Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques

2010 ◽  
Keyword(s):  
United States ◽  
Life History ◽  
Environmental Change ◽  
Fish Assemblages ◽  
Spatial Scales ◽  
The United States ◽  
Life History Strategies ◽  
Population Responses ◽  
Hydrologic Variability ◽  
Reproductive Life

<em>Abstract</em>.—The flow regime is considered the primary driver of physical processes in riverine ecosystems; thus we expect that the trait composition of fish assemblages might respond similarly to hydrologic variability, even at broad spatial scales. Here, we test the hypothesis that freshwater fish life history strategies on two continents (southern United States and eastern Australia) converge along gradients of hydrologic variability and primary productivity at the drainage scale. Our results show that the fishes of the United States and Australia conform to the three-dimensional adaptive space arising from the trade-offs among three basic demographic parameters of survival, fecundity, and onset and duration of reproductive life. Species from both continents represent the endpoints in adaptive space defining the periodic (19% versus 33% for the United States and Australia, respectively), opportunistic (69% versus 52%), and equilibrium life history strategies (12% versus 15%). We found evidence that fish life history composition of drainage basins in the two continents have converged across similar gradients of hydrologic variability and productivity despite phylogenetic and historical differences. Moreover, these relationships were largely consistent with predictions from life history theory. Increasing hydrologic variability has promoted the greater prevalence of opportunistic strategists (a strategy that should maximize fitness in environmental settings dominated by unpredictable environmental change) while concurrently minimizing the persistence of periodic-type species (a strategy typically inhabits seasonal, periodically suitable environments). Our study provides a conceptual framework of management options for species in regulated rivers because life history strategies are the underlying determinants for population responses to environmental change and therefore can be used to classify typical population responses to flow alteration or mitigation via environmental flow prescriptions.

scholarly journals Ecology-driven stereotypes override race stereotypes

2015 ◽  
Vol 113 (2) ◽  
pp. 310-315 ◽  
Author(s):  
Keelah E. G. Williams ◽  
Oliver Sng ◽  
Steven L. Neuberg
Keyword(s):  
United States ◽  
Life History ◽  
Life History Theory ◽  
The United States ◽  
Life History Strategies ◽  
Racial Groups ◽  
Black And White ◽  
Lay Understanding ◽  
Per Se ◽  
Rule Out

Why do race stereotypes take the forms they do? Life history theory posits that features of the ecology shape individuals’ behavior. Harsh and unpredictable (“desperate”) ecologies induce fast strategy behaviors such as impulsivity, whereas resource-sufficient and predictable (“hopeful”) ecologies induce slow strategy behaviors such as future focus. We suggest that individuals possess a lay understanding of ecology’s influence on behavior, resulting in ecology-driven stereotypes. Importantly, because race is confounded with ecology in the United States, we propose that Americans’ stereotypes about racial groups actually reflect stereotypes about these groups’ presumed home ecologies. Study 1 demonstrates that individuals hold ecology stereotypes, stereotyping people from desperate ecologies as possessing faster life history strategies than people from hopeful ecologies. Studies 2–4 rule out alternative explanations for those findings. Study 5, which independently manipulates race and ecology information, demonstrates that when provided with information about a person’s race (but not ecology), individuals’ inferences about blacks track stereotypes of people from desperate ecologies, and individuals’ inferences about whites track stereotypes of people from hopeful ecologies. However, when provided with information about both the race and ecology of others, individuals’ inferences reflect the targets’ ecology rather than their race: black and white targets from desperate ecologies are stereotyped as equally fast life history strategists, whereas black and white targets from hopeful ecologies are stereotyped as equally slow life history strategists. These findings suggest that the content of several predominant race stereotypes may not reflect race, per se, but rather inferences about how one’s ecology influences behavior.

scholarly journals THE LIFE-HISTORY OF THE NORTHERN MOLE-CRICKET—GRYLLOTALPA BOREALIS

