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    Dating origin orchidaceae barbra walters dating a married senator

    The diversification of appears even more correlated to late Tertiary climatic fluctuations than previously suggested.With the incorporation of new fossils in the orchid phylogeny and the use of a method that is arguably more adequate given the present data, our results represent the most up-to-date estimate of divergence times in orchids. A correct time estimation is essential for our understanding of the mechanisms underlying the diversification of orchids, and could contribute to discern between alternative hypotheses of diversification - such as significant increases in speciation rates temporally correlated to climatic changes, tectonic events, or radiation of pollinators., the Orchidaceae lack a definitive fossil record and thus many aspects of their evolutionary history remain obscure.Here we report an exquisitely preserved orchid pollinarium (of Meliorchis caribea gen. nov.) attached to the mesoscutellum of an extinct stingless bee, Proplebeia dominicana, recovered from Miocene amber in the Dominican Republic, that is 15–20 million years (Myr) old.Moreover, two new orchid fossils described in 2009 have not yet been incorporated in a molecular dating analysis.Here we compare the ages of major orchid clades estimated under two widely used methods, a Bayesian relaxed clock implemented in BEAST and Penalized Likelihood implemented in r8s.Our results indicate that the most recent common ancestor of extant orchids lived in the Late Cretaceous (76–84 Myr ago), and also suggest that the dramatic radiation of orchids began shortly after the mass extinctions at the K/T boundary.

    Taxonomy of the orchid family is difficult and dynamic, because it is so large (now approximately 27,000 accepted species) and many new species are described annually (see references listed at the Orchid Tree, Florida Museum of Natural History: ATOLrefs.htm; Cameron 1999 and references therein; Williams 2013).While some have single flowers, most have inflorescences with multiple flowers arranged around a stalk.The flowers are pollinated by insects, in some cases by birds, and it is common for flowers to have petals modified into perches or guides for their pollinators.The Orchidaceae have about 28,000 currently accepted species, distributed in about 763 genera.The determination of which family is larger is still under debate, because verified data on the members of such enormous families are continually in flux.

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