Deborah Ann Roach

Deborah Ann Roach
University of Virginia | UVa · Department of Biology

About

45
Publications
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2,440
Citations

Publications

Publications (45)
Article
Full-text available
Simple demographic events, the survival and reproduction of individuals, drive population dynamics. These demographic events are influenced by genetic and environmental parameters, and are the focus of many evolutionary and ecological investigations that aim to predict and understand population change. However, such a focus often neglects the stoch...
Article
Full-text available
Oxidative stress and hormonal regulation are hallmarks of a/biotic stress responses in plants. However, little is known about their linkage with whole-organismal mortality in long-lived species. Here, we examined the validity of photo-oxidative stress markers and stress-related phytohormones as predictive proxies of mortality risk in the perennial...
Article
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Genetic differentiation and phenotypic plasticity jointly shape intraspecific trait variation, but their roles differ among traits. In short-lived plants, reproductive traits may be more genetically determined due to their impact on fitness, whereas vegetative traits may show higher plasticity to buffer short-term perturbations. Combining a multi-t...
Poster
Full-text available
Oxidative stress is a hallmark of organismal stress responses, both abiotic and biotic, and it is also tightly linked to whole-plant senescence in monocarpic plants. However, studies using oxidative stress markers as proxies of mortality in perennial plants are still lacking. Here, we aimed to determine the validity of using oxidative stress marker...
Article
Full-text available
Do all species experience the declines of old age? No. Do we currently have theories that accurately predict which species escape these declines? In PNAS, Warner et al. (1) demonstrate that the answer to this question is also “no.” Understanding the breadth and diversity of the patterns of aging across the tree of life is central to life history ev...
Article
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Premise of the study: Mammalian herbivores, particularly white-tailed deer, can have a major impact on plant abundance and distribution. However, plants can tolerate herbivory by increasing seed production or seed quality. We used the monocarpic perennial Prenanthes roanensis to examine tolerance to mammalian herbivory through seed quality and mod...
Article
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• The ecological consequences of plant competition have frequently been tested, but the evolutionary outcomes of these interactions have gone largely unexplored. The study of species invasions can make an important contribution to this field of research by allowing us to watch ecological and evolutionary processes unfold as a novel species is integ...
Article
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• Recent studies suggest that invasive plants compete reproductively with native plants by reducing the quantity or quality of pollinator visits. Although these studies have revealed ecological consequences of pollinator-mediated competition between invasive and native plants, the evolutionary outcomes of these interactions remain largely unexplore...
Article
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Empirical studies reveal aging occurs in wild populations. Consideration of the ecological and evolutionary consequences of these findings is critical for many areas of research, including life-history evolution, sexual selection, behavior, and applied ecology. Variation in the patterns of age-dependent declines of phenotypic traits has been found...
Article
Species' range limits can be caused by environmental gradients, and in such cases, abundance is thought to be highest in the center of a species range and decline towards the edge (the abundant-center model). Although in theory decreased abundance is caused by a decline in performance at the edge, it has been shown that performance and abundance ar...
Conference Paper
Background/Question/Methods As climate change begins to shift species’ ranges and cause population extinctions, it is critical to understand how species’ ranges are structured. The abundant-center model postulates that an environmental gradient in habitat quality from the center to the periphery of the range results in reduced abundance and perfo...
Article
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Premise of research. This study demonstrates that carryover effects from differences in early-life environmental conditions influence patterns of mortality, natural selection, and late-life phenotype. Methodology. Using the annual species Agrostemma githago, an experimental design was established to create different early-life environments and a co...
Article
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4 synthesis: The hypothesis that plants escape senescence generally assumes that plants can continue to grow larger and increase reproduction as they get older. The results here show that size and reproduction decline with age and the rates of these declines toward death are lifespan- and age-dependent. Further research is needed to delineate the...
Article
In an inbred population, selection may reduce the frequency of deleterious recessive alleles through a process known as purging. Empirical studies suggest, however, that the efficacy of purging in natural populations is highly variable. This variation may be due, in part, to variation in the expression of inbreeding depression available for selecti...
Conference Paper
Background/Question/Methods In natural populations, quantifying aging is often confounded because changes in mortality and reproduction may be influenced by both short-and long-term environmental fluctuations as well as age-dependent changes in performance. We will report on the results from a large, multiple cohort study, which has followed appr...
Article
Full-text available
The theory of evolution via natural selection predicts that the genetic composition of wild populations changes over time in response to the environment. Different genotypes should exhibit different demographic patterns, but genetic variation in demography is often impossible to separate from environmental variation. Here, we asked if genetic varia...
Article
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Plants rely on phenotypic plasticity to maintain performance and survive in changing environments. Stress such as herbivory has the potential to cause short- and long-term changes to a plant’s phenotype. In response to simulated herbivory by clipping, plants either may show lower growth and fecundity or may overcompensate and exceed the size and fe...
Conference Paper
Background/Question/Methods Population projections are often used to assess life history evolution and population viability, but assume that past and future environmental variation stays within levels observed in the study and that the genetic composition of a population is either unchanging or inconsequential to population dynamics. Here, we asses...
Article
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Theory suggests that iteroparity may confer greater fitness than semelparity in situations in which temporal environmental variation is high and unpredictable. Variable age-specific mortality, density dependence, and other factors may also favor iteroparity over semelparity. Here, we empirically test the adaptive benefits of greater numbers of repr...
Article
