Divergent alternative mating tactics in convergent male reproductive morphs

Alternative reproductive phenotypes involve polymorphic behaviours and
forms within sexes. Testing whether behavioural variants such as
alternative tactics (e.g., sneaking or satellite behaviour) are initially
co-expressed or decoupled from morphological polymorphisms (e.g., weapon
size or colour pattern) can provide insight into the origins of
reproductive diversity. In Hawaiian field crickets (Teleogryllus
oceanicus), an eavesdropping parasitoid fly selected for rapid, parallel
evolution of male wing mutations that reduce acoustic signals. Two of
these, ‘flatwing’ and ‘curly-wing’, co-occur in populations alongside
ancestral ‘normal-wing’ males that can sing. These convergent alternative
morphs may both rely on satellite tactics in which non-singing males
position themselves near calling males to intercept females, rather than
attracting mates directly by producing a conspicuous song. Here we test
whether flatwing and curly-wing vary in their tendencies to express
satellite behaviour using playback experiments with virgin, unmanipulated
males simulating natural conditions. Surprisingly, flatwing males were
significantly less likely to behave as satellites than normal-wing or
curly-wing males. Normal-wing males with poorer body condition were more
likely to behave as satellites, consistent with theory and previous
findings, but the reduced-sound morphs showed no such
condition-dependence. Our findings suggest that morph-specific variation
in the tendency to adopt satellite behaviour may contribute to the
maintenance of convergent male reproductive morphs; future work would
benefit from testing whether such variation is driven by acoustic
self-assessment. A decoupled relationship between behavioural reproductive
tactics and morphological reproductive strategies may promote
diversification of alternative mating morphs in nature.