No Reproductive Interference from an Alien to a Native Species in Cerastium (Caryophyllaceae) at the Stage of Seed Production

Abstract

Reproductive interference, adverse interspecific interaction during the mating process, has been regarded as a powerful driver of species displacement between species. Recent empirical reports have described its importance in biological invasions. This study was undertaken to test whether a rare herbaceous plant species indigenous to Japan suffered reproductive interference from an alien species of the genus Cerastium. Field observations and a transplanting experiment were conducted to ascertain the effects of coexistence with an alien species on the seed production of the native species. Results show that coexistence with the alien species did not significantly decrease seed numbers, but it significantly affected the seed weight only in field observations. In this study, the reproductive process of the native species was examined only at or before the seed production stage. Because the interspecific pollen transfer might produce hybrids with low viability or fertility, reproductive interference cannot be denied in this study. To test reproductive interference at such latter stages, additional studies should be conducted. Consequently, detection of reproductive interference demands high costs in some species. Based on these results and suggestions, the necessity of narrowing down the target species for testing of reproductive interference is discussed to elucidate the universality of reproductive interference.

Island biogeography as a test of reproductive interference

“…Instead, the invasion by V. persica probably brought about the habitat alteration of V. p. lilacina on the mainland. The exclusion of native plants by aliens has been claimed in some species to date (Ogawa and Mototani 1985;Cheng et al 2009;Takakura 2012). The present study differs from most prior studies in the following respect.…”

When does reproductive interference occur? Predictions and data

“…These results support the prediction that coexisting species pairs will not show strong reproductive interference, the contraposition of the statement that strong reproductive interference impedes species coexistence. Similar results can also be found between coexisting invasive and native species (Nishida et al, 2016;Takakura, 2012) or between coexisting invasive species (Takakura & Fujii, 2010).…”

“…The last two decades have witnessed increased interest in the ecological significance of reproductive interference (Coyne & Orr, 2004;Kyogoku, 2015). Whereas many studies have verified a substantial fitness cost associated with reproductive interference, suggesting its ecological significance, others have observed the virtual absence of reproductive interference among the species studied; heterospecific mating interactions may not occur, or may not be associated with fitness cost (e.g., Cothran, Stiff, Chapman, Wellborn, & Relyea, 2013;Ficetola & De Bernardi, 2005;Nishida, Hashimoto, Kanaoka, Takakura, & Nishida, 2016;Takakura, 2012). In this article, because heterospecific mating interactions are not necessarily associated with a large fitness cost, I distinguish the mere occurrence of heterospecific mating interactions from those that are associated with a fitness cost (i.e., reproductive interference).…”