In many large natural ecosystems, the influx of mutations can be expected to be quite large (>>1 over the characteristic turnover time of the population).  Therefore, we can say that, in such ecosystems, the timescales of ecological and evolutionary change are not well separated.  Because of this lack of timescale separation, it is possible for mutation, selection and ecological dynamics to feedback on one another.  In this talk, I will argue that common approaches to modeling the mutation process overlook known aspects of biology and thereby underestimate the impact of eco-evolutionary feedbacks.  I will propose a simple, biologically motivated model of mutation that restores the effect of these feedbacks.  When these mutational dynamics are coupled to an underlying model of ecology, I will show that the long-term behavior of the ecosystem can be impacted in counterintuitive ways.  I will demonstrate this in the context of two canonical classes of ecological models: 1) asymmetric predator-prey models (an archetype of chaotic ecology) 2) consumer-resource models (an archetype of stable ecology).  I will argue that similar eco-evolutionary feedbacks might be relevant in natural, laboratory, and human health-related ecosystems, in particular in phage-bacteria communities and in the clearance of pathogens by the adaptive immune system.