Some of the most famous time series in population ecology describe beautiful oscillations in population size, including our favourite flour beetles. Even in the absence of external forces (such as predation) such oscillations are not uncommon, and are typically attributed to negative density dependence. As populations become more crowded, the growth rate drops, and this feedback drives population cycles. But what processes and traits drive density dependence? Two general factors come to mind: density-dependent fecundity (i.e., less reproduction at high density), and density-dependent survival (i.e., fewer offspring survive to reproduction). In collaboration with Sandeep Krishna at NCBS, we show that in flour beetles, density-dependent survival is key to predict the shape and strength of density-dependent population growth. Even though female flour beetles change their fecundity in response to crowding, it is the density-dependent survival of their offspring that ultimately determines how populations grow in subsequent generations. Thus, we predict that survival rather than reproduction may offer greater population control — clues that may be useful for pest management and conservation alike. To know more, read the paper and this NCBS news article! And, enjoy this Vitruvian beetle by Nishant Asawadekar and Shyamsunder Buddh.
AdaptationLab 