Genetic variation in two widespread species of salamanders, Taricha granulosa and Taricha torosa

1976 ◽  
Vol 14 (7-8) ◽  
pp. 561-576 ◽  
Author(s):  
Dennis Hedgecock
Keyword(s):  
Genetic Variation ◽  
Taricha Granulosa ◽  
Widespread Species ◽  
Taricha Torosa

Population Genetics ofCaenorhabditis elegans: The Paradox of Low Polymorphism in a Widespread Species

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 147-157 ◽  
Author(s):  
Arjun Sivasundar ◽  
Jody Hey
Keyword(s):  
Genetic Variation ◽  
Microsatellite Loci ◽  
Population Expansion ◽  
Widespread Species ◽  
C Elegans ◽  
Model Research ◽  
The World ◽  
Natural Isolates ◽  
History Of ◽  
Low Levels

AbstractCaenorhabditis elegans has become one of the most widely used model research organisms, yet we have little information on evolutionary processes and recent evolutionary history of this widespread species. We examined patterns of variation at 20 microsatellite loci in a sample of 23 natural isolates of C. elegans from various parts of the world. One-half of the loci were monomorphic among all strains, and overall genetic variation at microsatellite loci was low, relative to most other species. Some population structure was detected, but there was no association between the genetic and geographic distances among different natural isolates. Thus, despite the nearly worldwide occurrence of C. elegans, little evidence was found for local adaptation in strains derived from different parts of the world. The low levels of genetic variation within and among populations suggest that recent colonization and population expansion might have occurred. However, the patterns of variation are not consistent with population expansion. A possible explanation for the observed patterns is the action of background selection to reduce polymorphism, coupled with ongoing gene flow among populations worldwide.

scholarly journals Climatic Refugia and Geographical Isolation Contribute to the Speciation and Genetic Divergence in Himalayan-Hengduan Tree Peonies (Paeonia delavayi and Paeonia ludlowii)

2021 ◽  
Vol 11 ◽  
Author(s):  
Yu-Juan Zhao ◽  
Gen-Shen Yin ◽  
Yue-Zhi Pan ◽  
Bo Tian ◽  
Xun Gong
Keyword(s):  
Genetic Variation ◽  
Late Quaternary ◽  
Demographic History ◽  
Nuclear Gene ◽  
Genetic Distances ◽  
Population Divergence ◽  
Widespread Species ◽  
Isolation With Migration ◽  
Isolation By Environment ◽  
Paeonia Delavayi

Himalaya and Hengduan Mountains (HHM) is a biodiversity hotspot, and very rich in endemic species. Previous phylogeographical studies proposed different hypotheses (vicariance and climate-driven speciation) in explaining diversification and the observed pattern of extant biodiversity, but it is likely that taxa are forming in this area in species-specific ways. Here, we reexplored the phylogenetic relationship and tested the corresponding hypotheses within Paeonia subsect. Delavayanae composed of one widespread species (Paeonia delavayi) and the other geographically confined species (Paeonia ludlowii). We gathered genetic variation data at three chloroplast DNA fragments and one nuclear gene from 335 individuals of 34 populations sampled from HHM. We performed a combination of population genetic summary statistics, isolation-with-migration divergence models, isolation by environment, and demographic history analyses. We found evidence for the current taxonomic treatment that P. ludlowii and P. delavayi are two different species with significant genetic differentiation. The significant isolation by environment was revealed within all sampled populations but genetic distances only explained by geographical distances within P. delavayi populations. The results of population divergence models and demographic history analyses indicated a progenitor–derivative relationship and the Late Quaternary divergence without gene flow between them. The coalescence of all sampled cpDNA haplotypes could date to the Late Miocene, and P. delavayi populations probably underwent a severe bottleneck in population size during the last glacial period. Genetic variation in Paeonia subsect. Delavayanae is associated with geographical and environmental distances. These findings point to the importance of geological and climatic changes as causes of the speciation event and lineage diversification within Paeonia subsect. Delavayanae.

scholarly journals Quantitative and molecular genetic variation in sympatric populations of Medicago laciniata and M. truncatula (Fabaceae): relationships with eco-geographical factors

2007 ◽  
Vol 89 (2) ◽  
pp. 107-122 ◽  
Author(s):  
MOUNAWER BADRI ◽  
HOUCINE ILAHI ◽  
THIERRY HUGUET ◽  
MOHAMED ELARBI AOUANI
Keyword(s):  
Genetic Variation ◽  
Genetic Variability ◽  
Local Adaptation ◽  
Quantitative Traits ◽  
Gene Diversity ◽  
Sympatric Populations ◽  
Widespread Species ◽  
Geographical Factors ◽  
Significant Difference ◽  
Selection For

