Shu-Mei Chang

University of Georgia | UGA · Department of Plant Biology

Contemporary anthropogenic changes in climate and landscape form a complex set of selective pressures acting on natural systems, yet, in many systems, we lack information about both whether and how organisms may adapt to these changes. In plants, research has focused on climate-induced changes in phenology and the resultant potential for disruption...

Contemporary anthropogenic changes in climate and landscape form a complex set of selective pressures acting on natural systems, yet, in many systems, we lack information about both whether and how organisms may adapt to these changes. In plants, research has focused on climate-induced changes in phenology and the resultant potential for disruption...

Sexual dimorphism in plant growth and/or reproductive responses to the surrounding environment has been documented in some plant species. In gynodioecious plants, it is especially important to understand whether females and hermaphrodites differ in their response to environmental stressors, as the fitness of females relative to hermaphrodites deter...

Sexual dimorphism in plant growth and/or reproductive responses to the surrounding environment has been documented in some plant species. In gynodioecious plants, it is especially important to understand whether females and hermaphrodites differ in their response to environmental stressors, as the fitness of females relative to hermaphrodites deter...

The repeated evolution of herbicide resistance has been cited as an example of genetic parallelism, wherein separate species or genetic lineages utilize the same genetic solution in response to selection. However, most studies that investigate the genetic basis of herbicide resistance examine the potential for changes in the protein targeted by the...

Objective: Oral health denotes general well-being, meaning that the person can perform functions such as eating, talking, and keeping smile. Those functions can impact on oral health-related quality of life (OHRQoL) with differences between sexes. In this study, we intended to examine sex differences and oral health behaviors in OHRQoL among instit...

The repeated evolution of herbicide resistance has been cited as an example of genetic parallelism, wherein separate species or genetic lineages utilize the same genetic solution in response to selection. However, most studies that investigate the genetic basis of herbicide resistance examine the potential for changes in the protein targeted by the...

Examining how the landscape may influence gene flow is at the forefront of understanding population differentiation and adaptation. Such understanding is crucial in light of ongoing environmental changes and the elevated risk of ecosystems alteration. In particular, knowledge of how humans may influence population structure is imperative to allow f...

Examining how the landscape may influence gene flow is at the forefront of understanding population differentiation and adaptation. Such understanding is crucial in light of ongoing environmental changes and the elevated risk of ecosystems alteration. In particular, knowledge of how humans may influence the structure of populations is imperative to...

Premise of the study: Abiotic environmental factors are often considered to be important in the distribution and maintenance of variation in sexual systems in flowering plants. Associations between sexes and abiotic factors are well documented in dioecious systems, but much less is known about this relationship in other sexually polymorphic system...

Plant–pollinator interactions are essential for successful plant reproduction in both natural and agricultural systems. These interactions are negatively impacted by recent large-scale alterations of the environments, particularly climate change. The responses of plants and pollinators to changing abiotic conditions that vary seasonally and geograp...

Human-mediated selection can strongly influence the evolutionary response of natural organisms within ecological timescales. But what traits allow for, or even facilitate, adaptation to the strong selection humans impose on natural systems? Using a combination of lab and greenhouse studies of 32 natural populations of the common agricultural weed,...

Human-mediated selection can strongly influence the evolutionary response of natural organisms within ecological timescales. But what traits allow for, or even facilitate, adaptation to the strong selection humans impose on natural systems? Using a combination of laboratory and greenhouse studies of 32 natural populations of the common agricultural...

Although fitness costs associated with plant defensive traits are widely expected, they are not universally detected, calling into question their generality. Here we examine the potential for life history trade-offs associated with herbicide resistance by examining seed germination, root growth, and above-ground growth across 43 naturally occurring...

Despite the negative economic and ecological impact of weeds, relatively little is known about the evolutionary mechanisms that influence their persistence in agricultural fields. Here, we use a resurrection ecology approach and compare the genetic and phenotypic divergence of temporally sampled seed progenies of Ipomoeapurpurea , an agricultural w...

Premise of the study: Pollen size varies greatly among flowering plant species and has been shown to influence the delivery of sperm cells to the eggs. Relatively little is known, however, about the functional significance of within-species genetic variation in pollen size. This study tests whether pollen size influences the relative siring succes...

Strong human-mediated selection via herbicide application in agroecosystems has repeatedly led to the evolution of resistance in weedy plants. Although resistance can occur among separate populations of a species across the landscape, the spatial scale of resistance in many weeds is often left unexamined. We assessed the potential that resistance t...

Weeds represent a major cause of agricultural losses worldwide. Most weeds share a common set of life history characteristics that predispose them to weediness, two of which are self-compatibility, which allows for ease of colonization through reproductive assurance, and high trait plasticity, which allows for tolerance of a wide variety of environ...

Background and Aims Gynodioecy, the co-occurrence of female and hermaphroditic individuals, is thought to be an intermediate step between hermaphroditism and separate sexes, a major transition in flowering plants. Because retaining females in a population requires that they have increased seed fitness (to compensate for the lack of pollen fitness),...

Background/Question/Methods Inbreeding depression (ID) is thought to influence population viability, and accordingly has been a major concern for conservation biologists. This concern is resurfacing as recent meta-analyses demonstrate increased selfing rates and reduced fitness in small, fragmented plant populations compared to large ones. Howeve...

