Northern conifers youngest of the species

Oct 04, 2012

Dramatic shifts in the planet's climate and geography over millions of years changed the course of evolutionary history for conifer trees, according to a Yale paper in the Proceedings of the National Academy of Sciences.

Yale researchers examined the and 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 led to isolated populations and the formation of new species, especially in mountainous environments where conifer diversity is high.

"Extreme 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 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 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 , 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."

Explore further: Scientists reveal global patterns of specialized feeding in insect herbivores

More information: The study, "Hemisphere-scale Differences in Conifer Evolutionary Dynamics," can be viewed at www.pnas.org/content/early/201… 621109.full.pdf+html

Related Stories

Earth history and evolution

May 03, 2012

In classical mythology, the cypress tree is associated with death, the underworld and eternity. Indeed, the family to which cypresses belong, is an ancient lineage of conifers, and a new study of their evolution affords a ...

Ancient birds from North America colonized the South

Jul 13, 2010

Scientists studying ancient species migration believe northern birds had the ability to colonise continents that southern species lacked. The research, published in Ecography, reveals how the ancient 'land ...

Southern Hemisphere Ants Richer and More Diversified

May 06, 2009

There are fewer species of ants in the northern hemisphere than in the southern hemisphere. This is the conclusion drawn by an international team of scientists that have studied 1,003 local ant assemblages ...

Recommended for you

Baleen whales hear through their bones

4 hours ago

Understanding how baleen whales hear has posed a great mystery to marine mammal researchers. New research by San Diego State University biologist Ted W. Cranford and University of California, San Diego engineer ...

Starving honey bees lose self-control

8 hours ago

A study in the journal of the Royal Society Biology Letters has found that starving bees lose their self-control and act impulsively, choosing small immediate rewards over waiting for larger rewards.

Chimps with higher-ranking moms do better in fights

Jan 28, 2015

For chimpanzees, just like humans, teasing, taunting and bullying are familiar parts of playground politics. An analysis of 12 years of observations of playground fights between young chimpanzees in East ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.