Meeting Abstract
To persist in variable climates, many organisms adopt switching between phenotypic states as a way of hedging their bets. Variable release from egg dormancy is a form of bet hedging that has major effects on population dynamics. Conventionally, Mormon crickets are thought to require a single winter to hatch, but at high elevation (2400 m) in the Bighorn Mountains, Wyoming, the population was shown to be biennial with development in the first summer arrested in a early embryonic stage known as ‘egg diapause.’ However, when males and females from the Bighorn Mountains were collected in August and paired in the lab, all but one of 43 females laid some eggs that reached late embryonic stages called ‘embryonic diapause’ and hatched after a single winter. Critical daylength is typically shorter as altitude or latitude increases. Reaching embryonic diapause prior to loss of growing degree days for development is essential for hatching the following spring. Without sufficient time to reach embryonic diapause, egg diapause is an alternative overwintering strategy for montane Mormon crickets. I tested the hypothesis that a critical parental daylength exists in the Bighorn Mountain population of Mormon crickets for which the eggs that are laid remain in egg diapause and delay development until the following summer. To test whether photoperiod serves as the parental cue, mating pairs were set in the same daily temperature and humidity profiles with twenty pairs on short daylength (12:12) and twenty pairs on long daylength (15:9). Females in short daylength laid more eggs that delayed development. They were also more likely to lay inviable eggs. Other fitness measures, such as hatchling mass, nymphal survivorship, and adult mass were not different between parental treatments. Diapause termination distributed over multiple years probably constitutes a bet-hedging strategy in an unpredictable environment.
