Impact of habitat loss on distributions of terrestrial vertebrates in a high-biodiversity region in Mexico

Abstract

Mexico is considered a country of biological megadiversity because of its exceptional species richness and endemism. However, much of Mexico’s biodiversity is under threat due to a variety of factors, in particular, habitat loss. The Mexican legal standard (Norma Oficial Mexicana; NOM-ECOL-059-2010) uses four criteria to analyze specieś extinction risk at a national scale. However, when prioritizing areas for biodiversity conservation it is also important to incorporate knowledge of the conservation status of species at a more localized scale (regional, state, or municipal levels) for identifying possible risks associated with population declines. This paper focuses on Guerrero, which is the fourth most biologically diverse state in Mexico. The total extent of the conservation areas in Guerrero is low, amounting to 0.09% of its total area. We analyzed data for 582 terrestrial vertebrate species in Guerrero (53 amphibians, 115 reptiles, 334 birds and 80 mammals), modeling their potential distribution using a maximum entropy algorithm, and 114,555 occurrence records, and 23 predictive environmental (19 climatic and four topographical) variables. The portion of the potential distribution for each species including only remnant natural habitat was designated as its predicted distribution. The area of the predicted distribution was used to compute the fraction of natural habitat remaining for each species overlapping within decreed protected areas at the state and national levels, that is, for Guerrero and all of Mexico. Results show significant differences in the fraction of species’ predicted distribution and species’ potential distribution at different scales (state and national) and differences between the vertebrate groups analyzed. Because quantitative conservation targets are typically set for individual species, this exercise enables an analysis of the impact of the habitat lost on each species’ distribution by assessing the fraction of its predicted distribution that coincides with protected areas. We conclude that this must be part of systematic conservation planning to prioritize areas for potential conservation in Guerrero.