About
38
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Introduction
I am broadly interested in plant ecology and evolution. Much of this work is driven by a desire to understand the complex interplay between the evolutionary causes and consequences of different reproductive and adaptive strategies. The core of my research falls under two major topics: The evolution of plant mating/breeding systems and evolutionary responses to climate change in plant populations.
Current institution
Education
August 2007 - June 2012
January 2005 - June 2007
August 1999 - June 2002
Publications
Publications (38)
Premise of Study
In a seminal body of theory, Lloyd showed that the fitness consequences of selfing will depend on its timing in anthesis. Selfing that occurs after opportunities for outcrossing or pollen dispersal can provide reproductive assurance when pollinators are limited and is expected to incur little cost, even when inbreeding depression i...
Both intrinsic and extrinsic forces work together to shape connectivity and genetic variation in populations across the landscape. Here we explored how geography, breeding system traits, and environmental factors influence the population genetic patterns of Triodanis perfoliata, a widespread mix-mating annual plant in the contiguous US. By integrat...
Plant-insect interactions are a key topic in evolutionary ecology, especially in the face of anthropogenic changes which threaten to disrupt these mutualisms. An in-depth pollinator survey for species in the genus Triodanis is performed here for the first time, with sampling covering four species and spanning a large portion of their geographic ran...
Using citizen science resources and projects in university education is a burgeoning pedagogical tool that can promote real-world application of science, autonomous learning, and understanding of self-efficacy in science learning. In this case study, we examined several factors relating to self-efficacy and skill growth in STEM and non-STEM majors...
Premise:
Understanding species' responses to climate change is a critical challenge facing biologists today. Though many species are widespread, few studies of climate-driven shifts in flowering time have examined large continuous spatial scales for individual species. And even fewer studies have examined these shifts at time scales greater than a...
The maintenance of outcrossing in cleistogamous plants that produce both open, facultatively outcrossing chasmogamous (CH), and closed, obligate selfing cleistogamous (CL) flowers is puzzling because CL reproduction is thought to be more reliable and less costly. A possible explanation for the maintenance of CH flowers is the avoidance of inbreedin...
Plant breeding systems can vary widely among populations, yet few studies have investigated abiotic factors contributing to variation across a broad geographic range. Here we investigate variation in reproductive traits of Triodanis perfoliata (Campanulaceae), a species that exhibits dimorphic cleistogamy, a condition in which individual plants hav...
Plant breeding systems can vary widely among populations, yet few studies have investigated abiotic factors contributing to variation across a broad geographic range. Here we investigate variation in reproductive traits of Triodanis perfoliata (Campanulaceae), a species that exhibits dimorphic cleistogamy, a condition in which individual plants hav...
Premise of research. The assumption of a trade-off between growth and defense is a major tenet of plant defense theory, though not all prior research has supported this trade-off. If this trade-off exists, plant genotypes that grow rapidly should be less well defended against herbivory than more slowly growing genotypes. Furthermore, selection for...
The incredible diversity of plant mating systems has fuelled research in evolutionary biology for over a century. Currently, there is broad concern about the impact of rapidly changing pollinator communities on plant populations. Very few studies, however, examine patterns and mechanisms associated with multiple paternity from cross-pollen loads. O...
To teach the most central concepts in evolutionary biology, we present an activity in pollination biology. Students play the role of either pollinator or flower and work through a set of scenarios to maximize plant fitness. This “Pollination Game” facilitates critical and inquiry-based thinking, and we accompany each round of the exercise with a se...
In an age of rapid global change, it is imperative that we continue to improve our understanding of factors that govern genetic differentiation in plants to inform biologically reasonable predictions for the future and enlighten conservation and restoration practices. In this special issue, we have assembled a set of original research and reviews t...
Premise of the study:
Project Baseline is a seed bank that offers an unprecedented opportunity to examine spatial and temporal dimensions of microevolution during an era of rapid environmental change. Over the upcoming 50 years, biologists will withdraw genetically representative samples of past populations from this time capsule of seeds and grow...
Premise of the study:
Climate change is a widely accepted threat to biodiversity. Species distribution models (SDMs) are used to forecast whether and how species distributions may track these changes. Yet, SDMs generally fail to account for genetic and demographic processes, limiting population-level inferences. We still do not understand how pred...
Understanding the genetic basis of natural phenotypic variation is of great importance, particularly since selection can act on this variation to cause evolution. We examined expression and allelic variation in candidate flowering time loci in
Brassica rapa
plants derived from a natural population and showing a broad range in the timing of first fl...
