When was madagascar formed

Humans have lived in Madagascar only for about 1, years. The first settlers on the island are believed to have arrived from Indonesia in Southeast Asia. For centuries, many small kingdoms ruled different areas of the island. France invaded the island in In , Madagascar finally became an independent nation. All rights reserved. Personality Quizzes.

Funny Fill-In. Amazing Animals. Weird But True! Party Animals. Try This! Explore More. Government of Madagascar. Madagascar Tourism. UN news about Madagascar. Republic of Madagascar Capital: Antananarivo. Mr Rajoelina earlier ran Madagascar as head of an interim authority in Read full media profile. Image source, Getty Images. French troops suppressed an uprising in One key line of evidence for investigating biogeography is phylogenetics.

We can use evidence gathered from living and fossil organisms to reconstruct their phylogeny — or evolutionary relationships. These phylogenies, combined with an understanding of the geologic history of a particular region, can help us figure out which lineages are where they are because of vicariance and which are there because of dispersal.

For an example, examine the diagram below. One land mass splits sequentially into three separate islands, and then a mountain range rises on one of these islands, effectively splitting it. Now imagine that additional tectonic action causes one more split. After that split, some members of species C disperse to the new island, and they evolve into a separate species stage 5 in the diagram.

It is most closely related to C, but it lives on an island that split off from a distant land mass. This suggests that E must have arrived at its present location by dispersal. So what about Madagascar? Do the phylogenies of Madagascar natives and their close relatives suggest that vicariance or dispersal has been at work? There are certainly some examples of vicariance. For example, the elephant bird — a ten foot tall relative of the ostrich that went extinct several hundred years ago — was endemic to Madagascar.

Phylogenetic, genetic, and fossil evidence all suggest that the elephant bird, along with the ostrich, arrived on Madagascar and India when these land masses were still connected to Australia and Antarctica via a land bridge. When India and Madagascar split, the elephant bird wound up surviving on Madagascar, while the ostrich was carried north with India and was eventually introduced to Eurasia when India collided with this continent. The presence of the elephant bird on Madagascar can be chalked up to vicariance; it was living on Madagascar land already, when Madagascar broke off of India.

However, most of the species on Madagascar today seem to be descended from individuals that dispersed there from Africa long after Madagascar was established as a separate island. For example, phylogenetic, genetic, and anatomical evidence all suggest that lemurs split from other primates on Africa around 62 million years ago and that the ancestral lemur lineage had dispersed to Madagascar by around 54 million years ago.

Once on the island, the lemur lineage diversified. Now there are at least 50 species of lemur, all endemic to Madagascar.

The evolutionary and biogeographic processes experienced by the lemurs are not unusual. Madagascar is home to many groups of endemic organisms with close within-group relationships. The simplest — or most parsimonious — explanation for this pattern is that, like the lemurs, the groups first arrived on the island by dispersal as a single lineage and then rapidly diversified.

This diversification was likely spurred on by other geologic and climactic characteristics of Madagascar. The east coast of the island is lined with a mountain range — and this causes different parts of the island to get drastically different amounts of rain. Hence, the island is made of many different habitat types — from deserts to rainforests — that have shifted and changed over the past 88 million years. This likely provided many opportunities for subpopulations to become isolated and evolve traits for specializing in different niches.

And that likely encouraged lineages to diversify. Today, Madagascar is one of the most diverse places on Earth.