scholarly journals Genetic differentiation and estimated levels of gene flow in members of the Gammarus pulex-group (Crustacea, Amphipoda) in western Europe

1990 ◽  
Vol 60 (1) ◽  
pp. 3-29 ◽  
Author(s):  
Maarten Scheepmaker
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Sibling Species ◽  
Gene Frequency ◽  
Western Europe ◽  
Distinct Species ◽  
Genetic Distances ◽  
The Other ◽  
Frequency Data ◽  
Population Sizes

Genetic differentiation of morphologically variable members of the G. pulex-group in northwestern Europe was investigated by electrophoresisat 20 enzyme loci. Five recently described related forms were examined with reference to the “classical” species G. pulex, G. wautieri and G. fossarum. G. pulex and G. wautieri were shown to be genetically homogeneous and clearly distinct species. In the other species, morphologicallysimilar forms were shown to be genetically distant, and inter-areal intraspecific genetic differentiation may warrant recognition of subspecies or sibling species. In some cases, levels of reproductive isolation of the forms involved could be assessed by cross-breeding experiments. To estimate dispersal capabilities, gene flow levels were indirectly estimated from gene frequency data. Gene flow levels are generally low and fluctuating population sizes may enhance the occurrence of stochastic processes. Dendrograms derived from genetic distances were compared with zoogeographical and paleoclimatological evidence. The distribution areas of the species involved correspond to patterns predicted by these data.

scholarly journals Microsatellite Characterization of Malaysian Mahseer (Tor spp.) for Improvement of Broodstock Management and Utilization

Animals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2633
Author(s):  
Poh Chiang Chew ◽  
Annie Christianus ◽  
Jaapar M. Zudaidy ◽  
Md Yasin Ina-Salwany ◽  
Chou Min Chong ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Genetic Relatedness ◽  
Genetic Distances ◽  
Group Method ◽  
Genetic Management ◽  
Principal Coordinates Analysis ◽  
Principal Coordinates ◽  
Geographical Regions

In this study, a mixture of Tor tambra and T. tambroides with unknown genetic background were collected from 11 localities in Malaysia for broodstock development and sperm cryo-banking. This study aims to assess the microsatellite (simple sequence repeat, SSR) variation, genetic diversity, genetic differentiation, level of gene flow, population structure, genetic relatedness and their demographic aspects among these Tor populations, in addition to establishing their SSR profile by employing 22 SSR markers via fragment analysis. Total genomic DNA was extracted from 181 samples (91 cryopreserved milt samples and 90 scale samples of live broodfish). Results showed the Tor spp. collection retained their genetic variation but exhibited excessive homozygosity among individuals within population. Moderate genetic differentiation was shown among the populations, with highly significant (p < 0.001) fixation indices (FST, FIS and FIT). A low gene flow over all loci (Nm 1.548) indicates little genetic variation transfer between populations. The genetic structures of all the populations were successfully resolved into four main clusters by an unweighted pair group method with arithmetic mean (UPGMA) dendrogram generated based on Nei’s genetic distances. The population structures based on principal coordinates analysis (PCoA) and the Bayesian model also suggested four distinct clusters following geographical regions and eight closely related populations. This study provided a useful baseline reference for better genetic management and utilization of the Tor spp. stocks in their breeding and conservation programmes.

scholarly journals Genetic differentiation of common reed (Phragmites australis) populations from selected lakes of Pomerania (NW Poland), revealed by electrophoretically detected peroxidase variability

2010 ◽  
Vol 17 (1) ◽  
pp. 19-22 ◽  
Author(s):  
Maria Krzakowa ◽  
Marcin Michalak
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Phragmites Australis ◽  
Common Reed ◽  
Genetic Distances ◽  
Edaphic Conditions ◽  
The Town ◽  
North Western ◽  
Nw Poland

Genetic differentiation of common reed (Phragmites australis) populations from selected lakes of Pomerania (NW Poland), revealed by electrophoretically detected peroxidase variabilityThree populations of common reed (Phragmites australis(Cav) Trin. ex Steud.), growing under differing edaphic conditions in lakes near the town of Koszalin (the Pomerania region in north-western Poland), were studied in respect to frequencies of electrophoretically detected allozymes in two peroxidase loci: a monomeric locus with three alleles and a dimeric locus with two alleles. On the basis of genetic distances, similarity between these populations and levels of variation were assessed both within populations (GST = 0.0376) and between populations (DST = 0.0194). Gene flow between populations was low (Nm= 6.399).

