144 Works

Data from: The evolution of parasite host range in heterogeneous host populations

Amanda Gibson, Helena Baffoe-Bonnie, McKenna Penley, Julie Lin, Raythe Owens, Arooj Khalid & Levi Morran
Theory on the evolution of niche width argues that resource heterogeneity selects for niche breadth. For parasites, this theory predicts that parasite populations will evolve, or maintain, broader host ranges when selected in genetically diverse host populations relative to homogeneous host populations. To test this prediction, we selected the bacterial parasite Serratia marcescens to kill Caenorhabditis elegans in populations that were genetically heterogeneous (50% mix of two experimental genotypes) or homogeneous (100% of either genotype)....

Pollen color morphs take different paths to fitness

Matthew Koski, Andrea Berardi & Laura Galloway
Color phenotypes are often involved in communication and are thus under selection by species interactions. However, selection may also act on color through correlated traits or alternative functions of biochemical pigments. Such forms of selection are instrumental in maintaining petal color diversity in plants. Pollen color also varies markedly, but the maintenance of this variation is little understood. In Campanula americana, pollen ranges from white to dark purple, with darker morphs garnering more pollinator visits...

Group composition of individual personalities alters social network structure in experimental populations of forked fungus beetles

Phoebe Cook, Olivia Baker, Robin Costello, Vincent Formica & Edmund Brodie
Social network structure is a critical group character that mediates the flow of information, pathogens, and resources among individuals in a population, yet little is known about what shapes social structures. In this study, we experimentally tested whether social network structure depends on the personalities of group members. Replicate groups of forked fungus beetles (Bolitotherus cornutus) were engineered to include only members previously assessed as either more social or less social. We found that individuals...

Data from: Nonlinearities between inhibition and T-type calcium channel activity bidirectionally regulate thalamic oscillations

Adam Lu, Christine Lee, Max Kleiman-Weiner, Brian Truong, Megan Wang, John Huguenard & Mark Beenhakker
Absence seizures result from 3-5 Hz generalized thalamocortical oscillations that depend on highly regulated inhibitory neurotransmission in the thalamus. Efficient reuptake of the inhibitory neurotransmitter GABA is essential, and reuptake failure worsens seizures. Here, we show that blocking GABA transporters (GATs) in acute brain slices containing key parts of the thalamocortical seizure network modulates epileptiform activity. As expected, we found that blocking either GAT1 or GAT3 prolonged oscillations. However, blocking both GATs unexpectedly suppressed oscillations....

Strength in numbers? Cytotype frequency mediates effect of reproductive barriers in mixed-ploidy arrays.

Brittany Sutherland, Tomas Miranda-Katz & Laura Galloway
When differentiated lineages come into contact, their fates depend on demographic and reproductive factors. These factors have been well-studied in taxa of the same ploidy, but less is known about sympatric lineages that differ in ploidy, particularly with respect to demographic factors. We assessed prezygotic, postzygotic, and total reproductive isolation in naturally-pollinated arrays of diploid-tetraploid and tetraploid-hexaploid population mixes of Campanula rotundifolia by measuring pollinator transitions, seed yield, germination rate, and proportion of hybrid offspring....

Data from: The geographic mosaic of arms race coevolution is closely matched to prey population structure

Michael Hague, Amber Stokes, Chris Feldman, Edmund Brodie &
Reciprocal adaptation is the hallmark of arms race coevolution. Local coadaptation between natural enemies should generate a geographic mosaic pattern where both species have roughly matched abilities across their shared range. However, mosaic variation in ecologically relevant traits can also arise from processes unrelated to reciprocal selection, such as population structure or local environmental conditions. We tested whether these alternative processes can account for trait variation in the geographic mosaic of arms race coevolution between...

Contrasting parasite-mediated reductions in fitness within vs. between patches of a nematode host

Louis Thomas Bubrig, Anne Nicole Janisch, Emily Marie Tillet & Amanda Gibson
Host and parasites interact across spatial scales, but parasite-mediated fitness effects are often measured at local scales only. Recent work suggests that parasites can reduce host fitness during dispersal between patches, highlighting the potential for both within- and between-patch effects to contribute to the net fitness consequences of parasitism. Building on this work, we measured the contribution of the dispersal phase to parasite-mediated reductions in host fitness. We used the nematode Caenorhabditis elegans and its...

Sex‐differences in disease avoidance behavior vary across modes of pathogen exposure

Carl N. Keiser, Volker H.W. Rudolf, Matthew C. Luksik & Julia B. Saltz
Sex‐differences in disease susceptibility are widespread, and these disparities are often compounded in cases where sexual dimorphism increases exposure risk to parasites for one sex more than the other. Studies rarely link sex‐differences in disease susceptibility to sex‐differences in infection avoidance behavior. Yet, understanding the intersection of hosts’ susceptibility to infection and infection avoidance behavior is essential to predicting infection risk variation. Here, we use the fruit fly Drosophila melanogaster and a generalist entomopathogenic fungus,...

Data from: Exploring density and frequency dependent interactions experimentally: an R program for generating hexagonal fan designs.