We know very little about aging (senescence) in natural populations, and even less about plant aging. Demographic aging is identified by an increasing rate of mortality following reproductive maturity. In natural populations, quantifying aging is often confounded because changes in mortality may be influenced by both short- and long-term environmen...
Article
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In many species, the physical act of mating and exposure to accessory gland proteins (Acps) in male seminal fluid reduces female survival and offspring production. It is not clear what males gain from harming their sexual partners or why females mate frequently despite being harmed. Using sterile strains of Drosophila melanogaster that differ in th...
Article
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In many species, increased mating frequency reduces maternal survival and reproduction. In order to understand the evolution of mating frequency, we need to determine the consequences of increased mating frequency for offspring. We conducted an experiment in Drosophila melanogaster in which we manipulated the mating frequency of mothers and examine...
Article
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In traditional deterministic models the conditions for the evolution of sex and sexual behavior are limited because their benefits are context dependent. In novel and adverse environments both multiple mating and recombination can help generate gene combinations that allow for rapid adaptation. Mating frequency often increases in conditions in whic...
Article
This chapter focuses on the application of evolutionary and demographic approaches to senescence and to the study of plants and the determination of mortality patterns and longevity. One of the major evolutionary theories, antagonistic pleiotropy, suggests that genes affecting traits negatively late in life may get established in a population if th...
Article
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Accurate measures of age-dependent mortality are critical to life-history analysis and measures of fitness, yet these measures are difficult to obtain in natural populations. Age-dependent mortality patterns can be obscured not only by seasonal variation in environmental conditions and reproduction but also by changes in the heterogeneity among ind...
Article
Negative senescence is characterized by a decline in mortality with age after reproductive maturity, generally accompanied by an increase in fecundity. Hamilton (1966) ruled out negative senescence: we adumbrate the deficiencies of his model. We review empirical studies of various plants and some kinds of animals that may experience negative senesc...
Article
Examines the variation in an individual's phenotype contributed by the maternal parent beyond the equal chromosomal contribution expected from each parent. Cytoplasmic genetic, endosperm nuclear and maternal phenotypic effects are distinguished. Such maternal influences are especially pronounced in the seed (size, mineral composition, dormancy and...
Article
Phenological patterns of flowering and fruiting can be influenced by the effects of reproductive time on seed production. We propose here that these patterns are also influenced by phenological effects on offspring quality. Furthermore, we hypothesize that there are cross-generational trade-offs between parental and offspring components of parental...
Article
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Life-history traits can play important roles in determining the course of ecological species interactions. We explored the consequences of host age on a host-pathogen interaction by quantifying pathogen frequency in an age-structured host population. Our project was motivated by an interest in whether the demographic structure of a host population...
Article
The major starting point to life history analysis is the schedule of reproduction and mortality; hence, knowledge of age-specific demographic dynamics is needed. The key ingredients to studies on age-specific demography must include large cohorts of individuals of known age, an accurate accounting of all individuals, and an experimental design to f...
Article
Most experimental studies of senescence have been done with short-lived organisms under controlled laboratory conditions and it is not clear whether the insights gained from these studies can be broadly generalized. This study was designed to detect senescence in a natural population and to compare the patterns of mortality for a single species in...
Article
Full-text available
Senescence is a decline in age-specific survival and reproduction with advancing age. Studies of evolutionary plant senescence are designed to explain this decline in life history components within the context of natural selection. A review of studies of plant demography reveals senescent declines in both annual and perennial plants, but also sugge...
Article
To understand the evolution of parental care behaviour, the cost of care must be evaluated in terms of lost reproductive potential. Using population genetics theory, a quantitative model of parental care is presented here to evaluate the allocation of resources between production and care of offspring, and care of grandoffspring. The results show t...
Article
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Success at the juvenile stage of the life cycle may have important consequences for the size-hierarchies and distribution patterns of adult plants. This study was designed to evaluate the factors contributing to variation in seed and seedling size in Anthoxanthum ordoratum. In experiments in the greenhouse and within the natural habitat of this spe...
Article
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Seeds of Geranium carolinianum were collected according to common female parent from 3 populations, then planted back in a randomized block design into one of the original populations. Individuals were harvested at early juvenile, late juvenile and adult stages, and the same traits were measured at each life stage. Genetic correlations measured bet...
Article
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The importance of the timing of seed production and of seed dispersal to the fitness of an annual plant was examined using Geranium carolinianum in the piedmont of North Carolina. Mature seeds were collected from naturally growing plants on four dates in May and June and were then sown back into the population on five dates in late May, June, and J...
Article
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Revegetation of an alpine area disturbed by excessive human activity along the Appalachian Trail was studied using the native species Arenaria groenlandica, Juncus trifidus, and Potentilla tridentata. Recruitment and mortality in populations of sown seed were recorded, and environmental parameters were measured in order to assess their impact on th...
Article
Typescript. Thesis (Ph. D.)--Duke University, 1984. Vita. Includes bibliographical references.
Article
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A comparison is made of the species of the above ground vegetation and the buried seeds in a tussock tundra meadow, northern Alaska. Vegetation types are compared across a boundary between two habitats which have distinct differences in above ground vegetation. Sixteen species germinated from the soil cores. There were distinct differences between...
Article
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Reproductive characteristics are reported for four plant species identified as potential early colonizers of disturbed alpine tundra in the White Mountains of New Hampshire. Arenaria groenlandica and Juncus trifidus showed high production of viable seed, high germination percentages, and relatively high (albeit short-range) seed mobility combining...

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