Abstract
Cell size may be important in understanding the thermal biology of ectotherms, as the regulation and consequences of cell size appear to be temperature dependent. Using a recently developed model system of triploid zebrafish (which have around 1.5-fold larger cells than their diploid counterparts) we examine the effects of cell size on gene expression, growth, development and swimming performance in zebrafish larvae at different temperatures. Both temperature and ploidy affected the expression of genes related to metabolic processes (citrate synthase and lactate dehydrogenase), growth and swimming performance. Temperature also increased development rate, but there was no effect of ploidy level. We did find interactive effects between ploidy and temperature for gene expression, body size and swimming performance, confirming that the consequences of cell size are temperature dependent. Triploids with larger cells performed best at cool conditions, while diploids performed better at warmer conditions. These results suggest different selection pressures on ectotherms and their cell size in cold and warm habitats.
Highlights
Cell size is emerging as an important trait in understanding the thermal biology of ectothermic animals, as the regulation and consequences of cell size appear to be dependent on temperature (Dufresne and Jeffery, 2011; Hessen et al, 2013; Alfsnes et al, 2017)
This study examined the effects of cell size on gene expression, growth, development and swimming performance in zebrafish larvae reared at different temperatures
Genome size matters for the biology of species
Summary
Cell size is emerging as an important trait in understanding the thermal biology of ectothermic animals, as the regulation and consequences of cell size appear to be dependent on temperature (Dufresne and Jeffery, 2011; Hessen et al, 2013; Alfsnes et al, 2017). A large variation in genome sizes is found (Horner and Macgregor, 1983; Gregory, 2001b; Jalal et al, 2015) and in extant fish, the variation in genome size spans the entire breadth of vertebrate genome sizes (Hardie and Hebert, 2004) This large variation in genome size can be partially attributed to whole-genome duplication (WGD) events in the teleost lineage after the divergence of tetrapods (Amores et al, 1998) and polyploidization events in chondrichtheans (cartilaginous fishes) (Stingo and Rocco, 2001), chondrosteans (sturgeons and bichirs) (Blacklidge and Bidwell, 1993) and in certain actinopterygians (ray-finned fishes) (Uyeno and Smith, 1972). Temperature-Dependent Effects of Cell Size have taken place following WGDs as genome size did not exponentially increase DNA content after consecutive WGDs, indicating that genome size and cell size is under selection
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