1892 ◽  
Vol 24 (11) ◽  
pp. 270-273
Author(s):  
E. W. Doran
Keyword(s):  
United States ◽  
Life History ◽  
The United States ◽  
General Distribution ◽  
Mole Cricket ◽  
History Of ◽  
Time Required

Although this is a common insect in many parts of the United States, it is not generally found in great numbers in any locality, and, notwith standing its general distribution, the various staes of the insect seem not to have been describe or figured.While I am not yet able to clear up all the points in its history, I have studied the insect in all its stages, though I have not reared it from the egg to maturity, on account of the time required for it to develop—in all probability three years.

scholarly journals Fine-Scale Population Genetic Structure and Within-Tree Distribution of Mating Types of Venturia effusa, Cause of Pecan Scab in the United States

2018 ◽  
Vol 108 (11) ◽  
pp. 1326-1336 ◽  
Author(s):  
Clive H. Bock ◽  
Carolyn A. Young ◽  
Katherine L. Stevenson ◽  
Nikki D. Charlton
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Asexual Reproduction ◽  
Population Genetic ◽  
Spatial Scales ◽  
The United States ◽  
Source Population ◽  
Mating Types ◽  
Fine Scale ◽  
Scale Population

Scab (caused by Venturia effusa) is the major disease of pecan in the southeastern United States. There is no information available on the fine-scale population genetic diversity or the occurrence of clonal types at small spatial scales that provides insight into inoculum sources and dispersal mechanisms, and potential opportunity for sexual reproduction. To investigate fine-scale genetic diversity, four trees of cultivar Wichita (populations) were sampled hierarchically: within each tree canopy, four approximately evenly spaced terminals (subpopulations) were selected and up to six leaflets (sub-subpopulations) were sampled from different compound leaves on each terminal. All lesions (n = 1 to 8) on each leaflet were sampled. The isolates were screened against a panel of 29 informative microsatellite markers and the resulting multilocus genotypes (MLG) subject to analysis. Mating type was also determined for each isolate. Of 335 isolates, there were 165 MLG (clonal fraction 49.3%). Nei’s unbiased measure of genetic diversity for the clone-corrected data were moderate to high (0.507). An analysis of molecular variance demonstrated differentiation (P = 0.001) between populations on leaflets within individual terminals and between terminals within trees in the tree canopies, with 93.8% of variance explained among isolates within leaflet populations. Other analyses (minimum-spanning network, Bayesian, and discriminant analysis of principal components) all indicated little affinity of isolate for source population. Of the 335 isolates, most unique MLG were found at the stratum of the individual leaflets (n = 242), with similar total numbers of unique MLG observed at the strata of the terminal (n = 170), tree (n = 166), and orchard (n = 165). Thus, the vast majority of shared clones existed on individual leaflets on a terminal at the scale of 10s of centimeters or less, indicating a notable component of short-distance dispersal. There was significant linkage disequilibrium (P < 0.001), and an analysis of Psex showed that where there were multiple encounters of an MLG, they were most probably the result of asexual reproduction (P < 0.05) but there was no evidence that asexual reproduction was involved in single or first encounters of an MLG (P > 0.05). Overall, the MAT1-1-1 and MAT1-2-1 idiomorphs were at equilibrium (73:92) and in most populations, subpopulations, and sub-subpopulations. Both mating types were frequently observed on the same leaflet. The results provide novel information on the characteristics of populations of V. effusa at fine spatial scales, and provide insights into the dispersal of the organism within and between trees. The proximity of both mating idiomorphs on single leaflets is further evidence of opportunity for development of the sexual stage in the field.

