Image_4_Trans-Arctic asymmetries, melting pots and weak species cohesion in the low-dispersal amphiboreal seaweed Fucus distichus.pdf

• Main Authors: João Neiva, Jorge Assis, Eliza Fragkopoulou, Gareth A. Pearson, Peter T. Raimondi, Laura Anderson, Dorte Krause-Jensen, Núria Marbà, Andrew Want, Olga Selivanova, Masahiro Nakaoka, W. Stewart Grant, Brenda Konar, Michael Y. Roleda, Mikael K. Sejr, Cristina Paulino, Ester A. Serrão
• Format: Still Image
• Language: unknown
• Published: 2024
• Subjects: Evolutionary Biology; Ecology; Invasive Species Ecology; Landscape Ecology; Conservation and Biodiversity; Behavioural Ecology; Community Ecology (excl. Invasive Species Ecology); Ecological Physiology; Freshwater Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Population Ecology; Terrestrial Ecology; intertidal; climate-driven range shifts; cryptic species; functional bottleneck; genetic hotspots and melting pots; niche unfilling; trans-Arctic phylogeography; Arctic; Alaska
• Online Access: https://doi.org/10.3389/fevo.2024.1356987.s004; https://figshare.com/articles/figure/Image_4_Trans-Arctic_asymmetries_melting_pots_and_weak_species_cohesion_in_the_low-dispersal_amphiboreal_seaweed_Fucus_distichus_pdf/25635003

Amphiboreal taxa are often composed of vicariant phylogroups and species complexes whose divergence and phylogeographic affinities reflect a shared history of chronic isolation and episodic trans-Arctic dispersal. Ecological filters and shifting selective pressures may also promote selective sweeps, niche shifts and ecological speciation during colonization, but these are seldom considered at biogeographical scales. Here we integrate genetic data and Ecologic Niche Models (ENMs) to investigate the historical biogeography and cohesion of the polymorphic rockweed Fucus distichus throughout its immense amphiboreal range, focusing on trans-Arctic asymmetries, glacial/interglacial dynamics, and integrity of sympatric eco-morphotypes. Populations were sampled throughout the Pacific and the Atlantic, from southern rear-edges to the high-Arctic. They were genotyped for seven microsatellites and an mtDNA spacer, and genetic diversity and structure were assessed from global to local scales. ENMs were used to compare niche divergence and magnitude of post-glacial range shifts in Pacific versus Atlantic sub-ranges. Haplotypic and genotypic data revealed distinct and seemingly isolated Pacific vs Arctic/Atlantic gene-pools, with finer-scale regional sub-structuring pervasive in the Pacific. MtDNA diversity was highly structured and overwhelmingly concentrated in the Pacific. Regionally, Alaska showed the highest intra-population diversity but the lowest levels of endemism. Some sympatric/parapatric ecotypes exhibited distinct genotypic/haplotypic compositions. Strikingly, niche models revealed higher Pacific tolerance to maximum temperatures and predicted a much more consolidated presence in the NE Atlantic. Glacial and modern ranges overlapped extensively in the Pacific, whereas the modern Atlantic range was largely glaciated or emerged during the Last Glacial Maximum. Higher genetic and ecogeographic diversity supports a primary Pacific diversification and secondary Atlantic colonization, also likely reflecting the much ...