Friday, 11 December 2020

LEMURS OF MADAGASCAR

These sweet babies are lemurs. You may have seen them as the stars in one of DreamWorks animated production Madagascar. 

These lovelies are social and like to live in groups of half a dozen to up to 30 individuals. A female leads the group, or troop, and will likely have mated with the stinkiest — think sexiest — male. 

Once they breed, mamma will give birth to one to a half dozen pups after a gestation period of about 100 to 107 days. The wee pups cling to mamma's belly for the first few weeks of life then crawl up to live on her back for the next few months. By three to six months, the wee ones are weaned and a year to three years later, this pup will be mature and ready to mate. If all goes well, some species can live up to 30 years — rather a long life in the wild.

Lemurs are mammals of the order Primates, divided into 8 families and consisting of 15 genera and around 100 highly diverse species — 105 to be exact. They are native only to the island of Madagascar.

Most lemurs are relatively small, have a pointed snout, large eyes, and a long tail. They are arboreal, living primarily in trees and nocturnal, preferring to be active at night, snacking on leaves, shoots, fruit, flowers, tree bark, nectar and sap.

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. They must have come over to the island clinging to floating vegetation.

Once on the island, the lemur lineage diversified. Now there are at least 105 species of lemur, all endemic to Madagascar. They range in size from just an ounce and just 9 to 11 cm in the case of the Madame Berthe's mouse lemurs to up to 15 to 22 lbs or 7 to 10 kilograms, in the case of the Indri.

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 geographic 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. Understanding where that diversity comes from requires understanding, not just the living world, but the geologic, geographic, and climactic histories that have shaped the evolution of lineages on the island. Now, human history in the making threatens to undo tens of millions of years of evolution in just a few years of political turmoil — unless safeguards can be put in place to protect Madagascar's unique biota from the instabilities of human institutions.

Cooper, A., Lalueza-Fox, C., Anderson, S., Rambaut, A., Austin, J., and Ward, R. (2001). Complete mitochondrial genome sequences of two extinct moas clarify ratite evolution. Nature 409:704-707.

Goodman, S. M., and Benstead, J. P. (2005). Updated estimates of biotic diversity and endemism for Madagascar. Oryx 39(1):73-77.

Evolution Berkeley: https://evolution.berkeley.edu/evolibrary/news/091001_madagascar

Vences, M., Wollenberg, K. C., Vieites, D. R., and Lees, D. C. (2009). Madagascar as a model region of species diversification. Trends in Ecology and Evolution 24(8):456-465.