Papers by Stephen Shuster
Ecology and Evolution, Mar 1, 2022
A key issue in evolutionary biology is whether selection acting at levels higher than the individ... more A key issue in evolutionary biology is whether selection acting at levels higher than the individual can cause evolutionary change. If it can, then conceptual and empirical studies must consider how selection operates at multiple levels of biological organization. Here, we test the hypothesis that estimates of broad‐sense community heritability, HC2, can be used to predict the evolutionary response by community‐level phenotypes when community‐level selection is imposed. Using an approach informed by classic quantitative genetics, we made three predictions. First, when we imposed community‐level selection, we expected a significant change in the average phenotype of arthropod communities associated with individual tree genotypes [we imposed selection by favoring high and low NMDS (nonmetric multidimensional scaling) scores that reflected differences in arthropod species richness, abundance and composition]. Second, we expected HC2 to predict the magnitude of the community‐level response. Third, we expected no significant change in average NMDS scores with community‐level selection imposed at random. We tested these hypotheses using three years of common garden data for 102 species comprising the arthropod communities, associated with nine clonally replicated Populus angustifolia genotypes. Each of our predictions were met. We conclude that estimates of HC2 account for the resemblance among communities sharing common ancestry, the persistence of community composition over time, and the outcome of selection when it occurs at the community level. Our results provide a means for exploring how this process leads to large‐scale community evolutionary change, and they identify the circumstances in which selection may routinely act at the community level.
... l. Wade, Michael John, 1949-ll. Title. lll. ... We show how the opportunity for sexual select... more ... l. Wade, Michael John, 1949-ll. Title. lll. ... We show how the opportunity for sexual selection, caused by the spatial and temporal clustering of female receptivity, is related to the ecological concept of mean crowding (sensu Lloyd 1967) applied directly to the spatial and temporal ...
Cambridge University Press eBooks, Dec 6, 2012
Journal of Experimental Marine Biology and Ecology, Feb 1, 1999
Remarkable temporal and spatial variations occur on selected body temperature (T sel) and locomot... more Remarkable temporal and spatial variations occur on selected body temperature (T sel) and locomotor performance for Plestiodon (Eumeces) chinensis, commonly known as Chinese skinks. However, the significance of these variations remains elusive. Th is study focuses on the eff ects of thermal environment and food availability on P. chinensis 's T sel and locomotor performance. Th e duration of thermal treatment (4h and 8h) displayed signifi cant eff ects on T sel , additionally the eff ects of thermal treatment were also dependent on food-availability. Th ere was no signifi cant variation in skink's T sel under diverse thermal treatments when suffi cient food was available. However, with insuffi cient food source, the T sel decreased with decrease in the duration of thermal treatment. Th ermal acclimation also aff ected locomotor performance of P. chinensis, as the 8h thermal treatment enhanced their locomotor performance. However, food availability alone had no signifi cant impact on the locomotor performance. Th erefore, the combination of thermal acclimation and food availability could cause variations in T sel and locomotor performance of skinks, suggesting that thermal environment and food condition in nature are important factors involved in temporal and spatial variations for T sel and locomotor performance.
Journal of Plant Ecology, 2017
Aims the functional advantages of arsenic (As) hyperaccumulation by plants are poorly understood.... more Aims the functional advantages of arsenic (As) hyperaccumulation by plants are poorly understood. One proposed benefit, termed elemental allelopathy, occurs when hyperaccumulated As is cycled from the plant back into the top layer of soil, allowing As hyperaccumulators to gain an advantage over intolerant species by increasing soil As concentrations ([As]) underneath their canopy. to date, there are no studies that detail the presence of increased soil [As] associated with As hyperaccumulators. In this study, we documented variation in the soil [As] associated with the Chinese brake fern, Pteris vittata L. and also compared the effects of environmentally relevant soil and solution [As] on competitor plant growth. Methods Four populations of P. vittata were identified in central Florida, USA. P. vittata tissue samples and soil samples were collected at the base of and at 3 m away from ferns in each population (n = 36). Five sample locations were randomly selected from each site, and soils from the base and 3 m away from each fern were collected to examine the effects of naturally occurring soil [As] on the germination and growth of a potential competitor plant (Oxalis stricta). Solutions with increasing [As] were also used to examine the threshold for negative effects of [As] on O. stricta growth. [As] were measured using inductively coupled plasma mass spectrometry (ICP-MS). Important Findings Overall, soil [As] from the base of ferns was nearly twice that of soil 3 m away indicating that ferns hyperaccumulate As. However, ferns and their associated soil, contained different [As] depending on their collection site, indicating that these populations accumulate and use [As] differently. O. stricta growth decreased and germination was delayed as solution and soil [As] increased. However, the relative distance from the fern that the soil was collected from did not affect growth, which would be expected with elemental allelopathy. Our results show that P. vittata is associated with higher soil [As] and these concentrations are sufficient to inhibit growth of competitors. However, the absence of a strong inhibitory relationship associated with proximity to the fern across all locations suggests that the possible functional advantages of elemental allelopathy may depend on site specific characteristics.
Journal of Pest Science
Rodent population control is a global problem, complicated by evolved non-responsiveness to roden... more Rodent population control is a global problem, complicated by evolved non-responsiveness to rodenticide treatment. Contraceptives could help mitigate this challenge, but questions remain about their efficacy, especially for rodenticide-resistant populations. We used an age-dependent demographic model to generate two hypotheses: Fertility reduction applied early in female lifetimes (1) is more effective in controlling rodent populations than when applied later in female lifetimes, and (2) is effective in controlling rodent populations that are expanding. Compared to controls, fertility reduction applied early, in mid-life, and late in female lifetimes, decreased, matched, and accelerated, respectively, the rates of population growth. Fertility reduction was effective in reducing population size only when sustained over multiple generations and was ineffective when application was episodic. Substituting classic Rattus norvegicus and Microtus agrestis life history data into our simulat...
