Showing papers by "University of Georgia published in 1988"
TL;DR: The Self-Evaluation Maintenance (SEM) model as discussed by the authors is composed of two dynamic processes, the reflection process and the comparison process, which have as component variables the closeness of another and the quality of that other's performance, which interact in affecting self-evaluation but do so in quite opposite ways in each of the processes.
Abstract: Publisher Summary This chapter discusses social behavior through self-evaluation maintenance (SEM) model. It describes several studies to provide a feel for the kind of research that has been completed in an attempt to explore the predictions of the model. The SEM model is composed of two dynamic processes. Both the reflection process and the comparison process have as component variables the closeness of another and the quality of that other's performance. These two variables interact in affecting self-evaluation but do so in quite opposite ways in each of the processes Model establishes the comprehensiveness of the research and the interactive quality of its predictions. Next, the SEM model is fit into the perspective of related work, including self-theories, social comparison theory, and Cialdini's BIRGing research. The chapter reviews the epistemological status of the model. It discusses some of the implications of the research for a variety of areas in psychology.
1,787 citations
TL;DR: The decomposition method can be an effective procedure for analytical solution of a wide class of dynamical systems without linearization or weak nonlinearity assumptions, closure approximations, perturbation theory, or restrictive assumptions on stochasticitiy as mentioned in this paper.
1,409 citations
TL;DR: The results of a meta-analysis of experimental studies which have examined ten different factors felt to influence response rates to mail surveys were reported in this article, which clearly defines the individual impact of each of the factors examined.
Abstract: This article reports the results of a meta-analysis of experimental studies which have examined ten different factors felt to influence response rates to mail surveys. The form of meta- analysis used clearly defines the individual impact of each of the factors examined. Results indicate that prenotification and follow-ups increase the response rate, as does the type of outgo- ing postage used. Furthermore, studies sponsored by a university receive greater returns. Increases in the size of the monetary incentive used appear to have decreasing marginal gains. Finally, some evidence exists to suggest that the color of the question- naire influences response rate. The extensive use of mail surveys coupled with the low response rates typically encountered has made the issue of mail survey response rate improvement an intriguing topic. High response rates have the obvi- ous benefits of increased sample size, reduced costs associated with follow-up contacts, and reduced concern over nonresponse bias. Many experiments have been conducted to measure the effectiveness of one or more of the factors expected to influence response rates. The purpose of this paper is to apply a form of meta-analysis to reported experimental findings to isolate and estimate the individual impact of several typical response rate enhancement techniques. The meta-analysis technique used avoids the problems associated with past similar efforts but is more restrictive in the factors which can be exam-
746 citations
TL;DR: A new implementation of the coupled cluster method including all single, double, triple and quadruple excitations (designated CCSDT) has been developed and carefully tested.
576 citations
552 citations
505 citations
TL;DR: The amino acid composition and sequence for the Lea proteins are unusual, five are extremely hydrophilic, four contain no cys or trp and 4 have sequence domains that suggest amphiphilic helical structures.
Abstract: Lea genes code for mRNAs and proteins that are late embryogenesis abundant in higher plant seed embryos. They appear to be ubiquitous in higher plants and may be induced to high levels of expression in other tissues and at other times of ontogeny by ABA and/or desiccation. Presented here are the genomic and cDNA sequences for 6 of these genes from cotton seed embryos and the derived amino acid sequences of the corresponding proteins. The Lea genes contain the standard sequence features of eucaryotic genes (TATA box and poly (A) addition sequences) and have 1 or more introns. Sequences differences between cDNA and genomic DNA confirm the existence of small multigene families for several Lea genes. The amino acid composition and sequence for the Lea proteins are unusual. Five are extremely hydrophilic, four contain no cys or trp and 4 have sequence domains that suggest amphiphilic helical structures. Hypothetical functions in desiccation survival, based on amino acid sequence, are discussed.
504 citations
TL;DR: This article examined the effect of answering a question about a specific component of life satisfaction on respondents' assessment of their overall satisfaction with life, and found that the use of primed information in forming subsequent judgments is determined by Grice's conversational norms.
Abstract: Two experiments examined the effects of answering a question about a specific component of life satisfaction on respondents' assessment of their overall satisfaction with life. The results suggest that the use of primed information in forming subsequent judgments is determined by Grice's conversational norms. In general, answering the specific question increases the accessibility of information relevant to that question. However, the effect that this has on the general judgment depends on the way in which the two questions are presented. When the two questions are merely placed in sequence without a conversational context, the answer to the subsequent general question is based in part on the primed specific information. As a result, the answer to the general question becomes similar to that for the specific question (i.e. assimilation). However, this does not occur when the two questions are placed in a communication context. Conversational rules dictate that communicators should be informative and should avoid redundancy in their answers. Therefore, when a specific and a general question are perceived as belonging to the same conversational context, the information on which the answer to the specific question was based is disregarded when answering the general one. This attenuates the assimilation effect. The conditions under which these different processes occur are identified and experimentally manipulated, and the implications of these findings for models of information use in judgment are discussed.
463 citations
TL;DR: The authors' analyses indicate that the interactions of complex-type Asn-linked chains with the lectin are dependent on sialic acid linkages and are not dependent on either the branching pattern of the mannose residues or the presence of poly-N-acetyllactosamine sequences.
461 citations
TL;DR: It is proposed that BRLA is a nucleic acid-binding protein whose expression in vegetative cells is sufficient to induce sporulation through its role in regulating expression of conidiation-specific genes.
420 citations
TL;DR: In this paper, the authors examined concreteness effects in lexical decision using a sentence context-lexical decision and found that the benefits of context were larger for abstract words than for concrete words when the abstract words were rated low in context availability.
01 Apr 1988
TL;DR: In this article, a response to Gartner's critique of definitions posited by Carland, Hoy, Boulton and Carland (1984) for "entrepreneur" and "small business owner" is presented.
Abstract: This paper is a response to Gartner's critique of definitions posited by Carland, Hoy, Boulton and Carland (1984) for “entrepreneur” and “small business owner.” The paper concludes that both trait and behavioral approaches to research are necessary in order to understand the concept of entrepreneurship.
TL;DR: In this paper, a residual centering approach is proposed for evaluating in teraction hypotheses and general effect analysis for path (causal) models contain ing interactions, which is based on hierarchical moderated regression (HMR) analysis.
Abstract: Hierarchical moderated regression (HMR) analysis may lead to interpretational problems in tests of mod erator (interaction) hypotheses. An alternative, resid ual-centering approach is described and compared to traditional HMR analysis. Procedures for evaluating in teraction hypotheses and general effect analysis proce dures are described for path (causal) models contain ing interactions. Index terms: Confirmatory analysis, Effect analysis in path models, Goodness-of- fit tests, Hierarchical moderated regression, Media tors, Moderated regression, Multicollinearity, Path models, Residual centering.
TL;DR: In this article, the authors used historical aerial photography to analyze spatial patterns of land use from the 1930's to the 1980's and found that the landscape has become less fragmented and more connected during the past 50 years.
Abstract: The objectives of this study were to determine how landscape patterns in Georgia, USA have changed through time and whether the spatial patterns varied by physiographic region. Historical aerial photography was used to analyze spatial patterns of land use from the 1930's to the 1980's. Land use patterns were quantified by: (1) mean number and size of patches; (2) fractal dimension of patches; (3) amount of edge between land uses; and (4) indices of diversity, dominance, and contagion. Forest cover increased in aerial extent and in mean patch size. The mean size of agricultural patches increased in the coastal plain and decreased in the mountains and piedmont. Edges between land uses decreased through time, indicating less dissection of the landscape. Fractal dimensions also decreased, indicating simpler patch shapes. Indices of diversity and dominance differed through time but not among regions; the contagion index differed among regions but not through time. A geographic trend of decreasing diversity and increasing dominance and contagion was observed from the mountains to the lower coastal plain. Landscape patterns exhibited the greatest changes in the piedmont region. Overall, the Georgia landscape has become less fragmented and more connected during the past 50 years. Changing patterns in the landscape may have implications for many ecological processes and resources.
Journal Article•
TL;DR: Findings that CD is linked to parental psychopathology but ADD/ H is not confirmed, when CD and ADD/H co-occur, however, there is markedly more aggression and illegal activity in both fathers and children.
Abstract: The biological parents of 86 outpatient children aged 6 to 1 3 years were assessed using a structured diagnostic interview. Both mothers and fathers of children with Conduct Disorder (CD) (N = 37) were more likely to exhibit Antisocial Personality Disorder, and fathers were more likely to abuse substances. CD mothers exhibited more depression and the triad of Antisocial Personality Disorder. Substance Abuse, or Somatization Disorder. In contrast. Attention Deficit Disorder with Hyperactivity (ADD/H) (N = 18) was not associated with any parental disorder. However, fathers of children with both CD and ADD/H, which is associated with greater aggression and persistent law-breaking in children than CD alone, were markedly more likely to have a history of aggression, arrest, and imprisonment. These results confirm findings that CD is linked to parental psychopathology but ADD/ H is not. When CD and ADD/H co-occur, however, there is markedly more aggression and illegal activity in both fathers and children. J. Am. Acad. Child. Adolesc Psychiatry , 1988, 27. 2:163–170.
