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Ken Paige

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Richard Tabor Greene

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Institute for Geological and Geochemical Research, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences

University of Maryland, College Park

Ahmed A. Farghaly

Virginia Commonwealth University

Istituto Italiano di Tecnologia / Italian Institute of Technology

Theivasanthi Thirugnanasambandan

Kalasalingam University

Anilkumar G Garag

Chanakya University

University of Zurich, Switzerland

Milan Stanojevic

University of Zagreb

CPE Lyon

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Papers by Ken Paige

Characterization of Arabidopsis thaliana regrowth patterns suggests a trade-off between undamaged fitness and damage tolerance

Oecologia, Jun 24, 2017

Herbivory is a fundamental type of plant–animal interaction that presents substantial selection p... more Herbivory is a fundamental type of plant–animal interaction that presents substantial selection pressure on plants to replace lost tissues and to prevent subsequent losses in fitness. Apical herbivory, which entails removal or damage to the apical meristem, causes a change in plant architecture by disrupting the balance of hormones produced in part by the apical meristem. Therefore, for an annual semelparous plant, the ability to preserve reproductive success following damage (i.e., to tolerate damage) is largely dependent on the plant’s pre-damage investment into fitness and its regrowth pattern following damage. Using multiple regression analyses, we assessed the relationship of developmental and architectural traits of experimentally damaged plants relative to undamaged plants of 33 Arabidopsis thaliana genotypes that display a wide range of undamaged fitness and damage tolerance. Our analyses revealed evidence for an evolutionary bet-hedging strategy within a subset of genotypes to presumably maximize fitness under natural herbivory—genotypes with the greatest seed production when undamaged exhibited a significant reduction in seed yield when damaged, while genotypes with low undamaged seed production were the only genotypes whose seed yield increased when damaged. Patterns of endopolyploidy paralleled those of seed production, such that the increase in whole-plant ploidy by genome re-replication during growth/regrowth contributes to undamaged fitness, damage tolerance, and their trade-off. Overall, this study provides the first large-scale characterization of A. thaliana regrowth patterns and suggests that investment into fitness and endopolyploidy when undamaged may come at a cost to tolerance ability once damaged.

Status of the Small-Footed Bat, Myotis leibii leibii, in the Southern Ozarks

Journal of the Arkansas Academy of Science, 1982

Arkansas Academy of Science Immunization with somatic extracts provided essentially the same degr... more

Transcriptomics of plant responses to apical damage reveals no negative correlation between tolerance and defense

Plant Ecology, Jul 15, 2015

While one may expect the loss of plant tissue by animal herbivores to be universally detrimental ... more While one may expect the loss of plant tissue by animal herbivores to be universally detrimental to a plant's fitness, a wide range of tolerance responses exists, including undercompensation (lower fitness when damaged), equal compensation, and even overcompensation (increased fitness when damaged). Theory predicts that these responses could be constrained by the investment into defensive chemicals and structures produced for improving resistance in damaged tissues, and thus tolerance and induced defense could be considered alternative strategies to the selection pressure imposed by herbivory. To determine which genetic pathways underlie differences in compensatory (i.e., growth and fitness) responses to damage by tissue loss, and to test their relation with pathways involved in defense, we performed a controlled greenhouse study to measure total gene expression via RNA-sequencing of undamaged and mechanically damaged plants of three Arabidopsis thaliana genotypes that differ in their compensatory performances: Columbia-4, Landsberg erecta, and a recombinant inbred line (RIL) from a Columbia-4 9 Landsberg erecta cross. Among the many genetic pathways that responded to clipping, Columbia-4 significantly up-regulated genes involved in secondary defense chemistry and equally compensated for fitness while Landsberg erecta and the RIL both undercompensated and significantly down-regulated secondary defense pathways. The genotypes' different compensatory performances are thus positively correlated with their differential investments into secondary metabolism following tissue loss. This study identifies differential post-damage gene regulation of growth, developmental signaling, and environmental response pathways in A. thaliana, and provides the first transcriptomic evidence counter to the presumed tradeoff between tolerance and defense in plant-herbivore interactions.

An assessment of the molecular mechanisms contributing to tolerance to apical damage in natural populations of Arabidopsis thaliana

Plant Ecology, Dec 19, 2016

Herbivory imposes substantial selection pressure on plants, with the ability to regrow and mainta... more Herbivory imposes substantial selection pressure on plants, with the ability to regrow and maintain reproductive success a challenging but often necessary response by the plant. Despite the commonness of herbivore-induced damage, vast variation in tolerance ability exists among plants. Recent studies have suggested the role of endoreduplication (increasing ploidy within an individual) and the pentose phosphate pathway (a metabolic Keywords Herbivory Á Compensation Á Defense Á Glucose-6-phosphate dehydrogenase Á Ploidy Á Pentose phosphate pathway Communicated by William E. Rogers.

