Madagascar is a 144 million acre island located off the East of Africa. The island split from the African continent around 160 million years ago. This isolation led to the evolution of endemic species. The island houses 250,000 species, about 70% of them are endemic.

Madagascar

Because of its large size, Madagascar has a wide range of ecosystems, including rain forest, dry deciduous forests, spiny thickets, amongst others. Most of these ecosystems are considered to be in danger. According to the World Wildlife organization 97% of the dry deciduous forest of Madagascar have been depleted and destroyed since the first human settlement on the island. Because it covers a large portion of the island, this presentation will discuss the dry deciduous forest of Madagascar (orange section below).

Western Dry Deciduous Forest

Dry Deciduous Forest: Orange

The climate of the western dry deciduous forest is tropical. Temperatures range from an average maximum of 30°C to 33oC and an average minimum of 8° to 21oC. There are defined wet and dry seasons. Most of the precipitation happens between the months of October to April. A lot of the forests used to be tertiary limestone but it has been degraded over time. Now most of the western dry deciduous forests are formed by grasslands and secondary forests that have been extensively depleted. A portion of the secondary grasslands was created as vegetation was burned and it is now inhabitable for species that used to live there. Elevation rises as we move to east, but remains barely above sea level from the northern to the southern side of the island. Throughout the western side, canyons divide forests, separating flora and fauna.

Specialist species

Sifakas are considered to be a specialist species. They don't travel because theit biological make up is not designed for that. They leap on trees which makes them vulnerable as forests don't disappear.

Sifaka

Generalist species

Fat tailed dwarf lemur is considerd a specialist splices since their diet includes a variety of fruits, nectar, small vertebrates, and insects. Although they are native to the dry deciduous forest, they can thrive in primary forests, secondary forests, and the gallery forest of the southern spiny desert.

Fat tailed dwarf lemur [conservation status: least concern]

Fossa is one of the top predators in the western and eastern dry deciduous forest and the largest mammalian carnivore of Madagascar. It is an endemic species who preys mainly on lemurs. It thrives in a wide variety of habitats across the island and its diet varies according to their habitat. It is considered a keystone species since it controls the population of smaller mammals and it keeps the ecosystem it inhabits in balance.

Fossa [conservation status: vulnerable]

K-selected species

Female ring tailed lemurs have a gestation period of 135 to 145 days and almost always give birth to a single offspring at a time. The mother takes care of the offspring until it is able to feed on his own. The mortality rate at a stable environment in the wild is about 37%, which fairly low.

Ring tailed lemur

r-selected species

The Paratilapia polleni is a type of Cichlid fish endemic to Madagascar. They lay large amounts of eggs and their mortality rate is high and their lifespan is short.

Paratilapia polleni

Interspecific Competition

There is interspecific competition between different species of mouse lemurs in the western dry decidious forest of Madagascar. The Madame Berthe’s mouse lemur is the smallest known primate while the grey mouse lemur is much larger. They compete for land and resources. Especially during dry seasons, these species have to partition their habitat and resources as the habitable space is limited and highly contended amongst these and other species.

Madame Berthe’s mouse lemur

Grey mouse lemur

Predation

The fossa hunts on mouse lemur. It hunts on the ground and in trees. When the fossa is not breeding, it hunts individually and during breeding season they hunt in groups. They chase lemurs in the trees and attack them once on the ground.

Fossa

Mouse lemur

Mutualism

There is a mutualistic relationship between fat tailed dwarf lemurs and baobab trees. Baobab trees offer shelter for fat-tailed dwarf lemurs and they help the baobab pollinate.

Commensalism

There is a commensalistic relationship between fat tailed dwarf lemurs and a variety of parasitic plants. Fat-tailed dwarf lemurs smear their feces on the leaves and this helps parasitic plants germinate. The parasitic plants are benefitting from the lemurs' behavior while the lemur is neither harmed nor helped by the parasitic plants.

Parasitism

Lemurs carry parasites that take the lemurs's body as hosts. Parasite groups such as Plasmodium parasites contain the pathogens that Lyme disease and malaria respectively. These can be passed on to other animals and humans. Scientists believe that Madagascar's growing population has led lemurs to be in contact with more domestic pets, causing the pathogens to move more easily between populations.

Secondary Sccession

Sections of the dry deciduous forests of Madagascar are experiencing secondary succession. As land is deforested and burned, soil is still viable, but the flora and fauna that once lived there is no longer available. This causes new and old plants to grow and eventually, animals begin to habit the land. Some old species might come back while others might not. New species might also begin to habit the area. In Madagascar, large portions of dry deciduous forests have been deforested. As the land goes through secondary succession, it has been observed that previously endangered species of large lemurs have begun to habit the area. Secondary succession is not ideal, but it can sometimes help new plants and animals to thrive.