Dopamine and Serotonin Are Both Required for Mate-Copying in Drosophila melanogaster

Mate-copying is a form of social learning in which the mate-choice decision of an individual (often a female) is influenced by the mate-choice of conspecifics. Drosophila melanogaster females are known to perform such social learning, and in particular, to mate-copy after a single observation of one conspecific female mating with a male of one phenotype, while the other male phenotype is rejected. Here, we show that this form of social learning is dependent on serotonin and dopamine. Using a pharmacological approach, we reduced dopamine or serotonin synthesis in adult virgin females with 3-iodotyrosine (3-IY) and DL-para-chlorophenylalanine (PCPA), respectively, and then tested their mate-copying performance. We found that, while control females without drug treatment copied the choice of the demonstrator, drug-treated females with reduced dopamine or serotonin chose randomly. To ensure the specificity of the drugs, the direct precursors of the neurotransmitters, either the dopamine precursor L-3,4-dihydroxyphenylalanine (L-DOPA) or the serotonin precursor 5-L-hydroxytryptophan (5-HTP) were given together with the drug, (respectively 3-IY and PCPA) resulting in a full rescue of the mate-copying defects. This indicates that dopamine and serotonin are both required for mate-copying. These results give a first insight into the mechanistic pathway underlying this form of social learning in D. melanogaster

Not by transmission alone : the role of invention in cultural evolution

We are grateful to the Templeton World Charity Foundation, Inc. for funding this work and to the Diverse Intelligences research community for valuable conversations around these themes. S. Nöbel acknowledges IAST funding from the French National Research Agency (ANR) under the Investissements d’Avenir program, grant ANR-17-EUR-0010 and support by the Laboratoires d’Excellence TULIP (ANR-10-LABX-41). EA and MS acknowledge support from the US Army Research Office (W911NF‐17‐1‐0017 to EA).Innovation—the combination of invention and social learning—can empower species to invade new niches via cultural adaptation. Social learning has typically been regarded as the fundamental driver for the emergence of traditions and thus culture. Consequently, invention has been relatively understudied outside the human lineage—despite being the source of new traditions. This neglect leaves basic questions unanswered: what factors promote the creation of new ideas and practices? What affects their spread or loss? We critically review the existing literature, focusing on four levels of investigation: traits (what sorts of behaviours are easiest to invent?), individuals (what factors make some individuals more likely to be inventors?), ecological contexts (what aspects of the environment make invention or transmission more likely?), and populations (what features of relationships and societies promote the rise and spread of new inventions?). We aim to inspire new research by highlighting theoretical and empirical gaps in the study of innovation, focusing primarily on inventions in non-humans. Understanding the role of invention and innovation in the history of life requires a well-developed theoretical framework (which embraces cognitive processes) and a taxonomically broad, cross-species dataset that explicitly investigates inventions and their transmission. We outline such an agenda here. This article is part of the theme issue ‘Foundations of cultural evolution’.Publisher PDFPeer reviewe

Data-set Mate-copying of a costly variant

The file contains the data of the experiments presented in the paper. We tested wild type and Curly females for their innate preference for wild type and Curly males and then whether females of both phenotypes copy the choice of their conspecifics for a wild type or Curly male

Public information influences sperm transfer to females in sailfin molly males.

In animals, including humans, the social environment can serve as a public information network in which individuals can gather public information about the quality of potential mates by observing conspecifics during sexual interactions. The observing individual itself is also a part of this information network. When recognized by the observed conspecifics as an audience, his/her presence could influence the sexual interaction between those individuals, because the observer might be considered as a potential mate or competitor. One of the most challenging questions in sexual selection to date is how the use of public information in the context of mate choice is linked to the fitness of individuals. Here, we could show that public information influences mate-choice behaviour in sailfin molly males, Poecilia latipinna, and influences the amount of sperm males transfer to a female partner. In the presence of an audience male, males spent less time with the previously preferred, larger of two females and significantly more time with the previously non-preferred, smaller female. When males could physically interact with a female and were faced with an audience male, three audience females or no audience, males transferred significantly more sperm to a female partner in the presence of an audience male than with female audience or no audience and spent less time courting his female partner. This is the first study showing that public information use turns into fitness investment, which is the crucial factor to understand the role of public information in the dynamic processes in sexual selection

Data from: Mate-copying for a costly variant in Drosophila melanogaster females

Mate-copying is a form of social learning in which witnessing sexual interactions between conspecifics biases an observer individuals’ future mate-choice. Mate-copying exists in many vertebrates, as well as in Drosophila melanogaster. Here, we show that female fruit flies can copy the choice for mutant males [curly wings (Cy) mutants versus wild types (WT)] despite the fact that mating with Cy males induce a significant fitness cost for the observer female. When facing WT and Cy males, naive observer females of both phenotypes naturally prefer WT males. In a mate-copying experiment, naive observer Cy or WT females saw a demonstrator female copulating with either a Cy or a WT male aside a lonely male of the opposite phenotype. In the subsequent mate-choice test, Cy and WT observer female did not change their already high natural preference for WT males after witnessing a WT male copulating during the demonstration. Contrastingly, Cy and WT female increased their preference for the naturally non-preferred Cy males after witnessing a Cy male copulating, showing that mate-copying also exists for costly variants in invertebrates. Furthermore, mate-copying efficiency did not differ when using neutral artificial variants (colouring, Dagaeff et al. 2016, Animal Behaviour) versus phenotypic variants (this study), suggesting that these two types of experiments are equivalently suitable to study mate-copying. We finally discuss how mate-copying can participate to the maintenance of costly traits in a population

Mate-choice scores of males in the audience experiment and in the control.

<p>Mate-choice scores of males ( = time spent with the larger or smaller female/time spent with both females). In the audience experiment (A) an audience male was present in the second mate-choice test: In the control (B) no audience (empty Plexiglas cylinder) was present in the second mate-choice test.</p

Three treatments of the sperm transfer experiment.

<p>We used a tank for the focal male and a virgin female partner, and a separate tank for a single male audience (matched for body length with the focal male, left), three fertile females (matched for body length with the female partner) as audience (middle) and no audience (right). We videotaped the experiment and measured different types of courtship behaviour and the time the focal male and the female partner spent alone and together in the 5-cm inspection zone (grey area) in front of the audience tank. Males are presented as black fishes, females as grey fishes.</p

Time spent of focal males and their female partners in the inspection zone in front of the audience tank (<i>P</i>

<p>-<b>values after Bonferroni correction).</b></p