Variation in Feeding Habits between Two Syntopic Frog Species (Genus Lithobates) of a Tropical Habitat in the Atlantic Versant of Mexico
Lithobates johni and Lithobates berlandieri have, respectively, a restricted and a wide geographic distribution, and cohabit in the center of the Atlantic versant of Mexico. We analyze and compare the feeding habits of these two syntopic species, specifically evaluating differences in trophic niche breadth and overlap between sexes (L. johni = 35 females and 30 males; L. berlandieri = 25 females and 26 males) and seasons (L. johni = 45 from wet and 20 from dry seasons; L. berlandieri = 17 from wet and 34 from dry seasons). Both L. johni and L. berlandieri showed generalist feeding habits and were found to consume mainly arthropods; however, they also consumed vertebrates. In the wet season, L. johni males had higher stomach volume content than females, and L. berlandieri females had higher stomach volume content than males. In the dry season, L. johni females had higher stomach volume content than males, and a similar pattern was seen between sexes in L. berlandieri. Trophic niche breadth and dietary diversity were higher in L. berlandieri than in L. johni for both seasons. There was no trophic segregation between species in either season (wet or dry); however, we suggest that the differences in prey type consumed, dietary diversity, and trophic niche breadth might explain the coexistence of L. johni and L. berlandieri in the study area.
Lithobates johni y Lithobates berlandieri tienen una restringida y amplia área de distribución, respectivamente, y cohabitan en el centro de la vertiente del Atlántico de México. En el presente estudio, analizamos y comparamos los hábitos alimentarios de estas dos especies sintópicas, específicamente evaluando las diferencias en la amplitud y solapamiento del nicho trófico entre sexos (L. johni = 35 hembras y 30 machos; L. berlandieri = 25 hembras y 26 machos) y temporadas (L. johni = 45 de lluvias y 20 de secas; L. berlandieri = 17 de lluvias y 34 de secas). Ambas especies son generalistas y consumieron principalmente artrópodos; sin embargo, también consumieron vertebrados. En la temporada de lluvias, los machos tuvieron un mayor volumen del contenido estomacal que las hembras en L. johni, mientras que en L. berlandieri las hembras tuvieron un mayor volumen del contenido estomacal que los machos. En la temporada de secas, las hembras tuvieron un mayor volumen del contenido estomacal que los machos en L. johni, un patrón similar ocurrió entre sexos de L. berlandieri. La amplitud de nicho alimentario y la diversidad de la dieta fueron mayores en L. berlandieri que en L. johni en ambas temporadas. No hubo segregación trófica entre especies ni entre temporadas (lluvias y secas); sin embargo, sugerimos que las diferencias en los tipos de presas consumidas, en la diversidad de la dieta, y en la amplitud de nicho alimentario podrían explicar la coexistencia de L. johni and L. berlandieri en el sitio de estudio.Abstract
Resumen
Distribution of Lithobates johni and Lithobates berlandieri, and study area in the municipality of Molango de Escamilla, Hidalgo in Mexico.
Variation in volume content between species, sexes, and seasons in Lithobates johni (circles) and Lithobates berlandieri (squares), at Molango de Escamilla, Hidalgo. Vertical bars represent standard deviation.
(A) Variation in prey number between species and (B) seasons. Vertical bars represent standard deviation.
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