Biology subjects

Alex Perkins

Publications and source records attributed to Alex Perkins.

2 recordsLinked to original sources

bioRxiv2016

Model-based projections of Zika virus infections in childbearing women in the Americas

Zika virus is a mosquito-borne pathogen that is rapidly spreading across the Americas1. Due to a probable association between Zika virus infection and a congenital neurological disorder called microcephaly2, the epidemic trajectory of this viral infection poses a significant concern for the nearly 15 million children born in the Americas each year. The potential magnitude of the ongoing Zika epidemic is exceedingly difficult to gauge based on existing data3, due to a number of uncertainties that cloud the relationship between observed cases and true infections. As an alternative to methods that depend on unreliable case data, we developed and applied a new method that leverages highly spatially resolved data about drivers of Zika transmission to project that 1.1 (1.0-1.9) million infections in childbearing women and 64.2 (53.6-108.1) million infections across all demographic strata could occur before the first wave of the epidemic concludes. Our projection is largely consistent with annual, region-wide estimates of 53.8 (40.0-71.8) million infections by dengue virus4, which has many similarities to Zika. Our projection is also consistent with state-level data from Brazil on confirmed, Zika-associated microcephaly cases5, and it suggests that the current epidemic has the potential to negatively impact tens of thousands of pregnancies. These projections constitute an important early contribution to efforts to understand the potential magnitude of the Zika epidemic, and our methods offer a new way to make rapid assessments of the threat posed by emerging infectious diseases.

Ecology↗

bioRxiv2015

After the games are over: life-history trade-offs drive dispersal attenuation following range expansion

Increased dispersal propensity often evolves on expanding range edges due to the Olympic Village effect, which involves the fastest and fittest finding themselves together in the same place at the same time, mating, and giving rise to like individuals. But what happens after the ranges leading edge has passed and the games are over? Although empirical studies indicate that dispersal propensity attenuates following range expansion, hypotheses about the mechanisms driving this attenuation have not been clearly articulated or tested. Here we use a simple model of the spatiotemporal dynamics of two phenotypes, one fast and the other slow, to propose that dispersal attenuation beyond pre-expansion levels is only possible in the presence of trade-offs between dispersal and life-history traits. The Olympic Village effect ensures that fast dispersers pre-empt locations far from the ranges previous limits. When trade-offs are absent, this pre-emptive spatial advantage has a lasting impact, with highly dispersive individuals attaining equilibrium frequencies that are strictly higher than their introduction frequencies. When trade-offs are present, dispersal propensity decays rapidly at all locations. Our models results about the post-colonization trajectory of dispersal evolution are clear and, in principle, should be observable in field studies. We conclude that empirical observations of post-colonization dispersal attenuation offer a novel way to detect the existence of otherwise elusive trade-offs between dispersal and life-history traits.

Ecology↗