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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

DEAD-END. "Highly differentiated sex chromosomes—a degenerate, gene-poor Y chromosome, and an often dosage-compensated X—appear to represent an evolutionary dead-end." https://lnkd.in/dX2rADH View in LinkedIn

"FUSIONS between sex chromosomes and autosomes are relatively easy to detect from karyotypic data, and a large number of such fusions have been discovered." https://lnkd.in/g2CPWtY View in LinkedIn

"AN AUTOSOME is a chromosome that is not an allosome (a sex chromosome). Autosomes appear in pairs whose members have the same form but differ from other pairs in a diploid cell, whereas members of an allosome pair may differ from one another and thereby determine sex." https://lnkd.in/gP9J5mi View in LinkedIn

BOTH SYSTEMS AT ONCE. "In some taxa, such as fishes and squamate reptiles, both XY and ZW sex determination is found among closely related species (and even among populations within a species)." https://lnkd.in/g2CPWtY View in LinkedIn

FROG SEX CHROMOSOMES. "The existence of both male and female heterogametic individuals in one species is an extremely rare situation in nature, because some sex chromosome combinations produce offspring with sex ratios different from 1:1." http://www.pnas.org/content/112/34/E4752.full View in LinkedIn

FROGS. "As in most amphibians, sex chromosomes of the model species Xenopus tropicalis are homomorphic, complicating identification of the heterogametic sex. Using genetic approaches, we have proved the existence of three types of sex chromosomes (Y, W, and Z), defining three kinds of males (YZ, YW, and ZZ) and two kinds of females (ZW and WW)." https://lnkd.in/gvD548n View in LinkedIn

VARIABLE. "Two main sex chromosome systems can be found in vertebrates with genetic sex determination: XX/XY (in which males are heterogametic) and ZZ/ZW (with heterogametic females). Nevertheless, sex chromosomes are extraordinarily variable, and other combinations also can be found, ranging from female heterogamety with 00/0W or ZZ/Z0 sex chromosomes to male heterogamety with XX/X0 sex chromosomes. Furthermore, complex XY and ZW systems are possible when fusions, fissions, and translocations between sex chromosomes and autosomes take place (e.g., X1X2Y, XY1Y2, or Z1Z2W)." https://lnkd.in/gvD548n View in LinkedIn

HOMOLOGS. "In mammals, only a few X-linked genes have homologues on the Y chromosome, and several Y-linked genes are known that do not have homology to X-linked genes and have presumably been translocated to the Y from elsewhere; in D. melanogaster, all known Y-linked genes are in this latter category." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn