AUTHOR=Krams Indrikis A. , Krama Tatjana , Krams Ronalds , Trakimas Giedrius , Popovs Sergejs , Jõers Priit , Munkevics Maris , Elferts Didzis , Rantala Markus J. , Makņa Jānis , de Bivort Benjamin L. 

TITLE=Serotoninergic Modulation of Phototactic Variability Underpins a Bet-Hedging Strategy in Drosophila melanogaster

JOURNAL=Frontiers in Behavioral Neuroscience

VOLUME=15

YEAR=2021

URL=https://www.frontiersin.org/journals/behavioral-neuroscience/articles/10.3389/fnbeh.2021.659331

DOI=10.3389/fnbeh.2021.659331

ISSN=1662-5153

ABSTRACT=<p>When organisms’ environmental conditions vary unpredictably in time, it can be advantageous for individuals to hedge their phenotypic bets. It has been shown that a bet-hedging strategy possibly underlies the high inter-individual diversity of phototactic choice in <italic>Drosophila melanogaster</italic>. This study shows that fruit flies from a population living in a boreal and relatively unpredictable climate have more variable variable phototactic biases than fruit flies from a more stable tropical climate, consistent with bet-hedging theory. We experimentally show that phototactic variability of <italic>D. melanogaster</italic> is regulated by the neurotransmitter serotonin (5-HT), which acts as a suppressor of the variability of phototactic choices. When fed 5-HT precursor, boreal flies exhibited lower variability, and they were insensitive to 5-HT inhibitor. The opposite pattern was seen in the tropical flies. Thus, the reduction of 5-HT in fruit flies’ brains may be the mechanistic basis of an adaptive bet-hedging strategy in a less predictable boreal climate.</p>