Little evidence of adaptation potential to ocean acidification in sea urchins living in “Future Ocean” conditions at a CO₂ vent

Abstract

Ocean acidification (OA) can be detrimental to calcifying marine organisms, with stunting of invertebrate larval development one of the most consistent responses. Effects are usually measured by short‐term, within‐generation exposure, an approach that does not consider the potential for adaptation. We examined the genetic response to OA of larvae of the tropical sea urchin Echinometra sp. C. raised on coral reefs that were either influenced by CO2 vents (pH ~ 7.9, future OA condition) or nonvent control reefs (pH 8.2). We assembled a high quality de novo transcriptome of Echinometra embryos (8 hr) and pluteus larvae (48 hr) and identified 68,056 SNPs. We tested for outlier SNPs and functional enrichment in embryos and larvae raised from adults from the control or vent sites. Generally, highest FST values in embryos were observed between sites (intrinsic adaptation, most representative of the gene pool in the spawned populations). This comparison also had the highest number of outlier loci (40). In the other comparisons, classical adaptation (comparing larvae with adults from the control transplanted to either the control or vent conditions) and reverse adaptation (larvae from the vent site returned to the vent or explanted at the control), we only observed modest numbers of outlier SNPs (6–19) and only enrichment in two functional pathways. Most of the outliers detected were silent substitutions without adaptive potential. We conclude that there is little evidence of realized adaptation potential during early development, while some potential (albeit relatively low) exists in the intrinsic gene pool after more than one generation of exposure.

Limitations of cross‐ and multigenerational plasticity for marine invertebrates faced with global climate change

“…These environments are likely to exert strong selection on recruiting larvae. Selection post-settlement may promote genetic differences as seen in the selective survival of sea urchin larvae reared under acidification, although with reduced genetic diversity (Lloyd, Makukhov, & Pespeni, 2016;Uthicke et al, 2019). Resident species that lack a dispersal phase (e.g.…”

The male and female gonad transcriptome of the edible sea urchin, Paracentrotus lividus: identification of sex-related and lipid biosynthesis genes

“…For instance, in the sea urchins Strongylocentrotus intermedius (Zhan et al 2019), in Echinometra sp. embryos (Uthicke, Deshpande et al 2019) or in giant red sea urchin Mesocentrotus franciscanus (Gaitán-Espitia and Hofmann 2017), de novo assemblies achieved 82.5%, 91%, 88% of complete genes in eukaryotic database, respectively.…”

Cross‐generational response of a tropical sea urchin to global change and a selection event in a 43‐month mesocosm study

“…This has included research on Echinometra sp. C at vents to determine responses in adult physiology and growth (Uthicke et al, 2016), larval responses (Lamare et al, 2016), and population genomic responses (Uthicke et al, 2019). In these previous field‐based studies, we argued that the inference for multigenerational acclimatization in vent taxa is limited for organisms with planktonic life stages such as sea urchins.…”

“…Among sea urchins, potential for adaptation to climate change over longer time periods was examined on natural CO 2 vent systems (Uthicke et al, 2019) and coastal upwelling areas (Pespeni et al, 2012, 2013) employing population genomics and larval transplant experiments (Lamare et al, 2016). In addition to longer term responses to environmental change through differential expression and selection, population responses can also occur during more immediate chance events, such as pathogen‐induced disease outbreaks, often associated with climate extremes such as marine heatwaves (Minuti et al, 2021).…”

“…Observations over several generations, however, are still rare (Byrne et al, 2020;but see Cornwall et al, 2020) and often focus on smaller marine invertebrate taxa with short generation times (e.g., Coccolithophorids: Schluter et al, 2014, copepods: De Wit et al, 2016Thor & Dupont, 2015). Among sea urchins, potential for adaptation to climate change over longer time periods was examined on natural CO 2 vent systems (Uthicke et al, 2019) and coastal upwelling areas (Pespeni et al, 2012(Pespeni et al, , 2013 employing population genomics and larval transplant experiments (Lamare et al, 2016). In addition to longer term responses to environmental change through differential expression and selection, population responses can also occur during more immediate chance events, such as pathogen-induced disease outbreaks, often associated with climate extremes such as marine heatwaves (Minuti et al, 2021).…”