DNA-based quantification of Fusarium oxysporum f. sp. vasinfectum in environmental soils to describe spatial variation in inoculum density

Plant Disease ◽  
2022 ◽  
Author(s):  
Roy Davis ◽  
Thomas Isakeit ◽  
Thomas Chappell
Keyword(s):  
United States ◽  
Fusarium Oxysporum ◽  
Spatial Scales ◽  
The United States ◽  
Inoculum Density ◽  
Root Knot Nematode ◽  
West Texas ◽  
Sudden Appearance ◽  
Digital Polymerase Chain Reaction ◽  
Race 4

Fusarium wilt of cotton, caused by the soilborne fungal pathogen Fusarium oxysporum f. sp. vasinfectum (FOV), occurs in regions of the United States where cotton (Gossypium spp.) is grown. Race 4 of this pathogen (FOV4) is especially aggressive and does not require the co-occurrence of the root knot nematode (Meloidogyne incognita) to infect cotton. Its sudden appearance in far-west Texas in 2016 after many years of being restricted to California is of great concern, as is the threat of its continued spread through the cotton-producing regions of the United States. The aim of this research was to analyze the spatial variability of FOV4 inoculum density in the location where FOV4 is locally emerging, using quantitative and droplet digital polymerase chain reaction (qPCR and ddPCR) methods. Soil samples collected from a field with known FOV4 incidence in Fabens, Texas were analyzed. Appreciable variation in inoculum density was found to occur at spatial scales smaller than the size of plots involved in cultivar trial research, and was spatially autocorrelated (Moran’s I, Z = 17.73, p < 0.0001). These findings indicate that for cultivar trials, accounting for the spatial distribution of inoculum either by directly quantifying it or through the use of densely-distributed “calibration checks” is important to the interpretation of results.

Thinking through Scale: The Role of State Governance in Globalizing North Pacific Fisheries

10.1068/a3469 ◽  
2001 ◽  
Vol 33 (10) ◽  
pp. 1807-1827 ◽  
Author(s):  
Becky Mansfield
Keyword(s):  
United States ◽  
North Pacific ◽  
Global Economy ◽  
Urban Governance ◽  
Spatial Scales ◽  
Full Range ◽  
The United States ◽  
International Partnerships ◽  
The North ◽  
Static View

Debates about the relationship between globalization and state power have often relied on a static view of spatial scales as discrete stages for social interaction. Focusing instead on the ‘production of scale’, several researchers have argued that globalization leads to rescaling of the state, as regulatory powers are realigned both upwards to supranational regimes and downwards to regional, local, and urban governance structures. Although this perspective quite usefully treats scale as relational, this ‘glocalization’ argument remains somewhat schematic and does not allow for a full range of possible scalar configurations. Highlighting instead heterogeneity of scalar relations, in this paper I analyze the ways that United States' fishery development in the North Pacific produced both national power and transnational economic activity. After extending political jurisdiction over waters up to 200 nautical miles from shore, the United States implemented fishery development policies that emphasized the ‘Americanization’ of the Alaska pollock fishery at the expense of an international, particularly Japanese, fishery. The outcomes of these policies, however, have been international partnerships, foreign direct investment, and increased international trade, all of which have made the pollock industry simultaneously national and transnational. Efforts to assert and implement control over ocean territory produced both the national state and globalization, which were mutually reinforcing rather than antagonistic. Treating national states and the global economy as complex, contingent scalar configurations facilitates analysis of the causes of variability in state – economy relations.

scholarly journals Life diagrams: a methodological and analytical tool for accessing life histories

2019 ◽  
Vol 20 (1) ◽  
pp. 3-21
Author(s):  
Johanna Söderström
Keyword(s):  
United States ◽  
Life History ◽  
Life Histories ◽  
Research Participant ◽  
The United States ◽  
Political Mobilization ◽  
Analytical Tool ◽  
Research Participants ◽  
Post War

The article argues for the utility of life diagrams as a methodological and analytical tool across various life history projects. Using research on post-war political mobilization among former combatants (in Colombia, Namibia and the United States), the article demonstrates how a life diagram can modify the interview and become a useful analytical tool. During the interview the diagram helps both the research participant and the interviewer to compare different events, weigh various experiences, and ensure that all periods of the life are covered even if the interview is not done chronologically. During the analysis, the diagram offers a contrast with the transcript of the interview, and the shape of the life diagram can be compared across interviews in search of similar types. This visual turn can help address issues of empowerment, through promoting the research participants’ own interpretation of their lives.

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