Dnasis online dating
However, the fossil records of bony fishes may not adequately provide effective time constraints at multiple nodes.
The long PCR and subsequent short PCRs were performed as described previously [ DNA polymerase (Takara).Because freshwater fishes do not disperse easily through saltwater, their evolution may be tightly linked to the geological history of the landmasses on which they evolved .Cichlids (order Perciformes: family Cichlidae) are freshwater fishes that are mainly distributed in landmasses of Gondwanaland origin (Africa, South and Central America, Madagascar, and Indo/Sri Lanka) .In general, the occurrence of the earliest fossil assignable to a particular branch can define the lower boundary of divergence time for the node at which this branch departed from its sister branch .However, when the corresponding fossil data are inadequate or sparse, the lower time boundary based on such data could considerably postdate the true divergence time, potentially leading to inaccurate or imprecise dating results .In general, fossils of bony fishes are not considered well preserved.
Of the 425 teleostean families, 181 families do not have a fossil record.
The results of the phylogenetic analyses and divergence time estimations between continental cichlid clades were much more congruent with Gondwanaland origin and Cretaceous vicariant divergences than with Cenozoic transmarine dispersal between major continents.
We propose to add the biogeographic assumption of cichlid divergences by continental fragmentation as effective time constraints in dating teleostean divergence times.
The 10 cichlid taxa that we analyzed (Table ) cover species from major Gondwana-origin landmasses.
In addition, we chose 31 other teleosts, nine basal actinopterygians, and two sarcopterygians.
We conducted divergence time estimations among teleosts by incorporating these additional time constraints and achieved a considerable reduction in credibility intervals in the estimated divergence times.].