The Northern Highlands are a mountainous biogeographical

Biogeography

Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...

 region of northern Madagascar

Madagascar

The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

. The region includes the Tsaratanana Massif (with the highest mountain of Madagascar, Maromokotro

Maromokotro

Maromokotro is the highest mountain on Madagascar at high. It is located in the Tsaratanana Massif in the northern part of the island.-External links:* Picture of Maromokotro...

) and smaller nearby massifs such as Marojejy, Anjanaharibe-Sud, and Manongarivo. The Mandritsara Window separates the Northern from the Central Highlands

Central Highlands (Madagascar)

The Central Highlands, Central High Plateau, or Hauts-Plateaux are a mountainous biogeographical region in central Madagascar. They include the contiguous part of the island's interior above 800 m altitude...

 and apparently acts as a barrier to dispersal

Biological dispersal

Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...

 between the two highlands, leading to species pairs such as Voalavo gymnocaudus (Northern Highlands) and Voalavo antsahabensis (Central Highlands). None of the montane endemics of Tsaratanana are shared with the major massifs of the Central Highlands.

Literature cited

• Goodman, S.M., Rakotondravony, D., Randriamanantsoa, H.N. and Rakotomalala-Razanahoera, M. 2005. A new species of rodent from the montane forest of central eastern Madagascar (Muridae: Nesomyinae: Voalavo). Proceedings of the Biological Society of Washington 118(4):863–873.
• Goodman, S.M., Raxworthy, C.J., Maminirina, C.P. and Olson, L.E. 2006. A new species of shrew tenrec (Microgale jobihely) from northern Madagascar. Journal of Zoology 270:384–398.
• Raxworthy, C.J. and Nussbaum, R.A. 1996. Montane amphibian and reptile communities in Madagascar (subscription required). Conservation Biology 10(3):750–756.