Conservation Below the Species Level: Suitable Evolutionarily Significant Units among Mountain Vipers (the Montivipera raddei complex) in Iran

Abstract

Northern and western mountains of Iran are among the most important biodiversity and endemism hot spots for reptiles in the Middle East. Among herpetofauna, the montivipers represent an emblematic and fragmented endemic group for which estimating their level of genetic differentiation and defining conservation priorities is urgently needed. Here, we present the most comprehensive phylogenetic study on the Montivipera raddei species group comprising all 5 known taxa, among which 3 are endemic to Iran. Based on 2 mitochondrial genes, phylogenetic and phylogeographic analyses revealed 3 major lineages each presenting very contrasting distribution areas. The Iranian montivipers are highly structured in clades showing low genetic diversity and corresponding to high altitude summits. Molecular dating revealed the role of Quaternary paleo-climatic oscillations and altitudinal movements of montivipers in shaping genetic diversity and differentiation of these sky-island taxa. In addition, the best scenario of historical biogeography allowed identifying 3 possible refugial areas in Iran most likely arising by vicariance. Based on our mitochondrial results and pending additional data, we recognize 3 candidate species among the M. raddei complex: M. raddei, Montivipera latifii, and Montivipera kuhrangica that are coherent with their geographical distribution. We propose that the most appropriate evolutionary significant units for conservation of the montivipers are represented by 13 units among which 6 are recognized as high priority. Finally, we suggest some recommendations to the IUCN as well as to the Iranian conservation policies with respect to conservation prioritization.

The phylogeny, phylogeography, and diversification history of the westernmost Asian cobra (Serpentes: Elapidae: Naja oxiana) in the Trans‐Caspian region

“…Cyclical climatic fluctuations of the Pleistocene are assumed to have had an integral role in determining the spatial distribution, patterns of genetic diversity and historical demography of a multitude of Palearctic species (Avise, 2000; Hewitt, 2001). Studies on snakes living at high altitudes highlight that mountain vipers have been modified during the glacial climates of Pleistocene and have diversified as a result of the progression and recession of glaciers (Behrooz et al., 2018; Ding et al., 2011). Our findings corroborated that the western population of N. oxiana has a genetically uniform structure belonging to a single genetically homogeneous population, while also acknowledging the small number of samples from Afghanistan and Turkmenistan in our study.…”

Extinction risks of a Mediterranean neo-endemism complex of mountain vipers triggered by climate change

“…Another key assumption of ENMs is that a species is in equilibrium with the climate 67,73 , meaning that the observed distribution represents the total of suitable habitats of the species. Regarding the evolutionary history of Montivipera , high degrees of new-endemism, isolated distribution to mountain and limited dispersal abilities 45,74 might have eradicated the species from some areas that once were suitable. This could mean that Montivipera species might be isolated from otherwise suitable habitats, thus violating to some degree the equilibrium assumption.…”

Evolutionary history and postglacial colonization of an Asian pit viper (Gloydius halys caucasicus) into Transcaucasia revealed by phylogenetic and phylogeographic analyses

“…At that time, populations of central and western Alborz diverged from populations of the north-east. Results of ABC analyses suggested a bi-directional gene flow from northeastern Iran to northwestern and southern Azerbaijan through northern and southern slopes of the Alborz, strikingly similar to the intraspecific divergence of Montivipera raddei species occurring 1.88 Myr in the Alborz, north-western and Zagros Mountains 13 . Meanwhile, the second divergence occurred between clades of central Alborz and western Alborz (1.09; 95% HPD: 0.64–1.64 Myr).…”

“…Recent research indicates that continental glaciers in Iran during the Pleistocene 12,13 , as well as the current climate change in northern Iran 14 , could have, respectively, led to latitudinal and altitudinal distribution shifts in a number of species, particularly poikilothermic animals, which are noted for their sensitivity to changes in temperature 15 . The Caucasian pit viper Gloydius halys caucasicus (Nikolsky, 1916) is distributed throughout southeastern Azerbaijan, southern Turkmenistan (Kopet Dagh Mountains), from northeastern to northwestern Iran, and northwestern Afghanistan, and is relatively common across the Alborz Mountains.…”

“…Moreover, the growing concern toward conservation of genetic diversity calls for accurately defining evolutionary significant units (ESUs) based on evolutionary histories of relevant taxa 36 (see 37 for a review of ESU definitions), as species-based units cannot always prove applicable to all conservation strategies 38 . Thus, phylogenetic and phylogeographic inferences are applied to conservation planning below the species level 13,39 .…”