scholarly journals The Limits to Parapatric Speciation II: Strengthening a Preexisting Genetic Barrier to Gene Flow in Parapatry

2018 ◽  
Author(s):  
Alexandre Blanckaert ◽  
Joachim Hermisson
Keyword(s):  
New Species ◽  
Gene Flow ◽  
Genetic Barrier ◽  
New Mutation ◽  
Genetic Incompatibility ◽  
Complex Process ◽  
Parapatric Speciation ◽  
The Impact ◽  
New Mutations

AbstractParapatric speciation has recently received a lot of attention. By encompassing the whole continuum between allopatric and sympatric scenarios, it includes many potential scenarios for the evolution of new species. Building upon previous work, we investigate how a genetic barrier to gene flow, that relies on a single postzygotic genetic incompatibility, may further evolve. We consider a continent island model with three loci involved in pairwise Dobzhansky-Muller incompatibilities (DMIs). Using a deterministic and analytic approach, we derive the conditions for invasion of a new mutation and its consequences on an already existing genetic barrier to gene flow. We focus on quantifying the impact of the epistasis generated by the new mutation on the genetic barrier. We show that the accumulation of genetic incompatibilities in the presence of gene flow is a complex process, where new mutations can either strengthen or destroy a preexisting barrier. In particular, preexisting polymorphism and incompatibilities do not always facilitate the growth of the genetic barrier by accumulation of further barrier genes. Migration may disrupt the snowball effect (the accelerating rate of DMI accumulation in allopatry) because incompatibilities are directly tested by selection. Our results also show an ambiguous role of gene flow, which can either impede or facilitate the strengthening of the genetic barrier. Overall, our results illustrate how the inclusion of gene flow renders the building of a genetic barrier difficult to analyze.

scholarly journals The limits to parapatric speciation 3: evolution of strong reproductive isolation in presence of gene flow despite limited ecological differentiation

2020 ◽  
Vol 375 (1806) ◽  
pp. 20190532 ◽  
Author(s):  
Alexandre Blanckaert ◽  
Claudia Bank ◽  
Joachim Hermisson
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Local Adaptation ◽  
Theme Issue ◽  
Genetic Barrier ◽  
Incipient Species ◽  
Postzygotic Reproductive Isolation ◽  
Minimal Configuration ◽  
Parapatric Speciation ◽  
Two Populations

Gene flow tends to impede the accumulation of genetic divergence. Here, we determine the limits for the evolution of postzygotic reproductive isolation in a model of two populations that are connected by gene flow. We consider two selective mechanisms for the creation and maintenance of a genetic barrier: local adaptation leads to divergence among incipient species due to selection against migrants, and Dobzhansky–Muller incompatibilities (DMIs) reinforce the genetic barrier through selection against hybrids. In particular, we are interested in the maximum strength of the barrier under a limited amount of local adaptation, a challenge that many incipient species may initially face. We first confirm that with classical two-locus DMIs, the maximum amount of local adaptation is indeed a limit to the strength of a genetic barrier. However, with three or more loci and cryptic epistasis, this limit holds no longer. In particular, we identify a minimal configuration of three epistatically interacting mutations that is sufficient to confer strong reproductive isolation. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers’.

scholarly journals The Impact of Melatonin and NLRP3 Inflammasome on the Expression of microRNAs in Aged Muscle

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 524
Author(s):  
Ramy KA Sayed ◽  
Marisol Fernández-Ortiz ◽  
José Fernández-Martínez ◽  
Paula Aranda Martínez ◽  
Ana Guerra-Librero ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Nlrp3 Inflammasome ◽  
Gastrocnemius Muscle ◽  
Pcr Analysis ◽  
Physiological Mechanisms ◽  
Complex Process ◽  
Regulatory Machinery ◽  
The Impact ◽  
First Time

