Evolution of Neo-Sex Chromosomes in<i>Silene diclinis</i>

Howell, Elaine C.; Armstrong, Susan J.; Filatov, Dmitry A.

doi:10.1534/genetics.109.103580

Cited by 49 publications

(59 citation statements)

References 32 publications

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“…Such a translocation is expected to generate a tetravalent during male meiosis, a scenario that might be tested by karyotypic analysis of male testes. Neo-sex chromosomes resulting from reciprocal translocations have been documented in both animals and plants (see, for example, Howell et al, 2009), with patterns of translocation that may also vary between populations (see, for example, Grabowska-Joachimiak et al, 2015). Co-segregation of multiple sex chromosomes has notably been documented in some populations of Rana tagoi, where male heteromorphy for C-banding patterns suggests that both chromosome pairs 8 and 9 co-segregate as sex chromosomes (Ryuzaki et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

The genetic contribution to sex determination and number of sex chromosomes vary among populations of common frogs (Rana temporaria)

et al. 2016

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The patterns of sex determination and sex differentiation have been shown to differ among geographic populations of common frogs. Notably, the association between phenotypic sex and linkage group 2 (LG 2 ) has been found to be perfect in a northern Swedish population, but weak and variable among families in a southern one. By analyzing these populations with markers from other linkage groups, we bring two new insights: (1) the variance in phenotypic sex not accounted for by LG 2 in the southern population could not be assigned to genetic factors on other linkage groups, suggesting an epigenetic component to sex determination; (2) a second linkage group (LG 7 ) was found to co-segregate with sex and LG 2 in the northern population. Given the very short timeframe since post-glacial colonization (in the order of 1000 generations) and its seemingly localized distribution, this neo-sex chromosome system might be the youngest one described so far. It does not result from a fusion, but more likely from a reciprocal translocation between the original Y chromosome (LG 2 ) and an autosome (LG 7 ), causing their cosegregation during male meiosis. By generating a strict linkage between several important genes from the sex-determination cascade (Dmrt1, Amh and Amhr2), this neo-sex chromosome possibly contributes to the 'differentiated sex race' syndrome (strictly genetic sex determination and early gonadal development) that characterizes this northern population.

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Section: Discussionmentioning

confidence: 99%

The genetic contribution to sex determination and number of sex chromosomes vary among populations of common frogs (Rana temporaria)

et al. 2016

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“…Interestingly, a closely related species, S. diclinis, has also undergone a rearrangement involving the sex chromosomes. A reciprocal Y-autosome translocation has added material to the Y, but not to the X, chromosome; in male meiosis, the S. diclinis X therefore pairs with the ancestral Y region (the majority of the translocated Y 1 ), while the rest of Y 1 pairs with the unrearranged autosome (which would segregate as a neo-X), which, in turn, pairs with the Y 2 (Howell et al 2009). This rearrangement must differ from the ones that we infer here because the S. diclinis X is not rearranged, and therefore it would not explain our observation that previously autosomal genes have become linked to X-linked genes in female meiosis.…”

Section: Figurementioning

confidence: 99%

Expansion of the Pseudo-autosomal Region and Ongoing Recombination Suppression in the Silene latifolia Sex Chromosomes

