Plant conservation in the Mesoamerican biodiversity hotspot: a case study on the Piper genus in Veracruz (Mexico)

Maintaining floristic diversity in recognized biodiversity hotspots is a priority for ecosystem conservation. However, different taxonomical treatments often lead to over or underestimation of floristic diversity in species-rich groups, in particular in Tropical regions as Mesoamerica where floristic surveys are less detailed. Also, understanding the effects of climate changes on species distribution is an emerging question of conservation biology and ecological studies. Here, we used the species-rich genus Piper (Piperaceae) in Veracruz, as a model system to compare reported and actual species richness and to model their occurrence under a climate change scenario. We compared morphological characters of specimens preserved in three of the main Mexican herbaria and then applied new taxonomical treatments. We also used environmental niche models (ENMs) as implemented in Maxent to detect the effects of climate changes on species with different levels of habitat specificity and with specialized biotic interactions. We found that from a total of 108 Piper species reported in Veracruz, 80 were consistent to the new taxonomical treatments due to synonymy or misidentification. ENMs showed that the main determinants of Piper distribution are linked to temperature and precipitations depending on the species. Therefore, different species are likely to respond differently to climate changes. As expected, species with higher habitat specificity and species exhibiting specialized mutualisms are more likely to experience niche contractions. This study shows the importance of reconsidering species richness and of modelling species distribution including specialized ecological interactions as prerequisite for establishing conservation criteria.