Comments on: Extra chromosomes allow all-female lizards to reproduce without males

By: Katharine

Katharine — Tue, 23 Feb 2010 13:42:14 +0000

Shhh. Don’t give female or male gender separatists any ideas.

By: Blackbird

Blackbird — Mon, 22 Feb 2010 22:18:58 +0000

Cool post! It illustrates you can be parthenogenetic (i.e. virgin birth) and sexual (meiotic recombination happens). That’s why the comparison with bdelloids (asexual – apomictic- parthenogens) is not too good. This whiptail system is more akin to some obligatory selfing plants!

By: Bob

Bob — Mon, 22 Feb 2010 14:21:50 +0000

Just a minor point…when the chromosomes are doubled, it makes four chromosomes, each with two sister chromatids, rather than eight chromosomes. In normal diploid species, there is never a 4N stage. When the DNA replicates, sister chromatids are produced, but this doesn’t double the chromosome number.

By: Ed Yong

Ed Yong — Sun, 21 Feb 2010 22:12:13 +0000

Stogoe – yeah, they are. It’s not quite as disastrous as for some other asexual animals. Being hybrids, the original generation received different sets of genes from mother and father and their altered style of meiosis helps to preserve these differences. But they’re still not generating much in the way of new diversity (unlike, say, the rotifers in the articles I linked to at the end). In the grand scheme of things, these whiptails may well be brief evolutionary experiments, transient buds at the tips of the tree of life.
Prof.Pedant – yep, which is why you’ll notice that I never said that the offspring are genetically identical. Nor did I use the word cloning anywhere. :-p

By: Prof.Pedant

Prof.Pedant — Sun, 21 Feb 2010 21:34:18 +0000

“all-female whiptails have a subtly different style of meiosis. They double their chromosomes twice before everything kicks off, creating eight copies of each. During the normal two rounds of cell division, these copies are partitioned two apiece among the four daughter cells”
Between cross-over among the chromosomes and variations in the partitioning of chromosomes I would expect that in recently derived ‘all-female lineages’ not all of the off-spring would be genetically identical….just quite similar.

By: stogoe

stogoe — Sun, 21 Feb 2010 21:20:08 +0000

If these whiptail lizards are just doubling up on their own chromosomes, aren’t they then missing out on the genetic diversity benefits of sexual reproduction?