Theory suggests that catastrophic earth-history events can drive rapid biological evolution, but empirical evidence for such processes is scarce. Destructive geological events such as earthquakes can represent large-scale natural experiments for inferring such evolutionary processes. We capitalized on a major prehistoric (800 yr BP) geological uplift event affecting a southern New Zealand coastline to test for the lasting genomic impacts of disturbance. Genome-wide analyses of three co-distributed keystone kelp taxa revealed that post-earthquake recolonization drove the evolution of novel, large-scale intertidal spatial genetic ‘sectors’ which are tightly linked to geological fault boundaries. Demographic simulations confirmed that, following widespread extirpation, parallel expansions into newly vacant habitats rapidly restructured genome-wide diversity. Interspecific differences in recolonization mode and tempo reflect differing ecological constraints relating to habitat choice and dispersal capacity among taxa. This study highlights the rapid and enduring evolutionary effects of catastrophic ecosystem disturbance and reveals the key role of range expansion in reshaping spatial genetic patterns.

Aim: Phylogeographic studies on a number of Western Palaearctic taxa imply that the southern Caspian Sea region served as a refugium during the Last Glacial Maximum (LGM). Nevertheless, the LGM biogeography of the terrestrial and freshwater organisms in this region is poorly understood. By studying phylogeography of a species of freshwater crab, we unravel the location of probable local refugia and colonization patterns across this topographically complex landscape.Location: Southern Caspian Sea region.Taxon: The freshwater crab Potamon ibericum. Methods:We inferred the demographic history of Potamon ibericum using 163 mtDNA Cox1 sequences from 16 localities. For a subset of specimens, we amplified mtDNA 16S and four nuclear markers (28S, Histone3, Enolase, NaK) to confirm the phylogeographic structure. We tested Pleistocene expansion-contraction dynamics, using species distribution modelling (SDM) and assessed morphological variability by geometric-morphometric methods. Results: Mitochondrial markers revealed the existence of three parapatrically distributed lineages in the western, central and eastern parts of the region. The more conserved nuclear markers did not reflect this. The SDM revealed the fundamental niche expansion of P. ibericum along the southern Caspian Sea during the LGM, agreeing with results from the Cox1 data of demographic expansions. Despite strong morphological resemblance, geometric-morphometrics elucidated clinal carapace shape variation. Main Conclusions: Considering the Caspian Sea level fluctuations during the late Pleistocene, we hypothesize a scenario of demographic contraction during interglacial/warmer conditions, due to the Caspian Sea transgression and latitudinal range shift within the narrow distribution of the species between the southern Caspian Sea and northern slopes of the Alborz Mountains. During the glacial periods, the sea regressed and moist and warm conditions, characterizing glacial refugia, became prevalent in the region and caused isolated populations to expand. Our study confirms the deep transverse phylogeographic break, previously identified for Darevskia lizards in the region, and adds support to the presence of several LGM refugia in the southern Caspian Sea region.

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Refugia are critical for the maintenance of biodiversity during the periods of Quaternary climatic oscillations. The long‐term persistence of refugial populations in a large continuous refugium has resulted in a homogenous pattern of genetic structure among populations, while highly structured evolutionary lineages characterize the restriction of refugial populations to smaller subrefugia. These mechanisms have resulted in the identification of hot spots of biodiversity within putative glacial refugia. We studied phylogeography of Potamon ibericum (Brachyura: Potamidae) in the drainages of the western Caucasus biodiversity hot spot (i.e., Colchis and the Caucasus) to infer spatial genetic structure and potential refugia for a freshwater crab in this region. These areas have traditionally considered as a refugium due to the presence of Tertiary relict species. We integrated population genetic data and historical demographic analysis from cytochrome oxidase subunit I sequences and paleoclimatic data from species distribution modeling (SDM). The results revealed the lack of phylogeographic structure and provided evidence for demographic expansion. The SDM presented a rather homogenous and large refugium that extended from northeast Turkey to Colchis during the last glacial period. In contrast to these findings, previous phylogeographic study on P. ibericum of the eastern Caucasus biodiversity hot spot (i.e., Hyrcania) identified multiple independent refugia. By combining these results, we explain the significance of this important western Palearctic hot spot of biological diversity in shaping the geographic distribution of intraspecific genetic diversity in a freshwater taxon.

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The structure and dynamics of ecological communities can be profoundly influenced by environmental disturbance (Newman, 2019;Pickett et al., 1989;Sousa, 1984). Specifically, when disruption eliminates populations from a habitat patch, a new community assembly process will be initiated (Fukami, 2015). Most community assembly studies are limited to real-time observations of contemporary events

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