Geographic variation, niche breadth and genetic differentiation at different geographic scales in the mussels Mytilus californianus and M. edulis

1978 ◽  
Vol 49 (4) ◽  
pp. 363-375 ◽  
Author(s):  
J. S. Levinton ◽  
T. H. Suchanek
Keyword(s):  
Genetic Differentiation ◽  
Geographic Variation ◽  
Niche Breadth ◽  
Mytilus Californianus

The adaptive significance of dorsal spine variation in the fourspine stickleback, Apeltes quadracus, I. Geographic variation in spine number

1984 ◽  
Vol 62 (7) ◽  
pp. 1329-1339 ◽  
Author(s):  
D. M. Blouw ◽  
D. W. Hagen
Keyword(s):  
Genetic Differentiation ◽  
Geographic Variation ◽  
Adaptive Significance ◽  
Maritime Provinces ◽  
Selective Agents ◽  
Apeltes Quadracus ◽  
Remarkable Result ◽  
Fourspine Stickleback ◽  
Very High Frequencies ◽  
Spine Number

The goal of our research is to investigate the adaptive significance of a polymorphism for the number of dorsal spines in Apeltes quadracus, the fourspine stickleback. One approach we take is to search for correlations between phenotypes and environments. To this end we collected Apeltes and scored environments at 570 sites in the Maritime Provinces of Canada. In this paper we describe geographic variation in spine number and evaluate how reliably it reflects genetic differentiation among sites. Morph frequencies are highly differentiated geographically. We describe four kinds of variation: relatively constant frequencies, gentle clines, steep clines, and remarkably abrupt changes (called "intrusions") where frequencies at some sites differ greatly from those at a larger number of surrounding sites. Most of the variation among sites is due to differences in the frequencies of the four- and five-spined morphs. However, a remarkable result is that the three-spined morph, which is rare or absent elsewhere in the range, reaches very high frequencies in Bras D'Or Lake. Our evidence suggests this variation among sites reflects substantial genetic differentiation. The differentiation is favorable for detecting selective agents, if indeed selection is responsible.

Electrophoretic, Chromosomal and Morphometric Studies on the Red-Necked Wallaby, Macropus Rufogriseus (Desmarest).

1979 ◽  
Vol 27 (3) ◽  
pp. 433 ◽  
Author(s):  
PG Johnston ◽  
GB Sharman
Keyword(s):  
Genetic Differentiation ◽  
Geographic Variation ◽  
Preliminary Data ◽  
Genetic Similarity ◽  
Chromosomal Variation ◽  
Electrophoretic Variation ◽  
Genetic Loci ◽  
Polymorphic Loci ◽  
The Mean

Geographic variation in island and mainland Australian populations of M. rufogriseus was investigated by electrophoretic, chromosomal and skull morphometric studies. Electrophoretic variation was observed at 9 of the 21 genetic loci examined. The mean proportion of polymorphic loci per population was 0.230 and individuals were on the average heterozygous at 6.5% of their loci. Coefficients of genetic similarity between populations ranged from 0.925 to 0.986, which is indicative of little genetic differentiation between populations. No chromosomal variation was observed in animals from the mainland, Tasmania and the Bass Strait islands. Preliminary data on breeding patterns suggest that females from King I. and Flinders I. are seasonal breeders, as has been reported for M. rufogriseus from Tasmania. It is concluded that M. rufogriseus should be divided into two subspecies: M. r. rufogriseus from Tasmania and the Bass Strait islands; M. r. banksianus from mainland Australia.

Asynchrony of Seasons: Genetic Differentiation Associated with Geographic Variation in Climatic Seasonality and Reproductive Phenology

2014 ◽  
Vol 184 (3) ◽  
pp. 352-363 ◽  
Author(s):  
Ignacio Quintero ◽  
Sebastián González-Caro ◽  
Paul-Camilo Zalamea ◽  
Carlos Daniel Cadena
Keyword(s):  
Genetic Differentiation ◽  
Geographic Variation ◽  
Reproductive Phenology

Genetic and plastic responses in geographic differentiation of Bromus rubens populations

1978 ◽  
Vol 56 (7) ◽  
pp. 873-879 ◽  
Author(s):  
K. K. Wu ◽  
S. K. Jain
Keyword(s):  
Genetic Differentiation ◽  
Geographic Variation ◽  
Function Analysis ◽  
Natural Populations ◽  
Central Valley ◽  
Habitat Diversity ◽  
Quantitative Characters ◽  
Local Environments ◽  
Geographical Distances ◽  
Controlled Environments

Populations of B. rubens were sampled in the northern and central Coastal Ranges and northern Central Valley of California to study the geographic variation patterns. Quantitative estimates of variation were obtained on plants collected in nature, and their progenies were grown under controlled environments. Discriminant function analysis was used to estimate the variation among populations in both natural and controlled environments for four quantitative characters. These variations appear approximately proportional to the geographical distances among localities and to the measures of genetic differentiation. It was found that for these four quantitative characters, about 12–27% of the total geographic variation among natural populations of B. rubens was contributed by genetic differentiation, while the rest (73–88%) was contributed by the so-called plastic response (nongenetic variation) to different local environments. This finding suggested that phenotypic plasticity is important for the wide adaptability of this species.The similarity between the dendrogram patterns of both genetic similarity and phenotypic similarity for esterases and quantitative characters, respectively, suggested that the observed variation may be adaptive and correlated with environmental components of climate and habitat diversity. Such comparisons of different character sets may provide a useful way of deriving the adaptive basis of geographic variation.

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