Carly Rozins, Janis Antonovics, Michael Hood & Jae Hoon Cho
Species interactions and diversity are strongly impacted by local processes, with both the density of a focal species and its frequency in the community having an impact on its growth, survival, and fecundity. Yet, studies that attempt to control for variation in both frequency and density have traditionally required a large number of replicates. Hexagonal fan designs can include a range of both densities and frequencies in a single plot, providing large economies in space...

Data from: Broad geographic sampling reveals predictable, pervasive, and strong seasonal adaptation in Drosophila

Heather E. Machado, Alan O. Bergland, Ryan Taylor, Susanne Tilk, Emily Behrman, Kelly Dyer, Daniel K. Fabian, Thomas Flatt, Josefa González, Talia L. Karasov, Iryna Kozeretska, Brian P. Lazzaro, Thomas JS Merritt, John E. Pool, Katherine O’Brien, Subhash Rajpurohit, Paula R. Roy, Stephen W. Schaeffer, Svitlana Serga, Paul Schmidt, Dmitri Petrov & Bernard Kim
To advance our understanding of adaptation to temporally varying selection pressures, we identified signatures of seasonal adaptation occurring in parallel among Drosophila melanogaster populations. Specifically, we estimated allele frequencies genome-wide from flies sampled early and late in the growing season from 20 widely dispersed populations. We identified parallel seasonal allele frequency shifts across North America and Europe, demonstrating that seasonal adaptation is a general phenomenon of temperate fly populations. Seasonally fluctuating polymorphisms are enriched at...

Westward range expansion from middle latitudes explains the Mississippi River discontinuity in a forest herb of eastern North America

Carly Prior, Nate Layman, Matthew Koski, Laura Galloway & Jeremiah Busch
It is often expected that temperate plants have expanded their geographic ranges northward from primarily southern refugia. Evidence for this hypothesis is mixed in eastern North American species, and there is increasing support for colonization from middle latitudes. We studied genome-wide patterns of variation in RADseq loci to test hypotheses concerning range expansion in a North American forest herb (Campanula americana). First, spatial patterns of genetic differentiation were determined. Then phylogenetic relationships and divergence times...

Male competition reverses female preference for male chemical cues

Lisa Mitchem
Females must choose among potential mates with different phenotypes in a variety of social contexts. Many male traits are inherent and unchanging, but others are labile to social context. Competition, for example, can cause physiological changes that reflect recent wins and losses which fluctuate throughout time. We may expect females to respond differently to males depending on the outcome of their most recent fight. In Bolitotherus cornutus (forked fungus beetles), males compete for access to...

An experimental test of parasite adaptation to common vs. rare host genotypes

Amanda Gibson, P. Signe White, McKenna Penley, Jacobus De Roode & Levi Morran
A core hypothesis in coevolutionary theory proposes that parasites adapt to specifically infect common host genotypes. Under this hypothesis, parasites function as agents of negative frequency-dependent selection, favoring rare host genotypes. This parasite-mediated advantage of rarity is key to the idea that parasites maintain genetic variation and select for outcrossing in host populations. Here, we report the results of an experimental test of parasite adaptation to common vs. rare host genotypes. We selected the bacterial...

Dead litter of resident species first facilitates and then inhibits sequential life stages of range-expanding species

Rachel Smith, Julie Blaze & James Byers
1. Resident species can facilitate invading species (biotic assistance) or inhibit their expansion (biotic resistance). Species interactions are often context-dependent and the relative importance of biotic assistance versus resistance could vary with abiotic conditions or the life stage of the invading species, as invader stress tolerances and resource requirements change with ontogeny. In northeast Florida salt marshes, the abundant dead litter (wrack) of the native marsh cordgrass, Spartina alterniflora, could influence the expansion success of...

Does genetic diversity protect host populations from parasites? A meta-analysis across natural and agricultural systems

Amanda Gibson & Anna Nguyen
If parasites transmit more readily between closely related hosts, then parasite burdens should decrease with increased genetic diversity of host populations. This important hypothesis is often accepted at face value - notorious epidemics of crop monocultures testify to the vulnerability of host populations that have been purged of diversity. Yet the relationship between genetic diversity and parasitism likely varies across contexts, differing between crop and non-crop hosts and between experimental and natural host populations. Here,...

Intercontinental dispersal and whole‐genome duplication contribute to loss of self‐incompatibility in a polyploid complex

Brittany Sutherland, Brandie M. Quarles & Laura F. Galloway
Premise of the Study Angiosperm species often shift from self-incompatibility to self-compatibility following population bottlenecks. Across the range of a species, population bottlenecks may result from multiple factors, each of which may affect the geographic distribution and magnitude of mating-system shifts. We describe how intercontinental dispersal and genome duplication facilitate loss of self-incompatibility. Methods Self and outcross pollinations were performed on plants from 24 populations of the Campanula rotundifolia polyploid complex. Populations spanned the geographic...