Regrowth patterns and rosette attributes contribute to the differential compensatory responses of Arabidopsis thaliana genotypes to apical damage

Plant Biology, Nov 2, 2015

A plant's compensatory performance refers to its ability to maintain or increase its reproductive... more A plant's compensatory performance refers to its ability to maintain or increase its reproductive output following damage. The ability of a plant to compensate depends on numerous factors including the type, severity, frequency and timing of damage, the environmental conditions and the plant's genotype. Upon apical damage, a cascade of hormonal and genetic responses often produces dramatic changes in a plant's growth, development, architecture and physiology. All else being equal, this response is largely dependent on a plant's genotype, with different regrowth patterns displayed by different genotypes of a given species. In this study, we compare the architectural and growth patterns of two Arabidopsis thaliana genotypes following apical damage. Specifically, we characterise regrowth patterns of the genotypes Columbia-4 and Landsberg erecta, which typically differ in their compensation to apical meristem removal. We report that Landsberg erecta suffered reductions in the number of stems produced, maximum elongation rate, a delay in reaching this rate, lower average rosette quality throughout the growing period, and ultimately, less aboveground dry biomass and seed production when damaged compared to undamaged control plants. Columbia-4 had no reductions in any of these measures and maintained larger rosette area when clipped relative to when unclipped. Based on the apparent influence of the rosette on these genotypes' compensatory performances, we performed a rosette removal experiment, which confirmed that the rosette contributes to compensatory performance. This study provides a novel characterisation of regrowth patterns following apical damage, with insights into those measures having the largest effect on plant performance.

A Second Record of Typhlichthys subterraneus (Pisces: Amblyopsidae) from Arkansas

Southwestern Naturalist, Feb 21, 1981

Individual and Population Shifts in Flower Color by Scarlet Gilia: A Mechanism for Pollinator Tracking

Science, Jan 18, 1985

Individual plants and populations ofscarlet gilia (Ipomopsis aggregata) shift from darker to ligh... more Individual plants and populations ofscarlet gilia (Ipomopsis aggregata) shift from darker to lighter corolla colors during the flowering season. Shifts to lighter color coincide with emigration of hummingbirds from the system. In the absence of hummingbirds, lighter colors attract the remaining pollinator, a hawkmoth. Comparison ofplants that shift to lighter colors with those that fail to shift

The effects of plant variation on pollination and herbivory : adaptive responses by scarlet gilia

Overcompensation in Response to Mammalian Herbivory: The Advantage of Being Eaten

The American Naturalist, Mar 1, 1987

There are two major opposing views of the effects of herbivores on plant growth and reproduction ... more There are two major opposing views of the effects of herbivores on plant growth and reproduction (McNaughton 1983). The most common view is that herbivory is detrimental to plants (Mattson and Addy 1975; Morrow and LaMarche 1978; Simberloff et al. 1978; Kinsman and Platt 1984; Whitham and Mopper 1985) and represents a selective pressure for the evolution of plant defenses. In sharp

Molecular genetics of Asian longhorned beetles: introduction, invasion, and spread in North America

We have used molecular techniques to study the genetic structure of Asian longhorned beetle (ALB)... more We have used molecular techniques to study the genetic structure of Asian longhorned beetle (ALB) populations in North America, allowing us to assess the dispersal behavior of the adult beetles, the extent to which populations have spread in urban areas, and the potential for future spread. We have extracted and sequenced DNA from individuals of six populations; four from China, one from New York and one from Chicago. Three regions of the mitochondrial genome have been assessed for variation among populations. Sequenced gene regions include cytochrome oxidase I and II, and a portion of the large ribosomal subunit of the 16S rRNA. Unfortunately, screens of over 500 base pairs of sequence from each of these gene regions either showed little variation (telling us little about population structure) or were unreadable when sequenced.

Herbivory and Soil Water Availability Induce Changes in Arbuscular Mycorrhizal Fungal Abundance and Composition

Microbial Ecology

We tested the prediction that abundance and composition of arbuscular mycorrhizal fungi (AMF) in ... more We tested the prediction that abundance and composition of arbuscular mycorrhizal fungi (AMF) in Ipomopsis aggregata roots and soils are influenced by ungulate herbivory and drought conditions by examining the effects in a field setting over two years. We used a multi-metric approach to quantify AMF root colonization, AMF reproduction, and AMF community composition in roots and soils. We incorporated complimentary community characterization assays by morphologically identifying spores from trap cultures and the use of terminal restriction fragment length polymorphism (T-RFLP) fingerprinting. Herbivory caused a twofold increase in spore production, an increase in AMF taxa diversity in roots, and a shift in AMF species composition in rhizosphere soils. The impact of herbivory was dependent on water availability, which differed in the two contrasting years. This study demonstrates that both soil water availability and herbivory shape arbuscular mycorrhizal fungi communities. The changes to mycorrhizal communities may help in understanding mycorrhizal function in changing climates.