Bergero

Qiu

Forrest³

et al. 2013

Genetics

122

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There are two very interesting aspects to the evolution of sex chromosomes: what happens after recombination between these chromosome pairs stops and why suppressed recombination evolves. The former question has been intensively studied in a diversity of organisms, but the latter has been studied largely theoretically. To obtain empirical data, we used codominant genic markers in genetic mapping of the dioecious plant Silene latifolia, together with comparative mapping of S. latifolia sex-linked genes in S. vulgaris (a related hermaphrodite species without sex chromosomes). We mapped 29 S. latifolia fully sex-linked genes (including 21 newly discovered from transcriptome sequencing), plus 6 genes in a recombining pseudo-autosomal region (PAR) whose genetic map length is 25 cM in both male and female meiosis, suggesting that the PAR may contain many genes. Our comparative mapping shows that most fully sex-linked genes in S. latifolia are located on a single S. vulgaris linkage group and were probably inherited from a single autosome of an ancestor. However, unexpectedly, our maps suggest that the S. latifolia PAR region expanded through translocation events. Some genes in these regions still recombine in S. latifolia, but some genes from both addition events are now fully sex-linked. Recombination suppression is therefore still ongoing in S. latifolia, and multiple recombination suppression events have occurred in a timescale of few million years, much shorter than the timescale of formation of the most recent evolutionary strata of mammal and bird sex chromosomes. It is now understood that the large nonrecombining regions of sex chromosomes in mammals have expanded over evolutionary time, forming "evolutionary strata" with differing levels of sequence divergence between X-and Y-gene pairs, from ancient highly diverged regions, to regions in which the genes started diverging much more recently, which are located closest to the pseudo-autosomal region (PAR) on the X chromosome genetic and physical maps (Lahn and Page 1999;Skaletsky et al. 2003;Marais et al. 2008). The more recent evolutionary strata were formed by recombination suppression in regions formed by an addition of autosomal genetic material to the sex chromosomes (Waters et al. 2001), demonstrating that suppressed recombination spread from the ancestral sex chromosomal region into initially recombining regions. The PAR is shared across Eutherian mammals (despite differences in its boundary and the recent addition of a second PAR, PAR2, in humans), which is a physically small remnant of the added region, which is still autosomal in marsupials (Waters et al. 2001).The major current explanation for the evolution of expanded nonrecombining regions of sex chromosomes is

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“…XY 1 Y 2 neosex chromosome systems have arisen in Humulus japonicus (Kihara and Hirayoshi 1932;Kim et al 2008), and Silene diclinis (Howell et al 2009), and twice independently in Rumex (Smith 1963(Smith , 1969Navajas-Perez et al 2005), and Viscum fischeri has a multiple Y system (Barlow and Wiens 1976). These situations probably evolved by X-autosome translocations (Figure 1; changing the ancestrally autosomal element into a chromosome that segregates from the new arm of the X, denoted by Y 2 , while Y 1 denotes the ancestral Y), although fission of the Y cannot yet be ruled out in Rumex; genetic maps using genic markers might be able to establish whether the Y chromosomes still carry functional genes (as in Silene; see for instance Marais et al 2008), in which case their gene content could be compared and this possibility tested.…”

Section: Genetic Mapping Of Sex-determining Regionsmentioning

confidence: 99%

The Birds and the Bees and the Flowers and the Trees: Lessons from Genetic Mapping of Sex Determination in Plants and Animals

2010

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The ability to identify genetic markers in nonmodel systems has allowed geneticists to construct linkage maps for a diversity of species, and the sex-determining locus is often among the first to be mapped. Sex determination is an important area of study in developmental and evolutionary biology, as well as ecology. Its importance for organisms might suggest that sex determination is highly conserved. However, genetic studies have shown that sex determination mechanisms, and the genes involved, are surprisingly labile. We review studies using genetic mapping and phylogenetic inferences, which can help reveal evolutionary pattern within this lability and potentially identify the changes that have occurred among different sex determination systems. We define some of the terminology, particularly where confusion arises in writing about such a diverse range of organisms, and highlight some major differences between plants and animals, and some important similarities. We stress the importance of studying taxa suitable for testing hypotheses, and the need for phylogenetic studies directed to taxa where the patterns of changes can be most reliably inferred, if the ultimate goal of testing hypotheses regarding the selective forces that have led to changes in such an essential trait is to become feasible.

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Evolution of Neo-Sex Chromosomes inSilene diclinis

Cited by 49 publications

References 32 publications

The genetic contribution to sex determination and number of sex chromosomes vary among populations of common frogs (Rana temporaria)

The genetic contribution to sex determination and number of sex chromosomes vary among populations of common frogs (Rana temporaria)

Expansion of the Pseudo-autosomal Region and Ongoing Recombination Suppression in the Silene latifolia Sex Chromosomes

The Birds and the Bees and the Flowers and the Trees: Lessons from Genetic Mapping of Sex Determination in Plants and Animals

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