Does past evolutionary history under different mating regimes influence the demographic dynamics of interspecific competition?

Abstract

Interspecific interactions are contingent upon organism phenotypes, and thus phenotypic evolution can modify interspecific interactions and affect ecological dynamics. Recent studies have suggested that male–male competition within a species selects for capability to reproductively interfere with a closely related species. Here, we examine the effect of past evolutionary history under different mating regimes on the demographic dynamics of interspecific competition in Callosobruchus seed beetles. We used previously established experimental evolution lines of Callosobruchus chinensis that evolved under either forced lifelong monogamy or polygamy for 17 generations, and examined the demographic dynamics of competition between these C. chinensis lines and a congener, Callosobruchus maculatus . Callosobruchus chinensis was competitively excluded by C. maculatus in all trials. Time series data analyses suggested that reproductive interference from C. chinensis was relatively more important in the trials involving polygamous C. chinensis than those involving monogamous C. chinensis , in accordance with the potentially higher reproductive interference capability of polygamous C. chinensis . However, the estimated signs and magnitudes of interspecific interactions were not fully consistent with this explanation, implying the evolution of not only reproductive interference but also other interaction mechanisms. Our study thus suggests multifaceted effects of sexually selected traits on interspecific competitive dynamics.

Successful mating and hybridisation in two closely related flatworm species despite significant differences in reproductive morphology and behaviour

“…A mate choice experiment showed that males from polyandrous populations had a higher probability of mating than those from monogamous populations 93 , potentially due to having evolved under strong male-male competition and hence initiating courtship faster and more frequently than monogamous males 94 . Similarly, an experimental evolution study on a seed beetle, Callosobruchus chinensis , also showed that beetles evolved under a polygamous regime caused stronger reproductive interference on the congener, C. maculatus , than beetles evolved under a monogamous regime 95 , 96 . In addition to the above examples, multiple empirical studies have proposed a role of sexual selection in occurrence of reproductive interference between species 97 , 98 .…”

Seed beetles as a modern model system of interspecific competition

“…Competition outcomes are not always consistent across studies. Although the typical outcome is the extinction of C. maculatus (as was the case in Kishi et al, 2009), some studies have shown the extinction of C. chinensis (Fujii, 1969;Ishii & Shimada, 2008;Kyogoku et al, 2019;Utida, 1953). Kawatsu and Kishi (2018) reanalyzed the results of Kishi et al (2009) and Ishii and Shimada (2008) using a time series analysis technique and found evidence for the action of stronger reproductive interference in the experiment of Kishi et al (2009) than that of Ishii and Shimada (2008).…”

“…In a typical laboratory setting where adults are not provided food or water, resource competition is limited to the larval stage, whereas reproductive interference is limited to the adult stage. This life‐stage specific occurrence of competitive interactions allowed several studies to examine the relative importance of the two modes of species interactions (Kawatsu & Kishi, 2018; Kishi et al, 2009; Kyogoku et al, 2019).…”

“…Understanding the underlying mechanism of these between‐study differences will help us to better understand interspecific competitive interactions. Studies by Kawatsu and Kishi (2018), Kishi (2015), and Kyogoku et al (2019) are rare examples of attempts to explain the differences among competition trials involving different beetle strains, considering not only resource competition, but also reproductive interference. However, these studies focused on between‐strain differences in C. chinensis ; thus, we do not know how the differences among C. maculatus strains can influence the strength of reproductive interference, and how the variation in resource competition and reproductive interference (possibly interactively) can determine the eventual competition outcome.…”

“…In addition, population characteristics other than the strengths of interspecific interactions can influence competition outcome. For example, evolutionary change in female fecundity could underlie the different outcomes between the studies of Kishi et al (2009) and Kyogoku et al (2019) (see also Kyogoku & Sota, 2017b).…”