The evolutionary response of plants to increased UV-B radiation: Field studies with Arabidopsis thaliana

The response of a species to any environmental change is determined by both phenotypic and evolut... more The response of a species to any environmental change is determined by both phenotypic and evolutionary adjustments. To date, the majority of research concerning the response of terrestrial plants to increased UV-B radiation has focused on phenotypic adjustments. Recently we have initiated field studies aimed at assessing genetic variation for UV-B sensitivity within a natural population of Arabidopsis thaliana. This population consists of at least eight discrete genotypes that have been confirmed by RAPD analysis. We used an incomplete block design to assess the impact of UV-B (ambient and ambient + 6 kJ) and PAR (low and high) on these genotypes. The high UV-B treatment caused a significant reduction in fruit number and plant height while the high PAR treatment caused a significant increase in these variables. In addition, there was a marginally significant (p=0.1) UV-B x PAR x maternal line interaction for fruit number, indicating that genetic variation for UV-B sensitivity within this population depends on the PAR environment. The combination of high UV-B and high PAR caused a change in fruit number (relative to the ambient UV-B/high PAR treatment) ranging from an increase of 24% to a decrease of 47%. This range was much smaller in the lowmore » PAR treatment. These results indicate the potential for increased UV-B radiation to act as an agent of natural selection within this population.« less

Evaluating the genome-wide impacts of species translocations: the greater prairie-chicken as a case study

Conservation Genetics, 2021

A variety of conservation management strategies have been developed to address rapid, anthropogen... more A variety of conservation management strategies have been developed to address rapid, anthropogenically-driven biodiversity loss. The translocation of individuals from viable populations to those experiencing significant decline is one such strategy to increase genetic diversity and avoid extirpation, yet efficacy of this strategy has rarely been examined in detail utilizing genomic data. Here, we employ a conservation icon, the greater prairie-chicken ( Tympanuchus cupido pinnatus ), as a case study to demonstrate how genome-wide SNPs derived from RADseq offer the ability to assess translocation success with respect to the genomic aspects of genetic restoration, encompassing (1) the alleviation of inbreeding (2) the restoration of evolutionary potential, and (3) the maintenance of local variation. Genome-wide diversity estimates calculated from 356,778 SNPs demonstrate that translocations rescued the Illinois population from severe inbreeding and lack of genetic diversity, restoring variation to levels comparable to the three non-bottlenecked source populations. Delineation of genetic structure using non-linked and ubiquitously genotyped SNPs reveal distinct genetic variation among the source and recipient populations as well as high levels of admixture in the post-translocation population resulting from translocations. Estimated ancestry derived from private alleles uncover introgression of unique variation from each source population as well as the maintenance of substantial levels of variation unique to Illinois. Our findings demonstrate that genome-wide analysis of variation is a valuable management tool for measuring the genomic effects of translocations and, subsequently, gauging genetic restoration success.

Dietary antioxidant vitamin C influences the evolutionary path of insecticide resistance in Drosophila melanogaster

Pesticide Biochemistry and Physiology, 2020

Herbivorous insects encounter a variety of toxic environmental substances ranging from ingested p... more Herbivorous insects encounter a variety of toxic environmental substances ranging from ingested plant defensive compounds to human-introduced insecticidal agents. Dietary antioxidants are known to reduce the negative physiological impacts of toxins in mammalian systems through amelioration of reactive oxygen-related cellular damage. The analogous impacts to insects caused by multigenerational exposure to pesticides and the effects on adaptive responses within insect populations, however, are currently unknown. To address these research gaps, we used Drosophila as a model system to explore adaptive phenotypic responses to acute dichlorodiphenyltrichloroethane (DDT) exposure in the presence of the dietary antioxidant vitamin C and to examine the structural genomic consequences of this exposure. DDT resistance increased significantly among four replicates exposed to a low concentration of DDT for 10 generations. In contrast, dietary intake of vitamin C significantly reduced DDT resistance after mutigenerational exposure to the same concentration of DDT. As to the genomic consequences, no significant differences were predicted in overall nucleotide substitution rates across the genome between any of the treatments. Despite this, replicates exposed to a low concentration of DDT without vitamin C showed the highest number of synonymous and non-synonymous variants (3196 in total), followed by the DDT plus vitamin C (1174 in total), and vitamin C alone (728 in total) treatments. This study demonstrates the potential role of diet (specifically, antioxidant intake) on adaptive genome responses, and thus on the evolution of pesticide resistance within insect populations.

