Flexible memory controls sperm competition responses in maleDrosophila melanogaster

Abstract

Article:Rouse, J orcid.org/0000-0001-8457-4623, Watkinson, K and Bretman, A orcid.org/0000-0002- 4421-3337 (2018) AbstractMales of many species use social cues to predict sperm competition and tailor their reproductive strategies, such as ejaculate or behavioural investment, accordingly. Whilst these plastic strategies are widespread, the underlying mechanisms remain largely unknown. Plastic behaviour requires individuals to learn and memorise cues associated with environmental change before using this experience to modify behaviour. Drosophila melanogaster respond to an increase in sperm competition threat by extending mating duration after exposure to a rival male. This behaviour shows lag times between environmental change and behavioural response suggestive of acquisition and loss of memory. Considering olfaction is important for a male's ability to assess the sperm competition environment, we hypothesised that an olfactory learning and memory pathway may play a key role in controlling this plastic behaviour. We assessed the role of genes and brain structures known to be involved in learning and memory. We show that sperm competition responses depend on anaesthesia sensitive memory, specifically the genes rut and amn. We also show that the lobes of the mushroom bodies are integral to the control of plastic mating behaviour. These results reveal the genetic and neural properties required for reacting to changes in the sperm competition environment.

The role of complex cues in social and reproductive plasticity

“…Though the study of complex cues has begun in the context of social and sexual plasticity (Bretman et al 2011b; Rouse and Bretman 2016; Rouse et al 2018), the benefits and costs are yet to be fully experimentally explored, especially in longitudinal studies. Such data would improve our understanding of how the perception of complex cues to inform social and reproductive plasticity evolved.…”

The microevolutionary response to male-limited X-chromosome evolution inDrosophila melanogasterreflects macroevolutionary patterns

“…Recent results suggest that vision may be more important to mating in Drosophila than was previously expected (Ribeiro et al 2018). Similarly, learned male mate choice has been demonstrated in the ancestral population (Verzijden et al 2015), and it is known that males use memory to evaluate their risk of sperm competition and allocate resources accordingly (Rouse et al 2018), so terms related to learning, memory and nervous system development may also be a result of selection via mating interactions.…”

Social effects on fruit fly courtship song

“…The memory mutant strains we used to investigate the role of learning in plastic song responses have been shown to display dysfunctional social responses and courtship learning (Griffith, ). For instance, amnesiac, but not dunce, do not increase mating duration in response to the presence of conspecific rivals (Rouse et al, ). Similarly, both amnesiac and dunce fail to suppress courtship efforts after unsuccessful mating attempts (Emmons & Lipton, ).…”

“…In experiment 1, we used D. melanogaster Canton‐S, and D. simulans 14021–0251.199 (San Diego stock centre). In experiment 2, we used D. melanogaster dunce and amnesiac mutants (on a Canton‐S background) that, respectively, show short‐ and middle‐term memory deficiencies (including courtship behavior) (Dubnau & Tully, ; Emmons & Lipton, ; Quinn & Dudai, ; Quinn, Sziber, & Booker, ; Rouse, Watkinson, & Bretman, ).…”