Sympatry with the devil: reproductive interference could hamper species coexistence
Present address: Amelie Bücker, University of Gießen, Institute of Landscape Ecology and Resources Management, Heinrich-Buff-Ring 26, D-35392 Gießen, Germany
Dr Axel Hochkirch, University of Osnabrück, Department of Biology/Chemistry, Division of Ecology, Barbarastr. 13, D-49076 Osnabrück, Germany. Tel.: 49 541 969 2854. Fax: 49 541 969 2815. E-mail: firstname.lastname@example.org
- 1As 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.
- 2We 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.
- 3In 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.
- 4Our 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.