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WRONG OLDER THEORY. "We uncover a striking diversity of sex chromosome configurations in Diptera, concealed underneath superficially similar karyotypes displaying male heterogamety. This diversity is in sharp contrast to the theory that differentiated sex chromosomes are highly stable and unlikely to be replaced, exemplified by the mammalian X, and emphasizes the importance of studying a variety of clades to obtain a truly global understanding of sex chromosome evolution." https://lnkd.in/dX2rADH View in LinkedIn

EVOLUTION OF TWO SEXES. "Sex chromosomes evolved from ordinary autosomes that acquired a sex-determining function and stopped recombining. Over evolutionary time, sex chromosomes differentiate, and the sex-limited chromosome—which is entirely sheltered from recombination—degenerates." https://lnkd.in/dX2rADH View in LinkedIn

TWISTS AND TURNS. "Some species have newly gained or secondarily lost their sex chromosomes; in others, a different chromosome has replaced the original sex chromosome or multiple chromosomal elements have become incorporated into the sex chromosomes; still other species have female heterogametic sex chromosomes." https://lnkd.in/dX2rADH View in LinkedIn

PARALLEL EVOLUTION. "Transcriptome analysis shows that dosage compensation has evolved multiple times in flies, consistently through up-regulation of the single X in males. However, X chromosomes generally show a deficiency of genes with male-biased expression, possibly reflecting sex-specific selective pressures." https://lnkd.in/dX2rADH View in LinkedIn

HIDDEN DIVERSITY. "Here, we use whole-genome analysis in 37 fly species belonging to 22 different families of Diptera and uncover tremendous hidden diversity in sex chromosome karyotypes among flies. We identify over a dozen different sex chromosome configurations, and the small dot chromosome is repeatedly used as the sex chromosome, which presumably reflects the ancestral karyotype of higher Diptera." https://lnkd.in/dX2rADH View in LinkedIn

GREAT VARIATION. "Sex is a universal feature of eukaryotic organisms, yet tremendous variation in sex determination mechanisms exists even among closely related species, or among individuals within a species." https://lnkd.in/dX2rADH View in LinkedIn

NON-RECOMBINING. "The Chlamydomonas mating-type locus and incompatibility locus regions of some fungi with systems with two incompatibility types include large nonrecombining genome regions that differ in size, gene content and representation of transposable elements. The heteromorphic sex chromosomes of bryophytes, which are primarily haploid, represent a similar situation, although it is not yet known whether these homologous chromosome pairs show genetic degeneration." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

YOUNG CHROMOSOMES. "We review some recently published results on sex chromosomes in a diversity of species. We focus on several fish and some plants whose sex chromosomes appear to be 'young', as only parts of the chromosome are nonrecombining, while the rest is pseudoautosomal." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

"THE SHELTERING of recessive or partly recessive Y-linked deleterious mutations from selection due to their permanent heterozygosity” occurs. http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

"THE EVOLUTION of a pair of chromosomes that differ in appearance between males and females (heteromorphic sex chromosomes) has occurred repeatedly across plants and animals. Recent work has shown that the male heterogametic (XY) and female heterogametic (ZW) sex chromosomes evolved independently from different pairs of homomorphic autosomes in the common ancestor of birds and mammals but also that X and Z chromosomes share many convergent molecular features." https://lnkd.in/gT_EcE7 View in LinkedIn