Sympatry with the devil: reproductive interference could hamper species coexistence

Abstract

Summary 1.As species are often considered discrete natural units, interspecific sexual interactions are often disregarded as potential factors determining community composition. Nevertheless reproductive interference, ranging from signal jamming to hybridization, can have significant costs for species sharing similar signal channels. 2. We combined laboratory and field experiments to test whether the coexistence of two congeneric ground-hopper species with overlapping ranges might be influenced by sexual interactions. 3. In the laboratory experiment the number of conspecific copulations of Tetrix ceperoi decreased substantially in the presence of Tetrix subulata . Males of T. ceperoi performed more mating attempts with heterospecific females, whereas females of T. subulata rejected these heterospecific approaches more often than those of conspecifics. Although no heterospecific matings occurred in the laboratory, the reproductive success of T. ceperoi was reduced substantially in field experiments. Negative effects on T. subulata were found only at high densities. 4. Our results suggest that reproductive interference could have similar consequences as competition, such as demographic displacement of one species ('sexual exclusion'). As reproductive interference should be selected against, it may also drive the evolution of signals (reproductive character displacement) or promote habitat, spatial or temporal segregation.

Three Modes of Adaptive Speciation in Spatially Structured Populations

“…Even though these studies typically focus on interference between species that are already fully isolated, the results are likely to be relevant also for incipient species and intraspecific polymorphisms. Most importantly, these studies show that reproductive interference can have severe fitness consequences and can lead to the extinction of rare species due to "sexual exclusion" (Kuno, 1992;Hochkirch et al, 2007;Thum, 2007;Kishi et al, 2009). Some authors have argued that sexual exclusion may be more important for structuring communities than competitive exclusion (Gröning & Hochkirch, 2008 and references therein), and that it may explain the non-overlapping geographical distributions of some closely related species (Thum, 2007).…”

Life‐history divergence facilitates regional coexistence of competing Ficedula flycatchers

“…Thus, there is likely to be strong interspecific competition over both breeding territories and food resources. In addition, reproductive interference may also lead to exclusion where the breeding distributions of closely related species overlap (e.g., Hochkirch et al 2007, Gro¨ning andHochkirch 2008). Female flycatchers prefer males of their own species as mates (Saetre et al 1997), but they occasionally hybridize, especially when males of their own species are rare (C. Wiley et al, unpublished manuscript).…”

Reproductive interference by male Drosophila subobscura on female D. persimilis: A laboratory experiment

“…However, few known model systems are ideal for studying ecological and evolutionary effects of reproductive interference, and several proposed cases thus far are inferential. For example, while inter‐specific matings in the groundhoppers Tetrix ceperoi and T. subulata interfere with conspecific matings in the laboratory, and although they rarely co‐occur in the same sites, it is not yet known whether the rarity of the former is due to reproductive interference (Hochkirch et al., 2007). Further, encounter rates between these species in the wild may be low as a result of microhabitat differences (Gröning, Lücke, Finger, & Hochkirch, 2007).…”