Differential gene expression in laboratory strains of human head and body lice when challenged withBartonella quintana, a pathogenic bacterium

Insect Molecular Biology, 2014

Human head and body lice are obligatory hematophagous ectoparasites that belong to a single speci... more Human head and body lice are obligatory hematophagous ectoparasites that belong to a single species, Pediculus humanus. Only body lice, however, are vectors of the infectious Gram-negative bacterium Bartonella quintana. Because of their near identical genomes, yet differential vector competence, head and body lice provide a unique model system to study the gain or loss of vector competence. Using our in vitro louse-rearing system, we infected head and body lice with blood containing B. quintana in order to detect both differences in the proliferation of B. quintana and transcriptional differences of immune-related genes in the lice. B. quintana proliferated rapidly in body lice at 6 days postinfection, but plateaued in head lice at 4 days postinfection. RNAseq and quantitative real-time PCR validation analyses determined gene expression differences. Eight immunoresponse genes were observed to be significantly different with many associated with the Toll pathway: Fibrinogen-like protein, Spaetzle, Defensin 1, Serpin, Scavenger receptor A and Apolipoporhrin 2. Our findings support the hypothesis that body lice, unlike head lice, fight infection from B. quintana only at the later stages of its proliferation.

Comparison of the transcriptional profiles of head and body lice

Insect Molecular Biology, 2012

Head and body lice are both blood-feeding parasites of humans although only the body louse is a p... more Head and body lice are both blood-feeding parasites of humans although only the body louse is a potent disease vector. In spite of numerous morphological and life history differences, head and body lice have recently been hypothesized to be ecotypes of the same species. We took a comparative genomics approach to measure nucleotide diversity by comparing expressed sequence tag data sets from head and body lice. A total of 10 771 body louse and 10 770 head louse transcripts were predicted from a combined assembly of Roche 454 and Illumina sequenced cDNAs from whole body tissues collected at all life stages and during pesticide exposure and bacterial infection treatments. Illumina reads mapped to the 10 775 draft body louse gene models from the whole genome assembly predicted nine presence/absence differences, but PCR confirmation resulted in a single gene difference. Read per million base pair estimates indicated that 14 genes showed significant differential expression between head and body lice under our treatment conditions. One novel microRNA was predicted in both lice species and 99% of the 544 transcripts from Candidatus riesia indicate that they share the same endosymbiont. Overall, few differences exist, which supports the hypothesis that these two organisms are ecotypes of the same species.

Overcompensation: a 30‐year perspective

Ecology, 2019

Biomass removal by herbivores usually incurs a fitness cost for the attacked plants, with the tot... more Biomass removal by herbivores usually incurs a fitness cost for the attacked plants, with the total cost per unit lost tissue depending on the value of the removed tissue (i.e., how costly it is to be replaced by regrowth). Optimal defense theory, first outlined in the 1960s and 1970s, predicted that these fitness costs result in an arms race between plants and herbivores, in which selection favors resistance strategies that either repel herbivores through morphological and chemical resistance traits in order to reduce their consumption, or result in enemy escape through rapid growth or by timing the growth or flowering to the periods when herbivores are absent. Such resistance against herbivores would most likely evolve when herbivores are abundant, cause extensive damage, and consume valuable plant tissues. The purpose of this Special Feature is to celebrate the 30th anniversary of the phenomenon of overcompensation, specifically, where the finding has brought us and where it is l...

The role of invertase isoforms in overcompensation following mammalian herbivory: are they functionally redundant?

ABSTRACT Background/Question/Methods Previous studies have shown that some plants can increase fi... more ABSTRACT Background/Question/Methods Previous studies have shown that some plants can increase fitness following herbivory by compensating for tissues lost, i.e., they overcompensate. Yet little is known about the genetic mechanisms leading to enhanced growth and reproduction in plant species exhibiting overcompensation. Our recent studies have uncovered several genes involved in carbohydrate metabolism that appear to be important in fitness compensation and in particular the phenomenon of overcompensation. Among others, genes involved include the cytosolic invertases. Overall there are 12 genes that code for invertase and all are involved in hydrolyzing sucrose. Here we address the issue of functional redundancy of these isoforms in the compensatory response using a combination of gene expression assays and knockout mutants in an Arabidopsis ecotype that overcompensates (Columbia) and an ecotype that undercompensates (Landsberg erecta) following the removal of apical dominance. Results/Conclusions Results indicated elevated expression levels of all invertase genes in Columbia following clipping and higher relative levels of expression than the undercompensating plant Landsberg erecta following clipping. Although there appears to be functional redundancy in the level of expression for each of the 12 isoforms, knockout studies show a mixture of results from no affect from the knockout to altering the compensatory response from overcompensation to equal or under compensation. Thus, particular isoforms appear to be differentially important in the phenomenon of overcompensation and are not functionally redundant.

