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Articles 1 - 13 of 13
Full-Text Articles in Plant Breeding and Genetics
Isolation Of Gametophytic Selection And Selective Embryo Abortion In Mimulus Guttatus, Desmond C. Willson
Isolation Of Gametophytic Selection And Selective Embryo Abortion In Mimulus Guttatus, Desmond C. Willson
University Honors Theses
A lack of genomic studies examining gametophytic selection (GS) and selective embryo abortion (SEA)--which occur during the reproduction of angiosperms--leaves questions regarding the adaptive and evolutionary effects of these processes. Analyzing deviations from Mendelian segregation offers an avenue for identifying loci targeted by GS and SEA, and their contributions to purging of genetic load. However, other selective processes such as meiotic drive and cytonuclear interactions, as well as pollen and ovule abortion, can cause distortion. To distinguish the effects of GS and SEA from other causes of distortion, we will perform reciprocal crosses between highly homozygous and highly heterozygous individuals …
Next Generation Sequencing Identifies Population Structure And Signatures Of Local Adaptation In Red Alder (Alnus Rubra Bong.), Jacob Brent Loveless
Next Generation Sequencing Identifies Population Structure And Signatures Of Local Adaptation In Red Alder (Alnus Rubra Bong.), Jacob Brent Loveless
Dissertations and Theses
Red alder (Alnus rubra Bong.) is the dominant hardwood tree species in the Pacific Northwest. Red alders are only found in western North America, generally within 200 km of the coast and below 1000 m in elevation--although there are several disjunct populations in the northern Rocky Mountains in Idaho. Commonly a riparian species, the shade intolerant red alder generates most of the leaf litter in the streams and rivers it occupies which has been shown to greatly influence the decomposer communities. This, in turn, has a cascading effect throughout the entire riparian ecosystem greatly influencing multiple levels of the …
Anatomical Analysis Of Somatic Mutation Accumulation In Mimulus Guttatus, Amanda Burrell
Anatomical Analysis Of Somatic Mutation Accumulation In Mimulus Guttatus, Amanda Burrell
University Honors Theses
Plants are seemingly immortal in their abilities to survive long periods of dormancy in different life stages, live for thousands of years, and even grow into whole forests from one clone, all through a series of mitotic and meiotic events, but how many mutations do plants acquire in their lifetime? And just how many of these mutations are heritable? To answer these questions, first we must answer: how many cell divisions are there in the length of a stem? The purpose of this study is to answer just that by establishing a protocol for estimating the number of germ cell …
Effects Of Reactive Oxygen Species On Life History Traits Of Caenorhabditis Elegans, Samson William Smith
Effects Of Reactive Oxygen Species On Life History Traits Of Caenorhabditis Elegans, Samson William Smith
Dissertations and Theses
Evolutionary life history theory predicts that tradeoffs among fitness-related phenotypes will occur as a result of resource limitations and/or physiological constraints. Such tradeoffs are defined as the cost(s) incurred on one component of fitness (e.g., reproduction) by the increased expression of another fitness-related trait (e.g., longevity). Only recently have researchers begun to investigate the mechanistic bases of life history tradeoffs. A recent proposal is that reactive oxygen species (ROS) have a central role in shaping life history traits and tradeoffs. Research on disparate animal taxa has highlighted strong correlations between oxidative stress resistance and fitness-related life history traits, for example. …
Sporophytic Inbreeding Depression In Mosses Occurs In A Species With Separate Sexes But Not In A Species With Combined Sexes, Philip J. Taylor, Sarah M. Eppley, Linley K. Jesson
Sporophytic Inbreeding Depression In Mosses Occurs In A Species With Separate Sexes But Not In A Species With Combined Sexes, Philip J. Taylor, Sarah M. Eppley, Linley K. Jesson
Biology Faculty Publications and Presentations
Inbreeding depression is a critical factor countering the evolution of inbreeding and thus potentially shaping the evolution of plant sexual systems. Current theory predicts that inbreeding depression could have important evolutionary consequences, even in haploid-dominant organisms. To date, no data have been reported on inbreeding depression in moss species. Here, we present data on the magnitude of inbreeding depression in sporophytic traits of moss species with contrasting breeding systems. In eratodon purpureus (Ditrichaceae), a moss species with separate sexes, self-fertilizations between sibling gametophytes (intergametophytic selfing) significantly reduced fitness in two of four traits quantified, with seta length and capsule length …
Contributions Of Heterosis And Epistasis To Hybrid Fitness, Mitchell B. Cruzan
Contributions Of Heterosis And Epistasis To Hybrid Fitness, Mitchell B. Cruzan
Biology Faculty Publications and Presentations
Early-generation hybrid fitness is difficult to interpret because heterosis can obscure the effects of hybrid breakdown. We used controlled reciprocal crosses and common garden experiments to distinguish between effects of heterosis and nuclear and cytonuclear epistasis among morphotypes and advanced-generation hybrid derivative populations in the Piriqueta caroliniana (Turneraceae) plant complex. Seed germination, growth, and sexual reproduction of first-generation hybrids, inbred parental lines, and outbred parental lines were compared under field conditions. Average vegetative performance was greater for hybrids than for inbred lines, and firstseason growth was similar for hybrids and outbred parental lines. Hybrid survival surpassed that of inbred lines …
Patterns Of Fitness And Fluctuating Asymmetry Across A Broad Hybrid Zone, Mitchell B. Cruzan
Patterns Of Fitness And Fluctuating Asymmetry Across A Broad Hybrid Zone, Mitchell B. Cruzan
Biology Faculty Publications and Presentations