Gynodioecy, the co-occurrence of female and hermaphroditic individuals within a population, is an important intermediate in the evolution of separate sexes. The first step, female maintenance, requires females to have higher seed fitness compared with hermaphrodites. A common mechanism thought to increase relative female fitness is inbreeding depre...

One key objective in evolutionary ecology is to understand the magnitude of inbreeding depression expressed across sex-specific components of fitness. One major component of male fitness is fertilization success, which depends on male gametic performance (sperm and pollen performance in animals and plants, respectively). Inbreeding depression in ma...

• Premise of the study: Microsatellite primers were developed for Geranium carolinanum, a North American winter annual herb, for use in population genetic analyses. • Methods and Results: Genomic DNA enriched for repeat-containing fragments was sequenced on the Roche 454 Titanium platform, resulting in 470 primer pairs developed from 1115 microsate...

This article documents the addition of 153 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Brassica oleracea, Brycon amazonicus, Dimorphandra wilsonii, Eupallasella percnurus, Helleborus foetidus, Ipomoea purpurea, Phrynops geoffroanus, Prochilodus argenteus, Pyura sp., Sylvia a...

Studies of invasive species often demonstrate that exotic or invasive plants have reduced levels of predation when first introduced into novel geographic areas. In some systems, native predators may subsequently be introduced and the plant-predator association is re-established. In this study, we analyzed a recent reassociation between the introduc...

Many diverse questions in ecology and evolution have been addressed using species belonging to the genus Ipomoea, commonly referred to as the morning glory genus. Ipomoea exhibits a wide range of diversity in floral color, growth form, mating system and tolerance to environmental factors, both within and among species, and as such has been a focal...

Understanding how the mating system varies with population size in plant populations is critical for understanding their genetic and demographic fates. We examined how the mating system, characterized by outcrossing rate, biparental inbreeding rate, and inbreeding coefficient, and genetic diversity varied with population size in natural populations...

Populations containing both females and hermaphrodites (dimorphic) are generally found in drier sites than those with only hermaphrodites (monomorphic). The sex-differential plasticity hypothesis (SDP) suggests that this is caused by hermaphrodites reducing allocation to seeds in harsh environments, allowing female establishment. We proposed that a...

Individuals in large plant populations are expected to benefit from increased reproductive success relative to those in small populations because of the facilitative effects of large aggregations on pollination. As populations become small, the inability to attract sufficient numbers of pollinators can reduce reproduction via pollen limitation. Thi...

This study used both quantitative and qualitative analyses to examine the influence of written arguments on learning in a college level introductory biology class and the types of metacognition employed by students while writing. Comparison of a treatment and control group indicates that the writing assignments used had minimal impact on overall co...

Plant death is the most common effect resulting from the application of glyphosate, the active ingredient in the herbicide Roundup 1 . Individual seedlings of the morning glory, Ipomoea purpurea L. Roth, however, have been shown to exhibit tolerance to glyphosate, surviving after what should have been a lethal dose. Those that grow and reach reprod...

Aim We examine several hypotheses emerging from biogeographical and fossil records regarding glacial refugia of a southern thermophilic plant species. Specifically, we investigated the glacial history and post-glacial colonization of a forest understorey species, Trillium cuneatum. We focused on the following questions: (1) Did T. cuneatum survive...

Plant species with separate genders often exhibit gender differences in traits related to reproductive allocation. In gynodioecious species, females often produce more seeds than do hermaphrodites, leading to a higher reproductive cost. The mechanisms that allow females to meet the high costs of reproduction are currently under debate. In this stud...

Summary • Small and low-density populations often suffer significant reductions in reproduction, as exemplified by studies on rare and threatened species. While this phenomenon is less studied in common species, if general, it should not be restricted to those in peril. We addressed this assertion by examining the effects of plant abundance, measur...

In gynodioecious species, females coexist with hermaphrodites in natural populations even though hermaphrodites attract more pollinators, are capable of reproducing through pollen, and can self-fertilize. This study tests the hypothesis that inbreeding depression helps to maintain females in natural populations. It also examines whether gender line...

Comparisons between rare species and their more common congener species can provide valuable information for conservation. Reproductive traits have previously been shown to be critical for reproductive success and persistence of rare species. In this study, we compared floral, seedpod, and seed traits of two Baptisia species (one endangered and one...

This study examined the impact of cooperative learning activities on student achievement and attitudes in large-enrollment (>250) introductory biology classes. We found that students taught using a cooperative learning approach showed greater improvement in their knowledge of course material compared with students taught using a traditional lecture...

For a newly arising mutation affecting a trait under selection, its degree of dominance relative to the preexisting allele(s) strongly influences its evolutionary impact. We have estimated dominance parameters for spontaneous mutations in a subset of lines derived from a highly inbred founder of Arabidopsis thaliana by at least 17 generations of mu...

One of the major evolutionary trends in flowering plants is the evolution of unisexual flowers (male or female) from perfect flowers. This transition has occurred repeatedly in many taxa and has generated a wonderful array of variation in sexual expression among species. Theoretical studies have proposed a number of mechanisms to explain how this l...

Plant transcription factors often contain domains that evolve very rapidly. Although it has been suggested that this rapid evolution may contribute substantially to phenotypic differentiation among species, this suggestion has seldom been tested explicitly. We tested the validity of this hypothesis by examining the rapidly evolving non-DNA-binding...