Abstract: Selection acting on unmeasured individual variation is a common source of bias in the analysis of populations. It has been shown to affect measured rates of mortality, the survival of endangered species, the scope of neutral theories of biodiversity and molecular evolution, measured risks of diseases whether non-communicable or infections, the efficacy of interventions such as vaccines or symbionts, and it may be an underappreciated cause for the reproducibility crisis that medicine, psychology and other life and social sciences currently travers. Building on these insights, we have addressed how selection on individual variation appears to have affected the course of the coronavirus disease (COVID-19) pandemic.

This form of variation that responds to selection and impacts within-cohort population dynamics, termed frailty variation by Vaupel et al.~(1979), constitutes a most genuine phenomenon that scientific disciplines have been dismissing for decades. I will present some examples and discuss the mixed attitudes towards what is arguably the most elusive concept in population dynamics.

N.B. This talk is suitable for non-experts, as well as students.