Increases in the mean and variability of thermal regimes result in differential phenotypic responses among genotypes during early ontogenetic stages of lake sturgeon (Acipenser fulvescens)

Abstract

Climate change is affecting thermal conditions worldwide. Understanding organismal responses associated with predicted changes are essential for predicting population persistence. Few studies have examined the effects of both increased mean and variance in temperature on organismal traits, particularly during early life stages. Using lake sturgeon (Acipenser fulvescens) from Black Lake, MI, we tested whether phenotypic variation differed among families reared in two constant (10 and 18°C) and two fluctuating‐temperature treatments (10–19°C) representing temperatures experienced in the river and a simulated anthropogenic disturbance. Body length, body area, and yolk‐sac area were quantified at hatch. Family‐by‐treatment interactions explained up to 50% of the variance observed among families in offspring hatch traits. Families incubated in 18°C and the fluctuating anthropogenic treatment had 6–10 times higher variance in traits than those incubated at 10°C. Hatched larvae were placed in raceways with ambient river water. Emergence body length, emergence timing, and growth were quantified upon emergence. Families differed in time to emergence and growth with the greatest range observed in the 18°C treatment. Results demonstrate that differential responses among genotypes to changes in the mean and variability of thermal incubation regimes can affect traits at hatch as well as a subsequent ontogenetic stage.

Thermal adaptation and phenotypic plasticity in a warming world: Insights from common garden experiments on Alaskan sockeye salmon

“…These results were similar to other studies that found differences in alevin mass were largely driven by family or population, as opposed to temperature treatment (Burt et al, 2012;Hendry et al, 1998;Whitney et al, 2014). Our findings were inconsistent with other studies (Burt et al, 2012;Drinan et al, 2012;Haugen & Vøllestad, 2000;Hendry et al, 1998) There is increasing interest in understanding the role of the timing of temperature delivery to developing embryos beyond consideration of average temperatures (Dammerman et al, 2016;Fuhrman et al, 2017;Steel et al, 2012;Tillotson, 2015). In a series of common garden experiments, Murray and Beacham (1987) Tillotson, 2015).…”

“…Other studies (Beacham & Murray, 1989;Haugen & Vøllestad, 2000;Kinnison, Unwin, Hershberger, & Quinn, 1998;Wood & Fraser, 2015) that focused on population-level differences also found a similar lack of genetic differences in hatch timing in regimes representing natural conditions (but see Jensen et al, 2008;Whitney et al, 2014). We expected to observe population differences while others did not because of the inclusion of fluctuating thermal regimes, which has produced significant population (Fuhrman et al, 2017) and family-level differences (Dammerman et al, 2016;Steel et al, 2012;Tillotson, 2015). Furthermore, we expected this because we used populations that use a shared rearing environment later during their early life history and we expected their phenology, even with very different developmental thermal regimes, to generally synchronize given their shared recipient environment.…”

“…In a series of common garden experiments, Murray and Beacham (1987) Tillotson, 2015). In a similar common garden study with lake sturgeon (Acipenser fulvescens), Dammerman et al (2016) In other words, as incubation time grew increasingly longer in the less variable treatments, the variation around mean incubation time is expected to increase. As such, even though the thermal regime in MIROC was more variable, mean incubation time was much shorter, which likely decreased variation in hatching relative to the longer, less thermally variable treatments, PP_AVG and PP_MIROC.…”

“…There is increasing interest in understanding the role of the timing of temperature delivery to developing embryos beyond consideration of average temperatures (Dammerman et al, 2016;Fuhrman et al, 2017;Steel et al, 2012;Tillotson, 2015). In a series of common garden experiments, Murray and Beacham (1987) Tillotson, 2015).…”

“…But, there is far more evidence for population-specific adaptation of spawning time (e.g., Brannon, 1987;Hodgson & Quinn, 2002;Kinnison et al, 2008), as opposed to developmental rates, which appears to respond less to selection (Beacham & Murray, 1990;Kinnison et al, 2008). While populations tend to exhibit less local adaptation in developmental rates than spawning time, recent work testing the effect of incubation thermal regime variability on development rate and emergence size found genetic differences at both the family (Dammerman, Steibel, & Scribner, 2016;Steel et al, 2012) and population levels (Fuhrman, Larsen, Steel, Young, & Beckman, 2017). Furthermore, studies testing these factors often lack direct comparisons of populations experiencing contrasting natal thermal regimes within shared systems, rarely take place in high latitude habitats experiencing more rapid and extreme change, and poorly account for plausible predictions of climate change because of the use of thermal treatments that lack natural variability or represent temperatures unlikely to be experienced in nature.…”