Genetic Differentiation among Populations of the Northern Redbelly Dace (Phoxinus eos) in Ontario

1994 ◽  
Vol 51 (6) ◽  
pp. 1218-1228 ◽  
Author(s):  
C. Anna Toline ◽  
Allan J. Baker
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Fish Species ◽  
Protein Electrophoresis ◽  
The Other ◽  
Population Divergence ◽  
Average Heterozygosity ◽  
Weinberg Equilibrium ◽  
Hardy Weinberg Equilibrium ◽  
Population Substructuring

Eighteen populations of northern redbelly dace (Phoxinus eos) from three regions in Ontario were examined genetically using protein electrophoresis. Differentiation among regions was greater (FST = 0.100) than within them (FST = 0.045–0.064), suggesting that levels of gene flow are high enough to prevent differentiation through drift only within regions. Levels of heterozygosity, percent polymorphic loci, and number of alleles per locus are high relative to other fish species, which suggests that populations of dace in this study have not been subject to severe bottlenecks. Thus, population divergence has apparently occurred gradually over the last 10 000 yr. Average heterozygosity was not correlated with pond area. Thus, populations in Algonquin Park are not more prone to the effects of drift than those in the other two regions. Populations from the Sudbury region were genetically differentiated from those in Algonquin Park and from near Kingston, a result consistent with the historical biogeography of Ontario. Despite relatively high levels of heterozygosity, observed levels in this study deviated significantly from those expected from Hardy–Weinberg equilibrium. The breeding biology of P. eos and other fish suggests that our results may be explained by the presence of population substructuring in the localities sampled.

scholarly journals GENETIC CHANGE AND RATES OF CLADOGENESIS

Genetics ◽  
1975 ◽  
Vol 81 (4) ◽  
pp. 757-773
Author(s):  
John C Avise ◽  
Francisco J Ayala
Keyword(s):  
Genetic Differentiation ◽  
Genetic Distance ◽  
Genetic Divergence ◽  
Natural Populations ◽  
Genetic Distances ◽  
Genetic Change ◽  
The Other ◽  
Limited Information ◽  
History Of ◽  
The Relationship

ABSTRACT Models are introduced which predict ratios of mean levels of genetic divergence in species-rich versus species-poor phylads under two competing assumptions: (1) genetic differentiation is a function of time, unrelated to the number of cladogenetic events and (2) genetic differentiation is proportional to the number of speciation events in the group. The models are simple, general, and biologically real, but not precise. They lead to qualitatively distinct predictions about levels of genetic divergence depending upon the relationship between rates of speciation and amount of genetic change. When genetic distance between species is a function of time, mean genetic distances in speciose and depauperate phylads of equal evolutionary age are very similar. On the contrary, when genetic distance is a function of the number of speciations in the history of a phylad, the ratio of mean genetic distances separating species in speciose versus depauperate phylads is greater than one, and increases rapidly as the frequency of speciations in one group relative to the other increases. The models may be tested with data from natural populations to assess (1) possible correlations between rates of anagenesis and cladogenesis and (2) the amount of genetic differentiation accompanying the speciation process. The data collected in electrophoretic surveys and other kinds of studies can be used to test the predictions of the models. For this purpose genetic distances need to be measured in speciose and depauperate phylads of equal evolutionary age. The limited information presently available agrees better with the model predicting that genetic change is primarily a function of time, and is not correlated with rates of speciation. Further testing of the models is, however, required before firm conclusions can be drawn.

Molecular and morphological evidence for and against gene flow in sympatric apomicts of the North American Crepis agamic complex (Asteraceae)This paper is one of a selection of papers published in the Special Issue on Systematics Research.

Botany ◽  
2008 ◽  
Vol 86 (8) ◽  
pp. 877-885 ◽  
Author(s):  
Jeannette Whitton ◽  
Katrina M. Dlugosch ◽  
Christopher J. Sears
Keyword(s):  
Gene Flow ◽  
North American ◽  
Distinct Species ◽  
The Other ◽  
Morphological Data ◽  
Morphological Evidence ◽  
Hybrid Zones ◽  
Sympatric Populations ◽  
Contact Zones ◽  
The North

