Temporal Genetic Stability Within and Restricted Migration (Gene Flow) Between Local Populations of the Blackberry-Grain Aphid Sitobion fragariae in South-East England

10.2307/4877 ◽  
1990 ◽  
Vol 59 (2) ◽  
pp. 497 ◽  
Author(s):  
H. D. Loxdale ◽  
C. P. Brookes
Keyword(s):  
Gene Flow ◽  
Genetic Stability ◽  
Local Populations ◽  
Grain Aphid ◽  
Sitobion Fragariae ◽  
South East England

scholarly journals Economic valuation of natural pest control of the summer grain aphid in wheat in South East England

2018 ◽  
Vol 30 ◽  
pp. 149-157 ◽  
Author(s):  
Han Zhang ◽  
Michael P.D. Garratt ◽  
Alison Bailey ◽  
Simon G. Potts ◽  
Tom Breeze
Keyword(s):  
Pest Control ◽  
Economic Valuation ◽  
Grain Aphid ◽  
South East England ◽  
Natural Pest Control

Invited Minireview: Restoring Demographic Processes in Translocated Populations: The Case of Collared Lizards in the Missouri Ozarks Using Prescribed Forest Fires

2007 ◽  
Vol 53 (2) ◽  
pp. 179-196 ◽  
Author(s):  
Alan R. Templeton ◽  
Jennifer L. Neuwald ◽  
Hilary Brazeal ◽  
R. James Robertson
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Habitat Fragmentation ◽  
Forest Fires ◽  
Local Extinction ◽  
Management Policy ◽  
Fire Scar ◽  
Local Populations ◽  
Collared Lizard ◽  
Rocky Habitats

Habitat fragmentation is one of the more important contributors to species endangerment, but one form of fragmentation, here called dispersal fragmentation, can often go unobserved for many years after it has occurred. Many species live in naturally fragmented habitats, but the local populations are interconnected genetically and demographically by dispersal through the environmental matrix in which the habitats are embedded. Because of dispersal, the local populations are not truly fragmented evolutionarily or ecologically. However, when human activities alter the environmental matrix such that dispersal is no longer possible, the population does indeed become fragmented even though they initially are present in the same habitats. An example of dispersal fragmentation via an altered environmental matrix is provided by the eastern collared lizard (Crotaphytus collaris collaris). This lizard lives on open, rocky habitats, called glades, that are embedded in the forests of the Ozarks, a highland region located primarily in Missouri and Arkansas in the USA. Forest fire suppression has reduced this habitat, resulting in severe habitat fragmentation, disruption of gene flow, loss of genetic variation within glade populations, and local extinction without recolonization. Beginning in 1982, glade habitats were restored by clearing and burning in the Peck Ranch area of the Missouri Ozarks, a region where the lizards had gone extinct. Starting in 1984, lizard populations were translocated from other Missouri glades onto restored glades at the Peck Ranch. Although these translocated populations survived well on the restored glades, no movement was detected between glades, some just 50 m apart, and no colonization of nearby restored glades, some just 60 m away, occurred between 1984 and 1993. Fragmentation, lack of colonization, no gene flow, and loss of genetic variation still persisted despite translocation reversing some of the local extinction. Fire scar data from trees and tree stumps indicated that forest fires were common in this area prior to European settlement, so in 1994 a new management policy of prescribed burning of both the glades and their forest matrix was initiated. Once the forest had been burned, the lizards could disperse kilometers through the forest, thereby reestablishing the processes of dispersal, gene flow, colonization, and local extinction followed by recolonization. This resulted in a dramatic increase in population size and inhabited area. By incorporating a landscape perspective into the management strategy, the eastern collared lizard has been successfully reestablished in a region of historic extirpation.

Geographic variability and wing plasticity in Sitona sulcifrons (Coleoptera: Curculionidae)

1994 ◽  
Vol 84 (2) ◽  
pp. 269-273
Author(s):  
Tomáš Pavlíček
Keyword(s):  
Gene Flow ◽  
Phenotypic Plasticity ◽  
Genetic Variability ◽  
Relative Size ◽  
The Other ◽  
Wing Size ◽  
Geographic Variability ◽  
Polymorphic Loci ◽  
Local Populations ◽  
Total Variability

AbstractGenetic variability in four polymorphic loci and variation in phenotypic plasticity in relation to the relative size of wings, were compared and contrasted among eight local populations of Sitonasulcifrons Thunberg from the Czech and Slovak republics. The distances between localities from which samples were taken were between 49 and 492 kilometres. The results demonstrated that: 1. The variability between populations was 5.5% and the other 94.5% of the total variability was realized within populations. 2. Significant differences in allozyme frequencies among populations existed when distances were more than 100 km. A similar trend was also found in variability of relative wing size in males among populations when distances were more than 200 km. 3. Overall, a significant deficiency of heterozygotes in relation to Hardy-Weinberg predictions existed from all samples. The results support the idea that, at least inagricultural areas, gene flow in S. sulcifrons does not seem to be strong enough to stabilize one large interbreeding population in distances over 100 kilometres.

