Spatial Phylogenetics, Biogeographical Patterns and Conservation Implications of the Endemic Flora of Crete (Aegean, Greece) under Climate Change Scenarios

Abstract

Human-induced biodiversity loss has been accelerating since the industrial revolution. The climate change impacts will severely alter the biodiversity and biogeographical patterns at all scales, leading to biotic homogenization. Due to underfunding, a climate smart, conservation-prioritization scheme is needed to optimize species protection. Spatial phylogenetics enable the identification of endemism centers and provide valuable insights regarding the eco-evolutionary and conservation value, as well as the biogeographical origin of a given area. Many studies exist regarding the conservation prioritization of mainland areas, yet none has assessed how climate change might alter the biodiversity and biogeographical patterns of an island biodiversity hotspot. Thus, we conducted a phylogenetically informed, conservation prioritization study dealing with the effects of climate change on Crete's plant diversity and biogeographical patterns. Using several macroecological analyses, we identified the current and future endemism centers and assessed the impact of climate change on the biogeographical patterns in Crete. The highlands of Cretan mountains have served as both diversity cradles and museums, due to their stable climate and high topographical heterogeneity, providing important ecosystem services. Historical processes seem to have driven diversification and endemic species distribution in Crete. Due to the changing climate and the subsequent biotic homogenization, Crete's unique bioregionalization, which strongly reminiscent the spatial configuration of the Pliocene/Pleistocene Cretan paleo-islands, will drastically change. The emergence of the 'Anthropocene' era calls for the prioritization of biodiversity-rich areas, serving as mixed-endemism centers, with high overlaps among protected areas and climatic refugia.

Keywords: CANAPE; Mediterranean flora; conservation prioritization; ecosystem services; endemism; phylogenetic diversity; phylogenetic endemism; plant diversity; vascular plants.

Figure 1

Map depicting Crete in the Mediterranean Sea. Lefka Ori (1), Idi (2), Dikti (3) and Thrypti (4) constitute the main massifs in Crete.

Figure 2

Map of significant phylogenetic endemism (PE) identified by the categorical analysis of neo- and paleo-endemism (CANAPE) analysis for 172 Cretan single island endemics for (A) the current time period and (B) the CCSM4 global circulation model (GCM) and the representative concentration pathway (RCP) 2.6. Dark grey cells contain no records.

Figure 3

Altitudinal distribution of the different types of endemism centers identified by the CANAPE analysis in Crete for (A) the current time period and (B) the CCSM4 global circulation model (GCM) and the representative concentration pathway (RCP) 2.6.

Figure 4

Map of Crete depicting the predicted distribution of areas of biotic homogenization with respect to Cretan single island endemic (SIE) species diversity (projected changes in phylogenetic beta diversity—ΔPBD), according to the CCSM4 2.6 global circulation model/representative concentration pathway compared to the current time period. Blue areas indicate a decrease in beta-diversity (biotic homogenization). Red areas indicate an increase in beta-diversity (biotic heterogenization).

Figure 5

Bioregionalization of Crete for (A) the current time period and (B) the CCSM4 global circulation model (GCM) and the representative concentration pathway (RCP) 2.6. Each color indicates a different biogeographical sector.