The study of sympatric populations of closely related plant species often reveals evidence of hybridization. Mechanisms that reduce outcrossing (e.g., selfing, apomixis) may allow co-occurrence without gene flow. In this study, we describe patterns of genetic variation in two contact zones, each comprising three closely related morphological types, that key to three distinct species in the North American Crepis agamic (apomictic) complex. We used RAPD markers to characterize individuals from two sites: one in northern California (Sardine Lookout) and another in northwestern Oregon (Summit Road). At Sardine Lookout, we discerned a total of four multilocus genotypes, two in one species, and one each in the other two species. Our findings suggest that distinct morphological types are maintained by absolute barriers to gene flow at this site. At Summit Road, we found greater genotypic diversity, with a total of 24 genotypes across 30 individuals. One of the morphological types was clearly genetically differentiated from the other two, with no variable markers shared with other species at this site. The two remaining species showed evidence of gene flow, with no unique markers discerning them. Morphological data tend to support this conclusion, with univariate and multivariate analyses indicating a pattern of variation spanning the two species. Taken together, these patterns suggest that contact zones need not represent hybrid zones, and that apomixis can serve as an effective barrier to gene flow that may allow for stable coexistence of close relatives.

scholarly journals Genetic differentiation and diversity of Callosobruchus chinensis collections from China

2015 ◽  
Vol 106 (1) ◽  
pp. 124-134 ◽  
Author(s):  
C.X. Duan ◽  
W.C. Li ◽  
Z.D. Zhu ◽  
D.D. Li ◽  
S.L. Sun ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Genetic Distances ◽  
Fixation Index ◽  
Group Method ◽  
Callosobruchus Chinensis ◽  
Chain Reactions ◽  
Information Index ◽  
Geographic Populations

AbstractCallosobruchus chinensis (Linnaeus) is one of the most destructive pests of leguminous seeds. Genetic differentiation and diversity analysis of 345 C. chinensis individuals from 23 geographic populations using 20 polymorphic simple sequence repeats revealed a total of 149 alleles with an average of 7.45 alleles per locus. The average Shannon's information index was 1.015. The gene flow and genetic differentiation rate values at the 20 loci ranged from 0.201 to 1.841 and 11.0–47.2%, with averages of 0.849 and 24.4%, respectively. In the 23 geographic populations, the effective number of alleles and observed heterozygosity ranged from 1.441 to 2.218 and 0.191–0.410, respectively. Shannon's information index ranged from 0.357 to 0.949, with the highest value in Hohhot and the lowest in Rudong. In all comparisons, the fixation index (FST) values ranged from 0.049 to 0.441 with a total FST value of 0.254 among the 23 C. chinensis populations, indicating a moderate level of genetic differentiation and gene flow among these populations. Analysis of molecular variance revealed that the genetic variation within populations accounted for 76.7% of the total genetic variation. The genetic similarity values between populations varied from 0.617 to 0.969, whereas genetic distances varied from 0.032 to 0.483. Using unweighted pair-group method using arithmetical averages cluster analysis, the 23 geographic collections were classified into four distinct genetic groups but most of them were clustered into a single group. The pattern of the three concentrated groups from polymerase chain reactions analysis showed a somewhat different result with cluster.

scholarly journals Human-driven genetic differentiation in a managed red deer population

2021 ◽  
Vol 67 (2) ◽  
Author(s):  
Gerald Reiner ◽  
C. Klein ◽  
M. Lang ◽  
H. Willems
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Red Deer ◽  
Young Male ◽  
Genetic Exchange ◽  
Genetic Connectivity ◽  
Effective Population ◽  
Evolutionary Potential ◽  
Population Sizes ◽  
Populated Region

AbstractNineteen red deer areas in a densely populated region with a huge network of fenced motorways and the division into administrative management units (AMUs) with restricted ecological connectivity were investigated. In the season 2018/2019, a total of 1291 red deer samples (on average 68 per area) were collected and genotyped using 16 microsatellite markers. The results show a clear genetic differentiation between most of the AMUs. Fourteen AMUs may be combined into four regions with a considerable internal genetic exchange. Five areas were largely isolated or showed only a limited gene flow with neighbouring areas. Ten of the 19 AMUs had an effective population size below 100. Effective population sizes greater than 500–1000, required to maintain the evolutionary potential and a long-term adaptation potential, were not achieved by any of the studied AMUs, even when AMUs with an appreciable genetic exchange were aggregated. Substantial genetic differentiation between areas can be associated with the presence of landscape barriers hindering gene flow, but also with the maintenance of ‘red deer–free’ areas. Efforts to sustainably preserve the genetic diversity of the entire region should therefore focus on measures ensuring genetic connectivity. Opportunities for this goal arise from the establishment of game bridges over motorways and from the protection of young male stags migrating through the statutory ‘red deer–free’ areas.

Emended description and resurrection of Sciaphila tosaensis and S. megastyla (Triuridaceae)

Phytotaxa ◽  
2019 ◽  
Vol 413 (3) ◽  
pp. 231-243 ◽  
Author(s):  
KENJI SUETSUGU ◽  
AKIHIKO KINOSHITA ◽  
TIAN-CHUAN HSU
Keyword(s):  
Genetic Divergence ◽  
Taxonomic Status ◽  
Distinct Species ◽  
Molecular Data ◽  
Genetic Distances ◽  
The Other ◽  
Morphological Data ◽  
Flowering Stage ◽  
Emended Description ◽  
Morphological Differences

This paper presents a re-evaluation of the taxonomic status of Sciaphila tosaensis and S. megastyla (Triuridaceae) distributed in Japan and Taiwan. Based on the detailed morphological data, we concluded that these two species should both be treated as distinct species rather than synonyms of S. secundiflora. Sciaphila tosaensis differs from S. secundiflora and S. megastyla in having very narrow male perianth segments and female perianth segments distinctly shorter than male perianth segments. Sciaphila megastyla differs from the other two species in having very conspicuous style and stigma that is ca. 1.5 times as long as ovary in the flowering stage. Furthermore, a lectotype is designated of S. megastyla because its holotype has been lost. Molecular data also showed that there is considerable genetic divergence between S. tosaensis and S. megastyla, supporting that the morphological differences are mirrored by their genetic distances.

Allozyme variation and genetic divergence in the sand goby, Pomatoschistus minutus (Teleostei: Gobiidae)

2003 ◽  
Vol 83 (5) ◽  
pp. 1143-1149 ◽  
Author(s):  
S. Stefanni ◽  
E.S. Gysels ◽  
F.A.M. Volckaert ◽  
P.J. Miller
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Adriatic Sea ◽  
Allozyme Variation ◽  
Western Mediterranean ◽  
The Other ◽  
Sand Goby ◽  
Sea Levels ◽  
Pomatoschistus Minutus ◽  
The North

Samples of the widely distributed sand goby Pomatoschistus minutus have been investigated genetically from ten localities in the north-eastern Atlantic, North Sea, western Mediterranean and Adriatic Sea. Levels of genetic diversity and differentiation were assessed with starch (SGE) and cellulose acetate (CAGE) gel electrophoresis for 13 enzyme systems. Genetic differentiation between spatial samples points to a reduction or even absence of gene flow between the Adriatic and the other samples, including the western Mediterranean Sea (pair-wise FST=0.37 and 0.32 for SGE and CAGE respectively). The sample from the Adriatic Sea was clearly differentiated from the other samples at the lactate dehydrogenase loci LDH-A* (SGE and CAGE) and LDH-C* (CAGE). Values for genetic differentiation between Venetian and other sand gobies were of the same order of magnitude as between P. minutus and its closest relative P. lozanoi, suggesting allopatric speciation in the lagoon of Venice. At locations outside the Adriatic Sea, the sand goby has the typical features of a marine fish with a high level of gene flow and a low degree of genetic differentiation.

scholarly journals Genetic variability and evolutionary dynamics of atypical Papaya ringspot virus infecting Papaya

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258298
Author(s):  
Anam Saleem ◽  
Zahid Ali ◽  
Shyi-Dong Yeh ◽  
Wajeeha Saeed ◽  
Amna Binat Imdad ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Evolutionary Dynamics ◽  
Genetic Distances ◽  
Full Length ◽  
Ringspot Virus ◽  
Genomic Sequences ◽  
Papaya Ringspot Virus ◽  
Cp Gene ◽  
Geographical Position

Papaya ringspot virus biotype-P is a detrimental pathogen of economically important papaya and cucurbits worldwide. The mutation prone feature of this virus perhaps accounts for its geographical dissemination. In this study, investigations of the atypical PRSV-P strain was conducted based on phylogenetic, recombination and genetic differentiation analyses considering of it’s likely spread across India and Bangladesh. Full length genomic sequences of 38 PRSV isolates and 35 CP gene sequences were subjected to recombination analysis. A total of 61 recombination events were detected in aligned complete PRSV genome sequences. 3 events were detected in complete genome of PRSV strain PK whereas one was in its CP gene sequence. The PRSV-PK appeared to be recombinant of a major parent from Bangladesh. However, the genetic differentiation based on full length genomic sequences revealed less frequent gene flow between virus PRSV-PK and the population from America, India, Colombia, other Asian Countries and Australia. Whereas, frequent gene flow exists between Pakistan and Bangladesh virus populations. These results provided evidence correlating geographical position and genetic distances. We speculate that the genetic variations and evolutionary dynamics of this virus may challenge the resistance developed in papaya against PRSV and give rise to virus lineage because of its atypical emergence where geographic spread is already occurring.

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