The neuropeptide FLP-17 regulates an oviposition behavior in the nematode Caenorhabditis elegans that increases maternal reproductive fitness in low oxygen environments

SUMMARYThe ability for animals to adapt their behaviors to specific environments is imperative to increase their evolutionary success. This is particularly true for behaviors such as parental behaviors that directly affect reproductive fitness. Here, we identified an oviposition behavior in the nematode C. elegans that increases the survival of the young. In standard laboratory culture, the bacterivorous hermaphrodite mothers lay eggs across a 2D E. coli lawn with no discernable pattern. However, in 3D culture they display a stereotypical behavior in which they temporarily leave the bacteria to lay eggs far away from the E. coli colony, resulting in a scattered ring of eggs located outside the bacteria. This oviposition behavior requires low oxygen levels and is regulated by the neuropeptide FLP-17 and its cognate receptor EGL-6. We confirm that a circuitry involving the oxygen-sensing BAG neurons and the vulva muscle-controlling HSN motor neurons regulates oviposition behavior. We show that loss of proper oviposition behavior results in lower reproductive fitness for the mothers and embryonic lethality for the eggs laid in bacteria under hypoxic conditions. Finally, we show that the degree of oviposition behavior varies among wild strains of C. elegans found in nature. The ability for C. elegans mothers to sense their environments and adjust their behaviors in adverse conditions is likely an adaptation that has allowed the worm to thrive in diverse and often hazardous habitats.