Data used in timing is everything: Dichogamy and pollen germinability underlie variation in autonomous selfing among populations

Laura Galloway & Matthew Koski
Premise of the study: The evolution of multiple floral traits often underlies the transition from outcrossing to selfing. Such traits can influence the ability to self, and the timing at which selfing occurs, which in turn affects the costs of selfing. Species that display variation in autonomous selfing provide an opportunity to dissect the phenotypic changes that contribute to variability in the mating system. Methods: In a common garden, we measured dichogamy and herkogamy in...

Hormonal pleiotropy structures genetic covariance

Tyler Wittman, Christopher Robinson, Joel McGlothlin & Robert Cox
Quantitative genetic theory proposes that phenotypic evolution is shaped by G, the matrix of genetic variances and covariances among traits. In species with separate sexes, the evolution of sexual dimorphism is also shaped by B, the matrix of between-sex genetic variances and covariances. Despite considerable focus on estimating these matrices, their underlying biological mechanisms are largely speculative. We experimentally tested the hypothesis that G and B are structured by hormonal pleiotropy, which occurs when one...

The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans

Collin Gross, Collin Gross, J Duffy, Kevin Hovel, Melissa Kardish, Pamela Reynolds, Christoffer Boström, Katharyn Boyer, Mathiew Cusson, Johan Eklöf, Aschwin Engelen, Klemens Eriksson, Joel Fodrie, John Griffin, Clara Hereu, Masakazu Hori, A Randall Hughes, Mikhail Ivanov, Pablo Jorgensen, Claudia Kruschel, Kun-Seop Lee, Jonathan Lefcheck, Karen McGlathery, Per-Olav Moksnes, Masahiro Nakaoka … & Jay Stachowicz
While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30º of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed...

Data from: Opportunities to catalyze improved healthcare access in pluralistic systems: a cross-sectional study in Haiti

Molly Klarman, Justin Schon, Youseline Cajusma, Stacey Maples, Valery M Beau De Rochars, Chantale Baril & Eric J Nelson
Introduction. Gains to ensure global healthcare access are at risk of stalling because some old resilient challenges require new solutions. Our objective was to identify determinants of intended versus actual care-seeking behaviors in a pluralistic healthcare system that is reliant on both conventional and non-conventional providers and discover opportunities to catalyze improved healthcare access. Methods. A cross-sectional study was conducted among households with children less than 5 years of age in Haiti. Households were randomly...

Data from: A sensory bias overrides learned preferences of bumblebees for honest signals in Mimulus guttatus

Ariela Haber, James Sims, Mark Mescher, Consuelo De Moraes & David Carr
Insect pollinators readily learn olfactory cues, and this is expected to select for “honest signals” that provide reliable information about floral rewards. However, plants might alternatively produce signals that exploit pollinators’ sensory biases, thereby relaxing selection for signal honesty. We examined the innate and learned preferences of Bombus impatiens for Mimulus guttatus floral scent phenotypes corresponding to different levels of pollen rewards in the presence and absence of the innately attractive floral volatile compound β-trans-bergamotene....

Group and individual social network metrics are robust to changes in resource distribution in experimental populations of forked fungus beetles

Robin Costello, Phoebe Cook, Vincent Formica &
Social interactions drive many important ecological and evolutionary processes. It is therefore essential to understand the intrinsic and extrinsic factors that underlie social patterns. A central tenet of the field of behavioral ecology is the expectation that the distribution of resources shapes patterns of social interactions. We combined experimental manipulations with social network analyses to ask how patterns of resource distribution influence complex social interactions. We experimentally manipulated the distribution of an essential food and...

Data from: Phenotypic assortment mediates the effect of social selection in a wild beetle population

Vincent A. Formica, Joel W. McGlothlin, Corlett Wolfe Wood, Malcolm E. Augat, R. Eileen Butterfield, Mollie E. Barnard &
Social interactions often have major fitness consequences, but little is known about how specific interacting phenotypes affect the strength of natural selection. Social influences on the evolutionary process can be assessed using a multilevel selection approach that partitions the effects of social partner phenotypes on fitness (referred to as social or group selection) from those of the traits of a focal individual (nonsocial or individual selection). To quantify the contribution of social selection to total...

Data from: Signal diversification in Oecanthus tree crickets is shaped by energetic, morphometric, and acoustic trade-offs

Laurel B. Symes, Matthew P. Ayres, Colleen P. Cowdery & Robin A. Costello
Physiology, physics, and ecological interactions can generate trade-offs within species, but may also shape divergence among species. We tested whether signal divergence in Oecanthus tree crickets is shaped by acoustic, energetic, and behavioral trade-offs. We found that species with faster pulse rates, produced by opening and closing wings up to twice as many times per second, did not have higher metabolic costs of calling. The relatively constant energetic cost across species is explained by trade-offs...

Data from: Scale dependence of sex ratio in wild plant populations: implications for social selection

Brian J. Sanderson, Malcolm E. Augat, Douglas R. Taylor, & Edmund D. Brodie
Social context refers to the composition of an individual's social interactants, including potential mates. In spatially structured populations, social context can vary among individuals within populations, generating the opportunity for social selection to drive differences in fitness functions among individuals at a fine spatial scale. In sexually polymorphic plants, the local sex ratio varies at a fine scale and thus has the potential to generate this opportunity. We measured the spatial distribution of two wild...

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