scholarly journals The genetics of postzygotic isolation in the Drosophila virilis group.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 527-537 ◽  
Author(s):  
H A Orr ◽  
J A Coyne
Keyword(s):  
Reproductive Isolation ◽  
X Chromosome ◽  
Related Species ◽  
Hybrid Sterility ◽  
Drosophila Virilis ◽  
Female Sterility ◽  
Postzygotic Isolation ◽  
Male And Female ◽  
Virilis Group ◽  
Drosophila Virilis Group

Abstract In a genetic study of postzygotic reproductive isolation among species of the Drosophila virilis group, we find that the X chromosome has the largest effect on male and female hybrid sterility and inviability. The X alone has a discernible effect on postzygotic isolation between closely related species. Hybridizations involving more distantly related species also show large X-effects, although the autosomes may also play a role. In the only hybridization yet subjected to such analysis, we show that hybrid male and female sterility result from the action of different X-linked loci. Our results accord with genetic studies of other taxa, and support the view that both Haldane's rule (heterogametic F1 sterility or inviability) and the large effect of the X chromosome on reproductive isolation result from the accumulation by natural selection of partially recessive or underdominant mutations. We also describe a method that allows genetic analysis of reproductive isolation between species that produce completely sterile or inviable hybrids. Such species pairs, which represent the final stage of speciation, cannot be analyzed by traditional methods. The X chromosome also plays an important role in postzygotic isolation between these species.

An X chromosome effect responsible for asymmetric reproductive isolation between male Drosophila virilis and heterospecific females

Genome ◽  
2009 ◽  
Vol 52 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Desirée Nickel ◽  
Alberto Civetta
Keyword(s):  
Reproductive Isolation ◽  
X Chromosome ◽  
Drosophila Virilis ◽  
Interspecific Crosses ◽  
Closely Related Species ◽  
Virilis Group ◽  
Failed Fertilization ◽  
Backcross Populations ◽  
Early Zygote ◽  
Male Mate

Reproductive isolation between closely related species is expressed through uncoordinated courtship, failed fertilization, and (or) postzygotic barriers. Behavioural components of mating often form an initial barrier to hybridization between species. In many animals, females are responsible for mating discrimination in both intra- and interspecific crosses; males of Drosophila virilis group represent an exception to this trend. Using overall productivity tests, we show that a lower proportion of D. virilis males sire progeny when paired with a heterospecific female ( Drosophila novamexicana or Drosophila americana texana ) for 2 weeks. This suggests male mate discrimination or some other kind of asymmetrical incompatibility in courtship and mating or early zygote mortality. We used males from D. virilis – D. novamexicana and from D. virilis – D. a. texana backcross populations to map chromosome effects responsible for male reproductive isolation. Results from the analysis of both backcross male populations indicate a major X chromosome effect. Further, we conduct a male behavioural analysis to show that D. virilis males significantly fail to continue courtship after the first step of courtship, when they tap heterospecific females. The combined results of a major X chromosome effect and the observation that D. virilis males walk away from females after tapping suggest that future studies should concentrate on the identification of X-linked genes affecting the ability of males to recognize conspecific females.

scholarly journals Multiple Genes Cause Postmating Prezygotic Reproductive Isolation in the Drosophila virilis Group

2016 ◽  
Vol 6 (12) ◽  
pp. 4067-4076 ◽  
Author(s):  
Yasir H Ahmed-Braimah
Keyword(s):  
Reproductive Isolation ◽  
Evolutionary Biology ◽  
Drosophila Virilis ◽  
Chromosome 2 ◽  
Reproductive Barriers ◽  
Zygote Formation ◽  
Virilis Group ◽  
Genetic Level ◽  
Genomic Regions ◽  
Drosophila Virilis Group

Abstract Understanding the genetic basis of speciation is a central problem in evolutionary biology. Studies of reproductive isolation have provided several insights into the genetic causes of speciation, especially in taxa that lend themselves to detailed genetic scrutiny. Reproductive barriers have usually been divided into those that occur before zygote formation (prezygotic) and after (postzygotic), with the latter receiving a great deal of attention over several decades. Reproductive barriers that occur after mating but before zygote formation [postmating prezygotic (PMPZ)] are especially understudied at the genetic level. Here, I present a phenotypic and genetic analysis of a PMPZ reproductive barrier between two species of the Drosophila virilis group: D. americana and D. virilis. This species pair shows strong PMPZ isolation, especially when D. americana males mate with D. virilis females: ∼99% of eggs laid after these heterospecific copulations are not fertilized. Previous work has shown that the paternal loci contributing to this incompatibility reside on two chromosomes, one of which (chromosome 5) likely carries multiple factors. The other (chromosome 2) is fixed for a paracentric inversion that encompasses nearly half the chromosome. Here, I present two results. First, I show that PMPZ in this species cross is largely due to defective sperm storage in heterospecific copulations. Second, using advanced intercross and backcross mapping approaches, I identify genomic regions that carry genes capable of rescuing heterospecific fertilization. I conclude that paternal incompatibility between D. americana males and D. virilis females is underlain by four or more genes on chromosomes 2 and 5.

