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.

Extinction Risk Assessment of the Greek Endemic Flora

“…This situation may however change dramatically in the foreseeable future, since most Greek endemics are either very narrowly-distributed ( Supplementary Materials Table S1 ) or occur in areas highly affected by human activities ([ 38 , 49 ]— Figure 3 ). Another key factor that may contribute to an increased extinction rate in Greece, is the inability of a significant portion of the Greek endemics to track the shift of their realized niche in a changing climate, as exemplified by the single island endemics of Crete [ 97 ] or other rare plant taxa occurring in Greece (e.g., [ 98 , 99 , 100 , 101 ]).…”

Past connections with the mainland structure patterns of insular species richness in a continental‐shelf archipelago (Aegean Sea, Greece)

“…However, we did not investigate the issue further as it goes beyond the scope of this study. For angiosperms, the lack of influence of biogeographic affinity can partially be attributed to the fact that a large portion (~40%) of the present Aegean flora has reached the Aegean islands due to human action in prehistoric or early historic times (Greuter, 1971(Greuter, , 1979Kougioumoutzis et al, 2020). For reptiles, the lack of effect of biogeographic affinity could result from similar levels of diversity in the various source communities "seeding" the different islands east and west of the Aegean Trench (Foufopoulos et al, 2011).…”

An Orchid in Retrograde: Climate-Driven Range Shift Patterns of Ophrys helenae in Greece

“…For instance, Ophrys argolica and O. delphinensis, two orchids occurring in Greece are projected to face a severe loss of their distribution areas, with the latter projected to become extinct [74]. The same holds true for all endemic Cretan orchids [32], which are expected to face severe mean losses of their distribution areas (min: 73.6% -Epipactis cretica; max: 99.3% -Ophrys omegaifera subsp. fleischmannii).…”

“…Consequently, many studies exist dealing with the factors affecting the biogeographical and biodiversity patterns in Greece ( [30] and references therein). Nevertheless, very few studies have taken into consideration the impacts of climate change on plant distribution patterns [31][32][33][34][35] and none has yet assessed if the projected future distribution shifts constitute a physiological response previously experienced by the given taxon in question. After all, incorporating past climate projections in ecological niche modelling may further our understanding of species responses to climate change [36], and could lead to the development of efficient conservation schemes [37].…”