TL;DR: A new classification scheme is presented, built on the work of Porter and Abell, as a first step toward developing an “optimal” business strategy classification system.
Abstract: Porter's (1980) and Abell's (1980) attempts to classify business strategies have several fundamental limitations After discussing the objectives and attributes of “scientific” classification systems, this article presents a new classification scheme, built on the work of Porter and Abell, as a first step toward developing an “optimal” business strategy classification system.
TL;DR: An empirically derived cluster analysis of three factors derived from factor analyses of teacher ratings of ADD symptoms produced three distinct clusters: patients without ADD, those with both inatt attention and hyperactivity, and a group that exhibited inattention and sluggish tempo but not hyperactivity.
Abstract: DSM-III-R provides a unidimensional definition of attention deficit-hyperactivity disorder (ADHD), based on the assumption that inattention, impulsivity, and motor hyperactivity are unitary aspects of the same dimension. The definition of undifferentiated attention deficit disorder (UADD), however, contradicts this assumption by treating inattention as a separate dimension. The present study evaluated these assumptions empirically. A cluster analysis of three factors derived from factor analyses of teacher ratings of ADD symptoms and a broader list of ADD symptoms produced three distinct clusters: patients without ADD, those with both inattention and hyperactivity, and a group that exhibited inattention and sluggish tempo but not hyperactivity. The association was very strong between the empirically derived clusters and clinical DSM-III diagnoses of ADD with and without hyperactivity. These findings do not support the DSM-III-R unidimensional definition of ADHD.
TL;DR: The status and security of fishes in North American deserts have steadily declined in this century due to man's activities in this naturally fragile region by developing two zoogeographic models of isolation and gene flow by suggesting three areas of experimentation needed to better understand and manage genetic stocks of desert fishes.
Abstract: The status and security of fishes in North American deserts have steadily declined in this century due to man's activities in this naturally fragile region. We address genetic aspects of the population structure of desert fishes as applicable to conservation and recovery programs by developing two zoogeographic models of isolation and gene flow. In the Death Valley model populations are isolated, with no chance of natural gene flow among them. Genetic diversity within populations tends to be low, but genetic divergence among populations within a species is high. In the Stream Hierarchy model, a complicated hierarchical genetic structure exists and is a function of geographic proximity and connectivity of habitats. Within-habitat genetic diversity tends to be higher, and among-habitat differentiation lower, than in the Death Valley model. These two systems must be recognized as distinct and managed differently. We also suggest three areas of experimentation needed to better understand and manage genetic stocks of desert fishes: relationships between heterozygosity and fitness, experimental mixing of similar stocks to examine effects of increased heterozygosity, and analysis of the relative roles of genetic adaptation and phenotypic plasticity in local differentiation.
Resuman: El estatus y la seguridad de los peces en los desiertos Norteamericanos ha empeorado a un ritmo sostenido durante este siglo debido a las actividades del hombre en esta region de naturaleza fragil. Discutimos aspectos geneticos de la estructura poblacional de peces del desierto con respecto a su aplicabilidad a programas de conservacion y recuperacion mediante el desarrollo de dos modelos zoogeograficos de aislamiento y frujo genetico. En el modelo de Death Valley, las poblaciones estan aisladas, sin ninguna oportunidad para el flujo de material genetico entre ellas. La diversidad genetica dentro de estas poblaciones tiende a ser baja, pero la divergencia genetica entre poblaciones de una especie dada es alta. En el modelo de stream hierarchy, existe una complicada estructura genetica jerarquizada y esta esta dada en funcion de la proximidad geografica y la conectividad de habitats. La diversidad genetica al interior de un habitat tiende a ser Mas alta y la differenciacion entre habitats mas baja que las del modelo de Death Valley. Debe reconocerse que estos dos sistemas son distintos y deben ser manejados differentemente. Tambien sugerimos tres areas de expetimentacion requeridas para comprender y manejar mejor los stocks geneticos de peces del desierto: relaciones entre heterocigoticidad y adecuacion, mezcla experimental de stocks similares para examinar los efectos al aumento de heterocigoticidad, y el analisis de los roles relativos de la adaptacion genetica y la plasticidad fenotipica con respecto en la differenciacion local.