Additional file 1: of The role of invertases in plant compensatory responses to simulated herbivory

Table S1. Primers used for evaluating gene expression of the invertase isoenzymes. Table S2. Prim... more Table S1. Primers used for evaluating gene expression of the invertase isoenzymes. Table S2. Primers used for genotyping the T-DNA knockout lines. Table S3. P values of comparisons of gene expression between clipped and unclipped plants in ecotype Columbia-4 at different growth stages following removal of apical dominance. Table S4. P values of comparisons of gene expression between clipped and unclipped plants in ecotype Landsberg erecta at different growth stages following removal of apical dominance. (DOC 106Â kb)

Gene expression analysis of compensatory responses to herbivory yields differences in growth, reproduction, and defensive chemistry

Characterization of Arabidopsis thaliana regrowth patterns suggests a trade-off between undamaged fitness and damage tolerance

Oecologia, Jun 24, 2017

Herbivory is a fundamental type of plant–animal interaction that presents substantial selection p... more Herbivory is a fundamental type of plant–animal interaction that presents substantial selection pressure on plants to replace lost tissues and to prevent subsequent losses in fitness. Apical herbivory, which entails removal or damage to the apical meristem, causes a change in plant architecture by disrupting the balance of hormones produced in part by the apical meristem. Therefore, for an annual semelparous plant, the ability to preserve reproductive success following damage (i.e., to tolerate damage) is largely dependent on the plant’s pre-damage investment into fitness and its regrowth pattern following damage. Using multiple regression analyses, we assessed the relationship of developmental and architectural traits of experimentally damaged plants relative to undamaged plants of 33 Arabidopsis thaliana genotypes that display a wide range of undamaged fitness and damage tolerance. Our analyses revealed evidence for an evolutionary bet-hedging strategy within a subset of genotypes to presumably maximize fitness under natural herbivory—genotypes with the greatest seed production when undamaged exhibited a significant reduction in seed yield when damaged, while genotypes with low undamaged seed production were the only genotypes whose seed yield increased when damaged. Patterns of endopolyploidy paralleled those of seed production, such that the increase in whole-plant ploidy by genome re-replication during growth/regrowth contributes to undamaged fitness, damage tolerance, and their trade-off. Overall, this study provides the first large-scale characterization of A. thaliana regrowth patterns and suggests that investment into fitness and endopolyploidy when undamaged may come at a cost to tolerance ability once damaged.

Status of the Small-Footed Bat, Myotis leibii leibii, in the Southern Ozarks

Journal of the Arkansas Academy of Science, 1982

Arkansas Academy of Science Immunization with somatic extracts provided essentially the same degr... more

Transcriptomics of plant responses to apical damage reveals no negative correlation between tolerance and defense

Plant Ecology, Jul 15, 2015

While one may expect the loss of plant tissue by animal herbivores to be universally detrimental ... more While one may expect the loss of plant tissue by animal herbivores to be universally detrimental to a plant's fitness, a wide range of tolerance responses exists, including undercompensation (lower fitness when damaged), equal compensation, and even overcompensation (increased fitness when damaged). Theory predicts that these responses could be constrained by the investment into defensive chemicals and structures produced for improving resistance in damaged tissues, and thus tolerance and induced defense could be considered alternative strategies to the selection pressure imposed by herbivory. To determine which genetic pathways underlie differences in compensatory (i.e., growth and fitness) responses to damage by tissue loss, and to test their relation with pathways involved in defense, we performed a controlled greenhouse study to measure total gene expression via RNA-sequencing of undamaged and mechanically damaged plants of three Arabidopsis thaliana genotypes that differ in their compensatory performances: Columbia-4, Landsberg erecta, and a recombinant inbred line (RIL) from a Columbia-4 9 Landsberg erecta cross. Among the many genetic pathways that responded to clipping, Columbia-4 significantly up-regulated genes involved in secondary defense chemistry and equally compensated for fitness while Landsberg erecta and the RIL both undercompensated and significantly down-regulated secondary defense pathways. The genotypes' different compensatory performances are thus positively correlated with their differential investments into secondary metabolism following tissue loss. This study identifies differential post-damage gene regulation of growth, developmental signaling, and environmental response pathways in A. thaliana, and provides the first transcriptomic evidence counter to the presumed tradeoff between tolerance and defense in plant-herbivore interactions.

An assessment of the molecular mechanisms contributing to tolerance to apical damage in natural populations of Arabidopsis thaliana

Plant Ecology, Dec 19, 2016

Herbivory imposes substantial selection pressure on plants, with the ability to regrow and mainta... more Herbivory imposes substantial selection pressure on plants, with the ability to regrow and maintain reproductive success a challenging but often necessary response by the plant. Despite the commonness of herbivore-induced damage, vast variation in tolerance ability exists among plants. Recent studies have suggested the role of endoreduplication (increasing ploidy within an individual) and the pentose phosphate pathway (a metabolic Keywords Herbivory Á Compensation Á Defense Á Glucose-6-phosphate dehydrogenase Á Ploidy Á Pentose phosphate pathway Communicated by William E. Rogers.

