Journal
GENOME BIOLOGY AND EVOLUTION
Volume 6, Issue 10, Pages 2681-2696Publisher
OXFORD UNIV PRESS
DOI: 10.1093/gbe/evu212
Keywords
amphioxus; Branchiostoma; Asymmetron; chordate evolution; transcriptome; innate immunity
Categories
Funding
- NSF [EIA-0216467]
- Rice University
- Sun Microsystems
- Sigma Solutions, Inc.
- Extreme Science and Engineering Discovery Environment (XSEDE) - National Science Foundation [OCI-1053575]
- Office of Science of the U.S. Department of Energy [DE-AC02-05CH11231]
- University of California, San Diego academic senate grant [MBR099S]
- National Science Council Taiwan [NSC101-2923-B-001-004-MY2, NSC102-2311-B-001-011-MY3]
- Academia Sinica Taiwan [AS-98-CDA-L06]
- Direct For Biological Sciences
- Division Of Integrative Organismal Systems [1353688] Funding Source: National Science Foundation
Ask authors/readers for more resources
Cephalochordates, the sister group of tunicates plus vertebrates, have been called living fossils due to their resemblance to fossil chordates from Cambrian strata. The genome of the cephalochordate Branchiostoma floridae shares remarkable synteny with vertebrates and is free from whole-genome duplication. We performed RNA sequencing from larvae and adults of Asymmetron lucayanum, a cephalochordate distantly related to B. floridae. Comparisons of about 430 orthologous gene groups among both cephalochordates and 10 vertebrates using an echinoderm, a hemichordate, and a mollusk as outgroups showed that cephalochordates are evolving more slowly than the slowest evolving vertebrate known (the elephant shark), with A. lucayanum evolving even more slowly than B. floridae. Against this background of slow evolution, some genes, notably several involved in innate immunity, stand out as evolving relatively quickly. This may be due to the lack of an adaptive immune system and the relatively high levels of bacteria in the inshore waters cephalochordates inhabit. Molecular dating analysis including several time constraints revealed a divergence time of similar to 120 Ma for A. lucayanum and B. floridae. The divisions between cephalochordates and vertebrates, and that between chordates and the hemichordate plus echinoderm clade likely occurred before the Cambrian.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available