| Symposium proposal | |
| Organizer: | Yun Ding (University of Pennsylvania) |
| How complex traits arise and evolve is a fundamental question in biology, with behavioral traits being among the most mysterious. The past few decades have revolutionized our understanding of the genetic and neuronal basis of animal behaviors through the rapid advancement of new tools and discoveries. However, we know extremely little about how evolutionary processes modify the genomes and sculpt the nervous systems to give rise to the extraordinary diversity of animal behavior observed in nature. The integration of genetics, development, and evolution gave rise to the field of Evolutionary development (Evo-Devo) that has revolutionized our understanding of morphological evolution. We feel that a functional synthesis of behavioral evolution by integrating genetics and neurobiology is timely and a specific discussion of this topic will provide exciting insights into this growing area of evolutionary biology. | |
S9-1
Exploring the neural basis for nuptial gift giving, an essential courtship repertoire in Drosophila subobscura
Daisuke Yamamoto1, Ryoya Tanaka2
1National Institute of Information and Communications Technology
2Nagoya University
2Nagoya University
Every animal species displays a behavioral repertoire specific to that species, yet how such behavioral diversity emerges in evolution remains poorly understood. As behavior is a readout of functions of the nervous system, behavioral diversity must derive from distinct circuit properties across species. To obtain clues to the mechanism whereby a novel behavioral repertoire emerges, we focus on nuptial gift giving in D. subobscura: a courting male regurgitates a drop of digested foods in front of a female, who sucks the droplet by extending her mouth part to his when she is receptive. Without nuptial gift, the female does not accept to mate with the male. D. subobscura is the sole species that routinely shows nuptial gift transfer in Drosophila thus far reported. To explore the neural basis for nuptial gift transfer, we engineered the genome of D. subobscura so that the gene fruitless (fru) likely playing the master regulator role for courtship circuit formation can be manipulated in this species for visualization, activation and inactivation of fru-expressing neurons (Tanaka et al., 2016, 2017). We also created a genetic tool kit for producing flip-out clones of manipulated cells for mosaic analysis of nuptial gift transfer: with this tool kit, a small number of clonal neurons can be tested for their ability to induce nuptial gift transfer upon artificial activation, for example (Tanaka et al., unpublished). Exhaustive mosaic analysis for nuptial gift transfer will lead us to the identification of the circuit module operating to produce this species-specific behavioral repertoire.
Tanaka, R. (2016) Insect Mol. Biol. 25, 355-361. doi: 10.1111/imb.12232.
Tanaka, R. (2017) J. Neurosci. 37, 11662-11674. doi: 10.1523/JNEUROSCI.1943-17.2017.
S9-2
Social behavior and scent signaling in house mice and relatives
Michael Sheehan1
1Neurobiology and Behavior, Cornell University
Lab mice, Mus musculus, are perhaps the most studied organism on the planet contributed a wide range of biological disciplines, including behavior and neuroscience. In contrast to the intense focus on understanding the mechanisms of regulating behavior within lab mice, there has been very little research that place lab mouse behavior in the context of wild house mice or closely related species. Here, I present results from new and ongoing work in the that seeks to fill this informational void discussing two related lines of research. First, I present data from replicated present field studies of spatial movement and social behavior in the common lab mouse strain C57BL6/J compared to wild-derived outbred house mice. While male lab and outbred mice show very similar patterns of movement and social behavior, female behavior is starkly different between lab and wild mice – with lab females being more gregarious and exploratory. These data suggest that domestication has had a larger effect on female compared to male social and spatial behavior in lab mice. Additionally, it demonstrates that feasibility of experimentally measuring and comparing aspects of social behavior in mice in a natural common garden setting. Second, I present work on the evolution of urinary protein pheromones and associated scent marking behavior in the genus Mus. House mice have recently evolved an expanded and highly variable repertoire of proteins that mediate a range of social behaviors. Close relatives have less protein in their urine and fewer protein variants, indicating that pheromone signaling has been evolving rapidly in the mouse lineage. In conjunction with different pheromones, species all vary in behavioral rules for the deposition of urine scent marks. These data highlight the opportunities for future analyses of behavioral evolution by taking advantage of the surprising behavioral diversity among the closest relatives of the model mammal.
