Morph identification in natural populations of alate female bird cherry aphids, Rhopalosiphum padi L., by multivariate methods

1994 ◽  
Vol 125 (1) ◽  
pp. 1-11 ◽  
Author(s):  
M S TAYLOR ◽  
G M TATCHELL ◽  
S J CLARK
Keyword(s):  
Rhopalosiphum Padi ◽  
Natural Populations ◽  
Multivariate Methods ◽  
Female Bird ◽  
Alate Female

scholarly journals Linear and geometric morphometrics as tools to resolve species circumscription in the Pseudolaelia vellozicola complex (Orchidaceae, Laeliinae)

2019 ◽  
Vol 152 (1) ◽  
pp. 53-67 ◽  
Author(s):  
Luiz Menini Neto ◽  
Cássio Van den Berg ◽  
Rafaela Campostrini Forzza
Keyword(s):  
Natural Populations ◽  
Distinct Species ◽  
Multivariate Methods ◽  
Brazilian Atlantic Forest ◽  
Morphometric Data ◽  
Elliptic Fourier Analysis ◽  
Linear Measurements ◽  
Species Circumscription ◽  
Eastern Brazil ◽  
Sufficient Magnitude

Background and aims – Pseudolaelia is a genus endemic to eastern Brazil, with 12 accepted species predominantly distributed across granitic inselbergs of the Brazilian Atlantic Forest. The aim of the present study was to distinguish between the very similar taxa P. aguadocensis, P. oliveirana, P. regentii and P. vellozicola, using morphometric data acquired as linear measurements and outlines capture with Elliptic Fourier Analysis (EFA) of the floral parts. Material and methods – We sampled 208 specimens from 11 natural populations of the above taxa. We measured 20 floral variables and for the EFA, and we extracted 24 shape variables from the Fourier coefficient matrices, which describe the outlines of the floral parts. In both cases the data were analyzed with multivariate methods (both ordination and clustering). Key results – We could not find morphological discontinuities with sufficient magnitude to consider P. aguadocensis, P. oliveirana and P. regentii as distinct species from P. vellozicola. Conclusions – We propose that P. vellozicola should be considered a polymorphic and widely distributed species, generally supported by both methods.

Estimating levels of gene flow between natural populations of cereal aphids (Homoptera: Aphididae)

1990 ◽  
Vol 80 (3) ◽  
pp. 331-338 ◽  
Author(s):  
Hugh D. Loxdale
Keyword(s):  
Gene Flow ◽  
Rhopalosiphum Padi ◽  
Natural Populations ◽  
Aphid Species ◽  
Cereal Aphids ◽  
Flight Behaviour ◽  
Primary Host ◽  
Advantages And Disadvantages ◽  
High Gene Flow ◽  
High Gene

AbstractGene flow between field populations of the cereal aphids Sitobion avenae (Fabricius), Sitobion fragariae (Walker) and Rhopalosiphum padi (Linnaeus) is examined using statistical analyses of allozyme frequency data (both Slatkin's and F statistics). Analysis using Slatkin's method confirms the conclusions previously drawn from earlier analyses. Thus there is found to be high gene flow between subpopulations of S. avenae and R. padi, and a more restricted level between local S. fragariae subpopulations, especially when infesting the secondary host (cocksfoot grass, Dactylis glomerata). The value of Nm (number of immigrants per generation) calculated for S. avenae was approximately 2 and is indicative of high gene flow i.e. Nm>1.0. Also, as previously found by x2 genetic contingency testing, the F statistical analysis confirms that S. fragariae subpopulations infesting D. glomerata are genetically more heterogeneous than those infesting the primary host, blackberry, Rubus fruticosus agg. Hence, there may be less gene flow between populations on the secondary host compared with that on the primary. The results obtained are compared with the flight behaviour of these particular aphid species and to their respective host plant abundances. The advantages and disadvantages of both Slatkin's method and F statistics for analysing insect population genetic structure are noted.

High-voltage electron microscopy of maxillary gland of spirochete-infected brine shrimp: lesion of efferent tubule

1988 ◽  
Vol 46 ◽  
pp. 362-363
Author(s):  
G. E. Tyson ◽  
M. J. Song
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Brine Shrimp ◽  
Natural Populations ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Infected Adult

Natural populations of the brine shrimp, Artemia, may possess spirochete- infected animals in low numbers. The ultrastructure of Artemia's spirochete has been described by conventional transmission electron microscopy. In infected shrimp, spirochetal cells were abundant in the blood and also occurred intra- and extracellularly in the three organs examined, i.e. the maxillary gland (segmental excretory organ), the integument, and certain muscles The efferent-tubule region of the maxillary gland possessed a distinctive lesion comprised of a group of spirochetes, together with numerous small vesicles, situated in a cave-like indentation of the base of the tubule epithelium. in some instances the basal lamina at a lesion site was clearly discontinuous. High-voltage electron microscopy has now been used to study lesions of the efferent tubule, with the aim of understanding better their three-dimensional structure.Tissue from one maxillary gland of an infected, adult, female brine shrimp was used for HVEM study.

Effect of acid deposition on trichome morphology and dogwood anthracnose biology

1992 ◽  
Vol 50 (1) ◽  
pp. 840-841
Author(s):  
Kyle T. Thornham ◽  
R. Jay Stipes ◽  
Randolph L. Grayson
Keyword(s):  
Acid Deposition ◽  
Disease Incidence ◽  
Natural Populations ◽  
Tree Disease ◽  
Flowering Dogwood ◽  
Discula Destructiva ◽  
Disease Induction ◽  
Dogwood Anthracnose ◽  
Trichome Morphology ◽  
Precipitation Events

Dogwood anthracnose, caused by Discula destructiva (1), is another new catastrophic tree disease that has ravaged natural populations of the flowering dogwood (Cornus florida) in the Appalachians over the past 15 years, and the epidemic is prognosticated to continue (2). An estimated 9.5 million acres have been affected, primarily in the Appalachian Mountains, from VA southwards, alone, and an estimated 50% of all dogwoods in PA have been killed. Since acid deposition has been linked experimentally with disease induction, and since the disease incidence and severity are more pronounced at higher elevations where lower pH precipitation events occur, we investigated the effect of acidic foliar sprays on moiphologic changes in the foliar cuticle and trichomes (3), the initial sites of infection and foci of Discula sporulation.

Madness, Mores, and Multivariate Methods

1978 ◽  
Vol 23 (11) ◽  
pp. 878-879
Author(s):  
LUIZ NATALICIO
Keyword(s):  
Multivariate Methods
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