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Biology Seminar: Postdoc Minisymposium

Gabriella W., Callin S., Leandro C., Simone D.R.
University of Washington, Department of Biology & Department of Urban Design and Planning
Seminar date:
Monday, October 21, 2019 - 12:00 to 13:00
HCK 132

Name: Dr. Gabriella Wolff
Lab: Riffell Lab

Title: Neuromodulation and Differential Learning Across Mosquito Species

Abstract: Mosquitoes can learn to change their host-feeding behaviors, such as shifting activity times to avoid bednets or switching from biting animals to biting humans, leading to the transfer of zoonotic diseases. Dopamine is critical for insect learning, but its role in the antennal lobe remains unclear, and it is unknown whether different mosquito species learn the same odor cues. We assayed aversive olfactory learning and dopaminergic brain innervation in four mosquito species with different host preferences and report here that they differentially learn odors salient to their preferred host and innervation patterns vary across species. Using genetically-encoded GCaMP6s Aedes aegypti, we mapped odor-evoked antennal lobe activity and report that glomeruli tuned to “learnable” odors have significantly higher dopaminergic innervation. Changes in dopamine expression in the antennal lobes of diverse invertebrate species may be an evolutionary mechanism to adapt olfactory learning circuitry without changing brain structure and confer to mosquitoes an ability to adapt to other hosts when their preferred are no longer present.

Name: Dr. Leandro Casiraghi
Lab: De la Iglesia Lab

Title: Moonlight modulates sleep in communities with limited access to artificial light

Abstract: Access to artificial light sources has modified human behavior and sleep phase relationships with the natural environment. We have shown recently that the availability of electric light might be a factor pushing people’s sleep onset to later times of the evening as well as reducing sleep duration, as compared to other subjects only relying on the solar light cue. In this work we study whether moonlight during the new and full moon phases can also modulate human sleep and behavior in the field. We recorded wrist-locomotor activity and sleep features for 30-60 days in subjects from three native Toba-Qom communities settled in the north region of Argentina: two rural communities with limited to no access to electricity, and a community living in the outskirts of an urban setting, with full access to electric light inside and outside their homes. We detected that the moon phase modulated activity and sleep features in the two rural groups, while no effects of moon phase were evident in the urban community. Subjects in the rural communities showed locomotor activity levels after twilight that were higher during full moons than during new moons, and sleep onsets which were delayed by approximately 20 minutes. These results suggest a role of moonlight as a driver of activity and delayed sleep in the evening and night in the absence of other light sources, while it becomes irrelevant in urban settings where environmental artificial light is ubiquitous. Our work is the first to describe human behavioral changes associated with moonlight and the availability of electric light.

Name: Dr. Callin Switzer
Lab: Daniel Lab

Title: Foraging decisions in uncertain environments: Do bumblebees have FOMO (fear of missing out)?

Abstract: Foraging animals face a challenging problem – visit the best-known reward or explore the environment for new rewards. Though theoretical approaches suggest that foragers may decrease exploration over time, few experiments have explicitly examined animals’ decision-making strategies in uncertain environments. Bumblebees provide an ideal system to study pollen-foraging, because their pollen-collecting behavior (floral sonication) can be easily quantified. They vibrate their flight muscles to shake pollen from flowers. Using open-source hardware and software, I built an automated system to quantify bees’ vibrations and transitions between flowers – one flower delivered pollen when sonicated and another did not. I found that bees did not visit the rewarding flower exclusively but maintained a constant ~6% chance of transitioning away from the rewarding flower (i.e. exploring the environment). This may be an adaptive strategy to keep bees from missing out on flowers that release pollen at different times of the day or to keep bees from continuing to visit flowers that are releasing diminishing resources.

Name: Dr. Simone Des Roches
Lab: Urban Ecology Research Lab/Alberti Lab

Title: The interacting effects of climate change and urbanization on Threespine Stickleback evolution

Abstract: Both climate change and urbanization can shape spatial and temporal variation within species. Still, few studies have investigated how potential interactions between these two drivers affect contemporary adaptive trait change. We resurveyed populations of Threespine Stickleback that had been sampled from Californian estuaries in the last 40-100 years. Historical samples demonstrated that stickleback lateral plate number, a defensive, streamlining trait with substantial genetic and environmental associations, declined with decreasing latitude and precipitation. Plate number is linked to a single Mendelian-inherited gene (“EDA”). The derived “low plated” phenotype, associated with two copies of the “low” EDA allele, often evolves rapidly in lentic (“lake-like”) habitats where plates hinder maneuverability in densely-vegetated, slow-moving water. We show that the low EDA allele may be increasingly selected for in estuaries that have become more lentic with decreased precipitation and streamflow. This habitat transformation is likely responsible for increases in low-plated stickleback both over time and with decreasing latitude. Stickleback from estuaries surrounded by extensive urbanization, however, highlight a notable exception: plate number has increased in estuaries that have undergone significant hydromodification – including the channelization and dredging that tend to increase streamflow and reduce biological habitat complexity. Variation in stickleback plate phenotype and genotype, therefore, may reflect divergent selection in estuary habitats that are transforming under urbanization versus climate change.

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