TL;DR: The observed molecular distances among mtDNA lineages were two to three orders of magnitude lower than predicted from census sizes of breeding females, suggesting that rate of mtDNA evolution is decelerated in these species and/or that long-term effective population size is vastly smaller than present-day population size.
Abstract: Using inbreeding theory as applied to neutral alleles inherited maternally, we generate expected probability distributions of times to identity by descent for random pairs of mitochondrial genotypes within a population or within an entire species characterized by high gene flow. For comparisons with these expectations, empirical distributions of times to most recent common ancestry were calculated (by conventional mtDNA clock calibrations) from mtDNA haplotype distances observed within each of three vertebrate species--American eels, hardhead catfish, and redwinged blackbirds. These species were chosen for analysis because census population size in each is currently large and because both genetic and life-history data are consistent with the postulate that historical gene flow within these species has been high. The observed molecular distances among mtDNA lineages were two to three orders of magnitude lower than predicted from census sizes of breeding females, suggesting that rate of mtDNA evolution is decelerated in these species and/or that long-term effective population size is vastly smaller than present-day population size. Several considerations point to the latter possibility as most likely. The genetic structure of any species is greatly influenced by historical demography; even for species that are currently abundant, mtDNA gene lineages appear to have been channeled through fairly small numbers of ancestors.
TL;DR: It is widely believed that women experience less skeletal muscle hypertrophy consequent to heavy-resistance training than men, but this hypothesis was tested using both traditional indirect indicators as well as a direct measure of muscle size using computed tomography scanning.
Abstract: It is widely believed that women experience less skeletal muscle hypertrophy consequent to heavy-resistance training than men. The purpose of this study was to test this hypothesis using both traditional indirect indicators as well as a direct measure of muscle size. Seven male experimental (ME), 8 female experimental (FE), and 7 control subjects were studied before and after a 16-wk weight training program, in which ME and FE trained 3 days.wk-1 at 70 to 90% of maximum voluntary contraction using exercise designed to produce hypertrophy of the upper arm and thigh. Strength increased significantly (P less than 0.05) in ME and FE, respectively, on elbow flexion (36.2 and 59.2%), elbow extension (32.6 and 41.7%), knee flexion (12.8 and 24.4%), and knee extension (28.8 and 33.9%) tests. Absolute changes were significantly greater in ME than FE in 2 of the 4 tests, whereas percentage changes were not significantly different. Substantial muscle hypertrophy occurred in the upper arms of both ME and FE as evidenced by significant increases in upper arm circumference (7.9 and 7.9%), bone-plus-muscle (B+M) cross-sectional area (CSA) estimated by anthropometry (17.5 and 20.4%), and muscle CSA determined from computed tomography scanning (15.9 and 22.8%). Changes by ME and FE were not significantly different, except for the absolute increase in estimated B+M CSA, which was significantly greater in ME (11.2 vs 7.4 cm2). No muscle hypertrophy occurred in the thigh of either ME and FE as evidenced by non-significant changes in thigh circumference (1.7 and 2.3%), B+M CSA (4.9 and 6.1%), and muscle CSA (2.9 and 2.9%). Changes by ME and FE in body weight, fat-free weight, and fat weight were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: In this paper, the authors examine the cost differences between public sales and private placements of debt for a sample of public utility issues and suggest that firms minimize the cost of issuing securities by selecting the market providing the lowest transaction costs.
TL;DR: Three types of hydrogenases have been isolated from the sulfate-reducing bacteria of the genus Desulfovibrio and it is suggested that selenium is a ligand to nickel and suggest that the redox active nickel is ligated by at least two cysteinyl thiolate and one selenocysteine selenolate residues.
