Navigation Links
Latitude and rain dictated where species lived
Date:5/12/2011

PROVIDENCE, R.I. [Brown University] Aggregating nearly the entire landmass of Earth, Pangaea was a continent the likes our planet has not seen for the last 200 million years. Its size meant there was a lot of space for animals to roam, for there were few geographical barriers, such as mountains or ice caps, to contain them.

Yet, strangely, animals confined themselves. Studying a transect of Pangaea stretching from about three degrees south to 26 degrees north (a long swath in the center of the continent covering tropical and semiarid temperate zones), a team of scientists led by Jessica Whiteside at Brown University has determined that reptiles, represented by a species called procolophonids, lived in one area, while mammals, represented by a precursor species called traversodont cynodonts, lived in another. Though similar in many ways, their paths evidently did not cross.

"We're answering a question that goes back to Darwin's time," said Whiteside, assistant professor of geological sciences at Brown, who studies ancient climates. "What controls where organisms live? The two main constraints are geography and climate."

Turning to climate, the frequency of rainfall along lines of latitude directly influenced where animals lived, the scientists write in a paper published this week in the online early edition of the Proceedings of the National Academy of Sciences. In the tropical zone where the mammal-relative traversodont cynodonts lived, monsoon-like rains fell twice a year. But farther north on Pangaea, in the temperate regions where the procolophonids predominated, major rains occurred only once a year. It was the difference in the precipitation, the researchers conclude, that sorted the mammals' range from that of the reptiles.

The scientists focused on an important physiological difference between the two: how they excrete. Mammals lose water when they excrete and need to replenish what they lose. Reptiles (and birds) get rid of bodily waste in the form of uric acid in a solid or semisolid form that contains very little water.

On Pangaea, the mammals needed a water-rich area, so the availability of water played a decisive role in determining where they lived. "It's interesting that something as basic as how the body deals with waste can restrict the movement of an entire group," Whiteside said.

In water-limited areas, "the reptiles had a competitive advantage over mammals," Whiteside said. She thinks the reptiles didn't migrate into the equatorial regions because they already had found their niche.

The researchers compiled a climate record for Pangaea during the late Triassic period, from 234 million years ago to 209 million years ago, using samples collected from lakes and ancient rift basins stretching from modern-day Georgia to Nova Scotia. Pangaea was a hothouse then: Temperatures were about 20 degrees Celsius hotter in the summer, and atmospheric carbon dioxide was five to 20 times greater than today. Yet there were regional differences, including rainfall amounts.

The researchers base the rainfall gap on variations in the Earth's precession, or the wobble on its axis, coupled with the eccentricity cycle, based on the Earth's orbital position to the sun. Together, these Milankovitch cycles influence how much sunlight, or energy, reaches different areas of the planet. During the late Triassic, the equatorial regions received more sunlight, thus more energy to generate more frequent rainfall. The higher latitudes, with less total sunlight, experienced less rain.

The research is important because climate change projections shows areas that would receive less precipitation, which could put mammals there under stress.

"There is evidence that climate change over the last 100 years has already changed the distribution of mammal species," said Danielle Grogan, a graduate student in Whiteside's research group. "Our study can help us predict negative climate effects on mammals in the future."


'/>"/>

Contact: Richard Lewis
Richard_Lewis@brown.edu
401-863-3766
Brown University
Source:Eurekalert  

Related biology news :

1. Evidence is weak for tropical rainforest 65 million years ago in Africas low-latitudes
2. Better food makes high-latitude animals bigger
3. Iron and biological production in the high-latitude North Atlantic
4. Earths biodiversity: What do we know and where are we headed?
5. Water, water, everywhere… but is it safe to drink?
6. Where did flowers come from?
7. Water, water everywhere focus of new sustainability project
8. Where unconscious memories form
9. Where did you get those eyes and that brain?
10. Tuning into cell signals that tell where sensory organs will form inside the ear
11. Where do the drugs go?
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Latitude and rain dictated where species lived
(Date:2/9/2016)... -- Vigilant Solutions announces today that an agency used its ... lead in a difficult homicide case. The agency then used ... suspect vehicle. Due to the ongoing investigation, the agency name ... the agency,s request. --> --> ... found deceased at an intersection here in the City. He ...
(Date:2/4/2016)... -- The field of Human Microbiome research and ... hubs of the biotechnology industry. While the Human ... human microbiota, have garnered a lot of attention ... has literally exploded in terms of both basic ... on biomedical aspects of research, development, and commercial ...
(Date:2/3/2016)... , Feb. 3, 2016 Vigilant Solutions ... Police Department in Missouri solved ... plate reader (LPR) data from Vigilant Solutions. ... case in which the victim was walking out of a convenience store and ... space next to his vehicle, striking his vehicle and ...
Breaking Biology News(10 mins):
(Date:2/11/2016)... ... February 11, 2016 , ... ... a new agreement with Bankok,Thailand-based Global Stem Cells Network (GSCN) to distribute exosome ... Latin American countries, including Mexico, Costa Rica, Dominican Republic, Colombia, Argentina, Nicaragua, Panama, ...
(Date:2/10/2016)...  The Maryland House of Delegates and House Speaker ... of Maryland School of Medicine Dean E. Albert ... Medical System President and CEO Robert Chrencik , ... honor given to the public by the leader of ... and Mr. Chrencik for their contributions to our ...
(Date:2/10/2016)...  IsoRay, Inc. (NYSE MKT: ISR), a medical technology ... applications for the treatment of prostate, brain, lung, head ... results for the second quarter and six months of ... --> --> Revenue was ... which ended December 31, 2015, a 12% increase compared ...
(Date:2/10/2016)... ... February 10, 2016 , ... HOLLOWAY ... of Pharmaceutical Engineering (ISPE) Rocky Mountain Chapter 21st Annual Vendor Exhibition on Thursday, ... more than 100 tables for its annual event, which will run from 3:00 ...
Breaking Biology Technology: