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
Joint research project on wastewater for reuse examines pond system in Namibia
19.12.2016 | Technische Universität Darmstadt
Scientists produce a new roadmap for guiding development & conservation in the Amazon
09.12.2016 | Wildlife Conservation Society
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
18.01.2017 | Life Sciences
18.01.2017 | Health and Medicine
17.01.2017 | Earth Sciences