Effect of body condition on mobility and mating success in a wild population of the scramble polygynous Cook Strait giant weta

• Published in: Behavioral ecology and sociobiology 2023, Vol.77 (1), p.5, Article 5
• Main Authors: Kelly, Clint D., Gwynne, Darryl T.
• Format: Article
• Language: English
• Subjects: Animal Ecology; Animal reproduction; Anostostomatidae; Behavioral Sciences; Biomedical and Life Sciences; Body weight; Endurance; Females; Field tests; Life Sciences; Males; Night; Original Article; Orthoptera; Population studies; Radio telemetry; Searching; Success; Telemetry; Travel; Zoology
• ISSN: 0340-5443; 1432-0762
• DOI: 10.1007/s00265-022-03278-3

Males in scramble competitive species that are in better condition are expected to have better endurance and thus be able to travel farther during bouts of mate searching. In this study, we use radio telemetry to field test the hypothesis that male Cook Strait giant weta Deinacrida rugosa (Orthoptera: Anostostomatidae) in better body condition accrue more mates because they are more mobile (i.e., travel farther per night in mate searches). Our study showed that males travel significantly farther, on average, each night than females and that individuals exhibit consistent travel distances and body conditions across days. As predicted, we found that male mating success was influenced by body condition and travel distance; however, contrary to expectation, both variables were negatively related to mating success. Contrary to expectation, we did not find an effect of body condition on travel distance in either sex nor did we find that increased nightly travel was more costly to body condition. We suggest that males in our study population that are lighter for their body weight (i.e., poorer condition) might be superior in sprints for nearby females. Consequently, these successful males will then reduce their movement because females are relatively sedentary. If a male is unable to acquire a female that is nearby, he is likely then obligated to engage in a prolonged mate search that is generally unsuccessful. Significance statement Males in better body condition are expected to be more successful in scrambles for mates because they should have better endurance and thus be able to travel farther while mate searching. Our field test found, as predicted, that the mating success of male Cook Strait giant weta Deinacrida rugosa (Orthoptera: Anostostomatidae) was influenced by body condition and travel distance; however, contrary to expectation, both variables were negatively related to mating success. Contrary to expectation, we found that nightly mate searching had no effect on body condition and vice versa. Our study presents rare evidence of male mating success in a scramble competitive species being affected by body condition and mate-searching effort (as measured by travel distance) albeit in a manner opposite to prediction.