Abstract
Marine organisms living at low temperatures tend to have larger genomes and larger cells which suggest that these traits can be beneficial in colder environments. In fish, triploidy (three complete sets of chromosomes) can be induced experimentally following fertilization, which provides a model system to investigate the hypothesis that larger cells and genomes offers a physiological advantage at low temperatures. We tested this hypothesis by measuring metabolic rates and swimming performance of diploid and triploid Atlantic salmon (Salmo salar) post smolts acclimated to 3 or 10.5°C. At 10.5°C, triploids had significantly lower maximum metabolic rates which resulted in a lower aerobic scope compared to diploids. In addition, triploids initiated ram ventilation at lower swimming speeds, providing further evidence of a reduced capacity to meet oxygen demands during strenuous activity at 10.5°C. However, at 3°C, metabolic rates and critical swimming speeds were similar between both ploidies, and as expected substantially lower than at 10.5 °C. Therefore, triploidy in colder environments did not provide any advantage over diploidy in terms of metabolic rate traits or swimming performance in Atlantic salmon. We therefore conclude that traits, other than aerobic scope and swimming performance, contribute to the trend for increased cell and genome size in marine ectotherms living in cold environments.
Highlights
A curious and widespread phenomenon in marine ecosystems is that ectotherms living at lower temperatures tend to have larger genomes and cell sizes (Arendt, 2007; Rees et al, 2007; Hessen et al, 2013)
This suggests that larger genomes and/or larger cell sizes provide some general advantages in colder environments, or that they are selected against in warmer environments
The marginal and conditional R2 of the final model was determined using the command “r.squaredGLMM”, which returns the variance explained when excluding or including the random effect, respectively (Nakagawa and Schielzeth, 2013). Following this we looked for ploidy interactions with tempera ture on aerobic scope (AS), critical swimming speed (Ucrit) and onset of ram ventilation (Uram)
Summary
A curious and widespread phenomenon in marine ecosystems is that ectotherms living at lower temperatures tend to have larger genomes and cell sizes (Arendt, 2007; Rees et al, 2007; Hessen et al, 2013). This suggests that larger genomes and/or larger cell sizes provide some general advantages in colder environments, or that they are selected against in warmer environments. Growth is expected to be positively associated with temperature and the lower surface area to volume rate of larger cells may limit nutrient and gas exchange, which could become a disadvantage at higher temperatures
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.