Abstract
Global climate change alters the dynamic of natural ecosystems and directly affects species distributions, persistence and diversity. The impacts of climate change may lead to dramatic changes in biotic interactions, such as pollination and seed dispersal. Life history traits are extremely important to consider the vulnerability of a species to climate change, producing more robust models than those based primarily on species distributions. Here, we hypothesized that rising temperatures and aridity will reduce suitable habitats for the endemic flora of the Caatinga, the most diverse dry tropical forest on Earth. Specifically, species with specialized reproductive traits (e.g. vertebrate pollination, biotic dispersal, obligatory cross-pollination) should be more affected by climate change than those with generalist traits. We performed two ecological niche models (current and future) to simulate the effects of climate change on the distribution area of endemic species in relation to life-history traits. We used the MIROC-ESM and CCSM4 models for both intermediate (RCP4.5) and highest predicted (RCP8.5) GHG emission scenarios, with a resolution of 30' (~1 km2). Habitat with high occurrence probability (>80%) of endemic species will be reduced (up to ~10% for trees, ~13% for non-arboreous, 10–28% for species with any pollination/reproductive system), with the greatest reductions for species with specialized reproductive traits. In addition, the likely concentration of endemic plants in the extreme northeastern portion of the Caatinga, in more mesic areas, coincides with the currently most human-modified areas of the ecosystem, which combined with climate change will further contract suitable habitats of endemic species. In conclusion, plant species endemic to the Caatinga are highly vulnerable to even conservative scenarios of future climate change and may lose much of their climatic envelopes. New protected areas should be located in the northeastern portion of the Caatinga, which hosts a more favorable climate, but is currently exposed to escalating agricultural intensification.
Highlights
At a global scale, climate change is mainly represented by increases in temperature and divergent changes in precipitation regimes, which will likely become more variable and extreme [1, 2]
The overall extent of suitable habitat will be significantly reduced for endemic species exhibiting any habit, pollination system, reproductive system, and abiotic dispersal mode under both climate change scenarios (Table 3; Fig 3A–3D)
In terms of biotic dispersal modes, high occurrence probability areas are not predicted to be significantly altered for endemic plant species under any of the climate change scenarios considered here (Table 3; Fig 3D)
Summary
Climate change is mainly represented by increases in temperature and divergent changes in precipitation regimes, which will likely become more variable and extreme [1, 2]. In South America, novel climate-vegetation equilibrium conditions are predicted, in which savannas may replace some tropical rainforest areas and semi-desert areas may replace much of the drought polygon of northeastern Brazil (geographic polygon bound by the annual 800-mm isohyet) [6]. In response to these emergent climatic conditions, species may persist within their original distribution range due to acclimatization and phenotypic plasticity, migrate to new areas of suitable climatic conditions, or may undergo local extinctions By affecting organisms from single populations to entire biomes, climate change may exhibit a broad footprint in divergent levels of biological organization across different regions on Earth [5, 10]
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