Size Ratios Among Sympatric Neotropical Cats

Data were gathered on body weight, body length, relative maximum bite force and relative maximum gape for six sympatric species of neotropical cats (Felidae) to see if constant size ratios occur between adjacent species or if the minimum ratio in a series is greater than expected by chance. Although clearly likely to be correlated, these four parameters were thought to have potential for some independent variation and independent influence on prey capture abilities. None of the four sets of ratios was statistically distinguishable from random when all six species were included in the analysis; however, the ratios for relative maximum gape among just the four largest species were significantly more even and the minimum ratio significantly greater than expected by chance among four species. This constancy occurs because of departures of jaw lengths from what would be expected by the average allometric relationship between this parameter and total body size. Competitive character displacement is a possible explanation for the constant ratios in maximum gape of the larger species, but it is not the only possibility.