Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The effect of climate change on the patterns of bird distribution east and west of Wallace's Line

10.04.2008
Indo-Malayan region is one of the richest bird species areas in the world. Researchers in Universiti Malaysia Sarawak found that sea level and climate changes during the last glacial period played a key role in the diversification of birds in this region where bird species gradually diversified when sea levels were low. This continues until today.

The evolutionary processes leading to the development of new species, their extinction, immigration and emigration may be influenced by both historical and contemporary mechanisms.

For instance, falling sea levels and climate during the last glacial period (about 18,000 to 10,000 years before present) had developed a savanna-like habitat in the "exposed" land area that connects the current landmasses in Sundaland (the Malay Peninsula, Sumatera, Java and Borneo). Such massive changes are predicted to have played a key role in influencing faunal composition and geographic distribution of species in the Southeast Asia region.

The current pattern of bird fauna distribution is predicted to fit the proposed landbridges or dispersal routes that appear due to the physical splitting of once continuous area by the processes of continental drift and changes in sea levels during the Last Glacial Maximum (LGM).

A study head by Asociate Professor Dr Mustafa Abdul Rahman of Universiti Malaysia Sarawak (UNIMAS), was conducted to compare the patterns of bird's species distribution in the Wallacea, Sunda and Sahul Shelf (the subregions and island of Thailand, Peninsular Malaysia, Sumatra, Borneo, Java, Bali, Lombok, Sulawesi, the Philippines and New Guinea).

Data on bird fauna in Southeast Asia, as well as New Guinea, was taken from documented field guides. A total of 88 families (with 479 genera and 1718 species) of resident breeding birds were collated (migrant species excluded). This accounts for about 17.6% of the total number of bird species in the world, making this region one of the richest bird's species regions in the world.

Analysis of species similarity among the 10 subregions/island in the study supports the model of biogeographic divergence based on historical changes in sea levels. At each of the three subgroups, the distribution of land and water birds revealed a major transition line that fitted with the glacial model.

New Guinea and the Philippines showed little species resemblance with the rest of the subregions/islands in this study. This finding agrees with the geographic position of New Guinea lying on the continental shelf of Australia and sharing much of its fauna with that island-continent.

The Philippines, on the other hand, was never joined to the Sunda Shelf's islands and mainland Asia during the last glacial period, because of the presence of deep water channels (>200m deep) that separate Philippines from the region. Even when sea level was predicted to have dropped as much as 160 m during the glacial periods, that still failed to connect the Philippines (except Palawan) archipelago with Borneo and the rest of the region.

Their findings suggest that bird's species diversification took place across a range of glacial stages, with ancient diversification between families taking place at a time of lower sea level. Diversification within families occurs at a time when Sumatra moved away from mainland Asia to form a group with Borneo. Diversification within species related closely to mainland Asia.

The pattern of distribution suggests that the descendant that crossed over from mainland Asia or remained in Sumatra during the glacial and inter-glacial period may have perished and became extinct, especially those families that have few species and shows vulnerability to environmental changes and human intervention.

While the findings support the glacial model of Southeast Asia's geographical distribution of biodiversity over space and time, it does not agree with the proposed faunal boundaries of Wallace’s line that separates the zoogeographical regions of Asia and Australasia -- the finding does not point to the major faunal transition between Bali and Lombok as well as between Borneo and Sulawesi. Instead their findings at family level agree with Mayr's line which cuts at the west of Lombok, allowing Lombok to be grouped with Java and Bali.

The bird species composition in Bali shows more resemblance to Java and Borneo while Lombok shares more of its genera and species with Sulawesi; and the bird compositions of Borneo and Sulawesi have little resemblance even at the family level even though the two islands are separated by a 50 km wide Straits of Makasar.

Resni Mona | ResearchSEA
Further information:
http://www.unimas.my/
http://www.researchsea.com

More articles from Earth Sciences:

nachricht Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>