A quantitative genetic approach to assess the evolutionary potential of a coastal marine fish to ocean acidification

Abstract

Assessing the potential of marine organisms to adapt genetically to increasing oceanic CO2 levels requires proxies such as heritability of fitness-related traits under ocean acidification (OA). We applied a quantitative genetic method to derive the first heritability estimate of survival under elevated CO2 conditions in a metazoan. Specifically, we reared offspring, selected from a wild coastal fish population (Atlantic silverside, Menidia menidia), at high CO2 conditions (∼2300 μatm) from fertilization to 15 days posthatch, which significantly reduced survival compared to controls. Perished and surviving offspring were quantitatively sampled and genotyped along with their parents, using eight polymorphic microsatellite loci, to reconstruct a parent–offspring pedigree and estimate variance components. Genetically related individuals were phenotypically more similar (i.e., survived similarly long at elevated CO2 conditions) than unrelated individuals, which translated into a significantly nonzero heritability (0.20 ± 0.07). The contribution of maternal effects was surprisingly small (0.05 ± 0.04) and nonsignificant. Survival among replicates was positively correlated with genetic diversity, particularly with observed heterozygosity. We conclude that early life survival of M. menidia under high CO2 levels has a significant additive genetic component that could elicit an evolutionary response to OA, depending on the strength and direction of future selection.

You Better Repeat It: Complex CO2 × Temperature Effects in Atlantic Silverside Offspring Revealed by Serial Experimentation

“…Despite being an annual fish with high population connectivity, Atlantic silversides exhibit local adaptation for traits involved in growth and environmental sex determination [77], which are likely maintained through the continuous selection of locally suited genotypes [78]. As previously demonstrated, early life survival under high CO 2 conditions is a heritable trait in this species, suggesting that CO 2 tolerance could evolve [63]. Local adaptation to acidified habitats through the selection and maintenance of CO 2 -tolerant traits has been demonstrated in other taxa [29].…”

“…The target level for high CO 2 was 2200 µatm (~7.50 pH), a level that is commonly experienced by silverside offspring in late spring and summer (Figure 1), but also represents the maximum prediction of average OA for the next 300 years [67] and therefore a common benchmark in many OA studies [61][62][63]. The target level for the extreme CO 2 treatment was 6000 µatm (~7.15 pH) during experiment 1, but was reduced to 4200 µatm (~7.20 pH) for experiments 3 and 5.…”

“…Trait are abbreviated as embryo survival (ES), hatch length (HL), larval survival (LS), and growth rate (GR). Strip-spawning protocols maximized fertilization success, while enabling random distribution of embryos across replicates [61,63]. For each experiment, eggs from 12+ running-ripe females were gently mixed into shallow plastic dishes lined with 1-mm plastic window screening.…”

An updated synthesis of the observed and projected impacts of climate change on the chemical, physical and biological processes in the oceans

“…Nevertheless, evidence of a few examples of genetic variations are emerging and have been observed in sea urchins and polychaete worms (Calosi et al, 2013;Kelly et al, 2013;Pespeni et al, 2013), as well as genetic variations in fish that could illicit evolutionary adaptation (Malvezzi et al, 2015). Acclimatization and trans-generational phenotypic plasticity over longer-term experiments have been observed in sea urchins (Dupont et al, 2013) and carry over effects of brief exposure to acidification on growth of oyster larvae (Hettinger et al, 2013).…”

Genotyping Live Fish Larvae: Non-Lethal and Noninvasive DNA Isolation from 3–5 day Old Hatchlings

“…The ability to genotype fish larvae is leading to important advances in several fields, including aquatic toxicology (14), global climate change (5), population genetics (6,7), aquaculture (8,9), and developmental and biomedical genetics (10,11). The small size of fish larvae limits tissue availability; thus, when live specimens are not required, DNA yields are maximized by digesting dissected body parts (e.g., eye balls or caudal peduncles) or entire specimens (References 5, 12, 13, and especially Reference 14).…”