Deeply conserved synteny resolves early events in vertebrate evolution

Area of Science:

• Genomics
• Evolutionary Biology
• Comparative Genomics

Background:

• The role of ancient whole-genome duplications in early vertebrate evolution is widely accepted but poorly understood.
• Key aspects like the number, timing, and mechanisms of these events remain elusive.

Purpose of the Study:

• To reconstruct the genomic history of vertebrates.
• To elucidate the number, timing, and mechanisms of ancient genome duplications.

Main Methods:

• Comparative genomics using a new chromosome-scale sequence of the invertebrate chordate amphioxus.
• Analysis of chromosomal conserved synteny patterns.

Main Results:

• Vertebrate karyotypes are derived from 17 ancestral chordate and 19 ancestral bilaterian linkage groups through fusion, rearrangement, and duplication.
• Two distinct ancient duplications were resolved.
• The first duplication, an autotetraploidization, is shared by all extant vertebrates (mid/late Cambrian).
• The second duplication, an allotetraploidization from extinct progenitors, is specific to jawed vertebrates (mid-late Ordovician).

Conclusions:

• The study resolves the history of two major ancient genome duplications in vertebrate evolution.
• These genomic events correlate with major diversification periods in vertebrate lineages.