Alternative reproductive strategies and the maintenance of female color polymorphism in damselflies

Abstract

Genetic polymorphisms are powerful model systems to study the maintenance of diversity in nature. In some systems, polymorphisms are limited to female coloration; these are thought to have arisen as a consequence of reducing male mating harassment, commonly resulting in negative frequency‐dependent selection on female color morphs. One example is the damselfly Ischnura elegans, which shows three female color morphs and strong sexual conflict over mating rates. Here, we present research integrating male tactics, and female evolutionary strategies (female mating behavior and morph‐specific female fecundity) in populations with different morph‐specific mating frequencies, to obtain an understanding of mating rates in nature that goes beyond the mere measure of color frequencies. We found that female morph behavior differed significantly among but not within morphs (i.e., female morph behavior was fixed). In contrast, male tactics were strongly affected by the female morph frequency in the population. Laboratory work comparing morph‐specific female fecundity revealed that androchrome females have lower fecundity than both of the gynochrome female morphs in the short term (3‐days), but over a 10‐day period one of the gynochrome female morphs became more fecund than either of the other morphs. In summary, our study found sex‐specific dynamics in response to different morph frequencies and also highlights the importance of studying morph‐specific fecundities across different time frames to gain a better understanding of the role of alternative reproductive strategies in the maintenance of female‐limited color polymorphism.

Molecular and ecological signatures of an expanding hybrid zone

“…Ischnura elegans has become an eco‐evolutionary model species because of its enigmatic female‐limited genetic color polymorphism and has been studied extensively for its population morph dynamics (Cordero & Andrés, ; Sánchez‐Guillén, Hansson, Wellenreuther, Svensson, & Cordero‐Rivera, ), the genetics of color (Chauhan, Wellenreuther, & Hansson, ; Chauhan et al., ; Sánchez‐Guillén, Van Gossum, & Cordero‐Rivera, ), and the processes maintaining the color polymorphism in nature (Sánchez‐Guillén et al., ; Svensson, Abbott, & Hardling, ; Takahashi, Yoshimura, Morita, & Watanabe, ). Ischnura elegans and I. graellsii are closely related (Sánchez‐Guillén et al., under revision) and share many phenotypic traits, including many preference traits for habitats.…”

A transposable element insertion is the switch between alternative life history strategies

“…Finally, our results and others (e.g. side-blotched lizards 29 & damselflies 30 ) suggest that investigating to what extent ALHS are associated with color variation in other systems is warranted, especially in cases where such variation is female limited.…”

Evolving social dynamics prime thermal tolerance during a poleward range shift

“…Ischnura elegans exhibits a genetically based, female-limited colour polymorphism (Sánchez-Guillén et al, 2005): androchromes resemble males with blue-green thorax and blue abdominal segment 8, whereas infuscans (olive-green thorax, brown segment 8) and infuscans-obsoleta (brown thorax and segment 8) are visually distinct from males and are collectively referred to as gynochromes (Cordero et al, 1998). Female morphs exhibit divergent behaviours and life histories (Van Gossum et al, 2001;Sánchez-Guillén et al, 2017), and site-specific colour morph frequencies have been shown to exhibit negative frequency-dependent dynamics (Takahashi et al, 2014;Le Rouzic et al, 2015) because common morphs exhibit decreased fecundity due to mating harassment under their scramble competition mating system (Van Gossum et al, 2001;Gosden & Svensson, 2007). Moreover, androchromes may receive additional protection from harassment due to their resemblance to males (intersexual mimicry; Gosden & Svensson, 2009).…”