Abstract: Three types of hydrogenases have been isolated from the sulfate-reducing bacteria of the genus Desulfovibrio. They differ in their subunit and metal compositions, physico-chemical characteristics, amino acid sequences, immunological reactivities, gene structures and their catalytic properties. Broadly, the hydrogenases can be considered as 'iron only' hydrogenases and nickel-containing hydrogenases. The iron-sulfur-containing hydrogenase ([Fe] hydrogenase) contains two ferredoxin-type (4Fe-4S) clusters and an atypical iron-sulfur center believed to be involved in the activation of H2. The [Fe] hydrogenase has the highest specific activity in the evolution and consumption of hydrogen and in the proton-deuterium exchange reaction and this enzyme is the most sensitive to CO and NO2-. It is not present in all species of Desulfovibrio. The nickel-(iron-sulfur)-containing hydrogenases [( NiFe] hydrogenases) possess two (4Fe-4S) centers and one (3Fe-xS) cluster in addition to nickel and have been found in all species of Desulfovibrio so far investigated. The redox active nickel is ligated by at least two cysteinyl thiolate residues and the [NiFe] hydrogenases are particularly resistant to inhibitors such as CO and NO2-. The genes encoding the large and small subunits of a periplasmic and a membrane-bound species of the [NiFe] hydrogenase have been cloned in Escherichia (E.) coli and sequenced. Their derived amino acid sequences exhibit a high degree of homology (70%); however, they show no obvious metal-binding sites or homology with the derived amino acid sequence of the [Fe] hydrogenase. The third class is represented by the nickel-(iron-sulfur)-selenium-containing hydrogenases [( NiFe-Se] hydrogenases) which contain nickel and selenium in equimolecular amounts plus (4Fe-4S) centers and are only found in some species of Desulfovibrio. The genes encoding the large and small subunits of the periplasmic hydrogenase from Desulfovibrio (D.) baculatus (DSM 1743) have been cloned in E. coli and sequenced. The derived amino acid sequence exhibits homology (40%) with the sequence of the [NiFe] hydrogenase and the carboxy-terminus of the gene for the large subunit contains a codon (TGA) for selenocysteine in a position homologous to a codon (TGC) for cysteine in the large subunit of the [NiFe] hydrogenase. EXAFS and EPR studies with the 77Se-enriched D. baculatus hydrogenase indicate that selenium is a ligand to nickel and suggest that the redox active nickel is ligated by at least two cysteinyl thiolate and one selenocysteine selenolate residues.(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: Common methods of treatment of plant samples prior to sterol extraction led to reduced recoveries of ergosterol, but the least destructive method was direct placement and storage in methanol.
Abstract: Portions of published procedures for measurement of ergosterol content of decomposing plants were examined for their influence upon ergosterol yield. Common methods of treatment of plant samples prior to sterol extraction (e.g., oven drying, freezing, lyophilization) led to reduced recoveries of ergosterol (ca. 20 to 80%). The least destructive method was direct placement and storage in methanol. Photoconversion of ergosterol is not likely to cause losses during analysis, but losses are likely if there is insufficient mixing during neutral-lipid partitioning from base-hydrolysis reagents. Homogenization (two times for 2 min) and refluxing (2 h) in methanol were equally effective in extracting ergosterol. Direct extraction in base-hydrolysis reagents was less effective (by ca. 40%).
TL;DR: The energetic demand of microorganisms in natural waters and the flux of energy between microorganisms and metazoans has been evaluated by empirical measurements in nature, in microcosms and mesocosms, and by simulation models, but empirical evidence is mixed.
Abstract: The energetic demand of microorganisms in natural waters and the flux of energy between microorganisms and metazoans has been evaluated by empirical measurements in nature, in microcosms and mesocosms, and by simulation models. Microorganisms in temperate and tropical waters often use half or more of the energy fixed by photosynthesis. Most simulations and some experimental results suggest significant energy transfer to metazoans, but empirical evidence is mixed. Considerations of the range of growth yields of microorganisms and the number of trophic transfers among them indicate major energy losses within microbial food webs. Our ability to verify and quantify these processes is limited by the variability of assimilation efficiency and uncertainty about the structure of microbial food webs. However, even a two-step microbial chain is a major energy sink.
TL;DR: Clinicopathologic findings from two golden retriever dogs with an inherited, progressive, degenerative muscle disease that were studied until 27 and 40 months of age are described and potential contributing pathophysiologic mechanisms are discussed in relation to Duchenne muscular dystrophy.
Abstract: Clinicopathologic findings from two golden retriever dogs with an inherited, progressive, degenerative muscle disease that were studied until 27 and 40 months of age are described. Initial clinical signs included stilted gait and simultaneous advancement of their pelvic limbs. Further gait restriction and muscle hypertrophy eventually occurred. Serum creatine kinase was dramatically elevated (greater than 10,000 U/L). There were persistent "spontaneous" high-frequency discharges (pseudomyotonia) on electromyographic evaluation. Features of both muscle fiber degeneration (hyaline fibers, myophagocytosis) and regeneration (small basophilic fibers) were seen on light microscopy. Similar ultrastructural changes (fiber hypercontraction, increased myoblasts) were present. On morphometric histochemical evaluation, mean fiber diameter of both type 1 and 2 fibers was increased compared with controls in two of three muscles examined. There was no apparent fiber type predominance. Scattered ragged red fibers were seen, but this appeared to be a nonspecific finding of either muscle fiber regeneration or degeneration. These findings and potential contributing pathophysiologic mechanisms are discussed in relation to Duchenne muscular dystrophy.