We estimated levels of developmental instability in leaves, as indicated by fluctuating asymmetry (i.e., random deviations from perfect bilateral symmetry), across a broad hybrid zone between two taxa in the Piriqueta caroliniana complex. Previous studies have indicated that this hybrid zone was initiated in southern Florida and has expanded northward. We found that plants from the hybrid zone generally had higher levels of leaf developmental instability than plants from allopatric regions, but the increase in asymmetry was not substantial. Although it is usually assumed that developmental instability is associated with lower fitness, these Piriqueta hybrids from central Florida are similar …
Comparative Studies Of Evolutionary Responses To Light Environments In Arabidopsis, Massimo Pigliucci, Heidi Pollard, Mitchell B. Cruzan
Comparative Studies Of Evolutionary Responses To Light Environments In Arabidopsis, Massimo Pigliucci, Heidi Pollard, Mitchell B. Cruzan
Biology Faculty Publications and Presentations
In this article, we compare the reaction norms to foliage shade (changes in light quality, spatially fine-grained environmental variation) and photoperiod (day length, spatially coarse-grained environmental variation) in several haplotypes of Arabidopsis thaliana from Scandinavia. We found that both across-environment means and phenotypic plasticities evolved continuously and very rapidly within this group. Both character means and trait plasticities were highly integrated, in part as predicted by the adaptive plasticity hypothesis for response to foliage shade (the so-called shade-avoidance syndrome). We found that a significant but small fraction of the variance in across-treatment trait means and plasticities in response to one …
Investigating The Relationship Between Cryptococcus Fagisuga And Fagus Grandifolia In Great Smoky Mountains National Park, Ashley B. Morris, Randall L. Small, Mitchell B. Cruzan
Investigating The Relationship Between Cryptococcus Fagisuga And Fagus Grandifolia In Great Smoky Mountains National Park, Ashley B. Morris, Randall L. Small, Mitchell B. Cruzan
Biology Faculty Publications and Presentations
Focuses on a study which investigated the relationship between Cryptococcus fagisuga and Fagus grandifolia in Great Smoky Mountains National Park. Potential for genetic resistance; Methods; Results and discussion.
Reproductive Biology Of Melilotus Officinalis (L.) Lam (Fabaceae: Papilionoideae): Morphology, Seed/Ovule Ratios And Ovule Abortion Patterns, Susan Lee Schouten
Reproductive Biology Of Melilotus Officinalis (L.) Lam (Fabaceae: Papilionoideae): Morphology, Seed/Ovule Ratios And Ovule Abortion Patterns, Susan Lee Schouten
Dissertations and Theses
Melilotus officinalis, an introduced herbaceous species within the Papilionoideae, has a fixed ovule abortion pattern. In its primarily single-seeded, indehiscent fruits, with an average of 6.98 ovules/fruit, this species matured the basal-most ovule in 67.63% and the second basal-most ovule in 24.22% of the fruits studied. This pattern contrasts with other legumes studied, which abort the basal-most ovules or those at either end of the fruit. Workers propose interaction between two opposing gradients--that of maternal resources from the basal end of the fruit and of fertilization from the stylar end. Several lines of evidence indicate that all ovules are …
Intrapopulation Sex Ratio Variation In The Salt Grass Distichlis Spicata, Sarah M. Eppley, Maureen L. Stanton, Richard K. Grosberg
Intrapopulation Sex Ratio Variation In The Salt Grass Distichlis Spicata, Sarah M. Eppley, Maureen L. Stanton, Richard K. Grosberg
Biology Faculty Publications and Presentations
In many dioecious plant populations, males and females appear to be spatially segregated, a pattern that is difficult to explain given its potentially high costs. However, in asexually propagating species, spatial segregation of the sexes may be indistinguishable from superficially similar patterns generated by random establishment of a few genets followed by extensive clonal spread and by gender-specific differences in rates of clonal spread. In populations where a significant fraction of individuals are not flowering and gender cannot be assigned to this fraction, apparent spatial segregation of the sexes may be due to differential flowering between the sexes. We confirm …
Genetic Markers In Plant Evolutionary Ecology, Mitchell B. Cruzan
Genetic Markers In Plant Evolutionary Ecology, Mitchell B. Cruzan
Biology Faculty Publications and Presentations
Genetic markers have provided plant ecologists with a method of assessing levels of genetic relatedness among individuals and populations. In recent years a number of techniques based on DNA sequence variation have been developed to complement allozyme methods that are already widely used. Some of these new markers are more variable than protein-based markers, allowing more precise estimates of genetic differences among individuals and populations. Other DNA-based markers are based on organelle genomes that are inherited uniparentally. These cytoplasmic markers can provide a method for assessing the separate effects of seed and pollen dispersal on gene flow within and among …
Postpollination Mechanisms Influencing Mating Patterns And Fecundity: An Example From Eichhornia Paniculata, Mitchell B. Cruzan
Postpollination Mechanisms Influencing Mating Patterns And Fecundity: An Example From Eichhornia Paniculata, Mitchell B. Cruzan
Biology Faculty Publications and Presentations
Plant mating systems are influenced by the amount and genetic composition of pollen grains deposited on stigmas and by the ability of recipients to discriminate among pollen from different sources. We describe an experimental procedure that uses limiting and excess pollinations with mixtures of genetically marked pollen to partition the siring success of donors into three components: prefertilization gamete attrition (failure of male gametophytes before fertilization), pollen competitive ability (differences in pollen tube growth rate), and postfertilization gamete attrition (embryo abortion). Regression models for the relationships of pollen load size with each pollen's siring success and total recipient fecundity indicate …