How does the magnitude of genetic variation affect ecological and reproductive character displacement?

Abstract

While previous studies on character displacement tended to focus on trait divergence and convergence as a result of long‐term evolution, recent studies suggest that character displacement can be a special case of evolutionary rescue, where rapid evolution prevents species extinction by weakening interspecific competition. Here we analyzed a simple model to examine how the magnitude of genetic variation affects evolutionary rescue via ecological and reproductive character displacement that weakens interspecific competition in exploitation of shared resources (i.e., resource competition) and in the mating process caused by incomplete species recognition (i.e., reproductive interference), respectively. We found that slow trait divergence due to small genetic variance results in species extinction in reproductive character displacement but not in ecological character displacement. This is because one species becomes rare in slow character displacement, and this causes deterministic extinction due to minority disadvantage of reproductive interference. On the other hand, there is no deterministic extinction in the process of ecological character displacement. Furthermore, species extinction becomes less likely in the case of positive covariance between ecological and reproductive traits as divergence of the ecological trait (e.g., root depths) increases the divergence speed of the reproductive trait (e.g., flower colors) and vice versa. It will be interesting to compare intraspecific genetic (co)variance of ecological and reproductive traits in future studies for understanding how ecological and reproductive character displacement occur without extinction.

Frequency‐dependent community dynamics driven by sexual interactions

“…However, recent empirical studies have shown the potential importance of positive frequency-dependence due to reproductive interference in insects (Kawatsu & Kishi, 2018;Ohsaki et al, 2020), fish (Tsurui-Sato et al, 2019), and plants (Christie & Strauss, 2020;Johnson et al, 2022;Nishida et al, 2020) as well as other taxa. In parallel, theoretical models have been developed and analyzed for understanding the effects of frequency-dependent interference (Iritani & Noriyuki, 2021;Kishi & Nakazawa, 2013;Kuno, 1992;Paton & Bonsall, 2019;Schreiber et al, 2019;Yoshimura & Clark, 1994), density-dependent interference (Kyogoku & Sota, 2017;Yamamichi & Koizumi, 2020), and evolution for avoiding reproductive interference through reproductive character displacement (cf., reinforcement) (Goldberg & Lande, 2006;Irwin & Schluter, 2022;Konuma & Chiba, 2007;Kyogoku & Kokko, 2020;Kyogoku & Wheatcroft, 2020;Kyogoku & Yamaguchi, 2023;Morita & Yamamichi, 2023;Pfennig & Pfennig, 2009;Yamaguchi & Iwasa, 2013) or through selfing (Katsuhara et al, 2021) on population persistence and community dynamics.…”

Population Ecology 2024 Editorial

“…This special feature reviewed context dependency of community assembly rules and synthesized the current understanding of how the relative importance of multiple assembly processes changes with spatial scales, complexity, and time, both in the long and short terms. Second, “Sex and biological communities,” organized by Masato Yamamichi, was published with three papers (Marre et al, 2023; Morita & Yamamichi, 2023; Yamamichi et al, 2023), supported by our Special Feature Editor, Dr Akihiko Mougi. This special feature investigated the various effects of sexual reproduction on structures of ecological communities.…”

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

“…In addition, speciation processes can be studied from the perspective of eco-evolutionary dynamics. For example, rapid evolution in reproductive character displacement (reinforcement) can prevent population extinction by weakening reproductive interference and positive frequency-dependence in community dynamics due to incomplete reproductive isolation [ 111 , 112 ]. It may be interesting to study how the genetic basis of speciation (speciation genes: figure 3 c , d ) affects eco-evolutionary dynamics.…”