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Data from: Local adaptation and rapid evolution of aphids in response to genetic interactions with their cottonwood hosts

Citation

Smith, David et al. (2021), Data from: Local adaptation and rapid evolution of aphids in response to genetic interactions with their cottonwood hosts, Dryad, Dataset, https://doi.org/10.5061/dryad.18931zcv2

Abstract

Several studies have demonstrated the ecological consequences of genetic variation within a single plant species.  For example, these studies show that individual plant genotypes support unique composition of the plants’ associated arthropod community. By contrast, fewer studies have explored how plant genetic variation may influence evolutionary dynamics in the plant’s associated species.  Here, we examine how aphids respond evolutionarily to genetic variation in their host plant. We conducted two experiments to examine local adaptation and rapid evolution of the free-feeding aphid Chaitophorus populicola across genetic variants of its host plant, Populus angustifolia. To test for local adaptation, we collected tree cuttings and aphid colonies from three sites along an elevation / climate gradient and conducted a reciprocal transplant experiment. In general, home aphids (aphid transplanted onto trees from the same site) produced 1.7-3.4 times as many offspring as foreign aphids (aphids transplanted onto trees from different sites). To test for rapid evolution, we used 4 clonally replicated aphid genotypes and transplanted each onto 5 clonally replicated P. angustifolia genotypes. Each tree genotype started with the same aphid genotype composition. After 21 days (~two aphid generations), aphid genotype composition changed (i.e. aphids evolved) and some tree genotypes supported unique evolutionary trajectories of aphids. These results suggest that plant evolution in response to human perturbation, such as climate change and invasive species will also result in evolutionary responses in strongly interacting species that could cascade to affect whole communities.

Methods

To conduct the local adaptation experiment, we used a reciprocal transplant experiment in the greenhouse, using trees and aphids collected from three sites along an elevation / climate gradient (called "low", "mid", and "high"). We used 51 potted trees (15, 15 and 21 trees collected from the low, mid and high elevations respectively). Each potted tree received a single adult aphid.  Adult aphids were collected from the same three sites/elevations as the trees. After 30 days, the number of aphids was counted on each tree.  If only one aphid was counted, it was presumed that the aphid did not reproduce in the 30-day time period.  To measure the total number of offspring, we counted the total number of aphids minus one (to account for the single aphid that was initially placed on the tree).  

We conducted the rapid evolution experiment in a 15 year old common garden containing replicated narrowleaf cottonwood (Populus angustifolia) genotypes. We chose 5 cottonwood genotypes, each replicated 4 times (20 total trees). On each individual tree we placed 2 adults from each of 4 aphid genotypes.  We counted the number of aphid offspring (abundance) from each aphid genotype every day for the first 17 days, then every other day until day 21.   We then used non-metric multidimensional scaling (NMDS) on the aphid abundances such that each individual tree, on each sampling day received an NMDS score representing the aphid genotype composition on that individual tree. 

Funding

University of Wisconsin-Madison, Award: Hilldale Undergraduate/Faculty research fellowship

National Science Foundation