Responses to artificial selection for locomotor activity: A focus on death feigning in red flour beetle

Abstract

Whole‐organism performance, including locomotor activity, is an important fitness trait in many animals. Locomotor activity is often classified into sprint speed and locomotor endurance and differences in sprint speed and locomotor endurance affect on other traits such as life‐history traits. Previous studies found that locomotor endurance, sprint speed and brain dopamine (DA) levels are correlated with artificial selection for death feigning (an anti‐predator behaviour that we refer to as ‘death‐feigning syndrome’) in some insect species. Thus, if the syndrome has a genetic basis, death feigning, sprint speed and brain DA levels may be affected by artificial selection for locomotor endurance. We artificially selected for locomotor endurance over 10 generations in the red flour beetle Tribolium castaneum, and established higher (H) and lower activity (L) strains, then compared their death‐feigning behaviour, sprint speed and brain DA levels. H‐strain beetles exhibited significantly shorter duration of death‐feigning, and significantly higher sprint speeds, suggesting variation in death‐feigning syndrome. Surprisingly, although brain DA expression affects various animal behaviours, we found no significant differences in the brain DA expressions of H‐ and L‐strain beetles. Thus, our results imply genetic correlations between locomotor endurance, sprint speed and death feigning, but not with brain DA expression, suggesting that differences in the biogenic amine results of our and previous studies may reflect differences in behavioural expression mechanisms.

The red flour beetle T. castaneum: elaborate genetic toolkit and unbiased large scale RNAi screening to study insect biology and evolution

“…Likewise, T. castaneum shows a more ancestral state with respect to the neuroendocrine system and the subesophageal ganglion has been studied with respect to adult neurogenesis [ 55 – 57 ]. Since the T. castaneum CNS is also amenable to systemic RNAi [ 58 , 59 ], there should be a future for behavioral genetics via RNAi in the beetle, for example to study circadian activity or in death feigning behavior [ 60 , 61 ].…”

Trade‐off between pre and post‐copulatory traits depends on locomotor activity in male Tribolium castaneum beetles

“…During scramble competition, average search speed or endurance (i.e., stamina, involving largely aerobic processes) is likely more important than maximal sprinting speed (a largely anaerobic process) for maximizing mate encounters (Moya‐Laraño, El‐Sayyid, & Fox, 2007). The selection regimes used in the present study were selected for 24 h of locomotor endurance, and endurance rather than speed differs between the two selection regimes (Matsumura et al, 2022); therefore, it is likely that high endurance also contributed to the high frequency of encounters with females. The mating activity of H males was higher than that of L males; thus, higher locomotor endurance may lead to increased mating success in T. castaneum males.…”

“…Methods for generating the T. castaneum lines with high and low locomotor endurance that we use here have been described previously (Matsumura et al, 2022). Briefly, 80 males and 80 females (all 21–35‐day‐old virgins) were randomly collected from the stock culture and each beetle was placed in a clear Petri dish (35 mm in width; 10 mm in height) lined with filter paper.…”

“…I also created replicate lines of each selection regime (H1–H4 and L1–L4, respectively). More details on the selection experiment were provided by Matsumura et al (2022).…”

“…In a previous study, artificial selection for locomotor endurance in T. castaneum adults was conducted over 12 generations, and selection regimes with genetically higher locomotor endurance (H) and lower locomotor endurance (L) were established (Matsumura et al, 2022). In the present study, I measured the number of matings and attractiveness as pre‐copulatory sexual traits and paternity success as a post‐copulatory sexual trait in males, and these reproductive traits were compared between H and L males.…”