 For example, in a population of New Zealand wrybill who make a living by searching for grubs under rocks, those that have a bent beak gain access to more calories.Those with bent beaks are able to better provide for their young, and at the same time they remove a disproportionate quantity of grubs from their environment, making it more difficult for those with straight beaks to provide for their own young.Throughout their lives, all the wrybills in the population do work to structure the form of the next generation.