Evolution in changing seas

Climate adaptation and vulnerability of foundation species in a global change hotspot

“…Hence, adaptive genetic variation in G. gemineoa (whose range extends northward along the east coast) associates most strongly with the dominant components of temperature variation throughout its range, as does adaptive variation in G. caespitosa (whose range is largely restricted to the south coast). This result emphasises the expected coupling of physical processes (e.g., oceanographic forcing) and evolutionary processes in the sea (Lotterhos et al, 2021), also detected in the handful of studies to so far link adaptive variants to physical characteristics of coastal ecosystems (Nielsen et al, 2021; Vranken et al, 2021; Wood et al, 2021). It may further suggest that sister Galeoalaria species have adapted to different selective pressures mediated by different components of temperature variation, facilitating poleward range shifts in G. gemineoa , especially, if conditions to which it has already adapted on the east coast extend southward with ongoing climate change.…”

“…Year-round, adults release gametes into the sea for external fertilization and embryogenesis (Chirgwin et al, 2020(Chirgwin et al, , 2021, then larvae spend ~2-3 weeks offshore, dispersed by currents, before transitioning to sessile life stages (juveniles and adults) onshore in the intertidal. As for other aquatic ectotherms, planktonic stages are thermal bottlenecks in the lifecycle, defining vulnerability to climate as well as population structure across species' ranges (Dahlke et al, 2020;Lotterhos et al, 2021;Rebolledo et al, 2020). Galeolaria caespitosa and G. gemineoa are said to diverge in the southeast hotspot near Ninety Mile Beach, due to historical vicariance, dispersal limitation, or lack of rocky habitat (Figure 1B; Styan et al 2008;Halt et al 2009).…”

“…By imposing different selective pressures, these components of climate change may have different consequences for biodiversity and lead to different risks of population decline (Bitter et al, 2021; Kingsolver & Buckley, 2017; Lande, 2014; Rescan et al, 2021; Ripa & Lundberg, 1996). To date, however, most assessments focus on adaptation to climate variables or proxies (precipitation, temperature, vegetation, elevation) relevant to terrestrial systems, whereas marine systems are underrepresented by comparison (Grummer et al, 2019; Lotterhos et al, 2021). Marine species often have high fecundity, large effective population sizes, and long-range dispersal at early life stages (gametes, embryos, and larvae) with high mortality, so that gene flow, selection, and drift play out in oceanographic settings that can strongly couple physical and evolutionary processes, while also decoupling the environments of early stages and adults.…”

“…Marine systems can therefore offer new genomic insights into climate adaptation and vulnerability (Liggins et al 2020), but studies remain rare (Vranken et al, 2021; Wood et al, 2021). They have not explored adaptation to environmental predictability, and are lacking for many species of ecological importance in regions undergoing rapid climate change where increased adaptation can be expected (Hill et al, 2011; Lotterhos et al, 2021).…”

“…They have not explored adaptation to environmental predictability, and are lacking for many species of ecological importance in regions undergoing rapid climate change where increased adaptation can be expected (Hill et al, 2011;Lotterhos et al, 2021).…”