Parsimony Analysis of Endemicity (PAE) of Mexican terrestrial mammals at different area units: When size matters

Abstract

Aim Parsimony analysis of endemicity (PAE) is a biogeographical method that uses a parsimony algorithm to obtain an area cladogram, based on taxa inhabiting the study areas. We compare its performance at different geographical units (1/2degrees and 1degrees quadrats, ecoregions and biogeographical provinces) to analyse distributional patterns of Mexican terrestrial mammals, in order to assess the importance of the size of area units. Location The area analysed corresponds to Mexico. Methods Parsimony analyses were based on 56,859 collection records, corresponding to 703 genera, species and subspecies. Four data matrices were constructed for: (1) 716 quadrats of 1/2degrees latitude x 1/2degrees longitude, (2) 230 quadrats of 1degrees latitude x 1degrees longitude, (3) fortyfive ecoregions and (4) fourteen biogeographical provinces. Results For the 1/2degrees quadrat matrix, we obtained six cladograms of 17,138 steps. For the 1degrees quadrat matrix, we obtained five cladograms (strict consensus with 9394 steps). For the matrix of ecoregions, we obtained twelve cladograms (strict consensus cladogram with 3009 steps). For the provinces, we obtained a single cladogram with 1603 steps. Main conclusions The best results were obtained with natural areas instead of quadrats. There seems to exist a trend to decrease the absolute number of steps and an increase in the absolute and relative number of synapomorphies as the size of the area units decreases, although this does not necessarily occur for the number of cladograms.