SummaryMedicago laciniata is restricted to south of the Mediterranean basin and it extends in Tunisia from the inferior semi-arid to Saharan stages, whereas M. truncatula is a widespread species in such areas. The genetic variability in four Tunisian sympatric populations of M. laciniata and M. truncatula was analysed using 19 quantitative traits and 20 microsatellites. We investigated the amplification transferability of 52 microsatellites developed in M. truncatula to M. laciniata. Results indicate that about 78·85% of used markers are valuable genetic markers for M. laciniata. M. laciniata displayed significantly lower quantitative differentiation among populations (QST=0·12) than did M. truncatula (QST=0·45). However, high molecular differentiations, with no significant difference, were observed in M. laciniata (FST=0·48) and M. truncatula (FST=0·47). Several quantitative traits exhibited significantly smaller QST than FST for M. laciniata, consistent with constraining selection. For M. truncatula, the majority of traits displayed no statistical difference in the level of QST and FST. Furthermore, these traits are significantly associated with eco-geographical factors, consistent with selection for local adaptation rather than genetic drift. In both species, there was no significant correlation between genetic variation at quantitative traits and molecular markers. The site-of-origin explains about 5·85% and 11·27% of total quantitative genetic variability among populations of M. laciniata and M. truncatula, respectively. Established correlations between quantitative traits and eco-geographical factors were generally more moderate for M. laciniata than for M. truncatula, suggesting that the two species exhibit different genetic bases of local adaptation to varying environmental conditions. Nevertheless, no consistent patterns of associations were found between gene diversity (He) and environmental factors in either species.

Genetic variation within the dasyurid marsupial genus Planigale

2000 ◽  
Vol 48 (5) ◽  
pp. 443 ◽  
Author(s):  
Mark J. Blacket ◽  
Mark Adams ◽  
Carey Krajewski ◽  
Michael Westerman
Keyword(s):  
Genetic Variation ◽  
South Australia ◽  
Taxonomic Diversity ◽  
12S Rrna ◽  
Rrna Gene ◽  
Widespread Species ◽  
Geographic Ranges ◽  
12S Rrna Gene ◽  
The Status ◽  
Taxonomic Changes

Genetic variation within the genus Planigale was examined through analyses of 12S rRNA gene sequences and allozymes. The level of genetic divergence between the five currently recognised Planigale species was compared and the magnitude of divergence among populations assessed. This examination of molecular variation within the genus revealed that Planigale contains far more taxonomic diversity than is currently recognised. Specifically, the Pilbara region of Western Australia probably contains two currently unrecognised Planigale species and there is substantial genetic heterogeneity within the widespread species P. maculata. Ambiguity over the status of several genetic and/or morphological forms within the genus indicates that further taxonomic changes are likely to be warranted in the future. This study also demonstrates that the currently accepted geographic ranges of many planigale species require careful re-evaluation and that many specimens in collections are apparently misidentified. This is especially true of P. ingrami, which appears to have a much greater range than is currently recognised, being present in South Australia.

Genetic variation in populations of the endemic Achillea millefolium ssp. megacephala from the Athabasca sand dunes and the widespread ssp. lanulosa in western North America

1996 ◽  
Vol 74 (7) ◽  
pp. 1138-1146 ◽  
Author(s):  
Brett G. Purdy ◽  
Randall J. Bayer
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Gene Diversity ◽  
Sand Dunes ◽  
Achillea Millefolium ◽  
Starch Gel Electrophoresis ◽  
Widespread Species ◽  
Polymorphic Loci ◽  
Endemic Taxon ◽  
Starch Gel

As part of an analysis of genetic diversity in endemic taxa of the Athabasca sand dunes in northern Saskatchewan, Canada, genetic variation was examined by starch gel electrophoresis in six populations of the endemic Achillea millefolium ssp. megacephala, and 13 populations of the closely related widespread taxon, A. millefolium ssp. lanulosa. Endemic populations had more alleles per locus, a higher percentage of polymorphic loci, and greater genetic diversity than did populations of the widespread taxon. At polymorphic loci, total gene diversity was comparable in both taxa, although within-population gene diversity was higher in the endemic taxon. Population differentiation (GST) was considerably lower in ssp. megacephala than in ssp. lanulosa, although GST values were reduced when the parameter was calculated separately for geographic subdivisions of the widespread taxon. Our results differ from previous studies in which the endemic is typically depauperate of genetic variation relative to related widespread species. We suggest that obligate sexual reproduction and the absence of long-term asexual reproduction may be one of a number of factors that help populations of ssp. megacephala maintain higher levels of genetic variation on the Athabasca sand dunes. Keywords: genetic variation, endemic, rare species, Athabasca sand dunes, Achillea millefolium.

