The concept of adaptation is a central, and sometimes misunderstood, theme in Darwinian evolution. Adaptation is the increase in fitness across subsequent generations and is how populations of species become “fitted” to their environments. The environment determines the character and magnitude of natural selection experienced by individuals but fluctuates both temporally and spatially. This fluctuation means populations are in a constant cat-and-mouse game to adapt to the environment and maximize their fitness. However, as environmental fluctuations become more severe due to ongoing climate change, it is unclear if contemporary natural selection can maintain populations, especially small or threatened populations.
My talk will report on a large-scale field experiment in an annual plant (Chamaecrista fasciculata – Partridge Pea) that quantified the capacity for adaptation, and then compared this prediction with the actual realized change in fitness across multiple generations. Finally, I will describe the potential for evolutionary rescue, where populations “evolve their way out of extinction” under contemporary natural selection.