While sleep is almost universal across the animal kingdom, sleep patterns and amount vary drastically between species. Further, individuals alter how much they sleep in response to their environments. While modulating sleep is likely important for an animal's survival, little is known about how this plasticity in sleeping behavior evolves. One ecological factor that affects how much an animal sleeps is food availability. Some species reduce sleep in response to a food-poor environment, presumably to increase the time available for foraging. However, others increase sleep under these conditions, which is likely a strategy to conserve energy when food is not available. This is referred to as sleep plasticity. This work examines the evolution of sleep plasticity using the blind Mexican cavefish as a focal species. By quantifying sleep in cavefish in their natural habitats across seasons, the researchers will connect naturally occurring, variable environmental conditions to the amount animals sleep. Further, sleep plasticity will be examined in crosses derived from cavefish and their surface fish counterparts, allowing for examination of the genetic basis of sleep plasticity. Together, these studies will provide unprecedented insight into how and why sleep plasticity has evolved, how sleep plasticity is impacted by environmental variables, and the underlying genetic influences on sleep plasticity. The captivating cavefish system will be leveraged to engage students through the development of a research-intensive course for undergraduates and a summer research mentoring program for high school students. Finally, a collaboration with FAU's Osher Lifelong Learning Institute will promote understanding of scientific research for retired citizens and provide research opportunities for local retirees.
Organisms regulate sleep in response to environmental factors, displaying sleep plasticity. One striking example of sleep plasticity is the change in sleep observed under different nutrient availability conditions. This project aims to understand the genetic basis of the evolution of sleep plasticity in the Mexican cavefish, Astyanax mexicanus. Cavefish sleep less than conspecific surface fish under ad libitum fed laboratory conditions. When starved, surface and cavefish have opposite responses: surface fish reduce sleep whereas cavefish increase sleep. This research program will test the hypothesis that cavefish have evolved sleep loss and altered sleep plasticity in response to a cave environment that strongly varies in food availability across seasons. The relationship between sleep plasticity and evolution in a variable environment are examined using three approaches: 1) surface-cave hybrids and cave-cave hybrids generated from multiple cave populations will be evaluated to elucidate the genetic architecture underlying sleep plasticity and to identify candidate genes for the evolution of this trait, 2) sleep, feeding, and food availability will be measured in the field across seasons in three different cavefish-containing caves to define these behaviors in natural habitats, and to determine the environmental conditions under which these behaviors have evolved, and 3) genomic and behavioral analyses will be performed on fish from different pools within the same cave that vary in food availability to uncover the genetic underpinnings of behavioral evolution within a single cave.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
