Fig 1.
Season effect on the diet of HP and LP guppies from the Aripo River.
Percent diet composition is shown for the dry (a) and the wet (b) seasons. Data showed here represent the estimated marginal means calculated by the MANCOVA on arcsin transformed data. Estimated marginal means and standard errors have been back-transformed for the graphical representation. Food categories analyzed are invertebrates, in dark grey and amorphous detritus. LP: low predation; HP: high predation. Bars represent ±1 SE.
Fig 2.
Correlation between guppy standard length and a) proportion of invertebrates and b) proportion of detritus in guppies diet from the Aripo River.
Wet season (filled diamonds) and dry season (open circles) fish are shown. Regression line shows the only significant relationship, which is between proportion of invertebrates in diet and guppy length during the wet season.
Table 1.
Univariate ANCOVA results on the effects of population of origin and season on the proportion of invertebrates and detritus in the diets of guppies from the Aripo River in Trinidad.
SS = sums of squares; df = degrees of freedom; MS = mean squares. All F-ratios are based on type-III sums of squares.
Table 2.
Diet composition of Guanapo River guppies from high predation (HP; N = 21) and low predation (LP; N = 21) sites during the dry season (data from [28]).
Proportions of the 3 food items are estimated marginal means (±SE) calculated by the MANCOVA (population of origin as the fixed effect and fish length as a covariate); data reported have been back-transformed.
Fig 3.
Correlation between fish standard length and guppies gut length in the Aripo River.
Guppies from high predation (HP, filled circles) and low predation (LP, open triangles) populations in the dry (a) and wet (b) season are shown. Data are not transformed and equations and R2 values are calculated on non-transformed data. Trendlines are exponential.
Fig 4.
Mean guppies gut length for HP and LP guppies during the dry and the wet season in the Aripo River.
Only data from guppies between 14 and 20 mm are included in this graph. Guppies from the HP (high predation) population are shown in filled circles, while guppies from the LP (low predation) population are in open triangles. Bars represent ±1 SE.
Fig 5.
Correlation between fish standard length and guppies gut length in the Guanapo River.
Fish from high predation (HP) are indicated with filled circles, and from low predation (LP) with open triangles. Data are not transformed and equations and R2 values are calculated on non-transformed data. Trendlines are exponential.
Fig 6.
Mean proportion of invertebrates in diets vs. mean relative gut length.
Only guppies between 14 and 20 mm were included. Each data point represents one site (Aripo HP and LP for both dry and wet season, and Guanapo HP and LP from the dry season). Relative gut length was calculated as the gut length divided by fish length. An average value was assigned for the proportion of invertebrates for each site, which was the estimated marginal mean obtained from the diet analysis (data for the Guanapo fish are from [28]).