Species-specific responses to tectonic disturbance
Species responses to environmental perturbations can be strongly governed by life-history strategies and habitat requirements (Sousa 1984; Ewers & Didham 2006). Although disturbances are critical for liberating new territories for recolonization, the survival of small refugial patches can still inhibit population genomic turnover in the disturbed patch (Fraser et al. 2018a). In our study, two species that tolerate subtidal conditions showed little or no evidence of historic disturbance. Specifically, only limited structuring was detected in the subtidal kelp D. willana . Additionally, the facultatively subtidal amphipod, P. karaka , was represented as a single, broadly panmictic population. This amphipod has enhanced swimming potential in water column (Fincham 1974; Lowry & Stoddart 1986) and has been reported from deeper sublittoral zones (Lowry & Stoddart 1983). These characteristics have possibly facilitated the survival of P. karaka through the uplift event by promoting host-switching to non-disturbed subtidal macroalgae such asMacrocystis pyrifera (Alonso 2012). On the contrary, while the chiton, O. neglectus, has the potential to survive under boulders on rocky shores (Salloum et al. 2020), the populations in Akatore did not persist through the coastal uplift and disruption of theDurvillaea hosts has left a significant genomic signature in the chiton populations. These findings suggest that microhabitat and dispersal ability can substantially influence species’ responses to major disturbance.
In summary, multispecies demographic analyses reveal a remarkably synchronous and concerted community-wide response to large-scale prehistoric disturbance. Moreover, our findings indicate that community-level genomic studies present a key approach for tracking the effects of major ecological perturbations increasingly expected under global change scenarios (e.g. Shive et al. 2018; Newman 2019; Ward et al. 2020).