scholarly journals Microsatellites and petal morphology reveal new patterns of admixture in Orchis hybrid zones

2021 ◽  
Vol 108 (8) ◽  
pp. 1388-1404
Author(s):  
Leif Bersweden ◽  
Juan Viruel ◽  
Bertrand Schatz ◽  
Joanna Harland ◽  
Roberta Gargiulo ◽  
...  
Keyword(s):  
Hybrid Zones

scholarly journals Landscape resistance constrains hybridization across contact zones in a reproductively and morphologically polymorphic salamander

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillermo Velo-Antón ◽  
André Lourenço ◽  
Pedro Galán ◽  
Alfredo Nicieza ◽  
Pedro Tarroso
Keyword(s):  
Contact Zone ◽  
Environmental Heterogeneity ◽  
Evolutionary Dynamics ◽  
Morphological Differentiation ◽  
Phenotypic Traits ◽  
Hybrid Zones ◽  
Landscape Resistance ◽  
Phenotypic Differentiation ◽  
Contact Zones

AbstractExplicitly accounting for phenotypic differentiation together with environmental heterogeneity is crucial to understand the evolutionary dynamics in hybrid zones. Species showing intra-specific variation in phenotypic traits that meet across environmentally heterogeneous regions constitute excellent natural settings to study the role of phenotypic differentiation and environmental factors in shaping the spatial extent and patterns of admixture in hybrid zones. We studied three environmentally distinct contact zones where morphologically and reproductively divergent subspecies of Salamandra salamandra co-occur: the pueriparous S. s. bernardezi that is mostly parapatric to its three larviparous subspecies neighbours. We used a landscape genetics framework to: (i) characterise the spatial location and extent of each contact zone; (ii) assess patterns of introgression and hybridization between subspecies pairs; and (iii) examine the role of environmental heterogeneity in the evolutionary dynamics of hybrid zones. We found high levels of introgression between parity modes, and between distinct phenotypes, thus demonstrating the evolution to pueriparity alone or morphological differentiation do not lead to reproductive isolation between these highly divergent S. salamandra morphotypes. However, we detected substantial variation in patterns of hybridization across contact zones, being lower in the contact zone located on a topographically complex area. We highlight the importance of accounting for spatial environmental heterogeneity when studying evolutionary dynamics of hybrid zones.

Hybrid Zones and the Genetic Architecture of a Barrier to Gene Flow Between Two Sunflower Species

Genetics ◽  
1999 ◽  
Vol 152 (2) ◽  
pp. 713-727 ◽  
Author(s):  
Loren H Rieseberg ◽  
Jeannette Whitton ◽  
Keith Gardner
Keyword(s):  
Genetic Study ◽  
Genetic Architecture ◽  
Chromosomal Rearrangements ◽  
Pollen Sterility ◽  
Model Organisms ◽  
Hybrid Zones ◽  
Reproductive Barriers ◽  
Natural Hybrid ◽  
Generation Times ◽  
Helianthus Petiolaris

Abstract Genetic analyses of reproductive barriers represent one of the few methods by which theories of speciation can be tested. However, genetic study is often restricted to model organisms that have short generation times and are easily propagated in the laboratory. Replicate hybrid zones with a diversity of recombinant genotypes of varying age offer increased resolution for genetic mapping experiments and expand the pool of organisms amenable to genetic study. Using 88 markers distributed across 17 chromosomes, we analyze the introgression of chromosomal segments of Helianthus petiolaris into H. annuus in three natural hybrid zones. Introgression was significantly reduced relative to neutral expectations for 26 chromosomal segments, suggesting that each segment contains one or more factors that contribute to isolation. Pollen sterility is significantly associated with 16 of these 26 segments, providing a straightforward explanation of why this subset of blocks is disadvantageous in hybrids. In addition, comparison of rates of introgression across colinear vs. rearranged chromosomes indicates that close to 50% of the barrier to introgression is due to chromosomal rearrangements. These results demonstrate the utility of hybrid zones for identifying factors contributing to isolation and verify the prediction of increased resolution relative to controlled crosses.

