Drafts by Etienne Danchin
We confront the core neoDarwinian tenet of blind variation, or random mutation, with classical a... more We confront the core neoDarwinian tenet of blind variation, or random mutation, with classical and recent models of genetic assimilation. We first argue that all the mechanisms proposed so far rely on blind genetic variation fueling natural selection. Then, we examine a new hypothetical mechanism of genetic assimilation, relying on nonblind genetic variation. Yet, we show that such a model still relies on blind variation of some sort to explain adaptation. Last, we discuss the very meaning of the tenet of blind variation. We propose a formal characterization of the tenet and argue that it should not be understood solely as an empirical claim, but also as a core explanatory principle.
Papers by Etienne Danchin
Scientific Reports, Dec 22, 2022
Although the environment is three-dimensional (3-D), humans are able to extract subtle informatio... more Although the environment is three-dimensional (3-D), humans are able to extract subtle information from two-dimensional (2-D) images, particularly in the domain of sex. However, whether animals with simpler nervous systems are capable of such information extraction remains to be demonstrated, as this ability would suggest a functional generalisation capacity. Here, we performed mate-copying experiments in Drosophila melanogaster using 2-D artificial stimuli. Mate copying occurs when naïve females observe the mating success of potential mates and use that social information to build their own mating preference. By replacing live demonstrations with (i) photos or (ii) simplified images of copulating pairs, we found that even crudely simplified images of sexual intercourse still elicit mate copying, suggesting that Drosophila is able to extract sex-related information even from a degraded image. This new method constitutes a powerful tool to further investigate mate copying in that species and sexual preferences in general. The high sensitivity of humans to two-dimensional (2-D) images, and particularly so in the context of sex, raises the question of whether that capacity is unique to our species. However, little is known on the perception of flat images in non-human animals 1 , although several zoos empirically began using images to study mate choice in captive animals with the goal of stimulating reproduction by mimicking situations of mate choice 2,3 . More generally, the use of artificial visual stimuli in a wide variety of behavioural experiments is becoming a powerful methodology across all taxa involving clay models, robots, pictures, video playbacks, computer animated stimuli or even the use of virtual reality techniques . Here, we report on a study in the model organism Drosophila melanogaster, where artificial visual stimuli have been used for decades mostly in simple forms to study navigation . However, all these approaches use the capacity of fruit flies to have a 3-D perception of their environment 17 . As we wanted to investigate whether they also use 2-D images as sources of information and whether they can extract information from them, we modified the protocol to study social learning in the context of mate choice, a form that usually is called mate copying. Mate copying occurs when, after observing another females' mate choice, an observer female tends to preferentially mate with the same male ("individual based" mate copying) or with males of the same phenotype ("trait based" mate copying) as the one chosen during the demonstration . Mate-copying experiments in the fruit fly consist of a demonstration where a virgin, naïve observer female can watch another female, the demonstrator, copulating with a male of a certain phenotype and a male of a contrasting phenotype being rejected, followed by a mate-choice test where the observer female can mate with one of the two male phenotypes 20 . We showed previously the sophistication of this social-learning strategy in D. melanogaster with experiments using demonstrations with real (living) conspecifics . To study whether fruit flies can extract the same kind of information from 2-D images, we thus simply replaced live demonstrations with flat images of a demonstrator female copulating with one male of a given colour, while a male of the other colour was standing by apparently rejected (Fig. ). The modification of such pictures and images (Fig. ) further allowed us to identify the important cues for mate copying in fruit flies. We found that demonstrations with photos or simplified static images in fruit fly mate-copying experiments still elicit as efficient mate copying as live demonstrations, provided that specific traits in demonstrator
Behavioral Ecology, Nov 9, 2021
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Evolutionary Ecology, Mar 17, 2021
Biological Journal of The Linnean Society, Mar 6, 2019
Functional Ecology, Feb 13, 2017
Molecular Ecology, Aug 2, 2020
Sex and hatching order modulate the association between MHC-II diversity and fitness in early-lif... more Sex and hatching order modulate the association between MHC-II diversity and fitness in early-life stages of a wild seabird
Biological Reviews, Sep 29, 2022
