The genome of the green anole lizard and a comparative analysis with birds and mammals

Abstract

The evolution of the amniotic egg was one of the great evolutionary innovations in the history of life, freeing vertebrates from an obligatory connection to water and thus permitting the conquest of terrestrial environments1. Among amniotes, genome sequences are available for mammals2 and birds3–5, but not for non-avian reptiles. Here we report the genome sequence of the North American green anole lizard, Anolis carolinensis. We find that A. carolinensis microchromosomes are highly syntenic with chicken microchromosomes, yet do not exhibit the high GC and low repeat content that are characteristic of avian microchromosomes3. Also, A. carolinensis mobile elements are very young and diverse – more so than in any other sequenced amniote genome. This lizard genome’s GC content is also unusual in its homogeneity, unlike the regionally variable GC content found in mammals and birds6. We describe and assign sequence to the previously unknown A. carolinensis X chromosome. Comparative gene analysis shows that amniote egg proteins have evolved significantly more rapidly than other proteins. An anole phylogeny resolves basal branches to illuminate the history of their repeated adaptive radiations.

Diversification in wild populations of the model organism Anolis carolinensis: A genome‐wide phylogeographic investigation

“…We find novel evidence for a step‐wise pattern of northward diversification out of Florida, a sister–group relationship between two major mainland clades, and gene flow between Florida and the mainland. The individual sequenced by the Broad Institute for the green anole genome project was collected in South Carolina (Alföldi et al., 2011); future resequencing efforts should reveal if it is indeed representative of the rest of the species in terms of genomic structure.…”

“…The green anole lizard ( Anolis carolinensis ) was the first nonavian reptile to have a complete genome sequence (Alföldi et al., 2011) and is an indispensable laboratory model for biomedical fields such as reproductive endocrinology (Lovern, Holmes, & Wade, 2004; Wade, 2012) and appendage regeneration (Hutchins et al., 2014). However, unlike studies using established models such as the house mouse ( Mus musculus ), which rely on inbred strains, green anole laboratory protocols are based on wild‐caught individuals.…”

Reassessment of genome size in turtle and crocodile based on chromosome measurement by flow karyotyping: close similarity to chicken

“…In contrast to HSA, whose smaller chromosomes sorted to both A and B groups, it is found that the larger chromosomes in GGA, TSC and CNI tend to have a lower than average GC content, whereas the smaller chromosomes have a higher than average GC content (figure 2a). ACA does not show this variation in GC content by chromosome size [11], suggesting that a common ancestor of bird, turtle and crocodile had two types of chromosomes correlated with chromosome size and GC content after divergence from the squamate ancestor. …”

“…ACA is 1.78 Gb in size with a 40.3 per cent total GC content according to the genome sequence data [11]. ACA has a few microchromosomes that are conserved between ACA and GGA, and that may have arisen in the reptile ancestor [11].…”

Pax2 modulates proliferation during specification of the otic and epibranchial placodes

“…We next attempted to identify the Pax8 gene in the chicken genome; BLAST searches toward whole genome assemblies (version 2.1 available at the Ensembl Genome Browser; versions 3.0, 3.1, and 3.2 available at The Genome Institute of Washington University; International Chicken Sequencing Consortium, 2004) using both human, zebrafish, and mouse Pax8 peptide sequences as queries only identified the chick Pax2 and Pax5 loci previously annotated. We also analysed genome assemblies of other diaspid species (zebra finch, turkey, and anole lizard) available at Ensembl (Warren et al, 2010;Alfoldi et al, 2011) and garter snake genome sequences (Schwartz et al, 2010) as well as publicly available transcriptome sequences (Tzika et al, 2011). In all these searches, no Pax8 orthologous sequence could be placed into the Pax8 clade in the molecular phylogenetic tree (Fig.…”