Geographic variation in the structure of oak hybrid zones provides insights into the dynamics of speciation

2011 ◽  
Vol 20 (23) ◽  
pp. 4995-5011 ◽  
Author(s):  
YAN-FEI ZENG ◽  
WAN-JIN LIAO ◽  
RÉMY J. PETIT ◽  
DA-YONG ZHANG
Keyword(s):  
Geographic Variation ◽  
Hybrid Zones

Chloroplast DNA polymorphism reveals geographic structure and introgression in the Quercus crassifolia × Quercus crassipes hybrid complex in Mexico

Botany ◽  
2008 ◽  
Vol 86 (3) ◽  
pp. 228-239 ◽  
Author(s):  
E. Tovar-Sánchez ◽  
P. Mussali-Galante ◽  
R. Esteban-Jiménez ◽  
D. Piñero ◽  
D. M. Arias ◽  
...  
Keyword(s):  
Parental Species ◽  
Diversity Index ◽  
Hot Spot ◽  
Haplotype Diversity ◽  
Hybrid Zones ◽  
Chloroplast Microsatellite ◽  
Colonization Routes ◽  
Allopatric Populations ◽  
Genetic Structure Of Populations ◽  
Hybrid Complex

Quercus crassifolia H. & B. and Quercus crassipes H. & B. are two common temperate forest species in Mexico that form hybrids when they occur in mixed (sympatric) areas. In this study, we used chloroplast microsatellite haplotypes to infer phylogeographic patterns onto the genetic structure of populations of both parental species, thus defining probable colonization routes throughout Mexico. Haplotype diversity in seven hybrid zones and four allopatric sites with nonmixed (allopatric) populations of both putative parental species was analyzed. To determine the expansion and colonization routes for the two species, we carried out a nested clade phylogeographic analysis that would allow us to infer the haplotype correspondence to a phylogeographical approach. In spite of sharing many common populations, we determined that there is a different genetic historical colonization for Q. crassipes and for Q. crassifolia. Hybrid populations had the highest levels of genetic variation (Gv), Shannon diversity index (H), and haplotype number (nh) in comparison with nonmixed/allopatric populations of their putative parentals. Furthermore, populations of hybrid zones showed the highest values of genetic differentiation FST, RST . Moreover, both species share four distinctive cpDNA haplotypes, which were most likely acquired by introgression through hybrids located in several populations throughout the Eje Neovolcánico area. This last region was confirmed to be a “hot spot” for oak diversity, a place in which different maternal lineages merged.

The interaction of Schistosoma haematobium and S. guineensis in Cameroon

2005 ◽  
Vol 79 (3) ◽  
pp. 193-197 ◽  
Author(s):  
B.L. Webster ◽  
L.A. Tchuem Tchuenté ◽  
J. Jourdane ◽  
V.R. Southgate
Keyword(s):  
Internal Transcribed Spacer ◽  
Schistosoma Haematobium ◽  
Introgressive Hybridization ◽  
Biological Data ◽  
Hybrid Zones ◽  
Hybridization Data ◽  
South West ◽  
Single Stranded Conformational Polymorphism ◽  
Second Internal Transcribed Spacer ◽  
Species Being

AbstractInteractions between schistosomes are complex with some different species being able to mate and hybridize. The epidemiology of schistosomiasis in specific areas of South West Cameroon has evolved remarkably over 30 years as a result of hybridization between Schistosoma guineensis and S. haematobium. Morphological and biological data suggest that S. haematobium replaced S. guineensis in areas of Cameroon through introgressive hybridization. Data are reported on the use of single stranded conformational polymorphism (SSCP) analysis of the nuclear ribosomal second internal transcribed spacer (ITS2) of individual schistosomes from hybrid zones of Cameroon. The data show that since 1990 S. haematobium has completely replaced S. guineensis in Loum, with S. haematobium and the recombinants still present in 2000. This study illustrates the complexities of the dynamics between S. haematobium and S. guineensis in South West Cameroon.

scholarly journals Restricted X chromosome introgression and support for Haldane's rule in hybridizing damselflies

