Life table analysis reveals variation in thermal tolerance among three species of theLecanegenus (Rotifera: Monogononta)

Abstract

Variation in thermal tolerance among related species plays an important role in establishing their range and distribution. We conducted life table experiments with three rotifer species of the Lecane genus at three temperatures (20, 25 and 30°C). The rotifers were fed on Nannochloropsis oculata at 106 cells.mL−1 to test the hypothesis that Lecane papuana (Murray, 1913) (a warm stenothermal species) would behave like a thermal specialist and perform better at higher temperatures than the cosmopolitan species Lecane bulla (Gosse, 1851) and Lecane cornuta (Muller, 1786). Consistent with our hypothesis, L. papuana grew better at 30°C than at 20 and 25°C, while at 30°C, L. cornuta grew poorly and L. bulla did not grow at all. All three species have longer lifespans with decreasing temperature. At 20°C, the net reproductive rates of L. cornuta (3.5 h−1 ) and L. papuana (3.58 h−1 ) were not significantly different, but were significantly greater than that of L. bulla (2.75 h−1 ). At 25°C, L. papuana had a lower net reproductive rate (6.33 h−1 ) than either L. bulla (11.33 h−1 ) or L. cornuta (7.12 h−1 ). However, at 30°C, L. papuana had a greater net reproductive rate (14.35 h−1 ) than L. cornuta (1.16 h−1 ).