Morphological studies have suggested that Ailurops ursinus is the sister taxon to all other phalangerids. Another species of interest is Strigocuscus celebensis, whose morphologically based taxonomic affinity has habitually been with trichosurins. This study uses nuclear sequence data from the breast cancer and ovarian cancer susceptibility gene 1 (BRCA1) to test previous mitochondrial DNA results and uses relaxed molecular clock methods to estimate divergence dates. celebensis and this clade as sister to Phalangerini.
The degree of penalization is determined by a smoothing parameter, the value of which is obtained objectively through a cross-validation procedure. Others assume that branch-specific rates are drawn from a single underlying distribution, such as a lognormal, gamma, or exponential distribution, the parameters of which are estimated from the data (Drummond et al. 2006; Rutschmann 2006), and their performance has been assessed in a number of studies (e.g., Ho et al. Observed genetic divergence is the product of 2 components (the substitution rate and the time elapsed) that cannot be separated without additional, independent information. The first are calibrations that impart temporal information about nodes in the evolutionary tree.In ‘The Biology of Australian Possums and Gliders’. CO;2&atitle=Periotic morphology in the trichosurin possums Strigocuscus celebensis and Wyulda squamicaudata (Diprotodontia, Phalangeridae) and a revised diagnosis of the tribe Trichosurini.&title=American Museum Novitates&date=2003&volume=3414&spage=1&epage=cf Article2ecfc1997462761$func [email protected]&aulast=Crosby&aufirst=K." target="_blank" (1987). • : With the exception of the age of the angiosperms themselves, these age estimates are generally younger than other recent molecular estimates and very close to dates inferred from the fossil record.We also provide dates for all major angiosperm clades (including 45 orders and 335 families [208 stem group age only, 127 both stem and crown group ages], sensu APG III).The molecular clock was first tested in 1962 on the haemoglobin protein variants of various animals, and is commonly used in molecular evolution to estimate times of speciation or radiation.