Environmental pressure rather than ongoing hybridization is responsible for an altitudinal cline in the morphologies of two oaks

2020 ◽  
Vol 13 (4) ◽  
pp. 413-422
Author(s):  
Ichiro Tamaki ◽  
Yae Yamada
Keyword(s):  
Contact Zone ◽  
Genetic Markers ◽  
Phenotypic Variation ◽  
Altitudinal Gradient ◽  
Morphological Traits ◽  
Leaf Morphology ◽  
Environmental Gradients ◽  
Reference Population ◽  
Environmental Pressure ◽  
Nuclear Microsatellite

Abstract Aims In a contact zone between related taxa, phenotypic variation can result from genetic and/or environmental gradients. This study aimed to clarify the cause of phenotypic variation in leaf morphology of two Quercus crispula varieties—crispula (QCC) and mongolicoides (QCM)—in their contact zone along an altitudinal gradient. Methods We measured 6 morphological traits of leaves and recorded genotypes of 13 nuclear microsatellite loci for 48 individuals in the contact zone and 24 individuals in each of the reference populations of QCC and QCM. We constructed a model explaining the phenotypic variation (leaf morphology) in relation to environmental (altitude) and genetic (ancestry from the reference population) gradients. Important Findings Both morphological and genetic markers distinguished the two varieties in the reference populations well. We were able to confirm the power of both morphological and genetic markers. Individuals within the contact zone population had intermediate ancestry that was slightly biased to QCM ancestry, and the distribution of their morphologies overlapped with those of the two varieties in the reference populations. The effect of altitude on leaf morphological traits was significant, while that of ancestry was not. Distributions of ancestry and interclass heterozygosity in the contact zone population resembled those in F2 or later generation hybrids. These results indicate that in the contact zone between QCC and QCM, there is no ongoing hybridization, but environmental pressure has created an altitudinal gradient in morphological traits through phenotypic plasticity and/or variation in functional genes.

Geographic range in Chthamalus along the west coast of North America

2005 ◽  
Vol 85 (2) ◽  
pp. 327-331 ◽  
Author(s):  
J.P. Wares ◽  
A.E. Castañeda
Keyword(s):  
North America ◽  
Cryptic Species ◽  
Genetic Markers ◽  
West Coast ◽  
Environmental Gradients ◽  
Geographic Range ◽  
The West ◽  
Barnacle Species ◽  
Range Overlap

Identification of the range boundaries and microgeographic distribution of cryptic species is greatly facilitated by the use of genetic markers. Here we characterize the geographic range overlap between two cryptic species, Chthamalus fissus and C. dalli, and show that as with other barnacle species, their distribution and abundance is probably dictated more by microhabitat characteristics and the presence of conspecifics than broader environmental gradients. We also show that C. dalli appears to be panmictic across the studied range.

scholarly journals Molecular Evidence for Hybrid Origin and Phenotypic Variation of Rosa Section Chinenses

Genes ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 996
Author(s):  
Chenyang Yang ◽  
Yujie Ma ◽  
Bixuan Cheng ◽  
Lijun Zhou ◽  
Chao Yu ◽  
...  
Keyword(s):  
Genetic Markers ◽  
Genetic Background ◽  
Morphological Traits ◽  
Taxonomic Status ◽  
Single Copy ◽  
Hybrid Origin ◽  
Biological Research ◽  
Molecular Evidence ◽  
Germplasm Resources ◽  
Wild Type

Rosa sect. Chinenses (Rosaceae) is an important parent of modern rose that is widely distributed throughout China and plays an important role in breeding and molecular biological research. R. sect. Chinenses has variable morphological traits and mixed germplasm. However, the taxonomic status and genetic background of sect. Chinenses varieties remain unclear. In this study, we collected germplasm resources from sect. Chinenses varieties with different morphological traits. Simple sequence repeat (SSR) markers, chloroplast markers, and single copy nuclear markers were used to explore the genetic background of these germplasm resources. We described the origin of hybridization of rose germplasm resources by combining different molecular markers. The results showed that the flower and hip traits of different species in R. sect. Chinenses were significantly different. The SSR analysis showed that the two wild type varieties have different genetic backgrounds. The double petal varieties of R. sect. Chinenses could be hybrids of two wild type varieties. A phylogenetic analysis showed that the maternal inheritance of sect. Chinenses varieties had two different origins. To some extent, variation in the morphological traits of double petal species of R. sect. Chinenses reflects the influence of cultivation process. This study emphasizes that different genetic markers vary in their characteristics. Therefore, analyzing different genetic markers in could provide an insight into highly heterozygous species.

