Biology subjects

Spigler, R. B.

Publications and source records attributed to Spigler, R. B..

2 recordsLinked to original sources

bioRxiv2026

Urbanization drives parallel shifts in morphology and colouration of Pieris rapae across three cities

Urbanization is a major driver of global environmental change, yet the evolutionary consequences for natural populations remain poorly understood. The cabbage white butterfly, Pieris rapae, is one of few butterfly species that thrives in cities, offering a unique opportunity to investigate whether urbanization drives parallel phenotypic evolution. In this study, we quantified phenotypic divergence between urban and non-urban populations across three independent metropolitan regions (Cleveland, Philadelphia, and Pittsburgh, U.S.), measuring body size, flight morphology, and wing pigmentation and reflectance in >500 field-caught individuals from 19 sites. Across regions, we found repeated reductions in overall body size and relative thorax mass in urban butterflies of both sexes, along with reduced relative forewing area in urban males, suggesting sex-specific impacts on mobility. Wing pigmentation showed limited urban-associated variation, but we detected novel sexual dimorphism in near-infrared reflectance within urban populations. Together, these results demonstrate repeatable divergence between urban and non-urban butterfly populations across multiple trait axes and suggest that plastic responses to urban stressors previously documented in experimental work manifest as consistent phenotypic shifts in natural populations.

ecology↗

bioRxiv2020

Too attractive to self: How pollinators can interfere with the evolution of selfing.

Pollinators are widely invoked to explain the evolution of selfing despite genetic conditions favoring outcrossing. But their role in maintaining outcrossing despite genetic conditions favoring selfing remains unexplored. We use consumer-resource models to explicitly consider the how the plant-pollinator mutualism can constrain the evolution of selfing. We model outcrossing as a function of attractiveness and account for the cost of attractiveness as a saturating, linear, or exponential function alongside the costs of selfing: inbreeding depression and pollen discounting. We show specific, clear combinations of ecological and genetic conditions where pure selfing can invade a resident population of partial selfers. Complete selfing can evolve in the face of pollen discounting so long as there is a cost to pollinator attraction and reward. However, we also predict conditions under which mixed mating is maintained even when inbreeding depression is low. Our model highlights how under some scenarios mixed mating represents the worst of both worlds, leaving plants to pay the costs of both inbreeding depression and attraction and even leading to extinction. By linking pollinator attraction to the selfing rate, our models provide a likely common mechanism to explain pollen discounting and an alternative evolutionary pathway to the selfing syndrome.

evolutionary biology↗