Climate Change and Mountain Building Led to Mammal Diversity Patterns

Climate Change and Mountain Building Led to Mammal Diversity Patterns

  1:22:00 AM    Science Lover

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Travel from the tropics to the poles, and you'll notice that the diversity of mammals declines with distance from the equator. Move from lowland to mountains, and you'll see diversity increase as the landscape becomes more varied. Ecologists have proposed various explanations for these well-known "biodiversity gradients," invoking ecological, evolutionary and historical processes.

Golden-mantled ground squirrel in Utah mountains and fossil squirrel jaw document high rodent diversity in topographically complex western North America today and 16 Million years ago. (Credit: Squirrel photo by Catherine Badgley; Fossil rodent jaw photo by University of California Museum of Paleontology (photo used with permission); Topographic pattern from MyTopo (used with permission))

New findings by University of Michigan researchers John A. Finarelli and Catherine Badgley suggest that the elevational patterns of diversity we see today have appeared, disappeared and reappeared over Earth's history and that these patterns arise from interactions between climate change and mountain building.

The results, published online in the journal Proceedings of the Royal Society B, also have implications for conservation efforts in the face of modern-day global warming, said Finarelli, a visiting assistant professor in the Department of Geological Sciences.

In their study, focused on the Miocene Epoch, which began around 23 million years ago and ended about 5 million years ago, Finarelli and Badgley evaluated diversity for more than 400 rodent species from adjacent regions that differed in geologic history and topography. The geologically "active region," which extends from the Front Range of the Rocky Mountains to the Pacific coast, has experienced several episodes of mountain-building and volcanic activity, and as a result has a topographically complex landscape. In contrast, the relatively flat Great Plains, has been more stable geologically.

The prevailing notion has been that diversity is greater in mountainous regions than in lowlands simply because the topography is more complex. As mountains rise up, new habitats are created, and areas that once were continuous become fragmented. Such changes offer opportunities for new species to arise, increasing diversity.

But climate also enters in, the new study shows. During the Miocene, long-term, global cooling was interrupted by warm intervals. In the active region, diversity increased during a warm interval from 17 to 14 million years ago that coincided with intensified mountain building and volcanic activity, the analysis revealed. During subsequent cooling, diversity declined in the mountains and increased on the plains.

"This pattern suggests that the elevational diversity gradient arises during historical episodes associated with global warming and mountain building," said Badgley, an assistant professor in the Department of Ecology and Evolutionary Biology and a research scientist in the Museum of Paleontology and the Department of Geological Sciences. "This gradient is not a long-term feature of North American biodiversity."

Although the research focused on ancient ecosystems, the findings have implications for modern times, Finarelli said. "Based on our finding that more complex regions are more sensitive to climate change, threatened areas in mountainous regions should be a particular conservation concern, with respect to human-mediated climate change."

The work also highlights the importance of studies that merge the disciplines of paleontology and biogeography, Finarelli said. "By marrying the two subjects, we can gain a better insight into the ecological and evolutionary processes shaping the world around us."

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Hundreds Of New Species Discovered In Eastern Himalayas

Hundreds Of New Species Discovered In Eastern Himalayas

  8:15:00 PM    Science Lover

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Over 350 new species including the world’s smallest deer, a “flying frog” and a 100 million-year old gecko have been discovered in the Eastern Himalayas, a biological treasure trove now threatened by climate change.

Flying frog (Rhacophorus suffry). The bright green, red-footed tree frog was described in 2007. It is a 'flying frog' because long webbed feet allow the species to glide when falling. (Credit: Copyright Totul Bortamuli / WWF Nepal)

A decade of research carried out by scientists in remote mountain areas endangered by rising global temperatures brought exciting discoveries such as a bright green frog that uses its red and long webbed feet to glide in the air.

One of the most significant findings was not exactly “new” in the classic sense. A 100-million year-old gecko, the oldest fossil gecko species known to science, was discovered in an amber mine in the Hukawng Valley in the northern Myanmar.

The WWF report The Eastern Himalayas – Where Worlds Collide details discoveries made by scientists from various organizations between 1998 and 2008 in a region reaching across Bhutan and north-east India to the far north of Myanmar as well as Nepal and southern parts of Tibet Autonomus Region (China).

“The good news of this explosion in species discoveries is tempered by the increasing threats to the Himalayas’ cultural and biological diversity,” said Jon Miceler, Director of WWF’s Eastern Himalayas Program. “This rugged and remarkable landscape is already seeing direct, measurable impacts from climate change and risks being lost forever.”

In December world leaders will gather in Copenhagen to reach an agreement on a new climate deal, which will replace the existing Kyoto Protocol.

The Eastern Himalayas- Where Worlds Collide describes more than 350 new species discovered - including 244 plants, 16 amphibians, 16 reptiles, 14 fish, 2 birds, 2 mammals and at least 60 new invertebrates.

The report mentions the miniature muntjac, also called the “leaf deer,” which is the world’s oldest and smallest deer species. Scientists initially believed the small creature found in the world’s largest mountain range was a juvenile of another species but DNA tests confirmed the light brown animal with innocent dark eyes was a distinct and new species.

The Eastern Himalayas harbor a staggering 10,000 plant species, 300 mammal species, 977 bird species, 176 reptiles, 105 amphibians and 269 types of freshwater fish. The region also has the highest density of Bengal tigers in the world and is the last bastion of the charismatic greater one-horned rhino.

WWF is working to conserve the habitat of endangered species such as snow leopards, Bengal tigers, Asian elephants, red pandas, takin, golden langurs, Gangetic dolphins and one-horned rhinos.

Historically, the rugged and largely inaccessible landscape of the Eastern Himalayas has made biological surveys in the region extremely difficult. As a result, wildlife has remained poorly surveyed and there are large areas that are still biologically unexplored.

Today further species continue to be unearthed and many more species of amphibians, reptiles and fish are currently in the process of being officially named by scientists.

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