scholarly journals Genomic landscape of reproductive isolation in Lucania killifish: The role of sex chromosomes and salinity

2019 ◽  
Author(s):  
Emma L. Berdan ◽  
Rebecca C. Fuller ◽  
Genevieve M. Kozak
Keyword(s):  
Reproductive Isolation ◽  
Salinity Tolerance ◽  
Sex Chromosomes ◽  
Genetic Architecture ◽  
Sex Chromosome ◽  
Salinity Gradient ◽  
Chromosome 1 ◽  
Hybrid Male ◽  
Bluefin Killifish ◽  
Sex Locus

ABSTRACTUnderstanding how speciation occurs and how reproductive barriers contribute to population structure at a genomic scale requires elucidating the genetic architecture of reproductive isolating barriers. In particular, it is crucial to determine if loci underlying reproductive isolation are genetically linked or if they are located on sex chromosomes, which have unique inheritance and population genetic properties. Bluefin killifish (Lucania goodei) and rainwater killifish (L. parva) are closely related species that have diverged across a salinity gradient and are reproductively isolated by assortative mating, hybrid male infertility, viability of hybrid offspring at high salinities, as well as reduced overall fitness of F2 offspring and backcrosses to L. goodei. We conducted QTL mapping in backcrosses between L. parva and L. goodei to determine the genetic architecture of sex determination, mate attractiveness, fertility, and salinity tolerance. We find that the sex locus appears to be male determining and located on a chromosome that has undergone a Robertsonian fusion in L. parva relative to L. goodei. We find that the sex locus on the fused chromosome is involved in several genomic incompatibilities, which affect the survival of backcrossed offspring. Among the backcrossed offspring that survived to adulthood, we find that one QTL for male attractiveness to L. goodei females is closely linked to this sex locus on chromosome 1. Males homozygous for L. goodei alleles at the sex locus laid more eggs with L. goodei females. QTL associated with salinity tolerance were spread across the genome but did not tend to co-localize with reproductive isolation. Thus, speciation in this system appears to be driven by reinforcement and indirect selection against hybrids rather than direct natural selection for salinity tolerance. Our work adds to growing evidence that sex chromosome evolution may contribute to speciation.

Polymorphism and differentiation of rainbow trout Y chromosomes

Genome ◽  
2004 ◽  
Vol 47 (6) ◽  
pp. 1105-1113 ◽  
Author(s):  
Alicia Felip ◽  
Atushi Fujiwara ◽  
William P Young ◽  
Paul A Wheeler ◽  
Marc Noakes ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Y Chromosome ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Morphological Differentiation ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Y Chromosomes ◽  
Cytogenetic Analyses ◽  
Clonal Lines ◽  
Sex Locus

Most fish species show little morphological differentiation in the sex chromosomes. We have coupled molecular and cytogenetic analyses to characterize the male-determining region of the rainbow trout (Oncorhynchus mykiss) Y chromosome. Four genetically diverse male clonal lines of this species were used for genetic and physical mapping of regions in the vicinity of the sex locus. Five markers were genetically mapped to the Y chromosome in these male lines, indicating that the sex locus was located on the same linkage group in each of the lines. We also confirmed the presence of a Y chromosome morphological polymorphism among these lines, with the Y chromosomes from two of the lines having the more common heteromorphic Y chromosome and two of the lines having Y chromosomes morphologically similar to the X chromosome. The fluorescence in situ hybridization (FISH) pattern of two probes linked to sex suggested that the sex locus is physically located on the long arm of the Y chromosome. Fishes appear to be an excellent group of organisms for studying sex chromosome evolution and differentiation in vertebrates because they show considerable variability in the mechanisms and (or) patterns involved in sex determination.Key words: sex chromosomes, sex markers, cytogenetics, rainbow trout, fish.

scholarly journals Ancestral and neo-sex chromosomes contribute to population divergence in a dioecious plant