Morphological and genetic variation within the widespread species Acacia victoriae (Mimosaceae)

2007 ◽  
Vol 20 (1) ◽  
pp. 54 ◽  
Author(s):  
Siti R. Ariati ◽  
Daniel J. Murphy ◽  
Stuart Gardner ◽  
Pauline Y. Ladiges
Keyword(s):  
Genetic Variation ◽  
Morphological Variation ◽  
Genetic Divergence ◽  
Arid Regions ◽  
Nuclear Dna ◽  
Northern Australia ◽  
Parsimony Analysis ◽  
Widespread Species ◽  
Central Australia ◽  
Semi Arid

Morphological variation in Acacia victoriae, a species widespread in arid and semi-arid regions of Australia, was analysed by phenetic methods of classification and ordination. Three morphological groups were identified on the basis of phyllode characters and are treated as subspecies. Populations with short, elliptic and tomentose phyllodes are confirmed as A. victoriae subsp. arida Pedley; this form occurs mainly in central Australia. Populations with linear to oblong, non-tomentose phyllodes are referred to subsp. victoriae; this subspecies is the most variable and widely distributed across Australia. Populations with very long, narrow phyllodes, distributed in northern Australia from the Kimberley to Queensland, are described as fasciaria subsp. nov. A small number of non-tomentose specimens with broad elliptic phyllodes from central Australia require further assessment. Thirteen accessions previously sequenced for internal spacer regions and external spacer regions of ribosomal nuclear DNA showed genetic divergence. Six accessions of subsp. fasciaria formed a clade in a parsimony analysis, confirming that the long phyllode form is genetically distinct.

The genetic variation in giant buttercup in New Zealand pastures

2015 ◽  
Vol 68 ◽  
pp. 112-117 ◽  
Author(s):  
G.J. Houliston ◽  
D.F. Goeke ◽  
L.A. Smith ◽  
S.V. Fowler
Keyword(s):  
Genetic Variation ◽  
New Zealand ◽  
Genome Size ◽  
Biological Agents ◽  
Native Range ◽  
Weed Species ◽  
Widespread Species ◽  
Northern Norway ◽  
Control Programmes ◽  
Ranunculus Acris

Giant buttercup (Ranunculus acris L) is a widespread species that ranges in latitude from northern Norway to Morocco in the native range and has a large naturalised range in several countries including New Zealand Like many weed species with wide natural distributions R acris is a complex made up of different genotypes and races across the native range This paper shows R acris in New Zealand has high chloroplast diversity and variation in genome size even within populations indicating that introduced material was diverse Although it is not yet possible to determine the origin of R acris populations in New Zealand preliminary comparisons to R acris sourced from other countries are presented The importance of identifying the correct origin of naturalised species before undertaking control programmes especially where biological agents will be employed is discussed

Genetic characterization of Meloidogyne incognita isolates from Turkey using sequence-related amplified polymorphism (SRAP)

Biologia ◽  
2012 ◽  
Vol 67 (3) ◽  
Author(s):  
Zübeyir Devran ◽  
Ömür Baysal
Keyword(s):  
Genetic Variation ◽  
Meloidogyne Incognita ◽  
Cost Effective ◽  
Nematode Species ◽  
Root Knot Nematode ◽  
Breeding Programs ◽  
Widespread Species ◽  
Resistant Varieties ◽  
Southern Root Knot Nematode

AbstractSouthern root knot nematode Meloidogyne incognita is the most widespread-species, causing serious yield losses in protected vegetables fields in the West Mediterranean region of Turkey. The knowledge of genetic variation within M. incognita is required for disease management and improvement of resistant varieties by breeding programs. In the present study, the isolates were classified into different groups based on sequence-related amplified polymorphism (SRAP) fingerprints. To our knowledge, this is the first study carried out on the characterization of M. incognita isolates using SRAP. The schematic diagram by tested primers to differentiate of M. incognita isolates was formed in discrimination of nematodes as an effective molecular tool since it is cost effective and easiness. Data presents a genetic variation on root-knot nematode species. These selected SRAP markers can be used to follow genetic structure and differentiation on M. incognita isolates in a certain region.

scholarly journals Molecular biogeography and host relations of a parasitoid fly

2019 ◽  
Author(s):  
David A. Gray ◽  
Henry D. Kunerth ◽  
Marlene Zuk ◽  
William H. Cade ◽  
Susan L. Balenger
Keyword(s):  
Genetic Variation ◽  
Range Expansion ◽  
Host Species ◽  
Host Finding ◽  
Molecular Techniques ◽  
Host Specialization ◽  
Population Divergence ◽  
New Host ◽  
Widespread Species ◽  
Gravid Females

AbstractSuccessful geographic range expansion by parasites and parasitoids may also require host range expansion. Thus the evolutionary advantages of host specialization may trade off against the ability to exploit new host species encountered in new geographic regions. Here we use molecular techniques and confirmed host records to examine biogeography, population divergence, and host flexibility of the parasitoid fly, Ormia ochracea (Bigot). Gravid females of this fly find their cricket hosts acoustically by eavesdropping on male cricket calling songs; these songs vary greatly among the known host species of crickets. Using both nuclear and mitochondrial genetic markers, we (1) describe the geographical distribution and sub-division of genetic variation in O. ochracea from across the continental United States, the Mexican states of Sonora and Oaxaca, and populations introduced to Hawaii; (2) demonstrate that the distribution of genetic variation among fly populations is consistent with a single widespread species with regional host specialization, rather than locally differentiated cryptic species, (3) identify the more-probable source populations for the flies introduced to the Hawaiian islands; (4) examine genetic variation and sub-structure within Hawaii; and (5) discuss specialization and lability in host-finding behavior in light of the diversity of cricket songs serving as host cues in different geographically separate populations.

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