Patterns of genetic diversity in the sumac gall aphid, Melaphis rhois

Genome ◽  
1991 ◽  
Vol 34 (5) ◽  
pp. 757-762 ◽  
Author(s):  
Paul D. N. Hebert ◽  
Terrie L. Finston ◽  
Robert Foottit
Keyword(s):  
Genetic Diversity ◽  
Life Cycle ◽  
Gene Flow ◽  
Gene Frequency ◽  
Dispersal Ability ◽  
Pest Species ◽  
Prior Work ◽  
Local Populations ◽  
Important Interaction ◽  
Plant Characteristics

In contrast to prior work on aphids, which has focused on pest species, the present study involved the analysis of genetic diversity in Melaphis rhois, a species that employs sumac and moss as alternate hosts. The life cycle involves a spring migration to sumac, with each sexual female producing a single offspring, which elicits a gall and subsequently proliferates clonally within it. Allozyme surveys at 52 sites in Ontario and Quebec established the absence of migration among galls and indicated that this species shares the low level of genetic diversity found in pest aphids. Genotypic frequencies in local populations of M. rhois showed frequent heterozygote deficits, suggesting the prevalence of inbreeding. Gene frequency divergence among populations was exceptionally pronounced, providing further evidence that gene flow was restricted. The unusual genetic attributes of this species suggest the important interaction among host-plant characteristics and the dispersal ability of aphids and their genetic systems.Key words: aphid, Melaphis, parthenogenesis, allozyme, cyclic parthenogen.

The Stock Concept, Discreteness of Fish Stocks, and Fisheries Management

1981 ◽  
Vol 38 (12) ◽  
pp. 1889-1898 ◽  
Author(s):  
J. A. MacLean ◽  
D. O. Evans
Keyword(s):  
Life History ◽  
Gene Flow ◽  
Fisheries Management ◽  
Life History Strategy ◽  
Stock Management ◽  
Fish Stocks ◽  
Local Populations ◽  
Subdivided Populations ◽  
Definition Of ◽  
Adaptive Nature

This paper examines the concept and definition of fish stocks and the processes that influence discreteness of these stocks in light of the tactics necessary for the application of the concept in management. Two approaches to the definition of stocks are discussed. These differ in the extent to which management inputs other than biological ones are considered. We consider definition to be less important than the adoption and development of a stock concept to provide a genetic perspective for fisheries management. The two central levels of the stock concept — the subdivision of species into local populations and the adaptive nature of genetic differences between these populations — are discussed with respect to the interlinked set of ecological and genetic processes that result in subdivision and determine the discreteness of these stocks. Genetic discreteness usually implies some restriction of gene flow, and spatial and temporal mechanisms of isolation are discussed with examples from the STOCS symposium. The structure of subdivided populations is seen as the result of behavioral processes that are one component of a set of coadapted traits, which collectively constitute a life history strategy. The necessity for managers to develop a new integrated view of species, which incorporates both ecological and genetic arguments, is discussed.Key words: stock concept, life history, gene flow, ecological and genetic discreteness, local adaptation stock management

scholarly journals GENETICS OF NATURAL POPULATIONS. XLIII. FURTHER STUDIES ON RATES OF DISPERSAL OF DROSOPHILA PSEUDOOBSCURA AND ITS RELATIVES

Genetics ◽  
1976 ◽  
Vol 82 (3) ◽  
pp. 493-506
Author(s):  
Jeffrey R Powell ◽  
Theodosius Dobzhansky ◽  
James E Hook ◽  
Harry E Wistrand
Keyword(s):  
Gene Flow ◽  
Natural Populations ◽  
Drosophila Pseudoobscura ◽  
Dispersal Capacity ◽  
Release Point ◽  
Local Populations ◽  
Species Population ◽  
Straight Lines ◽  
East West

ABSTRACT The amount of gene flow among local populations of a species is determined by the dispersal capacity of that species. Population samples of Drosophila pseudoobscura, D. persimilis, D. azteca, and D. miranda were collected, marked with ultraviolet fluorescent dusts, and released as soon as possible after capture. One and two days after release, recaptures were made on baits placed at 40-meter intervals in straight lines intersecting the release point. On alternative days, the baits were placed in North-South or in East-West directions. The distribution of the recaptured flies about the release point is very nearly normal. No significant differences between the dispersal rates of the four species are observed; however, males disperse slightly further than females. The variances averaged 50,822 m2 on the first day and 80,048 m2 on the second day and the estimated mean distances from the release point averaged 263 m and 361 m respectively. The genetic implications of the results are discussed.

Genetic structure after forest fragmentation: a landscape ecology perspective on Acer saccharum

1992 ◽  
Vol 70 (8) ◽  
pp. 1659-1668 ◽  
Author(s):  
Stephanie A. Foré ◽  
R. James Hickey ◽  
John L. Vankat ◽  
Sheldon I. Guttman ◽  
Robert L. Schaefer
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Forest Fragmentation ◽  
Acer Saccharum ◽  
Sugar Maple ◽  
Fragmented Landscape ◽  
Starch Gel Electrophoresis ◽  
Long Distance ◽  
Local Populations ◽  
Genetic Diversity And Structure

Fragmentation of large expanses of forests into small stands has isolated local populations of organisms. Sugar maple (Acer saccharum) was used to determine if the degree of forest fragment isolation affects genetic diversity and structure of local populations. Genetic data were collected from canopy (prefragmentation) and juvenile (postfragmentation) individuals in 15 woodlots. Genotypes were inferred from phenotypic enzyme patterns of seven enzymes representing eight loci extracted from cambium and resolved with starch gel electrophoresis. Analyses of allelic data indicated that genetic diversity was not significantly different between juvenile or canopy subdivisions, or between woodlots with low and high degrees of isolation. Genetic differentiation among woodlots was significantly greater for the canopy than for the juvenile subdivision. Estimates of gene flow indicate that postfragmentation gene flow rates are higher than prefragmentation rates. Apparently, sugar maple's high potential for long-distance gene flow is enhanced by altered wind flux across a fragmented landscape. The results also show that forest fragmentation does not always result in greater isolation of local populations. Key words: sugar maple, gene flow, conservation, isolation, allozymes.

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