BrSOC1 primers
Relative locations of primers designed for sequencing promotor orthologs (A–C) and Exon 6 (D) of BrSoc1 flowering time genes in Brassica rapa. Solid blue arrow indicates the start codon. Where applicable, colors indicate matching sets of primers. For specific locations and primer sequence information, see Table 1.
Accession numbers for BrFLC paralogs
BrFLCprimers
Relative locations of primers designed for sequencing promotor regions (A) and coding regions (B) of BrFLC flowering time genes in Brassica rapa. Solid blue arrow indicates the start codon. Where applicable, colors indicate matching sets of primers. (Note for FLC2, the primer set shown in green covers Exon 3 (forward) and Exon 5 (rever...
Understanding the genetic basis of natural phenotypic variation is of great importance, particularly since selection can act on this variation to cause evolution. We examined expression and allelic variation in candidate flowering time loci in Brassica rapa plants derived from a natural population and showing a broad range in the timing of first fl...
Understanding the genetic basis of natural phenotypic variation is of great importance, particularly since selection can act on this variation to cause evolution. We examined expression and allelic variation in candidate flowering time loci in Brassica rapa plants derived from a natural population and showing a broad range in the timing of first fl...
The inheritance of style-morphs was investigated in tetraploid populations of tristylous Oxalis alpina (Oxalidaceae) to determine if alleles controlling style-morphs are expressed at duplicated loci. In tetraploid populations, a dominant S allele leads to expression of the short-styled phenotype at the short/non-short locus and is epistatic to the...
The heterostylous reproductive system of Oxalis alpina in the Galiuro Mts. of Arizona was investigated using field surveys, controlled crosses in the greenhouse, and measurements of reproductive morphs. Although populations in the Pinaleño Mts. to the immediate east and in the Santa Catalina Mts. to the immediate west have derived distylous reprodu...
As climate change progresses, we are observing widespread changes in phenotypes in many plant populations. Whether these phenotypic changes are directly caused by climate change, and whether they result from phenotypic plasticity or evolution, are active areas of investigation. Here, we review terrestrial plant studies addressing these questions. P...
We investigated the role of morph-based differences in the expression of inbreeding depression in loss of the mid-styled morph from populations of tristylous Oxalis alpina. The extent of self-compatibility (SC) of reproductive morphs, the degree of self-fertilization, and the magnitude of inbreeding depression were investigated in three populations...
Premise of research. Tristylous populations of Oxalis alpina have three floral morphs (short-, mid-, and
long-styled), and populations appear to be at different stages in the evolution of distyly via loss of the mid-styled morph. In tristylous populations transitioning to distyly, asymmetrical incompatibility reactions could affect style-morph freq...
Pollination or fertilisation trigger floral senescence in a wide range of flowering plants, and yet little attention has been given to the implications of this phenomenon to mating system evolution. We examined the effects of pollination on floral senescence in the genus Leptosiphon. Species in the genus exhibit a wide range of breeding systems. In...
Premise of the study:
Variation among individuals in levels of inbreeding depression associated with selfing levels could influence mating system evolution by purging deleterious alleles, but empirical evidence for this association is limited.
Methods:
We investigated the association of family-level inbreeding depression and presumed inbreeding...
Self-fertilization can provide reproductive assurance during periods of low or unreliable pollinator visitation. Therefore, periods of low pollen receipt may favor evolutionary shifts from cross-fertilization to self-fertilization. Although reproductive assurance is hypothesized to be important in mating system evolution, it has been quantified in...
An association between vine habit and cordate leaf shape in higher plants has been reported, but previous comparative analyses have not taken into account phylogenetic history. We surveyed the flora of the Carolinas and used phylogenetic comparative methods to test the hypothesized relationship. We found 25 phylogenetically independent vine taxa in...
When fertilization triggers flower senescence, early autonomous selfing may cause flowers to senesce before pollen has dispersed, discounting unused pollen. Selfing-induced flower senescence was examined in Leptosiphon jepsonii, a species that varies in the timing of self-compatibility. In field and greenhouse experiments, fertilization had a large...
Experimental self- and cross-pollinations revealed that Leptosiphon jepsonii (formerly Linanthus jepsonii), an annual species, possesses a floral age-dependent form of self-incompatibility (SI) that confers delayed selfing. In field and growth room studies of two populations, self-pollination produced few to no pollen tubes when flowers were first...