Regrowth patterns and rosette attributes contribute to the differential compensatory responses of Arabidopsis thaliana genotypes to apical damage

Plant Biology, Nov 2, 2015

A plant's compensatory performance refers to its ability to maintain or increase its reproductive... more A plant's compensatory performance refers to its ability to maintain or increase its reproductive output following damage. The ability of a plant to compensate depends on numerous factors including the type, severity, frequency and timing of damage, the environmental conditions and the plant's genotype. Upon apical damage, a cascade of hormonal and genetic responses often produces dramatic changes in a plant's growth, development, architecture and physiology. All else being equal, this response is largely dependent on a plant's genotype, with different regrowth patterns displayed by different genotypes of a given species. In this study, we compare the architectural and growth patterns of two Arabidopsis thaliana genotypes following apical damage. Specifically, we characterise regrowth patterns of the genotypes Columbia-4 and Landsberg erecta, which typically differ in their compensation to apical meristem removal. We report that Landsberg erecta suffered reductions in the number of stems produced, maximum elongation rate, a delay in reaching this rate, lower average rosette quality throughout the growing period, and ultimately, less aboveground dry biomass and seed production when damaged compared to undamaged control plants. Columbia-4 had no reductions in any of these measures and maintained larger rosette area when clipped relative to when unclipped. Based on the apparent influence of the rosette on these genotypes' compensatory performances, we performed a rosette removal experiment, which confirmed that the rosette contributes to compensatory performance. This study provides a novel characterisation of regrowth patterns following apical damage, with insights into those measures having the largest effect on plant performance.

A Second Record of Typhlichthys subterraneus (Pisces: Amblyopsidae) from Arkansas

Southwestern Naturalist, Feb 21, 1981

Individual and Population Shifts in Flower Color by Scarlet Gilia: A Mechanism for Pollinator Tracking

Science, Jan 18, 1985

Individual plants and populations ofscarlet gilia (Ipomopsis aggregata) shift from darker to ligh... more Individual plants and populations ofscarlet gilia (Ipomopsis aggregata) shift from darker to lighter corolla colors during the flowering season. Shifts to lighter color coincide with emigration of hummingbirds from the system. In the absence of hummingbirds, lighter colors attract the remaining pollinator, a hawkmoth. Comparison ofplants that shift to lighter colors with those that fail to shift

The effects of plant variation on pollination and herbivory : adaptive responses by scarlet gilia

Overcompensation in Response to Mammalian Herbivory: The Advantage of Being Eaten

The American Naturalist, Mar 1, 1987

There are two major opposing views of the effects of herbivores on plant growth and reproduction ... more There are two major opposing views of the effects of herbivores on plant growth and reproduction (McNaughton 1983). The most common view is that herbivory is detrimental to plants (Mattson and Addy 1975; Morrow and LaMarche 1978; Simberloff et al. 1978; Kinsman and Platt 1984; Whitham and Mopper 1985) and represents a selective pressure for the evolution of plant defenses. In sharp

Molecular genetics of Asian longhorned beetles: introduction, invasion, and spread in North America

We have used molecular techniques to study the genetic structure of Asian longhorned beetle (ALB)... more We have used molecular techniques to study the genetic structure of Asian longhorned beetle (ALB) populations in North America, allowing us to assess the dispersal behavior of the adult beetles, the extent to which populations have spread in urban areas, and the potential for future spread. We have extracted and sequenced DNA from individuals of six populations; four from China, one from New York and one from Chicago. Three regions of the mitochondrial genome have been assessed for variation among populations. Sequenced gene regions include cytochrome oxidase I and II, and a portion of the large ribosomal subunit of the 16S rRNA. Unfortunately, screens of over 500 base pairs of sequence from each of these gene regions either showed little variation (telling us little about population structure) or were unreadable when sequenced.

Herbivory and Soil Water Availability Induce Changes in Arbuscular Mycorrhizal Fungal Abundance and Composition

Microbial Ecology

We tested the prediction that abundance and composition of arbuscular mycorrhizal fungi (AMF) in ... more We tested the prediction that abundance and composition of arbuscular mycorrhizal fungi (AMF) in Ipomopsis aggregata roots and soils are influenced by ungulate herbivory and drought conditions by examining the effects in a field setting over two years. We used a multi-metric approach to quantify AMF root colonization, AMF reproduction, and AMF community composition in roots and soils. We incorporated complimentary community characterization assays by morphologically identifying spores from trap cultures and the use of terminal restriction fragment length polymorphism (T-RFLP) fingerprinting. Herbivory caused a twofold increase in spore production, an increase in AMF taxa diversity in roots, and a shift in AMF species composition in rhizosphere soils. The impact of herbivory was dependent on water availability, which differed in the two contrasting years. This study demonstrates that both soil water availability and herbivory shape arbuscular mycorrhizal fungi communities. The changes to mycorrhizal communities may help in understanding mycorrhizal function in changing climates.