ABSTRACTAlthough conformity as a major driver for human cultural evolution is a well‐accepted and... more ABSTRACTAlthough conformity as a major driver for human cultural evolution is a well‐accepted and intensely studied phenomenon, its importance for non‐human animal culture has been largely overlooked until recently. This limited for decades the possibility of studying the roots of human culture. Here, we provide a historical review of the study of conformity in both humans and non‐human animals. We identify gaps in knowledge and propose an evolutionary route towards the sophisticated cultural processes that characterize humanity. A landmark in the study of conformity is Solomon Asch's famous experiment on humans in 1955. By contrast, interest in conformity among evolutionary biologists has only become salient since the turn of the new millennium. A striking result of our review is that, although studies of conformity have examined many biological contexts, only one looked at mate choice. This is surprising because mate choice is probably the only context in which conformity has self‐reinforcing advantages across generations. Within a metapopulation, i.e. a group of subpopulations connected by dispersing individuals, dispersers able to conform to the local preference for a given type of mate have a strong and multigenerational fitness advantage. This is because once females within one subpopulation locally show a bias for one type of males, immigrant females who do not conform to the local trend have sons, grandsons, etc. of the non‐preferred phenotype, which negatively and cumulatively affects fitness over generations in a process reminiscent of the Fisher runaway process. This led us to suggest a sex‐driven origin of conformity, indicating a possible evolutionary route towards animal and human culture that is rooted in the basic, and thus ancient, social constraints acting on mating preferences within a metapopulation. In a generic model, we show that dispersal among subpopulations within a metapopulation can effectively maintain independent Fisher runaway processes within subpopulations, while favouring the evolution of social learning and conformity at the metapopulation scale; both being essential for the evolution of long‐lasting local traditions. The proposed evolutionary route to social learning and conformity casts surprising light on one of the major processes that much later participated in making us human. We further highlight several research avenues to define the spectrum of conformity better, and to account for its complexity. Future studies of conformity should incorporate experimental manipulation of group majority. We also encourage the study of potential links between conformity and mate copying, animal aggregations, and collective actions. Moreover, validation of the sex‐driven origin of conformity will rest on the capacity of human and evolutionary sciences to investigate jointly the origin of social learning and conformity. This constitutes a stimulating common agenda and militates for a rapprochement between these two currently largely independent research areas.
Behavioral Ecology, Sep 24, 2020
Behavioural Processes, Apr 1, 2016
Individuals of many species, including invertebrates, have been shown to use social information i... more Individuals of many species, including invertebrates, have been shown to use social information in mate choice, notably by extracting information from the mating performance of opposite sex conspecifics, a process called "mate-choice copying" (MCC). Here, we performed four experiments with Drosophila melanogaster to investigate two aspects of MCC methodology: whether (i) providing positive and negative social information simultaneously or sequentially during the demonstration phase of the protocol, and (ii) male-male competition during the mate-choice test, affect MCC. We found that the simultaneous provision of positive and negative information during demonstrations hampered female MCC performance, compared to the sequential provision of information. This can be interpreted in two alternative, yet not exclusive, ways: (i) attentional mechanisms may restrict the focus of the brain to one source of information at a time, and/or (ii) the shorter duration of demonstrations in the simultaneous protocol may have not permit full social learning use and may explain the non-detection of MCC in that protocol. Moreover, we did not detect any significant effect of male-male competition on female choice. This study thus provides further evidence for MCC in D. melanogaster and expands on the necessary methodology for detailed studies.
Philosophical Transactions of the Royal Society B: Biological Sciences, 2021
Cultural evolution requires the social transmission of information. For this reason, scholars hav... more Cultural evolution requires the social transmission of information. For this reason, scholars have emphasized social learning when explaining how and why culture evolves. Yet cultural evolution results from many mechanisms operating in concert. Here, we argue that the emphasis on social learning has distracted scholars from appreciating both the full range of mechanisms contributing to cultural evolution and how interactions among those mechanisms and other factors affect the output of cultural evolution. We examine understudied mechanisms and other factors and call for a more inclusive programme of investigation that probes multiple levels of the organization, spanning the neural, cognitive-behavioural and populational levels. To guide our discussion, we focus on factors involved in three core topics of cultural evolution: the emergence of culture, the emergence of cumulative cultural evolution and the design of cultural traits. Studying mechanisms across levels can add explanatory...
Biological Journal of the Linnean Society, 2019
Inbreeding, i.e. the mating of genetically related individuals, can lead to reduced fitness and i... more Inbreeding, i.e. the mating of genetically related individuals, can lead to reduced fitness and is considered to be a major selective force of mate choice. Although inbreeding avoidance has been found in numerous taxa, individuals may face constraints when pairing, leading to mating with suboptimal partners. In such circumstances, individuals that are able to avoid factors exacerbating detrimental effects of inbreeding should be favoured. Using the socially and genetically monogamous black-legged kittiwake (Rissa tridactyla), we explored whether the detrimental effects of inbreeding are exacerbated by sperm ageing (i.e. the post-meiotic senescence of sperm cells, mainly occurring within the female tracts after copulation), and whether they can be mitigated by behavioural tactics. First, by experimentally manipulating the age of the fertilizing sperm, we found that hatching failure due to sperm ageing increased with higher genetic similarity between mates. We then investigated whethe...
