Related Experiment Video
Updated: Oct 10, 2026

Generation of Chimeric Axolotls with Mutant Haploid Limbs Through Embryonic Grafting
Published on: January 29, 2020
Rooting a phylogeny with homologous genes on opposite sex chromosomes (gametologs): a case study using avian CHD
1Museum of Zoology, University of Michigan, USA. jaime.garcia-moreno@uni-konstanz.de
Abstract:
We describe a previously unrecognized form of gene homology using the term "gametology," which we define as homology arising through lack of recombination and subsequent differentiation of sex chromosomes. We demonstrate use of gametologous genes to root each other in phylogenetic analyses of sex-specific avian Chromo-helicase-DNA binding gene (CHD) sequences. Phylogenetic analyses of a set of neognath bird sequences yield monophyletic groups for CHD-W and CHD-Z gametologs, as well as congruent relationships between these two clades and between them and current views of avian taxonomy. Phylogenetic analyses including paleognath bird CHD sequences and rooting with crocodilian CHD sequences, suggest an early divergence for paleognath CHD within the avian CHD clade. Based on our CHD analyses calibrated with avian fossil dates, we estimate the divergence between CHD-W and CHD-Z at 123 MYA, suggesting an early differentiation of sex chromosomes that predates most extant avian orders. In agreement with the notion of male-driven evolution, we find a faster rate of change in male-linked CHD-Z sequences.
Related Concept Videos
Evolutionary Relationships through Genome Comparisons
The Ratio of X Chromosome to Autosomes
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Lampbrush Chromosomes
LBCs are made up of two pairs of conjugating homologous chromatids. Each chromatid consists of alternatively positioned regions of condensed-inactive chromatin and loosely placed-active side loops, which can be contracted and extended. The loops resemble the...
Synteny and Evolution
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral chromosome underwent...
Gene Evolution - Fast or Slow?
In contrast, regions which code...
Crossing Over
