Sequential disturbances alter the outcome of inter‐genotypic interactions in a clonal plant

Abstract

Multiple disturbances can have contrasting or interactive effects on biodiversity. When disturbances result in reductions in abundance beyond the ability for a species to recover, regime shifts or local extinctions may result (reviewed in Buma, 2015; Paine et al., 1998; Turner, 2010). Disturbance can also affect diversity by reducing the average fitness differences between species, which reduces the impact of competition and delays (but does not prevent) exclusion (Chesson, 2000). However, the occurrence of multiple different types of disturbances can help promote the long-term coexistence of species if they create opportunities for niche differentiation in space or time (e.g. Chesson, 2000; Chesson & Huntly, 1997). This occurs if the different disturbances favour alternative ecological strategies such that the existence of multiple disturbances has a stabilizing effect on diversity (sensu Chesson, 2000), for example by creating a fluctuating environment in which no species is favoured for long enough to achieve

Local adaptation in a marine foundation species: Implications for resilience to future global change

“…For example, eelgrass traits that favor increased performance under winter light limited conditions are negatively correlated with traits that favor increased performance during summer marine heatwaves (DuBois et al, 2019). Similarly, eelgrass traits predicting greater competitive ability under warming or intense herbivory (simulated with leaf clipping) were not the same (Kollars et al, 2020). Negative correlations among only a few key traits can be sufficient to slow evolutionary response to changing climates (Etterson & Shaw, 2001).…”

“…valida abundance (as well as entire epifaunal communities) differed across sites only during the spring and summer (Figures 2b and 5a). Thus, evaluation of the importance of trade‐offs among multiple stressors should also consider the temporal variation in selective agents and the order that multiple stressors are experienced (Kollars et al, 2020). Instead of evidence for trade‐offs among specific stressors, we observed a strong trade‐off between maintaining performance at stressful sites (Millerton and Nick's Cove) and inability to increase growth under more benign conditions (Blakes Landing).…”

Disturbance decreases genotypic diversity by reducing colonization: Implications for disturbance–diversity feedbacks

“…The extinction of rare genotypes, regardless of treatment, is not surprising given that genets with few ramets likely have less reserves that can be shared intra-clonally via belowground connections (reviewed in Song et al 2013). What is unexpected is that clipping did not act as a selection agent, especially given previous research showing genotypic variation for tolerance to clipping among genotypes collected from this site (Kollars et al 2021). One possible explanation for the lack of discernable selection, despite genotypic variation for tolerance, is fluctuating selection generated by the temporally concentrated nature of the selective agent (e.g., Tiffin and Rausher 1999).…”

“…Grazing is seasonal and other selective agents may dominate during different times of the year. For example, heat tolerance may be important during the late summer and our previous work finds that warming and clipping favor distinct trait combinations (Kollars et al 2021).…”

“…This observation, coupled with research showing increased sexual recruitment of Zostera in areas of reduced standing biomass (Johnson et al, 2020; Reusch, 2006; Robertson & Mann, 1984), suggests that clipping disturbance may enhance genotypic diversity. However, clipping could reduce diversity if it created population bottlenecks that drive the stochastic loss of genets or if it acted as a selective agent by favoring more tolerant genotypes (Kollars et al, 2021). Therefore, we expected that clipping disturbance would increase both the colonization of new genets and the extinction of established genets, but we did not make an a priori prediction about how the combined effects of these two processes would drive net change in richness.…”