2019 ◽  
Author(s):  
Felix E.G. Beaudry ◽  
Spencer C.H. Barrett ◽  
Stephen I. Wright
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Demographic History ◽  
Population Divergence ◽  
Effective Population ◽  
Dioecious Plant ◽  
Fusion Event ◽  
Contemporary Gene Flow

ABSTRACTEmpirical evidence from several animal groups suggests that sex chromosomes may disproportionately contribute to reproductive isolation. This occurs particularly when sex chromosomes are associated with turnover of sex determination systems resulting from structural rearrangements to the sex chromosomes. We investigated these predictions in the dioecious plant Rumex hastatulus, which is comprised of populations of two sex chromosome cytotypes. Using population genomic analyses, we investigated the demographic history of R. hastatulus and explored the contributions of ancestral and neo-sex chromosomes to population genetic divergence. Our study revealed that the cytotypes represented genetically divergent populations with evidence for historical but not contemporary gene flow between them. In agreement with classical predictions, we found that the ancestral X chromosome was disproportionately divergent compared with the rest of the genome. Excess differentiation was also observed on the Y chromosome, even when using measures of differentiation that control for differences in effective population size. Our estimates of the timing of the origin of the neo-sex chromosomes in R. hastatulus are coincident with cessation of gene flow, suggesting that the chromosomal fusion event that gave rise to the origin of the XYY cytotype may have also been a key driver of reproductive isolation.

scholarly journals Sex chromosomes in meiotic, hemiclonal, clonal and polyploid hybrid vertebrates: along the ‘extended speciation continuum'

2021 ◽  
Vol 376 (1833) ◽  
pp. 20200103 ◽  
Author(s):  
Matthias Stöck ◽  
Dmitrij Dedukh ◽  
Radka Reifová ◽  
Dunja K. Lamatsch ◽  
Zuzana Starostová ◽  
...  
Keyword(s):  
Reproductive Isolation ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Dominance Hierarchies ◽  
Speciation Continuum ◽  
Well Differentiated ◽  
Evolution Understanding ◽  
Meiotic Aberrations ◽  
Male Heterogamety

We review knowledge about the roles of sex chromosomes in vertebrate hybridization and speciation, exploring a gradient of divergences with increasing reproductive isolation (speciation continuum). Under early divergence, well-differentiated sex chromosomes in meiotic hybrids may cause Haldane-effects and introgress less easily than autosomes. Undifferentiated sex chromosomes are more susceptible to introgression and form multiple (or new) sex chromosome systems with hardly predictable dominance hierarchies. Under increased divergence, most vertebrates reach complete intrinsic reproductive isolation. Slightly earlier, some hybrids (linked in ‘the extended speciation continuum') exhibit aberrant gametogenesis, leading towards female clonality. This facilitates the evolution of various allodiploid and allopolyploid clonal (‘asexual’) hybrid vertebrates, where ‘asexuality' might be a form of intrinsic reproductive isolation. A comprehensive list of ‘asexual' hybrid vertebrates shows that they all evolved from parents with divergences that were greater than at the intraspecific level (K2P-distances of greater than 5–22% based on mtDNA). These ‘asexual' taxa inherited genetic sex determination by mostly undifferentiated sex chromosomes. Among the few known sex-determining systems in hybrid ‘asexuals', female heterogamety (ZW) occurred about twice as often as male heterogamety (XY). We hypothesize that pre-/meiotic aberrations in all-female ZW-hybrids present Haldane-effects promoting their evolution. Understanding the preconditions to produce various clonal or meiotic allopolyploids appears crucial for insights into the evolution of sex, ‘asexuality' and polyploidy. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)’.

scholarly journals Gene flow mediates the role of sex chromosome meiotic drive during complex speciation

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Colin D Meiklejohn ◽  
Emily L Landeen ◽  
Kathleen E Gordon ◽  
Thomas Rzatkiewicz ◽  
Sarah B Kingan ◽  
...  
Keyword(s):  
Gene Flow ◽  
Sex Chromosomes ◽  
Population Genomics ◽  
Sex Chromosome ◽  
Hybrid Sterility ◽  
Sequence Divergence ◽  
Meiotic Drive ◽  
Hybrid Male ◽  
Local Sequence

