta mediaría la propensión al canibalismo en los lagartos Microlophus. Recopilamos la información disponible sobre dieta y canibalismo de las 22 especies de Microlophus. Encontramos una relativa alta incidencia del canibalismo en este género, el cual es exhibido por el 41% de las especies. Sin embargo, existen pocos reportes de canibalismo por cada especies. La propensión al canibalismo mostró una asociación positiva con la diversidad de la dieta, lo que sugiere que una dieta generalista podría dar lugar al canibalismo en los lagartos Microlophus. También encontramos que solo los adultos, en su mayoría machos, depredaron sobre los juveniles. Esta presión de depredación podría explicar la segregación del hábitat entre las clases etarias reportada en algunas de las especies de Microlophus que exhiben canibalismo. Finalmente, el canibalismo parece ser una condición ancestral en Microlophus, dado que ocurre en los dos clados principales del género. Más aún, el taxón hermano de Microlophus, Tropidurus, también incluye especies que exhiben canibalismo.ABSTRACT
RESUMEN
Relation between diet diversity and cannibalism propensity (number of reports of cannibalism, red open circles) and lizard consumption (number of reports of cannibalism and saurophagy, backfilled circles). Three species showed saurophagy, indicated by the ellipses. The lines correspond to linear regressions.
Cannibalistic behavior in Microlophus quadrivitattus. An adult captured a juvenile. (A) The juvenile was first grabbed by a leg, and attempted to escape. (B) After some movements, the adult grabbed the juvenile by the flank (Photos: Maximiliano Daigre).
Cannibalistic behavior in Microlophus atacamensis. An adult captured a juvenile. (A) At a distance, it was initially observed that something was hanging and shaking from the adult's head. (B) When observed more closely, it was evident that the adult grabbed a juvenile by the head. There was blood on the border of the adult's mouth, probably coming from the juvenile. Notice that the adult was shedding (Photos: Viviana Imil).
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