La Faculté des Sciences psychologiques et pédagogiques

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Mean (± SE) SDA coefficient, following consumption of 5% body mass as <i>Artemia</i>, at three acclimation temperatures in four groups of killifish.

<p>Each group comprised a species pair from either low altitude (<i>A. splendopleure</i> and <i>A. ahli</i>) or from high altitude (<i>A. cameronense</i> and <i>A. exiguum</i>), with two generations per species, an F0 generation captured in the wild and an F1 generation bred in captivity. The SDA coefficient is expressed as µg O₂ consumed, corrected to a body mass of 350 mg, n = between 11 and 13. Two-way ANOVA on log 10 transformed data revealed no significant overall effects of group (df = 3, F = 1.739, P = 0.163), temperature (df = 2, F = 1.354, P = 0.262) or interaction between group and temperature (df = 6, F = 1.227, P = 0.297), therefore no differences among individual groups or temperatures (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054345#pone.0054345.s011" target="_blank">Text S11</a> for details).</p

Reaction norms for mean (± SE) time required to complete the specific dynamic action response (T_SDA) as a function of acclimation temperature in four groups of killifish.

<p>Each group comprised a species pair from either low altitude (<i>A. splendopleure</i> and <i>A. ahli</i>), with both an F0 generation (white squares) and an F1 generation (grey squares), or from high altitude (<i>A. cameronense</i> and <i>A. exiguum</i>), with both an F0 generation (white circles) and an F1 generation (grey circles). F0 generation were captured in the wild, F1 generation were bred in captivity, n = between 5 and 7. A 2-way ANOVA found no effect of group (df = 3, F = 0.676, P = 0.568) or temperature (df = 2, F = 2.064, P = 0.131) but a significant interaction (df = 6, F = 12.695, P<0.001). At 19 and 28°C, a similar letter superscript indicates no significant difference among group means. Within a group, † indicates a difference between 19 and 25°C, § indicates a difference between 19 and 28°C, ‡ indicates a significant difference between 25 and 28°C (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054345#pone.0054345.s010" target="_blank">Text S10</a> for details).</p

Mean (± SE) routine metabolic rate (RMR) at three acclimation temperatures in four groups of killifish.

<p>Each group comprised a species pair from either low altitude (<i>A. splendopleure</i> and <i>A. ahli</i>) or from high altitude (<i>A. cameronense</i> and <i>A. exiguum</i>), with two generations per species, an F0 generation captured in the wild and an F1 generation bred in captivity. Metabolic rate is expressed as rates of oxygen uptake (µg h⁻¹), corrected to a body mass of 350 mg, n = between 11 and 13. A 2-way ANOVA on log-10 transformed values found an effect of group (df = 3, F = 3.512, P = 0.017), temperature (df = 2, F = 37.637, P<0.001) but no interaction between group and temperature (df = 6, F = 0.24, P = 0.96). Overall, low altitude F1 had lower RMR than high altitude F0, and overall RMR differed at all temperatures. There were, however, no differences among groups at any temperature. Within each group, Holm-Sidak pairwise comparisons revealed significant effects of temperature (^†, significantly different from 25°C; ^§, significantly different from 28°C, P<0.05, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054345#pone.0054345.s007" target="_blank">Text S7</a> for details).</p

Reaction norms for mean (± SE) time required to reach peak oxygen uptake during the specific dynamic action (T_peak) as a function of acclimation temperature in four groups of killifish.

