Empirical evidence for fast temperature-dependent body size evolution in rotifers

Abstract

Organisms tend to decrease in size with increasing temperature by phenotypic plasticity (the temperature-size rule; ectotherms) and/or genetically (Bergmann's rule; all organisms). In this study, the evolutionary response of body size to temperature was examined in the cyclically parthenogenetic rotifer Brachionus plicatilis. Our aim was to investigate whether this species, already known to decrease in size with increasing temperature by phenotypic plasticity, presents a similar pattern at the genetic level. We exposed a multiclonal mixture of B. plicatilis to experimental evolution at low and high temperature and monitored body size weekly. Within a month, we observed a smaller size at higher temperature, as compared to body size at lower temperature. The pattern was consistent for the size of both mature females and eggs; rotifers kept at high temperature evolved to be on average 14% (after 2 weeks) and 3% (after 3 weeks) smaller than the ones kept at low temperature (10 and 5% in the case of eggs, respectively). We therefore found that B. plicatilis is genetically programmed to adjust its body size-toenvironmental temperature.

Influence of temperature and conductivity on the life-history characteristics of a pampean strain of Brachionus plicatilis

“…These authors concluded that the eurioic B. plicatilis is exposed to a high variability of temperature in the environments where the species live acquiring a significant plasticity, and thus, can maintain a steady growth in these circumstances.We observed that females at lower temperatures produced fewer offspring per day, but remained reproductive longer, similar to the results obtained by Johnston and Snell (2016). An inverse relation between the adults' size and the temperature was detected in our experiments, and the same phenomenon was observed by Walczyńska et al (2017).…”

“…Our results on the influence of temperature are in agreement with those reported by Miracle and Serra (1989) and Yin and Zhao (2008) with different strains indicating that the maximum growth is achieved at temperatures between 24 and 30 °C. The pampean strain of B. plicatilis population growth was significantly different at both temperatures and these results disagreed with those obtained with a Spain strain by Walczyńska and Serra (2014) and Walczyńska et al (2017). These authors concluded that the eurioic B. plicatilis is exposed to a high variability of temperature in the environments where the species live acquiring a significant plasticity, and thus, can maintain a steady growth in these circumstances.We observed that females at lower temperatures produced fewer offspring per day, but remained reproductive longer, similar to the results obtained by Johnston and Snell (2016).…”

Ecological genomics of adaptation to unpredictability in experimental rotifer populations

“…Genomic signatures of rapid adaptation in laboratory populations through experimental evolution have been identified, supporting previous results showing rapid phenotypic divergence in rotifer populations, which evolved divergent life-history traits over a short time span 46 . Although other experimental evolution studies have shown adaptation to a range of selective pressures in rotifers 25,68 and other well-known cyclical parthenogens, such as Daphnia 69,70 , the genomic basis has been little explored. Genomic signatures of adaptation to environmental anthropogenic stressors were found in D .…”

Effects of astaxanthin on Brachionus manjavacas (Rotifera) population growth

“…Stress resistance and reproduction were evaluated in JMP Pro 12 (SAS Institute) using an ANOVA with Dunnett's test comparing each treatment to control. Theoretical dosing concentrations of astaxanthin at equilibrium were calculated using the estimation for the volume of rotifers described by Walczynska, Franch‐Gras, and Serra (). The average length and width of a B. manjavacas female are 254 μm × 202 μM, making the average volume of a rotifer 4.33 × 10 −5 cm 3 .…”