The World's fourth largest island reminds a large open-air museum and a sanctuary of nature. No other region on Earth contains such a high number of endemic species, that is, species that occur only on Madagascar and nowhere else.
Treefrog from northern Madagascar's rainforest (Boophis sambirano). This species belongs to a large radiation of frogs that probably colonized Madagascar from Asia, about 60-70 million years ago. Photo: Miguel Vences
Verreaux's sifaka carrying a young, Propithecus verreauxi. Photo: Miguel Vences
But how did these remarkable animals arrive on Madagascar? For long time, this question was unsolved and had been considered to be one of the largest biogeographic mysteries. Madagascar is isolated since the Cretaceous period from all other continents. Fossils from the end of that period, around 70 million years old, suggest a very different assemblage of ancient animals without any obvious relationships to Madgascar's current fauna: dinosaurs and marsupial mammals, lungfishes and gars, vegetarian crocodiles and giant toads walked on the island in that period.
Many species colonized Madagascar 60-70 million years before present
German researchers of the University of Braunschweig (TU Braunschweig) have worked for many years on the origins of Madagascar's unique animals, and this originally puzzling question has now been largely solved. In two articles published in parallel in the renowned scientific journal "Proceedings of the National Academy of Sciences of the USA (PNAS)" two research teams analyse the origins of Madagascar's vertebrates. The molecular genetic data generated in Braunschweig allowed to apply a so-called "molecular clock" dating of the colonization history and revealed that the origins of almost all of these unique animals are comparatively young, geologically speaking. "The ancestors of most of the striking animals attracting today's tourists to Madagascar arrived on the island around 60-70 million years before present. They all rafted over the ocean, mainly out of Africa" comments Prof. Miguel Vences who led the German team of researchers.
Probably during large thunderstorms, rafts such as big trees in Africa and Asia, were torn into the sea and some of them eventually arrived on Madagascar's shores – along with some miraculously surviving animals that found themselves like ancient versions of Robinson Crusoe in a totally unknown environment to which many of them succeeded to adapt.
Humans, the most dangerous species, reached Madagascar only 2000 years ago
The overseas dispersal theory is also supported by a second set of analyses: Statistically, Asian animals arrived on Madagascar mainly in ancient times when when only a low sea strait separated the two land masses. And colonizations from Africa became rare after a change in the regime of prevailing winds: Large storms, named Cyclones in the Indian Ocean, are an effective means to push large rafts such as trees over the ocean, but at present they typically move in the "wrong" direction, from Madagascar to Africa, and therefore do not favor colonizations. For about 15 million years, only very new new animal groups arrived in Madagascar, and the fauna of the island therefore could evolve in almost complete isolation, evolving the amazing specializations that we observe today. The most influential factor in their diversification was the tropical rainforest: Only those animal groups that adapted to this habitat succeeded in diversifying into the striking variety of species typical for Madagascar.
One animal, however, managed to arrive in very recent times to Madagascar: Humans only arrived in Madagascar about 2000 years ago and quickly disturbed the fragile ecosystem of the island. At that time, giants walked on Madagascar: giant tortoises, giant lemurs and giant flightless birds – all were hunted to extinction by humans within a few centuries. And today, the majority of Madagascar's unique wildlife are at risk by slash-and-burn agriculture, illegal logging and hunting. "Only intensified efforts of nature conservation can save this nature sanctuary that was assembled over a long period of 70 million years by animals stranding on its shores.", adds Angelica Crottini a biologist who did most of the laboratory analyses at Braunschweig.Crottini, A., O. Madsen, C. Poux, A. Strauß, D.R. Vieites, M. Vences (2012): Vertebrate time-tree elucidates the biogeographic pattern of a major biotic change around the K–T boundary in Madagascar. – Proceedings of the National Academy of Sciences of the USA, in press.
doi/10.1073/pnas.1113993109Contact: Prof. Dr. Miguel Vences
High-resolution versions of the same photographs can be downloaded at the following link: http://www.mvences.de/Vences_press_release_2012_photos.zip
Dr. Elisabeth Hoffmann | idw
Further reports about: > Boophis sambirano > Cretaceous period > Madagascar > Madagascar's rainforest > Molecular Target > Poison frogs > Proceedings of the National Academy of Sciences > Propithecus verreauxi > Verreaux's sifaka > colorful cichlid fishes > giant snakes > miniature chameleons > treefrog
Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
18.10.2017 | Materials Sciences
18.10.2017 | Physics and Astronomy
18.10.2017 | Physics and Astronomy