The evolutionary response of plants to increased UV-B radiation: Field studies with Arabidopsis thaliana

The response of a species to any environmental change is determined by both phenotypic and evolut... more The response of a species to any environmental change is determined by both phenotypic and evolutionary adjustments. To date, the majority of research concerning the response of terrestrial plants to increased UV-B radiation has focused on phenotypic adjustments. Recently we have initiated field studies aimed at assessing genetic variation for UV-B sensitivity within a natural population of Arabidopsis thaliana. This population consists of at least eight discrete genotypes that have been confirmed by RAPD analysis. We used an incomplete block design to assess the impact of UV-B (ambient and ambient + 6 kJ) and PAR (low and high) on these genotypes. The high UV-B treatment caused a significant reduction in fruit number and plant height while the high PAR treatment caused a significant increase in these variables. In addition, there was a marginally significant (p=0.1) UV-B x PAR x maternal line interaction for fruit number, indicating that genetic variation for UV-B sensitivity within this population depends on the PAR environment. The combination of high UV-B and high PAR caused a change in fruit number (relative to the ambient UV-B/high PAR treatment) ranging from an increase of 24% to a decrease of 47%. This range was much smaller in the lowmore » PAR treatment. These results indicate the potential for increased UV-B radiation to act as an agent of natural selection within this population.« less

Evaluating the genome-wide impacts of species translocations: the greater prairie-chicken as a case study

Conservation Genetics, 2021

A variety of conservation management strategies have been developed to address rapid, anthropogen... more A variety of conservation management strategies have been developed to address rapid, anthropogenically-driven biodiversity loss. The translocation of individuals from viable populations to those experiencing significant decline is one such strategy to increase genetic diversity and avoid extirpation, yet efficacy of this strategy has rarely been examined in detail utilizing genomic data. Here, we employ a conservation icon, the greater prairie-chicken ( Tympanuchus cupido pinnatus ), as a case study to demonstrate how genome-wide SNPs derived from RADseq offer the ability to assess translocation success with respect to the genomic aspects of genetic restoration, encompassing (1) the alleviation of inbreeding (2) the restoration of evolutionary potential, and (3) the maintenance of local variation. Genome-wide diversity estimates calculated from 356,778 SNPs demonstrate that translocations rescued the Illinois population from severe inbreeding and lack of genetic diversity, restoring variation to levels comparable to the three non-bottlenecked source populations. Delineation of genetic structure using non-linked and ubiquitously genotyped SNPs reveal distinct genetic variation among the source and recipient populations as well as high levels of admixture in the post-translocation population resulting from translocations. Estimated ancestry derived from private alleles uncover introgression of unique variation from each source population as well as the maintenance of substantial levels of variation unique to Illinois. Our findings demonstrate that genome-wide analysis of variation is a valuable management tool for measuring the genomic effects of translocations and, subsequently, gauging genetic restoration success.

Dietary antioxidant vitamin C influences the evolutionary path of insecticide resistance in Drosophila melanogaster

Pesticide Biochemistry and Physiology, 2020

Herbivorous insects encounter a variety of toxic environmental substances ranging from ingested p... more Herbivorous insects encounter a variety of toxic environmental substances ranging from ingested plant defensive compounds to human-introduced insecticidal agents. Dietary antioxidants are known to reduce the negative physiological impacts of toxins in mammalian systems through amelioration of reactive oxygen-related cellular damage. The analogous impacts to insects caused by multigenerational exposure to pesticides and the effects on adaptive responses within insect populations, however, are currently unknown. To address these research gaps, we used Drosophila as a model system to explore adaptive phenotypic responses to acute dichlorodiphenyltrichloroethane (DDT) exposure in the presence of the dietary antioxidant vitamin C and to examine the structural genomic consequences of this exposure. DDT resistance increased significantly among four replicates exposed to a low concentration of DDT for 10 generations. In contrast, dietary intake of vitamin C significantly reduced DDT resistance after mutigenerational exposure to the same concentration of DDT. As to the genomic consequences, no significant differences were predicted in overall nucleotide substitution rates across the genome between any of the treatments. Despite this, replicates exposed to a low concentration of DDT without vitamin C showed the highest number of synonymous and non-synonymous variants (3196 in total), followed by the DDT plus vitamin C (1174 in total), and vitamin C alone (728 in total) treatments. This study demonstrates the potential role of diet (specifically, antioxidant intake) on adaptive genome responses, and thus on the evolution of pesticide resistance within insect populations.

Differential gene expression in laboratory strains of human head and body lice when challenged withBartonella quintana, a pathogenic bacterium

Insect Molecular Biology, 2014

Human head and body lice are obligatory hematophagous ectoparasites that belong to a single speci... more Human head and body lice are obligatory hematophagous ectoparasites that belong to a single species, Pediculus humanus. Only body lice, however, are vectors of the infectious Gram-negative bacterium Bartonella quintana. Because of their near identical genomes, yet differential vector competence, head and body lice provide a unique model system to study the gain or loss of vector competence. Using our in vitro louse-rearing system, we infected head and body lice with blood containing B. quintana in order to detect both differences in the proliferation of B. quintana and transcriptional differences of immune-related genes in the lice. B. quintana proliferated rapidly in body lice at 6 days postinfection, but plateaued in head lice at 4 days postinfection. RNAseq and quantitative real-time PCR validation analyses determined gene expression differences. Eight immunoresponse genes were observed to be significantly different with many associated with the Toll pathway: Fibrinogen-like protein, Spaetzle, Defensin 1, Serpin, Scavenger receptor A and Apolipoporhrin 2. Our findings support the hypothesis that body lice, unlike head lice, fight infection from B. quintana only at the later stages of its proliferation.

