TY - JOUR
T1 - Divergence time estimates for the early history of animal phyla and the origin of plants, animals and fungi
AU - Wang, DYC
AU - Kumar, S
AU - Hedges, SB
PY - 1999/1/22
Y1 - 1999/1/22
N2 - In the past, molecular clocks have been used to estimate divergence times among animal phyla, but those time estimates have varied widely (1200-670 million years ago, Ma). In order to obtain time estimates that are more robust, we have analysed a larger number of genes for divergences among three well-represented animal phyla, and among plants, animals and fungi. The time estimate for the chordate-arthropod divergence, using 50 genes, is 993 ± 46 Ma. Nematodes were found to have diverged from the lineage leading to arthropods and chordates at 1177 ± 79 Ma. Phylogenetic analyses also show that a basal position of nematodes has strong support (P > 99%) and is not the result of rate biases. The three-way split (relationships unresolved) of plants, animals and fungi was estimated at 1576 ± 88 Ma. By inference, the basal animal phyla (Porifera, Cnidaria, Ctenophora) diverged between about 1200-1500 Ma. This suggests that at least six animal phyla originated deep in the Precambrian, more than 400 million years earlier than their first appearance in the fossil record.
AB - In the past, molecular clocks have been used to estimate divergence times among animal phyla, but those time estimates have varied widely (1200-670 million years ago, Ma). In order to obtain time estimates that are more robust, we have analysed a larger number of genes for divergences among three well-represented animal phyla, and among plants, animals and fungi. The time estimate for the chordate-arthropod divergence, using 50 genes, is 993 ± 46 Ma. Nematodes were found to have diverged from the lineage leading to arthropods and chordates at 1177 ± 79 Ma. Phylogenetic analyses also show that a basal position of nematodes has strong support (P > 99%) and is not the result of rate biases. The three-way split (relationships unresolved) of plants, animals and fungi was estimated at 1576 ± 88 Ma. By inference, the basal animal phyla (Porifera, Cnidaria, Ctenophora) diverged between about 1200-1500 Ma. This suggests that at least six animal phyla originated deep in the Precambrian, more than 400 million years earlier than their first appearance in the fossil record.
KW - Cambrian explosion
KW - Fungi
KW - Metazoa
KW - Molecular clock
KW - Plants
UR - http://www.scopus.com/inward/record.url?scp=0033593549&partnerID=8YFLogxK
U2 - 10.1098/rspb.1999.0617
DO - 10.1098/rspb.1999.0617
M3 - Article
C2 - 10097391
SN - 0962-8452
VL - 266
SP - 163
EP - 171
JO - Proceedings of the Royal Society B: Biological Sciences
JF - Proceedings of the Royal Society B: Biological Sciences
IS - 1415
ER -