Species Recognition and Patterns of Population Variation in the Reproductive Structures of a Damselfly Genus

Abstract

The selection pressures imposed by mate choice for species identity should impose strong stabilizing selection on traits that confer species identity to mates. Thus, we expect that such traits should show nonoverlapping distributions among closely related species, but show little to no variance among populations within a species. We tested these predictions by comparing levels of population differentiation in the sizes and shapes of male cerci (i.e., the clasper structures used for species identity during mating) of six Enallagma damselfly species. Cerci shapes were nonoverlapping among Enallagma species, and five of six Enallagma species showed no population variation across their entire species ranges. In contrast, cerci sizes overlapped among species and varied substantially among populations within species. These results, taken with previous studies, suggest that cerci shape is a primary feature used in species recognition used to discriminate conspecific from heterospecifics during mating.

Allometry of Male Grasping Apparatus in Odonates Does Not Suggest Physical Coercion of Females

“…McPeek and collaborators (2008McPeek and collaborators ( , 2009McPeek and collaborators ( , 2011 have determined a punctuated rate of evolution at the time of speciation and a reduced variance in inter-population differentiation for the grasping apparatus and mesostigmal plates in several Enallagma species. These pieces of evidence are coherent with the idea that both the grasping apparatus and mesostigmal plates have evolved to prevent interspecific mating and thus serve as a species isolation mechanism (McPeek et al 2008(McPeek et al , 2009(McPeek et al , 2011. This idea makes perfect sense for Enallagma and other species that show no precopulatory courtship, and where males simply chase females due to a poor ability to recognize conspecifics.…”

Non-adaptive radiation in damselflies

“…Studies on niche diversification have primarily concentrated on adults of the genus Calopteryx (Wellenreuther et al 2010a;Wellenreuther et al 2012), Enallagma (McPeek et al 1996McPeek and Peckarsky 1998;Brown et al 2000;Turgeon and McPeek 2002;Siepielski et al 2010) and Ischnura (Wellenreuther et al 2011;S anchez-Guill en et al 2012), while a lot less is known about larval ecology. Comparatively, more attention has been given to the role of nonecological selection on reproductive traits (see Box 2 for a summary of damselfly reproductive biology), including in Argia (Paulson 1974), Calopteryx (Svensson et al 2007;Svensson et al 2010Svensson et al , 2014Tynkkynen et al 2008b;Wellenreuther et al 2010a,b), Enallagma (Robertson and Patterson 1982;McPeek 1995;McPeek et al 2008McPeek et al , 2009McPeek et al , 2011, Ischnura (Paulson 1974;Monetti et al 2002;S anchez-Guill en et al 2005S anchez-Guill en et al , 2011aS anchez-Guill en et al 2012S anchez-Guill en et al , 2013a and Nehalenia (Van Gossum et al 2007). Given that the aim of this study was to examine the relative importance of ecological and nonecological forces in fuelling species diversity in damselflies, only those genera for which sufficient information was available for both categories were selected.…”

Assessing the potential information content of multicomponent visual signals: a machine learning approach

“…To be effective, species recognition signals should differ significantly in appearance between sympatric species but maintain similarity within species because stabilizing selection for easily identifiable signals should reduce phenotypic variation [20]. However, because multicomponent signals can vary on several non-redundant visual dimensions, it is possible that information additional to conspecific status is contained within face patterns [21].…”