 Teiidae (source code)

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= Teiidae
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<Teiidae> is a family of <lizards> within <Lacertoidea>, including the whiptails of <Aspidoscelis>. It is a separate lineage from <Gymnophthalmidae>. Beyond their place in reptile classification, some whiptails offer a striking example of <parthenogenesis>: females produce offspring without fertilization.<Integrated Analyses Resolve Conflicts over Squamate Reptile Phylogeny and Reveal Unexpected Placements for Fossil Taxa by Tod W. Reeder and others>[Results, Lacertoidea]{ref}

In a 2010 study of parthenogenetic <Aspidoscelis>, investigators asked how eggs could retain the parental complement of <chromosomes> and preserve <heterozygosity>. Chromosome imaging and fluorescent probes showed an extra premeiotic doubling, followed by pairing of genetically identical chromosome copies. The cells still underwent <meiosis> and <chromosomal crossover>; reproduction did not simply bypass the entire meiotic program.<Sister chromosome pairing maintains heterozygosity in parthenogenetic lizards by Aracely A. Lutes and others>[Abstract and Figures1–4]{ref}

A simplified genetic example explains the significance. Begin with distinguishable chromosome versions $A$ and $B$. After copying, matching $A$ with another $A$ and $B$ with another $B$ permits exchange between equivalent copies while retaining both parental versions in the unreduced egg. This differs from mechanisms that discard one version and thereby lose <heterozygosity>. The finding concerns particular parthenogenetic <species>; it does not make every member of <Teiidae> an asexual animal.

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