Dnasis online dating
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.].One of the most significant advances common to these new methods is the departure from the molecular clock assumption, which in many cases does not strictly hold.Another advance is the use of time constraints at multiple nodes, rather than the assignment of a discrete time value to a particular node, for rate calibration.This is useful because of the various uncertainties in divergence time estimations based on fossil evidence.However, the fossil records of bony fishes may not adequately provide effective time constraints at multiple nodes.We explored an alternative source of time constraints in teleostean phylogeny by evaluating a biogeographic hypothesis concerning freshwater fishes from the family Cichlidae (Perciformes: Labroidei).
Among the 54 fish taxa that we sampled, we newly determined the sequence data for six cichlid species.
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 .
The 10 cichlid taxa that we analyzed (Table ) cover species from major Gondwana-origin landmasses.