Muscular aging is a complex process and underlying physiological mechanisms are not fully clear. In recent years, the participation of the NF-kB pathway and the NLRP3 inflammasome in the chronic inflammation process that accompanies the skeletal muscle’s aging has been confirmed. microRNAs (miRs) form part of a gene regulatory machinery, and they control numerous biological processes including inflammatory pathways. In this work, we studied the expression of four miRs; three of them are considered as inflammatory-related miRs (miR-21, miR-146a, and miR-223), and miR-483, which is related to the regulation of melatonin synthesis, among other targets. To investigate the changes of miRs expression in muscle along aging, the impact of inflammation, and the role of melatonin in aged skeletal muscle, we used the gastrocnemius muscle of wild type (WT) and NLRP3-knockout (NLRP3−) mice of 3, 12, and 24 months-old, with and without melatonin supplementation. The expression of miRs and pro-caspase-1, caspase-3, pro-IL-1β, bax, bcl-2, and p53, was investigated by qRT-PCR analysis. Histological examination of the gastrocnemius muscle was also done. The results showed that age increased the expression of miR-21 (p < 0.01), miR-146a, and miR-223 (p < 0.05, for both miRs) in WT mice, whereas the 24-months-old mutant mice revealed decline of miR-21 and miR-223 (p < 0.05), compared to WT age. The lack of NLRP3 inflammasome also improved the skeletal muscle fibers arrangement and reduced the collagen deposits compared with WT muscle during aging. For the first time, we showed that melatonin significantly reduced the expression of miR-21, miR-146a, and miR-223 (p < 0.05 for all ones, and p < 0.01 for miR-21 at 24 months old) in aged WT mice, increased miR-223 in NLRP3− mice (p < 0.05), and induced miR-483 expression in both mice strains, this increase being significant at 24 months of age.

scholarly journals An additional area of apple domestication with crop-wild gene flow, and also cultivation of the local wild apple, in the Caucasus

2021 ◽  
Author(s):  
Hamid Bina ◽  
Hamed Yousefzadeh ◽  
Anthony Venon ◽  
Carine Remoue ◽  
Agnes Rousselet ◽  
...  
Keyword(s):  
Gene Flow ◽  
Fruit Tree ◽  
Plant Domestication ◽  
Gene Pools ◽  
The Caucasus ◽  
Wild Fruit ◽  
Apple Cultivars ◽  
Cultivated Populations ◽  
The Impact

Anthropogenic and natural divergence processes in crop-wild fruit tree complexes are less studied than in annual crops, especially in the Caucasus, a pivotal region for plant domestication. We investigated anthropogenic and natural divergence processes in apples in the Caucasus from using 26 microsatellite markers amplified on 508 wild and cultivated samples. We found two specific Iranian cultivated populations that were differentiated from Malus domestica, the standard cultivated apple worldwide, suggesting a specific local domestication process in Iran. Some Iranian apple cultivars belonged to the Caucasian wild apple gene pools, indicating that farmers also use local wild apple for cultivation. Substantial wild-crop and crop-crop gene flow were also inferred. We identified seven genetically differentiated populations of wild apples (Malus orientalis) in the Caucasus. Niche modeling indicated that these populations likely resulted from range changes linked to the last glaciation. This study pinpoints Iran as a key region in the evolution and domestication of apple and further demonstrates the role of gene flow during fruit tree domestication as well as the impact of climate change on the natural divergence of a wild fruit tree. The results also provide a practical base for apple conservation and breeding programs in the Caucasus.

scholarly journals The limits to parapatric speciation 3: Evolution of strong reproductive isolation in presence of gene flow despite limited ecological differentiation

2020 ◽  
Author(s):  
Alexandre Blanckaert ◽  
Claudia Bank ◽  
Joachim Hermisson
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Local Adaptation ◽  
Maximum Amount ◽  
Genetic Barrier ◽  
Incipient Species ◽  
Postzygotic Reproductive Isolation ◽  
Minimal Configuration ◽  
Parapatric Speciation ◽  
Two Populations

AbstractGene flow tends to impede the accumulation of genetic divergence. Here, we determine the limits for the evolution of postzygotic reproductive isolation in a model of two populations that are connected by gene flow. We consider two selective mechanisms for the creation and maintenance of a genetic barrier: local adaptation leads to divergence among incipient species due to selection against migrants, and Dobzhansky-Muller incompatibilities (DMIs) reinforce the genetic barrier through selection against hybrids. In particular, we are interested in the maximum strength of the barrier under a limited amount of local adaptation, a challenge that may initially face many incipient species. We first confirm that with classical two-locus DMIs, the maximum amount of local adaptation is indeed a limit to the strength of a genetic barrier. However, with three or more loci and cryptic epistasis, this limit holds no longer. In particular, we identify a minimal configuration of three epistatically interacting mutations that is sufficient to confer strong reproductive isolation.