Marker-based inferences about fecundity genes contributing to inbreeding depression in Mimulus guttatus

Genome ◽  
1994 ◽  
Vol 37 (6) ◽  
pp. 1005-1010 ◽  
Author(s):  
Yong-Bi Fu ◽  
Kermit Ritland
Keyword(s):  
Genetic Markers ◽  
Inbreeding Depression ◽  
Phenotypic Variation ◽  
Mimulus Guttatus ◽  
Selfed Progeny ◽  
Partial Dominance ◽  
Number Of Genes ◽  
Isozyme Loci ◽  
Deleterious Genes

Eight unlinked isozyme loci were used as genetic markers to characterize fecundity genes contributing to inbreeding depression in two selfed progeny arrays of Mimulus guttatus. Five fecundity traits were measured. Six of eight marked chromosomal segments were significantly associated with the expression of these traits. The number of genes detected for five traits in two progeny arrays varied, with an average of 2.8 genes per trait. Individual segments explained 1.44–9.29%, and together accounted for 3.85–11.32%, of phenotypic variation. Of 20 significant associations, 10 could be interpreted as exhibiting partial dominance, 7 overdominance, 3 partial recessivity, and 0 underdominance. Significant pairwise epistasis was rare. The results of this study suggest that inbreeding depression is caused by many deleterious genes of relatively small, partially dominant effects.Key words: linkage, isozymes, QTLs, inbreeding depression, Mimulus guttatus.

Relationship between genetic markers and morphological traits in a maize inbred lines collection

Euphytica ◽  
1995 ◽  
Vol 84 (2) ◽  
pp. 145-154 ◽  
Author(s):  
A. Bar-Hen ◽  
A. Charcosset ◽  
M. Bourgoin ◽  
J. Guiard
Keyword(s):  
Genetic Markers ◽  
Morphological Traits ◽  
Inbred Lines ◽  
Maize Inbred Lines

Leaf Morphology Along Environmental Gradients in Hawaiian Metrosideros Polymorpha

Biotropica ◽  
1994 ◽  
Vol 26 (1) ◽  
pp. 17 ◽  
Author(s):  
Geeske Joel ◽  
Gregory Aplet ◽  
Peter M. Vitousek
Keyword(s):  
Leaf Morphology ◽  
Environmental Gradients ◽  
Metrosideros Polymorpha

The Complexity of the Genotype-Phenotype Relationship and the Limitations of Using Genetic “Markers” at the Individual Level

1998 ◽  
Vol 11 (3-4) ◽  
pp. 373-389 ◽  
Author(s):  
Alan R. Templeton
Keyword(s):  
Genetic Markers ◽  
Phenotypic Variation ◽  
Disease Risk ◽  
Association Studies ◽  
Molecular Genetic ◽  
Genetic Research ◽  
Individual Treatment ◽  
Common Disease ◽  
Loss Of Function ◽  
Defective Gene

The ArgumentMany associations have recently been discovered between phenotypic variation and genetic loci, causing some to advocate what Robert Sinsheimer has called “a new eugenics” that would treat genetic “defects” in individuals prone to a disease. The first premise of this vision is that genetic association studies reveal the biological cause of the phenotypic variation. Once the responsible genes are known, the second premise is that we should focus upon changing “nature” rather than “nurture” by correcting the “defective” genes.The first premise is flawed because associations between genetic markers and phenotypes can be spurious, as shown by an example. Moreover, it is shown that using non-causative but associated genetic markers one at a time (the normal practice) can lead to incorrect predictions of disease risk for many individuals. Going from association to causation is a non-trivial step scientifically that has rarely been done in much of the human genetic research.Even when a particular locus does contribute to the phenotypic variation of interest, the first premise remains flawed because phenotypes in general arise from complex interactions among genes and between genes and environments as shown for genes associations with coronary artery disease (CAD). The ability of current molecular genetic tools to “fix” defective genotypes is extremely limited, but even if the technological problems could be overcome, the studies on CAD reveal no obvious “defective” gene to fix because the genetic effects are so context dependent (upon both other genes and environmental factors). Contrary to the second premise of the new eugenics, the more we learn about how different genotypes show variable responses to environments, the more important the environment becomes for individual treatment.The paradigm of a “defective gene” may work for classical Mendelian genetic diseases that are due to loss-of-function mutations. However, such mutations affect only a small portion of humanity. When the focus is changed to common disease and behavioral phenotypes, the “defective gene” paradigm is biologically meaningless and often harmful when applied to individuals. Thus, even when genes clearly do influence common phenotypic variation, the premises of the “new eugenics” are biologically indefensible.

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