DOI: 10.5061/dryad.18931zcv2
title: Data from: Local adaptation and rapid evolution of aphids in response to genetic interactions with their cottonwood hosts

description: 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.
description: To conduct the <strong>local adaptation
 experiment</strong>, 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 <strong>rapid evolution
 experiment</strong> in a 15 year old common garden containing
 replicated narrowleaf cottonwood (<em>Populus
 angustifolia</em>) 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.