scholarly journals Genome wide analysis of Ga1-s modifiers in maize

2019 ◽  
Author(s):  
Preston Hurst ◽  
Zhikai Liang ◽  
Christine Smith ◽  
Melinda Yerka ◽  
Brandi Sigmon ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genotyping By Sequencing ◽  
The United States ◽  
Reproductive Barrier ◽  
Sequencing Data ◽  
Genetic Incompatibility ◽  
Agricultural Plant ◽  
Dent Corn ◽  
Using Data ◽  
The Impact

ABSTRACTA one way reproductive barrier exists between most popcorn varieties and dent corn varieties grown in the United States. This barrier is predominantly controlled by the ga1 locus. Using data from a diverse population of popcorn accessions pollinated by a dent corn tester, we found that the non-reciprocal pollination barrier conferred by ga1 is more complex than previously described. Individual accessions ranged from 0% to 100% compatible with dent corn pollen. Using conventional genotyping-by-sequencing data from 371 popcorn accessions carrying Ga1-s, seven significant modifiers of dent pollen compatibility were identified on five chromosomes. One locus may either be a nonfunctional ga1 allele present within popcorn, or second necessary gene for the reproductive barrier in genetic linkage with ga1, while the other modifiers are clearly genetically unlinked. The existence of ga1 modifiers segregating in a popcorn genetic background may indicate selective pressure to allow gene flow between populations, which should be incorporated into future models of the impact of genetic incompatibility loci on gene flow in natural and agricultural plant populations.

scholarly journals Young Adults’ Experience of Appearance-Altering Orthognathic Surgery

2017 ◽  
Vol 55 (2) ◽  
pp. 238-247 ◽  
Author(s):  
Morna J. Liddle ◽  
Sarah R. Baker ◽  
Keith G. Smith ◽  
Andrew R. Thompson
Keyword(s):  
Young Adults ◽  
Orthognathic Surgery ◽  
Parental Communication ◽  
Raising Awareness ◽  
Complex Process ◽  
Semistructured Interviews ◽  
Dental Hospital ◽  
Initial Shock ◽  
The Impact

Objective: To gain an experiential account of the processes of change associated specifically with orthognathic surgery. Design: A qualitative design was used. Semistructured interviews were carried out with 7 participants approximately 1 week before and 6-8 weeks after surgery. The data were analyzed using interpretative phenomenologic analysis (IPA). Setting: Participants were recruited from a NHS Dental Hospital. Participants: Patients aged 16 to 25 years scheduled to undergo orthognathic surgery on both the upper and lower jaws were purposively sought to participate. Seven participants aged between 18 and 25 years and who had undergone a bimaxillary osteotomy completed interviews (5 females and 2 males). Results: Themes were identified in connection with the overall journey of treatment being a rite of passage; the treatment’s role in raising awareness about the anomalies in appearance; the initial shock at the changes that followed surgery; the uncertainty about treatment; the impact of actual negative reactions of others; and the role of significant others in the decision-making process. Conclusions: Participants described undergoing a much more complex process of adjustment to change in appearance than has been identified elsewhere within the literature, and the study highlights the nuanced fashion in which both medical and parental communication influence patient expectation and experience of surgery. There is a need to improve communication between clinicians, families, and young adults seeking orthognathic surgery. Further studies are needed to investigate the processes associated with seeking to change facial appearance resulting from other forms of dentofacial condition.

Intergroup Threat and Outgroup Attitudes

2013 ◽  
Vol 44 (5) ◽  
pp. 311-319 ◽  
Author(s):  
Marco Brambilla ◽  
David A. Butz
Keyword(s):  
Gay Men ◽  
Social Group ◽  
Welfare Recipients ◽  
Intergroup Attitudes ◽  
Social Policies ◽  
Intergroup Threat ◽  
Economic Threat ◽  
The Impact ◽  
General Climate

Two studies examined the impact of macrolevel symbolic threat on intergroup attitudes. In Study 1 (N = 71), participants exposed to a macrosymbolic threat (vs. nonsymbolic threat and neutral topic) reported less support toward social policies concerning gay men, an outgroup whose stereotypes implies a threat to values, but not toward welfare recipients, a social group whose stereotypes do not imply a threat to values. Study 2 (N = 78) showed that, whereas macrolevel symbolic threat led to less favorable attitudes toward gay men, macroeconomic threat led to less favorable attitudes toward Asians, an outgroup whose stereotypes imply an economic threat. These findings are discussed in terms of their implications for understanding the role of a general climate of threat in shaping intergroup attitudes.

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