Yale researchers examined the fossil record and genetic makeup of 489 out of more than 600 living conifer species and discovered that while most conifers belong to ancient lineages, most Northern Hemisphere species, including the majority of pines and spruces, appeared within the past 5 million years.
They argue that the migration of tree species and the contraction and expansion of their ranges in response to glacial cycles led to isolated populations and the formation of new species, especially in mountainous environments where conifer diversity is high.
"Extreme climatic shifts through time may have favored the replacement of older lineages with those better adapted to cooler and drier conditions," said Andrew Leslie, the study's co-author and a Yale postdoctoral associate, "resulting in high turnover rates and the disproportionate loss of ancient lineages."
The researchers also found that the lineages of existing conifers in the Southern Hemisphere are millions of years older than their counterparts in the Northern Hemisphere, and believe it is owing to fragmented ranges and mild, wetter habitats that favored their survival.
"The evolutionary history of conifers reflects a complex set of environmental interactions," said Peter Crane, a co-author, professor of botany and dean of the Yale School of Forestry & Environmental Studies. "Nevertheless, we found large-scale and consistent differences between the diversification of southern and northern conifer clades."
The majority of existing conifer species belongs to lineages that diversified during the Cenozoic Era, over 65 million years. Conifers such as firs, hemlocks, larches, pines, spruces (Pinaceae family), junipers and cypresses (Cupressoideae) are found across the Northern Hemisphere, whereas evergreens in the Araucariaceae and Podocarpaceae families and Callitroideae subfamily are found primarily in Argentina, Australia, New Guinea and New Zealand.
Michael Donoghue, a co-author of the study and Sterling Professor of Ecology and Evolutionary Biology, said temperate rainforests and broadleaf evergreen forests were common before the Pleistocene Epoch, which spanned 2.5 million years and ended 11,000 years ago, and are still present in New Zealand and in parts of Australia and South America.
"These now-fragmented habitats are among those in which older conifer lineages adapted to warmer or wetter climates and have survived at high diversity," he said. "The evolutionary histories of organisms are shaped by many factors, but this study suggests that global-scale geographic features can leave an unexpected imprint in the way in which groups evolve and diversify."
The study, "Hemisphere-scale Differences in Conifer Evolutionary Dynamics," can be viewed at http://www.pnas.org/content/early/2012/09/12/1213621109.full.pdf+html?with-ds=yes
David DeFusco | EurekAlert!
New research recovers nutrients from seafood process water
31.10.2018 | Chalmers University of Technology
Plant Hormone Makes Space Farming a Possibility
17.10.2018 | Universität Zürich
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly
The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
14.11.2018 | Life Sciences
14.11.2018 | Earth Sciences
14.11.2018 | Medical Engineering