The majority of my research focuses on life history tradeoffs and reproductive costs for scorpions (Arizona Bark Scorpion, Centruroides sculpturatus) and rattlesnakes (Sidewinders, Crotalus cerastes). Although they may seem like extremely different organisms, they appear to have similarities in the ways in which they cope with time and energy constraints.
What are Life History Tradeoffs?
The reproductive success of an organism is measured by how many offspring an individual produces over the course of their life. Theoretically, organisms could experience the highest reproductive success if they could devote an unlimited amount of resources to reproduction (offspring production). However, in nature many organisms are faced with limited resources, so they must allocate those resources to different activities (e.g. foraging, territorial defense, mating activities, thermoregulating etc). These energetic compromises are referred to as life history tradeoffs.
There are two tradeoffs that are often the focus of life history studies:
1. The tradeoff between CURRENT and FUTURE offspring, where resources invested in a current reproductive bout can only be increased at the expense of future reproduction, or future reproductive opportunities….and
2. The tradeoff between SURVIVAL and REPRODUCTION, where behavioral changes associated with reproduction result in an increased risk of mortality.
Tradeoffs that result in a decreased survival or reproductive potential are referred to as the costs of reproduction.