The non-volant mammal fauna of Mexico: Species richness in a megadiverse country

The mammalian fauna of Mexico is one of the world's richest. Mexico can be considered a true country of megadiversity because it has more species of non-volant mammals than any other country in the New World, even after taking account of the effect of size. A comparison with other political units of the New World showed that the country as a whole harbours more non-volant mammals than expected for its size, whereas individual Mexican states have about the number of species that would be expected for their area. Beta, or differentiation diversity and environmental heterogeneity, rather than alpha or within-habitat diversity, are the key factors that determine the unusually high species richness of the country.