TL;DR: The use of inhibitors from several sources should be helpful in augmenting natural levels so that homeostasis can be maintained.
TL;DR: A new method for high-resolution Northern (RNA) analysis showed that the trxA and cat mRNAs are degraded into discrete fragments which are significantly stabilized only in the triple mutant, a model for mRNA turnover is discussed.
Abstract: The degradation of mRNA in Escherichia coli is thought to occur through a series of endonucleolytic and exonucleolytic steps. By constructing a series of multiple mutants containing the pnp-7 (polynucleotide phosphorylase), rnb-500 (RNase II), and ams-1 (altered message stability) alleles, it was possible to study general mRNA turnover as well as the degradation of specific mRNAs. Of most interest was the ams-1 pnp-7 rnb-500 triple mutant in which the half-life of total pulse-labeled RNA increased three- to fourfold at the nonpermissive temperature. RNA-DNA hybridization analysis of several specific mRNAs such as trxA (thioredoxin), ssb (single-stranded-DNA-binding protein), uvrD (DNA helicase II), cat (chloramphenicol acetyltransferase), nusA (N utilization substance), and pnp (polynucleotide phosphorylase) demonstrated two- to fourfold increases in their chemical half-lives. A new method for high-resolution Northern (RNA) analysis showed that the trxA and cat mRNAs are degraded into discrete fragments which are significantly stabilized only in the triple mutant. A model for mRNA turnover is discussed.
TL;DR: Recognition and appreciation of the different colonization strategies of autogenic and allogenic helminths in respect of host vagility and ability to cross land or sea barriers and break down habitat isolation provides an understanding of, and explanation for, the observed patchy spatial distribution of many helminth communities.
Abstract: Examples of the apparently stochastic nature of freshwater fish helminth communities illustrating the erratic and unpredictable occurrence and distribution of many species are provided for six species of fish from several localities throughout Britain. By focussing on parasite colonization strategies two categories of helminths are recognized: autogenic species which mature in fish and allogenic species which mature in vertebrates other than fish and have a greater colonization potential and ability. Three groups of fish are distinguished: salmonids, in which helminth communities are generally dominated by autogenic species which are also responsible for most of the similarity within and between localities; cyprinids, in which they are dominated by allogenic species which are also responsible for most of the similarity within and between localities; and anguillids, whose helminth communities exhibit intermediate features with neither category consistently dominating nor providing a clear pattern of similarity. Recognition and appreciation of the different colonization strategies of autogenic and allogenic helminths in respect of host vagility and ability to cross land or sea barriers and break down habitat isolation, and their period of residence in a locality, whether transient or permanent, provides an understanding of, and explanation for, the observed patchy spatial distribution of many helminths. Comparison with other parts of the world indicates that colonization is a major determinant of helminth community structure.
TL;DR: A comparison between mtDNA data sets for Red-winged Blackbirds and deermice also sampled from across North America shows that intraspecific population structures of these two species differ dramatically.
Abstract: A continent-wide survey of restriction-site variation in mitochondrial DNA (mtDNA) of the Red-winged Blackbird (Agelaius phoeniceus) was conducted to assess the magnitude of phylogeographic population structure in an avian species. A total of 34 mtDNA genotypes was observed among the 127 specimens assayed by 18 restriction endonucleases. Nonetheless, population differentiation was minor, as indicated by (i) small genetic distances in terms of base substitutions per nucleotide site between mtDNA genotypes (maximum P ≈ 0.008) and by (ii) the widespread geographic distributions of particular mtDNA clones and phylogenetic arrays of clones. Extensive morphological differentiation among redwing populations apparently has occurred in the context of relatively little phylogenetic separation. A comparison between mtDNA data sets for Red-winged Blackbirds and deermice (Peromyscus maniculatus) also sampled from across North America shows that intraspecific population structures of these two species differ dramatically. The lower phylogeographic differentiation in redwings is probably due to historically higher levels of gene flow.