Animal Behaviour, Nov 1, 2016
Mate choice can strongly affect fitness in sexually reproducing organisms. A form of mate choice ... more Mate choice can strongly affect fitness in sexually reproducing organisms. A form of mate choice is mate copying, in which individuals use information about potential mates by copying the mate choice of other individuals. While many studies have documented mate copying, little is known about the effect of environmental conditions on this behaviour. Here, we report the first evidence that Drosophila melanogaster females can acquire a sexual preference for one male characteristic after witnessing a single mate choice event (i.e. speed learning). We also found that mate copying was correlated with air pressure and air pressure changes, so that females copied far more when air pressure was high and increasing, i.e. in good and improving weather conditions. These results reveal a quick social observational learning and highlight the potential importance of meteorological conditions for mate copying, a trait potentially driving reproductive isolation.
Little is known of the life history of vultures. The reintroduction program of Griffon Vultures (... more Little is known of the life history of vultures. The reintroduction program of Griffon Vultures (Gyps fulvus fulvus) in the Causses (south of the Massif Central, France) and extensive monitoring by capture-mark-resighting of the released birds allowed us to obtain the first estimates of their survival. Adult survival rates are high (oe = 0.987 + SE of 0.006). A release effect on adult survival was detected (only 0.743 + 0.006 survival during the first year after release). Young born in the wild (less than three years old) had an annual survival rate of 0.858 + 0.039. Mortality causes and erratic behavior of immature birds are considered in order to assess the effectiveness of this reintroduction program. Our results indicate that reintroductions of vultures and similar species should use adults that have bred in captivity within the target area rather than juveniles or immatures.
Trends in Ecology & Evolution, 2021
Science, 2004
Psychologists, economists, and advertising moguls have long known that human decision-making is s... more Psychologists, economists, and advertising moguls have long known that human decision-making is strongly influenced by the behavior of others. A rapidly accumulating body of evidence suggests that the same is true in animals. Individuals can use information arising from cues inadvertently produced by the behavior of other individuals with similar requirements. Many of these cues provide public information about the quality of alternatives. The use of public information is taxonomically widespread and can enhance fitness. Public information can lead to cultural evolution, which we suggest may then affect biological evolution.
Science, 2019
Thornquist and Crickmore claim that systematic experimental error may explain the results of Danc... more Thornquist and Crickmore claim that systematic experimental error may explain the results of Danchin and colleagues. Their claim rests on mistakes in their analyses, for which we provide corrections. We reassert that conformity in fruitflies predicts long-lasting mate-preference traditions.
Oxford Scholarship Online, 2017
This chapter confronts the neo-Darwinian core tenet of blind variation, or random mutation, with ... more This chapter confronts the neo-Darwinian core tenet of blind variation, or random mutation, with classical and recent models of genetic assimilation. We first argue that all the mechanisms proposed so far rely on blind genetic variation fueling natural selection. Then, we examine a new hypothetical mechanism of genetic assimilation, relying on nonblind genetic variation. Yet, we show that such a model still relies on blind variation of some sort to explain adaptation. Last, we discuss the very meaning of the tenet of blind variation. We propose a formal characterization of the tenet and argue that it should not be understood solely as an empirical claim, but also as a core explanatory principle.
The Journal of physiology, 2014
Physiology and evolutionary biology have developed as two separated disciplines, a separation tha... more Physiology and evolutionary biology have developed as two separated disciplines, a separation that mirrored the hypothesis that the physiological and evolutionary processes could be decoupled. We argue that non-genetic inheritance shatters the frontier between physiology and evolution, and leads to the coupling of physiological and evolutionary processes to a point where there exists a continuum between accommodation by phenotypic plasticity and adaptation by natural selection. This approach is also profoundly affecting the definition of the concept of phenotypic plasticity, which should now be envisaged as a multi-scale concept. We further suggest that inclusive inheritance provides a quantitative way to help bridging infra-individual (i.e. physiology) with supra-individual (i.e. evolution) approaches, in a way that should help building the long sough inclusive evolutionary synthesis.
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Drafts by Etienne Danchin
Papers by Etienne Danchin