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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

"LACK OF RECOMBINATION among most genes carried on Y or W chromosomes reduces the ability of selection to fix favourable mutations and to prevent the fixation of deleterious ones, due to Hill–Robertson interference among completely linked loci (hitch-hiking processes)." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

PHYSICALLY DIFFERENT. "The X and Y (or Z and W) chromosomes are often morphologically distinguishable (heteromorphic), with the Y or W being largely heterochromatic and containing a high proportion of repetitive DNA." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

DEGENERATION. "Cessation of recombination between large parts or all of the sex chromosomes is the ultimate cause of the degeneration of Y or W chromosomes." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

EVOLUTION OF SEX CHROMOSOMES. "Structurally distinct sex chromosomes (X and Y) are the most familiar mode of genetic sex determination and have evolved independently in many different taxa." https://lnkd.in/ggJdV57 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