Environmental fluctuations dampen the effects of clonal reproduction on evolutionary rescue

Abstract

Evolutionary rescue occurs when genetic change allows a population to persist in response to an environmental change that would otherwise have led to extinction. Most studies of evolutionary rescue assume that species have either fully clonal or fully sexual reproduction; however, many species have partially clonal reproductive strategies in which they reproduce both clonally and sexually. Furthermore, the few evolutionary rescue studies that have evaluated partially clonal reproduction did not consider fluctuations in the environment, which are nearly ubiquitous in nature. Here, we use individual‐based simulations to investigate how environmental fluctuations (either uncorrelated or positively autocorrelated) influence the effect of clonality on evolutionary rescue. We show that, for moderate magnitudes of environmental fluctuations, as was found in the absence of fluctuations, increasing the degree of clonality increases the probability of population persistence in response to an abrupt environmental change, but decreases persistence in response to a continuous, directional environmental change. However, with large magnitudes of fluctuations, both the benefits of clonality following a step change and the detrimental effects of clonality following a continuous, directional change are generally reduced; in fact, in the latter scenario, increasing clonality can even become beneficial if environmental fluctuations are autocorrelated. We also show that increased generational overlap dampens the effects of environmental fluctuations. Overall, we demonstrate that understanding the evolutionary rescue of partially clonal organisms requires not only knowledge of the species life history and the type of environmental change, but also an understanding of the magnitude and autocorrelation of environmental fluctuations.

How does genetic architecture affect eco-evolutionary dynamics? A theoretical perspective

“…Note that sexual reproduction, recombination and ploidy are fundamentally tightly related. ecological dynamics population extinction (evolutionary rescue) predator–prey cycles (including apparent and exploitative competition) genetic structure number of loci Orr & Unckless [ 91 ], Gomulkiewicz et al [ 92 ], Kardos & Luikart [ 93 ] Yamamichi & Ellner [ 94 ] recombination/epistasis Schiffers et al [ 95 ], Uecker & Hermisson [ 96 ] Patel & Bürger [ 97 ] clonal versus sexual reproduction/ploidy Orive et al [ 98 ], Uecker [ 99 ], Peniston et al [ 100 ] Schreiber et al [ 60 ], Doebeli & Koella [ 101 ], Doebeli [ 102 ], Bolnick et al [ 103 ] …”

Increased clonal growth in heavily harvested ecosystems failed to rescue ayahuasca lianas from decline in the Peruvian Amazon rainforest

“…The role of clonality and its relative contribution to population fitness and persistence is expected to be an evolutionary response or life history trade‐off between sexual and asexual reproduction driven by environmental stochasticity, disturbance (Silvertown, 2008), evolutionary history and genetic variance (Barrett, 2015; Hesse et al, 2008). In this context, clonality can serve as a mechanism for ecological and evolutionary rescue that allows certain plant species in decline to delay extinction and maintain genetic diversity in disturbed ecosystems (Franklin et al, 2021; Peniston et al, 2021; Silvertown, 2008). Although the importance of clonality or vegetative reproduction to population fitness of a few harvested species is well documented (see for e.g.…”