Crustacean Sexual Biology
Behavioral Ecology, Oct 20, 2021
Shuker and Kvarnemo's (2021) stimulating review advocates using what they see as a simple definit... more Shuker and Kvarnemo's (2021) stimulating review advocates using what they see as a simple definition of sexual selection, being "any
Data collected in the field in May 2009 in Socorro, NM. Data archived in Excel, JMP 9.0.2 was use... more Data collected in the field in May 2009 in Socorro, NM. Data archived in Excel, JMP 9.0.2 was used to create principle component measure of body size and transform data
Our 2-way ANOVA of the residuals for offspring number on female body length, to determine whether... more Our 2-way ANOVA of the residuals for offspring number on female body length, to determine whether the fertilities of the 3 male morphs differed or decreased with increasing mating frequency, was non-significant overall (F[5,85] =0.25, P =0.94) with non-significant effects of male morph (F[MORPH] =0.42, P =0.66) and mate order (F[ORDER] =2.21, P =0.64) and a non-significant interaction between these factors (F[MORPH*ORDER] =0.15, P =0.86). This result indicated that, although the they appear to invest different amounts of energy to somatic and gametic functions (Shuster 1989a), the 3 male morphs did not differ in their sexual competency with multiple matings. This result also confirmed that there were no significant differences in the fecundities of females mated with α-, β- and γ-males, and, consistent with Shuster (1989a), there were no significant differences in the numbers of undeveloped zygotes among females mated by α-, β- and γ-males (F[5,67] =0.18, P =0.97; F[MORPH] =0.31, P ...
The alpha males of the isopod Paracerceis sculpta allow reproductive females (here inside the spo... more The alpha males of the isopod Paracerceis sculpta allow reproductive females (here inside the sponge) to enter their host sponges; beta males and tiny gamma males, which are morphologically identical to females and juveniles, respectively (here seen on the outer sponge surface), attempt to sneak past the alpha male guarding the entrance to copulate with the females within.
Three discrete male morphs coexist in Paracerceis sculpta, a marine isopod crustacean inhabiting ... more Three discrete male morphs coexist in Paracerceis sculpta, a marine isopod crustacean inhabiting the northern Gulf of California. Ornamented a-males establish themselves in the spon- gocoels of intertidal sponges, where females congregate to breed. Smaller ,B-males, resembling sexually mature females, enter spongocoels by deception, while tiny y-males invade spongocoels by stealth. Isopods breed year-round, and the operational sex ratio fluctuates widely over short durations. When females are abundant, receptive females accumulate in spongocoels, and these spongocoels are preferentially invaded by ,B- and y-males. To test the hypothesis that the density of receptive females affects relative fertilization success among male morphs, individual ,B- and y-males, heterozygous for a dominant cuticular pigmentation allele, were placed in artificial spon- gocoels with an unmarked a-male and densities of one, two, and three unmarked, receptive females. The fertilization success of each male ...
Encyclopedia of Evolutionary Biology, 2016
The Operational Sex Ratio, or OSR, first defined as ‘the ratio of receptive females to potential ... more The Operational Sex Ratio, or OSR, first defined as ‘the ratio of receptive females to potential mating males at any one time,’ was designed to measure the level of competition for mates in animal populations. The apparent utility of the OSR as a proxy for sexual selection intensity established it as a standard metric for animal mating system research. However, the relationships between OSR and actual measures of sexual selection have proven inconsistent. Thus, while useful for characterizing known experimental populations, estimates of OSR are not equivalent to those for sexual selection and are unlikely account for observed patterns of evolutionary change.
Oikos, 2016
Natural selection as a result of plant-plant interactions can lead to local biotic adaptation. Th... more Natural selection as a result of plant-plant interactions can lead to local biotic adaptation. This may occur where species frequently interact and compete intensely for resources limiting growth, survival, and reproduction. Selection is demonstrated by comparing a genotype interacting with con-or hetero-specific sympatric neighbor genotypes with a shared site-level history (derived from the same source location), to the same genotype interacting with foreign neighbor genotypes (from different sources). Better genotype performance in sympatric than allopatric neighborhoods provides evidence of local biotic adaptation. This pattern might be explained by selection to avoid competition by shifting resource niches (differentiation) or by interactions benefitting one or more members (facilitation). We tested for local biotic adaptation among two riparian trees, Populus fremontii and Salix gooddingii, and the shrub Salix exigua by transplanting replicated genotypes from multiple source locations to a 17 000 tree common garden with sympatric and allopatric treatments along the Colorado River in California. Three major patterns were observed: 1) across species, 62 of 88 genotypes grew faster with sympatric neighbors than allopatric neighbors; 2) these growth rates, on an individual tree basis, were 44, 15 and 33% higher in sympatric than allopatric treatments for P. fremontii, S. exigua and S. gooddingii, respectively, and; 3) survivorship was higher in sympatric treatments for P. fremontii and S. exigua. These results support the view that fitness of foundation species supporting diverse communities and dominating ecosystem processes is determined by adaptive interactions among multiple plant species with the outcome that performance depends on the genetic identity of plant neighbors. The occurrence of evolution in a plant-community context for trees and shrubs builds on ecological evolutionary research that has demonstrated co-evolution among herbaceous taxa, and evolution of native species during exotic plants invasion, and taken together, refutes the concept that plant communities are always random associations.
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Papers by Stephen Shuster