How big is your Y? A genome sequence-based estimate of the size of the male-specific region in Megaselia scalaris.
The scuttle fly, Megaselia scalaris, is often cited as a model in which to study early sex chromosome evolution because of its homomorphic sex chromosomes, low but measurable molecular differentiation between sex chromosomes, and occasional transposition of the male-determining element to different chromosomes in laboratory cultures. Counterintuitively, natural isolates consistently show sex linkage to the second chromosome. Frequent natural transposition of the male-determining element should lead to the loss of male specificity of any nontransposed material on the previous sex-linked chromosome pair. Using next-generation sequencing data from a newly obtained natural isolate of M. scalaris, we show that even highly conservative estimates for the size of the male-specific genome are likely too large to be contained within a transposable element. This result strongly suggests that transposition of the male-determining region either is extremely rare or has not persisted recently in natural populations, allowing for differentiation of the sex chromosomes of this species.
Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom Biology Department, Duke University, Durham, North Carolina 27708 kenneth.hoehn@oriel.ox.ac.uk.
Kenneth B
KB
Hoehn
Biology Department, Duke University, Durham, North Carolina 27708.
Mohamed A F
MA
Noor
D000818:Animals; D004175:Diptera / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D049750:Genome, Insect; D008297:Male; D014998:Y Chromosome / Q000235:genetics*
YGS; male-specific; neo-Y chromosome; sex chromosome evolution