2021 ◽  
Author(s):  
Janne Swaegers ◽  
Rosa Ana Sanchez-Guillen ◽  
Pallavi Chauhan ◽  
Maren Wellenreuther ◽  
Bengt Hansson
Keyword(s):  
X Chromosome ◽  
Sex Chromosomes ◽  
Hybrid Zones ◽  
Haldane’S Rule ◽  
Haldane's Rule ◽  
Genome Wide ◽  
Determination System ◽  
Heterogametic Sex ◽  
Sex Determination System ◽  
Genomic Introgression

Contemporary hybrid zones act as natural laboratories for the investigation of species boundaries and allow to shed light on the little understood roles of sex chromosomes in species divergence. Sex chromosomes are considered to function as a hotspot of genetic divergence between species; indicated by less genomic introgression compared to autosomes during hybridisation. Moreover, they are thought to contribute to Haldane's rule which states that hybrids of the heterogametic sex are more likely to be inviable or sterile. To test these hypotheses, we used contemporary hybrid zones of Ischnura elegans, a damselfly species that has been expanding its range into the northern and western regions of Spain, leading to chronic hybridization with its sister species Ischnura graellsii. We analysed genome-wide SNPs in the Spanish I. elegans and I. graellsii hybrid zone and found (i) that the X chromosome shows less genomic introgression compared to autosomes and (ii) that males are underrepresented among admixed individuals as predicted by Haldane's rule. This is the first study in Odonata that suggests a role of the X chromosome in reproductive isolation. Moreover, our data adds to the few studies on species with X0 sex determination system and contradicts the hypothesis that the absence of a Y chromosome causes exceptions to Haldane's rule.

scholarly journals 42 Genetic differentiation of Russian goats and wild relatives based on microsatellite loci

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 19-20
Author(s):  
Marina I Selionova ◽  
Magomet M Aibazov ◽  
Tatyana V Mamontova ◽  
Sergey N Petrov ◽  
Veronica R Kharzinova ◽  
...  
Keyword(s):  
Genetic Distances ◽  
Wild Relatives ◽  
Hybrid Zones ◽  
Sample Collection ◽  
North Caucasus ◽  
Genetic Characteristics ◽  
The Third ◽  
The North ◽  
Central Caucasus ◽  
Capra Aegagrus

Abstract Goat breeding is a traditional livestock industry for many regions of Russia. Due to unpretentiousness and high adaptive qualities, the Karachai, Dagestan wool and Dagestan down breeds are widespread in the North Caucasus. Moreover, their uniqueness is determined by sharing a common habitat with their wild relatives, West Caucasian and Dagestani turs, thus forming hybrid zones. The aim of the research was to study allele pool and interbreed differentiation of domestic goat breeds and wild relatives by microsatellites. Research was performed based on 16 loci on the ABI 3130xl analyzer. Population genetic characteristics were calculated in GenAlEx 6.5, and the phylogenetic tree was constructed in Populations 1.2.30 and SplitsTree 4.14.5. The sample collection included goat breeds (n = 226): Karachai (KRCH), Dagestan down (DAGD), Dagestan wool (DAGW) (North Caucasus), Soviet wool (SOVW) (Siberia), Orenburg (OREN) (South Ural), and wild goats (n = 72). Wild goats comprised mountain goats: Siberian goats (Capra sibirica) from the Altai, Tajikistan, Kyrgyzstan and the Himalayas; bezoar goats (Capra aegagrus) from Turkey and Pakistan; and tur (Capra caucasica) from the West Caucasus (Kuban), Central Caucasus, and East Caucasus (Dagestan). The Karachai breed was characterized by the highest level of genetic diversity: the average number of alleles per locus (NA) and allelic richness (AR) were 9,154 and 7,713, respectively, while these indices varied from 6,538 to 7,538 and from 6,425 to 7,538 (Table 1) in other breeds, respectively. The values of genetic distances showed differentiation of Karachai, Dagestan down and Dagestan wool breeds from Orenburg and Soviet wool breeds (Table 2). The formation of three clusters was established. The first one included subspecies of the Caucasian tur, the second one comprised Siberian goats, and the third contained domestic goats. Bezoar goats were in the root of the third cluster that confirmed their participation as an ancestral form of domestic goats.

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