Comparison of the transcriptional profiles of head and body lice

Insect Molecular Biology, 2012

Head and body lice are both blood-feeding parasites of humans although only the body louse is a p... more Head and body lice are both blood-feeding parasites of humans although only the body louse is a potent disease vector. In spite of numerous morphological and life history differences, head and body lice have recently been hypothesized to be ecotypes of the same species. We took a comparative genomics approach to measure nucleotide diversity by comparing expressed sequence tag data sets from head and body lice. A total of 10 771 body louse and 10 770 head louse transcripts were predicted from a combined assembly of Roche 454 and Illumina sequenced cDNAs from whole body tissues collected at all life stages and during pesticide exposure and bacterial infection treatments. Illumina reads mapped to the 10 775 draft body louse gene models from the whole genome assembly predicted nine presence/absence differences, but PCR confirmation resulted in a single gene difference. Read per million base pair estimates indicated that 14 genes showed significant differential expression between head and body lice under our treatment conditions. One novel microRNA was predicted in both lice species and 99% of the 544 transcripts from Candidatus riesia indicate that they share the same endosymbiont. Overall, few differences exist, which supports the hypothesis that these two organisms are ecotypes of the same species.

Overcompensation: a 30‐year perspective

Ecology, 2019

Biomass removal by herbivores usually incurs a fitness cost for the attacked plants, with the tot... more Biomass removal by herbivores usually incurs a fitness cost for the attacked plants, with the total cost per unit lost tissue depending on the value of the removed tissue (i.e., how costly it is to be replaced by regrowth). Optimal defense theory, first outlined in the 1960s and 1970s, predicted that these fitness costs result in an arms race between plants and herbivores, in which selection favors resistance strategies that either repel herbivores through morphological and chemical resistance traits in order to reduce their consumption, or result in enemy escape through rapid growth or by timing the growth or flowering to the periods when herbivores are absent. Such resistance against herbivores would most likely evolve when herbivores are abundant, cause extensive damage, and consume valuable plant tissues. The purpose of this Special Feature is to celebrate the 30th anniversary of the phenomenon of overcompensation, specifically, where the finding has brought us and where it is l...

The role of invertase isoforms in overcompensation following mammalian herbivory: are they functionally redundant?

ABSTRACT Background/Question/Methods Previous studies have shown that some plants can increase fi... more ABSTRACT Background/Question/Methods Previous studies have shown that some plants can increase fitness following herbivory by compensating for tissues lost, i.e., they overcompensate. Yet little is known about the genetic mechanisms leading to enhanced growth and reproduction in plant species exhibiting overcompensation. Our recent studies have uncovered several genes involved in carbohydrate metabolism that appear to be important in fitness compensation and in particular the phenomenon of overcompensation. Among others, genes involved include the cytosolic invertases. Overall there are 12 genes that code for invertase and all are involved in hydrolyzing sucrose. Here we address the issue of functional redundancy of these isoforms in the compensatory response using a combination of gene expression assays and knockout mutants in an Arabidopsis ecotype that overcompensates (Columbia) and an ecotype that undercompensates (Landsberg erecta) following the removal of apical dominance. Results/Conclusions Results indicated elevated expression levels of all invertase genes in Columbia following clipping and higher relative levels of expression than the undercompensating plant Landsberg erecta following clipping. Although there appears to be functional redundancy in the level of expression for each of the 12 isoforms, knockout studies show a mixture of results from no affect from the knockout to altering the compensatory response from overcompensation to equal or under compensation. Thus, particular isoforms appear to be differentially important in the phenomenon of overcompensation and are not functionally redundant.

Additional file 1: of The role of invertases in plant compensatory responses to simulated herbivory

Table S1. Primers used for evaluating gene expression of the invertase isoenzymes. Table S2. Prim... more Table S1. Primers used for evaluating gene expression of the invertase isoenzymes. Table S2. Primers used for genotyping the T-DNA knockout lines. Table S3. P values of comparisons of gene expression between clipped and unclipped plants in ecotype Columbia-4 at different growth stages following removal of apical dominance. Table S4. P values of comparisons of gene expression between clipped and unclipped plants in ecotype Landsberg erecta at different growth stages following removal of apical dominance. (DOC 106Â kb)

Gene expression analysis of compensatory responses to herbivory yields differences in growth, reproduction, and defensive chemistry