During speciation, sex chromosomes often accumulate interspecific genetic incompatibilities faster than the rest of the genome. The drive theory posits that sex chromosomes are susceptible to recurrent bouts of meiotic drive and suppression, causing the evolutionary build-up of divergent cryptic sex-linked drive systems and, incidentally, genetic incompatibilities. To assess the role of drive during speciation, we combine high-resolution genetic mapping of X-linked hybrid male sterility with population genomics analyses of divergence and recent gene flow between the fruitfly species, Drosophila mauritiana and D. simulans. Our findings reveal a high density of genetic incompatibilities and a corresponding dearth of gene flow on the X chromosome. Surprisingly, we find that a known drive element recently migrated between species and, rather than contributing to interspecific divergence, caused a strong reduction in local sequence divergence, undermining the evolution of hybrid sterility. Gene flow can therefore mediate the effects of selfish genetic elements during speciation.

A cytological description of 10 taxa in Metacnephia (Diptera: Simuliidae)

1982 ◽  
Vol 60 (11) ◽  
pp. 2852-2865 ◽  
Author(s):  
William S. Procunier
Keyword(s):  
Complex System ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Nucleolar Organizer ◽  
Sex Bias ◽  
Sex Linkage ◽  
Chromosome Differentiation ◽  
Species Association ◽  
Chromosome Maps ◽  
Sex Locus

Cytological descriptions and phylogenetic relationships are presented for 10 blackfly taxa in Metacnephia. These descriptions are given in terms of standard polytene chromosome maps based on M. pallipes. All members are male chiasmate and differ from related Cnephia by a whole arm interchange between chromosomes I and II. Sex chromosome differentiation varies from undefined changes resulting in a short, nonpairing centromeric segment in X0Y1 males of M. amphora to a complex system in M. borealis. The latter system involves Y chromosome differentiation by associated inversions and sex linkage of the nucleolar organizer (NO). Metacnephia borealis exhibits a sex bias in NO expression with excess expression in females and an apparent conversion phenomenon which dosage compensates males. The closest members of Metacnephia differ only in their sex chromosomes and share floating inversions; more distant taxa differ by fixed inversions as well as sex chromosomes. IIIS-1, IIIS-2, and IIIS-3 may be polymorphic, sex linked, or fixed in different species of the group. Nonhomology of sex chromosomes of different species, association of the sex locus and NO, and presence of an identical supernumerary block on nonhomologous chromosomes indicate a mobility phenomenon for certain loci.

Sibling species of the blackfly Prosimulium onychodactylum (Simuliidae, Diptera): a salivary gland chromosome study

1983 ◽  
Vol 61 (12) ◽  
pp. 2816-2835 ◽  
Author(s):  
Lester J. Newman
Keyword(s):  
Salivary Gland ◽  
Reproductive Isolation ◽  
Sibling Species ◽  
Chromosome Pairing ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Homologous Pairing ◽  
Chromosome Markers ◽  
Chromosome Arm ◽  
Backcross Hybrids

Larvae of the morphospecies Prosimulium onychodactylum collected from two streams in northern Oregon are divided into 11 sibling species based on fixed and polymorphic inversions. The sibling species have differentiated sex chromosomes; each sibling species falls into one of two groups based on the chromosome arm which carries the sex chromosome markers. Males exhibit lack of homologous pairing or inversion heterzygosity and females have complete chromosome pairing or inversion homozygosity. There is a succession of sibling species which mature in the streams from January through September. Mature larvae of each sibling species are present for about 6 weeks; some are synchronic while others are allochronic. Some of the sibling species occur in the same stream and others are in different streams. Sibling species which are both synchronic and sympatric appear to be reproductively isolated. Reproductive isolation may not be complete for sibling species which are normally allopatric or allochronic; small numbers of F1 and backcross hybrids were found between some of these sibling species. The division of the morphospecies into sibling species was also observed in collections from Washington through northern California.

