Madame Berthe's Mouse Lemur - Ecology

Ecology

Mouse lemur species are considered cryptic species. The species-rich mouse lemurs (Microcebus spec.) are distributed over nearly all remaining forest areas of Madagascar with a high variability in species distribution patterns and are very similar morphologically. They are so similar, that the gray mouse lemur was considered the only mouse lemur until recent studies proved it to be otherwise. Along with other morphological similarities, the Madame Berthe’s mouse lemur and the gray mouse lemur share a similar diet (both containing the same food groups but in different proportions) and live in the same region of western Madagascar. Both Microcebus species have an omnivorous diet, and used the same food sources, including sugary homopteran secretions, fruit, flowers, gum, arthropods and small vertebrates (e.g. geckos, chameleons). Because of their recent common ancestry, closely related species ought to exhibit high similarities in their use of biotic and abiotic resources, susceptibility to predators and responses to disturbances and stress. However, despite the overlapping niches, studies have shown that the territories of the two mouse lemur species have very little to no overlap. The Madame Berthe's mouse lemur population is sparse and spread out over a more widespread area; while the gray mouse lemurs had a much denser population in a smaller area.

The reason for the lemur’s avoidance is not yet clearly known. The gray mouse lemur has several competitive advantages over Madame Berthe’s mouse lemur. It is about twice as large as Madame Berthe's mouse lemur. It also has the advantages of being a generalist, and having fewer deaths by predation (with 70% predation mortality for Madame Berthe’s mouse lemur, vs. 50% predation mortality for the gray mouse lemur). The areas used exclusively by each species share structural characteristics and food sources. Gray mouse lemurs are able to live in more types of vegetation than Madame Berthe’s mouse lemur yet have smaller, denser territories. This suggests that their avoidance does not stem from environmental differences, but rather by competitive coexistence.