<p>Each group comprised a species pair from either low altitude (<i>A. splendopleure</i> and <i>A. ahli</i>), with both an F0 generation (white squares) and an F1 generation (grey squares), or from high altitude (<i>A. cameronense</i> and <i>A. exiguum</i>), with both an F0 generation (white circles) and an F1 generation (grey circles). F0 generation were captured in the wild, F1 generation were bred in captivity, n = between 5 and 7. A 2-way ANOVA on log 10 transformed values found no effect of group (df = 3, F = 0.849, P = 0.470), but a significant effect of temperature (df = 2, F = 6.652, P = 0.002) and their interaction (df = 6, F = 6.015, P<0.001). Overall T_peak was lower at 25°C than at 19 or 28°C. At 19 and 28°C, a similar letter superscript indicates no significant difference among group means for that temperature. Within a group, † indicates a difference between 19 and 25°C, § indicates a difference between 19 and 28°C, ‡ indicates a significant difference between 25 and 28°C (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054345#pone.0054345.s009" target="_blank">Text S9</a> for details).</p

Figure 2

<p>Mean (± SE) rates of oxygen uptake in wild-caught individuals of two species of killifish, <i>A. ahli</i> from low altitude (left column) or <i>A. exiguum</i> from high altitude (right column), at three different acclimation temperatures. In each panel, data are for fish placed into respirometers at 1630 either fasted (white symbols) or when fed 5% of their body mass as live <i>Artemia</i> (black symbols). Rates of oxygen uptake are corrected to a body mass of 350 mg, n = 6 in all cases. See text for further details.</p

Map of Cameroon showing the distribution of the low altitude (LA) and high altitude (HA) <i>Aphyosemion</i> species.

<p>Altitudes below 350 m are in white, above 350 m in yellow. ,The LA species are almost exclusively present below 350 m (black dots), the HA species above 350 m (in blue). The arrows show where the animals were collected for the current study. Photos by Olivier Buisson (<i>A. ahli</i>, <i>A. cameronense</i> and <i>A. exiguum</i>) and Alf Persson (<i>A. splendopleure</i>).</p

Reaction norms for mean (± SE) peak oxygen uptake rate during the specific dynamic action (Mo_2-peak) as a function of acclimation temperature in four groups of killifish.

<p>Each group comprised a species pair from either low altitude (<i>A. splendopleure</i> and <i>A. ahli</i>), with both an F0 generation (white squares) and an F1 generation (grey squares), or from high altitude (<i>A. cameronense</i> and <i>A. exiguum</i>), with both an F0 generation (white circles) and an F1 generation (grey circles). F0 generation were captured in the wild, F1 generation were bred in captivity. Rates of oxygen uptake are corrected to a body mass of 350 mg, n = between 5 and 7. Two-way ANOVA found a significant effect of temperature (F = 6.064, d.f. = 2, P = 0.003) but not of group (F = 0.926, d.f. = 3, P = 0.430) or their interaction (F = 0.241, d.f. = 6, P = 0.962). This was due to higher overall peak at 25°C than at 19°C, although individual groups did not show significant effects (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054345#pone.0054345.s008" target="_blank">Text S8</a> for details).</p

Mean (± SE) appetite at three acclimation temperatures in four species of killifish, comprising an F0 generation of <i>A. ahli</i> and F1 generation of <i>A. splendopleure</i> from low altitude, or an F0 generation of <i>A. exiguum</i> and an F1 generation of <i>A. cameronense</i> from high altitude.

<p>Appetite is expressed as the percentage body mass of live <i>Artemia</i> consumed when fed a single meal <i>ad-libitum</i>, n = between 10 and 12. One-way ANOVA revealed no significant differences amongst groups (DF = 11, F = 1.279, P = 0.244; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054345#pone.0054345.s012" target="_blank">Text S12</a> for details).</p

Figure 3

<p>Specific dynamic action (SDA), expressed as rates of oxygen uptake, in two species of killifish, <i>A. ahli</i> from low altitude (LA, upper panel) or <i>A. exiguum</i> from high altitude (HA, lower panel), at three different acclimation temperatures, 19°C (white), 25°C (grey) and 28°C (black). The SDA was calculated as the net difference in oxygen uptake between animals that were either fasted, or fed 5% of their body mass as <i>Artemia</i> (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054345#pone-0054345-g002" target="_blank">Figure 2</a>). Values are means of n = 6 individuals from each species, rates are corrected to a body mass of 350 mg. Standard error bars are not shown to ease reading of the figure, but were approximately 10% of the mean value in all cases.</p