Speed or sperm: A potential trade-off between development and reproduction in the butterfly, Bicyclus anynana (Lepidoptera: Nymphalidae)

Abstract

Life-history theory predicts trade-offs between resources invested in reproduction and other fitness-related traits. To date, most studies have focused on potential reproductive trade-offs in females. However, it is now generally accepted that reproduction is also costly for males, and thus males too may be subject to trade-offs. We examined the relationship between development time and the production of both fertile and non-fertile sperm in males of the African bush brown butterfly (Bicyclus anynana) selected for short or long pre-adult development time. Fast developing males ejaculated fewer non-fertile sperm on their first mating, suggesting that there could be a trade-off between ejaculate production and development time in this species. Contrary to predictions, slow developing males were smaller, produced fewer fertile sperm and took longer to mate. We discuss why this might be the case, and suggest that there may be a cost to the production of non-fertile sperm in the Lepidoptera.

Keywords

• lepidoptera
• nymphalidae
• bicyclus anynana
• reproduction
• trade-off
• development time
• polymorphic sperm