scholarly journals Sex chromosome evolution, heterochiasmy and physiological QTL in the salmonid Brook Charr Salvelinus fontinalis

2017 ◽  
Author(s):  
Ben J. G. Sutherland ◽  
Ciro Rico ◽  
Céline Audet ◽  
Louis Bernatchez
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Genetic Architecture ◽  
Salvelinus Fontinalis ◽  
Sex Chromosome ◽  
Brook Charr ◽  
Determination System ◽  
Males And Females ◽  
Sex Determination System ◽  
Sex Determination Mechanisms

ABSTRACTWhole genome duplication can have large impacts on genome evolution, and much remains unknown about these impacts. This includes the mechanisms of coping with a duplicated sex determination system and whether this has an impact on increasing the diversity of sex determination mechanisms. Other impacts include sexual conflict, where alleles having different optimums in each sex can result in sequestration of genes into non-recombining sex chromosomes. Sex chromosome development itself may involve sex-specific recombination rate (i.e. heterochiasmy), which is also poorly understood. Family Salmonidae is a model system for these phenomena, having undergone autotetraploidization and subsequent rediploidization in most of the genome at the base of the lineage. The salmonid master sex determining gene is known, and many species have non-homologous sex chromosomes, putatively due to transposition of this gene. In this study, we identify the sex chromosome of Brook Charr Salvelinus fontinalis and compare sex chromosome identities across the lineage (eight species, four genera). Although non-homology is frequent, homologous sex chromosomes and other consistencies are present in distantly related species, indicating probable convergence on specific sex and neo-sex chromosomes. We also characterize strong heterochiasmy with 2.7-fold more crossovers in maternal than paternal haplotypes with paternal crossovers biased to chromosome ends. When considering only rediploidized chromosomes, the overall heterochiasmy trend remains, although with only 1.9-fold more recombination in the female than the male. Y chromosome crossovers are restricted to a single end of the chromosome, and this chromosome contains a large interspecific inversion, although its status between males and females remains unknown. Finally, we identify QTL for 21 unique growth, reproductive and stress-related phenotypes to improve knowledge of the genetic architecture of these traits important to aquaculture and evolution.

scholarly journals Proto-sex locus in large yellow croaker provides insights into early evolution of the sex chromosome

2020 ◽  
Author(s):  
Zhiyong Wang ◽  
Shijun Xiao ◽  
Mingyi Cai ◽  
Zhaofang Han ◽  
Wanbo Li ◽  
...  
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Draft Genome ◽  
Sex Reversal ◽  
Large Yellow Croaker ◽  
Larimichthys Crocea ◽  
Suppressed Recombination ◽  
Heterogametic Sex ◽  
Sex Locus

AbstractAutosomal origins of heterogametic sex chromosomes have been inferred frequently from suppressed recombination and gene degeneration manifested in incompletely differentiated sex chromosomes. However, the initial transition of an autosome region to a proto-sex locus has been not explored in depth. By assembling and analyzing a chromosome-level draft genome, we found a recent (evolved 0.26 million years ago), highly homologous, and dmrt1 containing sex-determination locus with slightly reduced recombination in large yellow croaker (Larimichthys crocea), a teleost species with genetic sex determination (GSD) and with undifferentiated sex chromosomes. We observed genomic homology and polymorphic segregation of the proto-sex locus between sexes. Expression of dmrt1 showed a stepwise increase in the development of testis, but not in the ovary. We infer that the inception of the proto-sex locus involves a few divergences in nucleotide sequences and slight suppression of recombination in an autosome region. In androgen-induced sex reversal of genetic females, in addition to dmrt1, genes in the conserved dmrt1 cluster, and the rest of the sex determination network were activated. We provided evidence that broad functional links were shared by genetic sex determination and environmental sex reversal.

scholarly journals Genome-Wide Analysis of Transposable Elements and Satellite DNAs in Spinacia Species to Shed Light on Their Roles in Sex Chromosome Evolution

