7. Cladistic Biogeography of Juglans ( Juglandaceae) Based on Chloroplast DNA Intergenic Spacer Sequences

Aradhya, Mallikarjuna K.; Potter, Daniel; Simon, Charles J.

doi:10.7312/motl13316-008

Cited by 22 publications

(19 citation statements)

References 43 publications

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“…In addition, there was an adaptation to Neogene cool climate (~23 to~3 mya) (Wolfe 1978) and other expansions towards Southeastern Europe and Central and South America during late Myocene (~12 to~5 mya). From studying chloroplast DNA (cpDNA) intergenic spacer sequences, it seems that the division within genus Juglans (Rhysocaryon, Cardiocaryon, and Dioscaryon sections only) occurred during a period ranging from~50 to~40 mya, which matches with fossil analyses (Aradhya et al 2006(Aradhya et al , 2007 (Fig. 2).…”

Section: Taxonomy and Originsupporting

confidence: 58%

“…This classification was confirmed with a study of the nucleotide sequences of the chloroplast gene matK and the internal transcribed spacers (ITS) and 5.8S gene of the nuclear ribosomal DNA (Stanford et al 2000) (Table 1). J. regia is widely disseminated and grown in many temperate regions of Europe, North and South America, South Africa, Asia, Australia, and New Zealand (Aradhya et al 2006). All species of the genus Juglans are diploid with 2n = 2x = 32 chromosomes (Woodworth 1930).…”

Section: Taxonomy and Originmentioning

confidence: 99%

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Walnut: past and future of genetic improvement

Bernard

Lheureux²,

Dirlewanger

2017

Tree Genetics & Genomes

163

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Persian or English walnut (Juglans regia L.), the walnut species cultivated for nut production, is one of the oldest food sources known. Persian walnuts, native to the mountain valleys of Central Asia, are grown worldwide in temperate areas. World production exceeds three million tons since 2012, mostly provided by China, the USA, and Iran. Despite very ancient culture of walnut species (Juglans spp.), breeding actually started in the twentieth century. Using a range of methodologies, from morphological markers to the most recent advances in genome analysis, many genetic studies of walnut have been conducted during the past 30 years, including examination of diversity, determination of relationships within or among germplasm collections and populations, phylogenetic and origin elucidation, genetic map construction, and biotic or abiotic stress investigations. The genetic improvement of walnut has undergone great evolution. The producing countries of the Middle East have widely studied morphological characteristics of walnut. The USA and France, for example, are behind important cultivar releases such as BChandler^and BFranquette.^Finally, genomics represents a major breakthrough in walnut improvement, in particular by recent sequencing of both chloroplast and nuclear genomes. This review summarizes worldwide molecular and Bomics^studies and gives an overview of the main walnut breeding programs.

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Section: Taxonomy and Originsupporting

confidence: 58%

Section: Taxonomy and Originmentioning

confidence: 99%

Walnut: past and future of genetic improvement

Bernard

Lheureux²,

Dirlewanger

2017

Tree Genetics & Genomes

163

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“…Divergence time was calculated as T = d A /2 μ , where μ is the rate of nucleotide substitution (Nei & Kumar, 2000). An average overall rate of cpDNA sequence divergence was taken as 0.772 × 10 −10 substitutions per site per year based on fossil records of Pterocarya and Juglans ( c. 54 million yr ago (Mya)) (Aradhya et al. , 2005).…”

Section: Methodsmentioning

confidence: 99%

Nuclear and chloroplast DNA phylogeography reveal two refuge areas with asymmetrical gene flow in a temperate walnut tree from East Asia

2010

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Summary• Recently, there has been a debate about whether the temperate forests of East Asia merged or fragmented during glacial periods in the Pleistocene. Here, we tested these two opposing views through phylogeographical studies of the temperate-deciduous walnut tree, Juglans mandshurica (Juglandaceae) in northern and northeastern China, as well as Japan and Korea.• We assessed the genetic structure of 33 natural populations using 10 nuclear microsatellite loci and seven chloroplast DNA (cpDNA) fragments.• The cpDNA data showed the complete fixation of two different haplotype lineages in northeastern vs northern populations. This pronounced phylogeographic break was also indicated by nuclear microsatellite data, but there were disparities regarding individual populations. Among those populations fixed for haplotype A (the northeastern group), three were clustered in the northern group and four showed evidence of mixed ancestry based on microsatellite data.• Our results support the hypothesis that two independent refugia were maintained across the range of J. mandshurica in the north of China during the last glacial maximum, contrary to the inference that all temperate forests migrated to the south (25-30°N). The discordance between the patterns revealed by cpDNA and microsatellite data indicate that asymmetrical gene flow has occurred between the two refugia.

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“…Thus, J. mandshurica is distributed parapatrically with J. cathayensis and allopatrically with J. ailantifolia . The three Asian butternuts are closely related, with minute morphological differences: J. mandshurica has often been characterized as a species with abaxially glabrescent leaflets and a fruiting spike with four or five nuts, whereas J. cathayensis was thought to differ in its tomentose leaflets and in having a fruiting spike with six to ten nuts (Lu et al ., ); J. ailantifolia is sometimes thought of as a variable taxa of J. mandshurica (Aradhya et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Phylogeographic breaks within Asian butternuts indicate the existence of a phytogeographic divide in East Asia

2015

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Summary East Asia has been hypothesized to be subdivided into two distinct northern and southern areas, separated by a band of dry climate that was far more severe in the early Tertiary but still exists today. However, this biogeographic hypothesis has rarely been tested using a molecular phylogeographic approach. We genotyped 70 populations throughout the distributional range of Asian butternuts (Juglans section Cardiocaryon) using eight chloroplast DNA regions, one single‐copy nuclear gene, and 17 nuclear microsatellite loci, supplemented with paleodistribution modeling of the major genetic clades. The genetic data consistently identified two clades, one northern, comprising Juglans mandshurica and Juglans ailantifolia, and one southern, comprising Juglans cathayensis. The two clades diverged through climate‐induced vicariance of an ancestral northern range during the mid‐Miocene and remained mostly separate thereafter, with geographical isolation of the Japanese Islands and refugial isolation or secondary contacts in the late Pleistocene producing further subdivision within the northern clade. But beyond all that, we also discovered a role of environmental adaptation in maintaining and/or reinforcing the north–south divergence. Asian butternuts offer a strong case for the existence of a biogeographic divide between the northern and southern parts of East Asia during the Neogene and into the Pleistocene.

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7. Cladistic Biogeography of Juglans ( Juglandaceae) Based on Chloroplast DNA Intergenic Spacer Sequences

Abstract: Geographic distribution of extant taxa of Juglans (Juglandaceae). The distribution of cultivated species J. regia extends beyond its natural home range.

Cited by 22 publications

References 43 publications

Walnut: past and future of genetic improvement

Walnut: past and future of genetic improvement

Nuclear and chloroplast DNA phylogeography reveal two refuge areas with asymmetrical gene flow in a temperate walnut tree from East Asia

Phylogeographic breaks within Asian butternuts indicate the existence of a phytogeographic divide in East Asia

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