Animals have numerous opportunities to acquire information from one another. Although common across taxa, social learning requires the integration of associative learning, memory and social behavior (LMS);and these vary considerably among individuals within a species. How do genetic differences cause alterations in neural functions that ultimately cause variability in social learning? To address this question it is important to identify the genes and neural circuits that play a role in LMS. Here we propose to analyze the molecular-genetic basis that underlies individual differences in LMS in the fruit fly Drosophila melanogaster. Flies have been used extensively as a model to study the genetic basis of development, behavior and learning and flies are social animals that aggregate in large groups. This confluence provides an opportunity to examine how individual genetic differences underlie variation in sociality and learning. We will develop flies as a model for the integrated analyses of the genetic, biochemical, physiological, and environmental components of LMS. We hypothesize that transcription in specific neural circuits is modified by experience and this contributes to long- term memory. Further, we hypothesize that variation in transcription in these same neural circuits across individuals contributes to the differences in LMS. In Drosophila, the mushroom body (MB) is the neural center of learning and cognition. Using a new molecular-genetic technique that allows for the purification of RNA from subsets of cells, we will examine the variation in both the MB transcriptome and the LMS behaviors of 192 recurrent heterozygous F1 genotypes. These F1 individuals will be obtained from progeny of 192 sequenced natural Raleigh strains, each crossed to a sequenced w1118 strain. We will be able to: i) determine how transcriptional variation in LMS is associated with phenotypic variation, ii) partition the cis- and trans- components of expression variation for every gene, iii) focus on cis- expression variation that is associated with behavioral variation, and iv) pinpoint cis- DNA polymorphisms likely contributing to cis- expression variation. Once we have identified causes of MB expression variation, we will connect the transcriptome with LMS: our goal is to identify the candidate genes and their polymorphisms associated with differences in LMS. We will measure larval and adult behaviors of focal genotypes with natural and major-effect alleles in the LMS candidate genes in several social contexts. We will then determine the transcriptional differences in the MB that are due to these social encounters. Subsequent functional analyses of candidate genes will provide mechanistic knowledge about how genes contribute to LMS. In sum, we propose an investigation where we synthesize genetic, molecular and behavioral information about individual genotypes to ultimately decipher aspects of the population genetics of social learning. We believe our inferences will illuminate, at several levels, the range of LMS variation maintained in natural populations of flies, thus providing insight into the genetic basis of LMS variation in other social organisms, including humans.

Public Health Relevance

PUBLIC HEALTH RELEVANCE: We will develop Drosophila melanogaster as a model for integrative analyses of the genetic, biochemical, physiological, and environmental components of social behavior. We will combine frontier genomic and molecular-genetic techniques that allow one to determine with high resolution the transcriptome in subsets of cells. Our research will identify candidate genes for associative learning, memory, and social interactions and move from associations to causation by mechanistic analyses. We will start answering several critical questions: how are learning and memory affected by different social experiences? How are learning, memory and sociality functionally integrated? And how do different social experiences alter gene expression in specific regions of the nervous system? Connecting the answers together will result in insights illuminating the maintenance of variation in natural populations, and in other social organisms including humans.

National Institute of Health (NIH)
National Institute of Mental Health (NIMH)
Research Project (R01)
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Genetic Variation and Evolution Study Section (GVE)
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Beckel-Mitchener, Andrea C
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University of Southern California
Schools of Arts and Sciences
Los Angeles
United States
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Signor, Sarah A; New, Felicia N; Nuzhdin, Sergey (2018) A Large Panel of Drosophila simulans Reveals an Abundance of Common Variants. Genome Biol Evol 10:189-206
Signor, Sarah A; Nuzhdin, Sergey V (2018) The Evolution of Gene Expression in cis and trans. Trends Genet 34:532-544
Saltz, J B (2017) Genetic variation in social environment construction influences the development of aggressive behavior in Drosophila melanogaster. Heredity (Edinb) 118:340-347
Newell, Nicole R; New, Felicia N; Dalton, Justin E et al. (2016) Neurons That Underlie Drosophila melanogaster Reproductive Behaviors: Detection of a Large Male-Bias in Gene Expression in fruitless-Expressing Neurons. G3 (Bethesda) 6:2455-65
Fear, Justin M; León-Novelo, Luis G; Morse, Alison M et al. (2016) Buffering of Genetic Regulatory Networks in Drosophila melanogaster. Genetics 203:1177-90
Kao, Joyce Y; Zubair, Asif; Salomon, Matthew P et al. (2015) Population genomic analysis uncovers African and European admixture in Drosophila melanogaster populations from the south-eastern United States and Caribbean Islands. Mol Ecol 24:1499-509
Fear, Justin M; Arbeitman, Michelle N; Salomon, Matthew P et al. (2015) The Wright stuff: reimagining path analysis reveals novel components of the sex determination hierarchy in Drosophila melanogaster. BMC Syst Biol 9:53
Kao, Joyce Y; Lymer, Seana; Hwang, Sea H et al. (2015) Postmating reproductive barriers contribute to the incipient sexual isolation of the United States and Caribbean Drosophila melanogaster. Ecol Evol 5:3171-82
Kurmangaliyev, Yerbol Z; Ali, Sammi; Nuzhdin, Sergey V (2015) Genetic Determinants of RNA Editing Levels of ADAR Targets in Drosophila melanogaster. G3 (Bethesda) 6:391-6
Foley, Brad R; Saltz, Julia B; Nuzhdin, Sergey V et al. (2015) A Bayesian Approach to Social Structure Uncovers Cryptic Regulation of Group Dynamics in Drosophila melanogaster. Am Nat 185:797-808

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