2021 ◽  
Vol 11 ◽  
Author(s):  
Ning Li ◽  
Xiaoyue Li ◽  
Jian Zhou ◽  
Li’ang Yu ◽  
Shufen Li ◽  
...  
Keyword(s):  
Sugar Beet ◽  
Sex Chromosomes ◽  
Dna Sequences ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Repetitive Sequences ◽  
Chromosome 1 ◽  
Sex Chromosome Evolution ◽  
Satellite Dnas ◽  
Heteromorphic Sex Chromosomes

Sex chromosome evolution has mostly been studied in species with heteromorphic sex chromosomes. The Spinacia genus serves as an ideal model for investigating evolutionary mechanisms underlying the transition from homomorphic to heteromorphic sex chromosomes. Among evolutionary factors, repetitive sequences play multiple roles in sex chromosome evolution while their forces have not been fully explored in Spinacia species. Here, we identified major repetitive sequence classes in male and female genomes of Spinacia species and their ancestral relative sugar beet to elucidate the evolutionary processes of sex chromosome evolution using next-generation sequencing (NGS) data. Comparative analysis revealed that the repeat elements of Spinacia species are considerably higher than of sugar beet, especially the Ty3/Gypsy and Ty1/Copia retrotransposons. The long terminal repeat retroelements (LTR) Angela, Athila, and Ogre may be accounted for the higher proportion of repeats in the spinach genome. Comparison of the repeats proportion between female and male genomes of three Spinacia species indicated the different representation in Spinacia tetrandra samples but not in the S. oleracea or S. turkestanica samples. From these results, we speculated that emergence of repetitive DNA sequences may correlate the formation of sex chromosome and the transition from homomorphic sex chromosomes to heteromorphic sex chromosomes as heteromorphic sex chromosomes exclusively existed in Spinacia tetrandra. Three novel sugar beet-specific satellites were identified and confirmed by fluorescence in situ hybridization (FISH); six out of eight new spinach-specific satellites were mapped to the short arm of sex chromosomes. A total of 141 copies of SolSat01-171-s were found in the sex determination region (SDR). Thus, the accumulation of satellite DNA on the short arm of chromosome 1 may be involved in the sex chromosome evolution in Spinacia species. Our study provides a fundamental resource for understanding repeat sequences in Spinacia species and their roles in sex chromosome evolution.

scholarly journals Gene flow mediates the role of sex chromosome meiotic drive during complex speciation

2015 ◽  
Author(s):  
Colin D. Meiklejohn ◽  
Emily L. Landeen ◽  
Kathleen E. Gordon ◽  
Thomas Rzatkiewicz ◽  
Sarah B. Kingan ◽  
...  
Keyword(s):  
Gene Flow ◽  
Sex Chromosomes ◽  
Population Genomics ◽  
Sex Chromosome ◽  
Hybrid Sterility ◽  
Meiotic Drive ◽  
Hybrid Male ◽  
Selfish Genetic Elements ◽  
Cryptic Sex

ABSTRACTDuring speciation, sex chromosomes often accumulate interspecific genetic incompatibilities faster than the rest of the genome. The drive theory posits that sex chromosomes are susceptible to recurrent bouts of meiotic drive and suppression, causing the evolutionary build-up of divergent cryptic sex-linked drive systems and, incidentally, genetic incompatibilities. To assess the role of drive during speciation, we combine high-resolution genetic mapping of X-linked hybrid male sterility with population genomics analyses of divergence and recent gene flow between the fruitfly species, Drosophila mauritiana and D. simulans. Our findings reveal a high density of genetic incompatibilities and a corresponding dearth of gene flow on the X chromosome. Surprisingly, we find that, rather than contributing to interspecific divergence, a known drive element has recently migrated between species, caused a strong reduction in local divergence, and undermined the evolution of hybrid sterility. Gene flow can therefore mediate the effects of selfish genetic elements during speciation.

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