S9-3
Mechanisms of Behavioral Evolution
Eva K Fischer1
1University of Illinois Urbana-Champaign
A fundamental question at the intersection of evolution, behavior, and neurobiology is how novel behaviors arise and are incorporated into existing neural systems. As alternative underlying mechanisms may drive shared organismal phenotypes solving this puzzle is intimately tied to understanding how behavior is coded across levels of organization – from genes, to gene networks, to cell types, to neural circuits, to physiology, to behavior. To address these questions, our research capitalizes on behavioral diversity in parental care within and between species of poison frogs. We have found core brain regions associated with caregiving across sexes and species of frogs are shared with those in mammals and vertebrates generally. In addition, we confirmed a role for hormones and neuropeptides associated with parental care across vertebrates and demonstrated an intriguing link between genes implicated in feeding behavior and parental care. This work contributes to our understanding of the maintenance and evolution of vertebrate social behavior.
S9-4
Olfactory and gustatory receptor neurons drive the perception of key floral odor in reward and rewardless pollination systems.
Dr. Binyan Lu1
1Institute of Botany, Chinese Academy of Science
Pollination originates from unintended interaction between plants and insects, whereas subsequently shapes their traits. The attraction of insects causes opposite fitness effects of both parties in reward pollination systems and in deceptive pollination systems. With seemingly evolutionary disadvantage, deceptive pollination systems widely exist, especially in Orchidaceae. Here we dissolved this paradox by investigating the neural mechanisms underlying the perception of a floral odor ethyl tiglate (ET) that is attractive to various drosophila pollinators of specialized reward and rewardless orchids. Furthermore, significantly increased amount of ET is emitted by several fermented fruits compared to the fresh ones, indicating that the orchids exploit the preference to a possible food signal in Drosophila. Next, by leveraging the neurogenetic model, D. melanogaster, we revealed that the Or92a olfactory sensory neurons (OSN) and Gr63a-OSN intriguingly drive the different valences of ET to determine the behavioral outcome. These results unveiled the coding of a floral signal cooperatively by olfactory and gustatory receptor neurons and the exploitation of a prevalent pollinator olfactory preference in reward and rewardless orchids.
S9-5
Broad reshaping of mosquito olfactory circuits during specialization on human hosts
Zhilei Zhao1,2, David Tian1,2, Andrew Salmons2, Sarah Maguire2, Carolyn S. McBride1,2
1Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544 USA
2Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544 USA
2Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544 USA
How neural circuits evolve during behavioral adaptation is a fundamental but largely unexplored question in biology. In Aedes aegypti mosquitoes, a form that specializes in biting humans has evolved from the ancestral generalists, spreading dangerous viruses to humans with devastating efficiency. Mosquitoes rely heavily on olfactory cues for many behaviors including host-seeking, suggesting that the olfactory circuits may have evolved rapidly during specialization on human hosts. However, a comprehensive picture of those evolutionary changes and how they lead to host shifts remain elusive. Here, we tackled this question by focusing on the primary olfaction center in mosquito brain, the antennal lobe (AL), and comparing its anatomy between the specialist and generalist mosquitoes. We found that although the overall AL architecture is conserved, the sizes of glomeruli, functional units of AL, demonstrated broad reshaping during evolution. Strikingly, the principal axis that explains the most variation in glomerular sizes aligns linearly with host preference. Many of the anatomical changes are consistent with expectations from previous neurogenetic and neurophysiological studies. Together, our study demonstrates how specialization on humans has extensively shaped the evolution of olfactory circuits in mosquitoes, and revealed specific neural targets for designing mosquito control strategies.