scholarly journals The Genetics of Reproductive Isolation in the Drosophila simulans Clade: X vs. Autosomal Effects and Male vs. Female Effects

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1243-1255 ◽  
Author(s):  
Hope Hollocher ◽  
Chug-I Wu
Keyword(s):  
Reproductive Isolation ◽  
Male Sterility ◽  
X Chromosome ◽  
Hybrid Sterility ◽  
Drosophila Simulans ◽  
Female Sterility ◽  
Hybrid Male ◽  
Hybrid Female ◽  
Hybrid Male Sterility ◽  
Hybrid Inviability

Abstract A strong effect of homozygous autosomal regions on reproductive isolation was found for crosses between the species in the Drosophila simulans clade. Second chromosome regions were introgressed from D. mauritiana and D. sechellia into D. simulans and tested for their homozygous effects on hybrid male and hybrid female sterility and inviability. Most introgressions are fertile as heterozygotes, yet produce sterile male offspring when made homozygous. The density of homozygous autosomal factors contributing to hybrid male sterility is comparable to the density of X chromosome factors for this level of resolution. Female sterility was also revealed, yet the disparity between male and female levels of sterility was great, with male sterility being up to 23 times greater than female sterility. Complete hybrid inviability was also associated with some regions of the second chromosome, yet there were no strong sex differences. In conclusion, we find no evidence to support a strong X chromosome bias in the evolution of hybrid sterility or inviability but do find a very strong sex bias in the evolution of hybrid sterility. In light of these findings, we reevaluate the current models proposed to explain the genetic pattern of reproductive isolation.

scholarly journals The genetic architecture of post-zygotic reproductive isolation between Anopheles coluzzii and An. quadriannulatus

2020 ◽  
Author(s):  
Kevin C. Deitz ◽  
Willem Takken ◽  
Michel A. Slotman
Keyword(s):  
Reproductive Isolation ◽  
Anopheles Gambiae ◽  
X Chromosome ◽  
Genetic Background ◽  
Epistatic Interaction ◽  
Hybrid Sterility ◽  
Anopheles Coluzzii ◽  
Hybrid Male ◽  
Backcross Population ◽  
Complex Species

AbstractThe Anopheles gambiae complex is comprised of eight morphologically indistinguishable species and has emerged as a model system for the study of speciation genetics due to the rapid radiation of its member species over the past two million years. Male hybrids between most An. gambiae complex species pairs are sterile, and some genotype combinations in hybrid males cause inviability. We investigated the genetic basis of hybrid male inviability and sterility between An. coluzzii and An. quadriannulatus by measuring segregation distortion and performing a QTL analysis of sterility in a backcross population. Hybrid males were inviable if they inherited the An. coluzzii X chromosome and were homozygous at one or more loci in 18.9 Mb region of chromosome 3. The An. coluzzii X chromosome has a disproportionately large effect on hybrid sterility when introgressed into an An. quadriannulatus genetic background. Additionally, an epistatic interaction between the An. coluzzii X and a 1.12 Mb, pericentric region of the An. quadriannulatus 3L chromosome arm has a statistically significant contribution to the hybrid sterility phenotype. This same epistatic interaction occurs when the An. coluzzii X is introgressed into the genetic background of An. arabiensis, the sister species of An. quadriannulatus, suggesting that this may represent one of the first Dobzhansky–Muller incompatibilities to evolve early in the radiation of the Anopheles gambiae species complex. We describe the additive effects of each sterility QTL, epistatic interactions between them, and genes within QTL with protein functions related to mating behavior, reproduction, spermatogenesis, and microtubule morphogenesis, whose divergence may contribute to post-zygotic reproductive isolation between An. coluzzii and An. quadriannulatus.

THE STUDY OF GENIC VARIATION BY ELECTROPHORETIC AND HEAT DENATURATION TECHNIQUES AT THE OCTANOL DEHYDROGENASE LOCUS IN MEMBERS OF THE DROSOPHILA VIRILIS GROUP

Genetics ◽  
1975 ◽  
Vol 80 (3) ◽  
pp. 637-650
Author(s):  
R S Singh ◽  
J L Hubby ◽  
L H Throckmorton
Keyword(s):  
Genetic Variation ◽  
Drosophila Virilis ◽  
Heat Denaturation ◽  
Virilis Group ◽  
Group A ◽  
Genic Variation ◽  
Drosophila Virilis Group ◽  
Octanol Dehydrogenase

ABSTRACT Heat denaturation studies of three different electrophoretic allozymes of octanol dehydrogenase were performed from 10 species of the Drosophila virilis group. A total of 18 alleles were discovered, and in 3 species in which electrophoretic studies indicated that the locus was monomorphic, heat denaturation showed that the locus was polymorphic. We show that electrophoretic studies underestimate the number of alleles at this locus by a factor of 2.6 in these species. The results are discussed in the light of the continuing controversy over selection and neutral theories of genetic variation.

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