Rapid burst of plants 90 mln yrs ago set stage for evolutionary explosions in other species

February 10th, 2009 - 3:26 pm ICT by ANI  

Washington, Feb 10 (ANI): A new study has shown that the ancestors of most modern trees diversified extremely rapidly 90 million years ago, setting the stage for the formation of forests that supported similar evolutionary bursts in animals and other plants.

The study, by University of Florida researchers, was based on DNA analysis from living flowering plants.

It focuses on diversification in the rosid clade, a group with a common ancestor that now accounts for one-third of the worlds flowering plants.

The forests that resulted in the rapid burst, provided the habitat that supported later evolutionary diversifications for amphibians, ants, placental mammals and ferns.

The burst of speciation over a 5-million-year span was one of three major radiations of flowering plants, known as angiosperms.

Shortly after the angiosperm-dominated forests diversified, we see this amazing diversification in other lineages, so they basically set the habitat for all kinds of new things to arise, said Pamela Soltis, study co-author and curator of molecular systematics and evolutionary genetics at UFs Florida Museum of Natural History.

Associated with some of the subsequent radiations is even the diversification of the primates, she added.

The study is the first to show the evolutionary relationships of these plants and provide evidence for their rapid emergence and diversification.

Because the diversification happened so quickly, at least in evolutionary terms, molecular methods were needed to sort out the branches of the rosid clades phylogenetic tree, a sort of family tree based on genetic relationships.

Only after sequencing many thousands of DNA base pairs, are genetic researchers able to tease apart the branches and better understand how plant species evolved.

The studys authors sequenced 25,000 base pairs of DNA and sampled a broad range of 104 species from the rosid clade.

According to Doug Soltis, co-author and chair of UFs botany department, I think one thing that becomes very clear from our phylogenetic trees when you look at them closely is that its not just one big explosion of species within the flowering plants. Theres a series of explosions.

The rosid clades diversification is one of at least three bursts in the early evolution of flowering plants.

More than 300,000 species of angiosperms exist, classified into an estimated 15,000 genera and more than 400 families.

Understanding how these plants are related is a large undertaking that could help ecologists better understand which species are more vulnerable to environmental factors such as climate change. (ANI)

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