Nearshore fish (Pholis gunnellus) persists across the North Atlantic through multiple glacial episodes

Historical gene flow constraints in a northeastern Atlantic fish: phylogeography of the ballan wrasse Labrus bergylta across its distribution range

The distribution and demographic patterns of marine organisms in the north Atlantic were largely shaped by climatic changes during the Pleistocene, when recurrent glacial maxima forced them to move south or to survive in northern peri-glacial refugia. These patterns were also influenced by biological and ecological factors intrinsic to each species, namely their dispersion ability. The ballan wrasse (Labrus bergylta), the largest labrid fish along Europe's continental margins, is a target for fisheries and aquaculture industry. The phylogeographic pattern, population structure, potential glacial refugia and recolonization routes for this species were assessed across its full distribution range, using mitochondrial and nuclear markers. The existence of a marked population structure can reflect both recolonization from three distinct glacial refugia and current and past oceanographic circulation patterns. Although isolated in present times, shared haplotypes between continental and Azores populations and historical exchange of migrants in both directions point to a common origin of L. bergylta. This situation is likely to be maintained and/or accentuated by current circulation patterns in the north Atlantic, and may lead to incipient speciation in the already distinct Azorean population. Future monitoring of this species is crucial to evaluate how this species is coping with current environmental changes.

Osteology of the crescent gunnel Pholis laeta and the phylogeny of the family Pholidae (Cottiformes, Zoarcoidei)

This study provides a complete description of the osteology of the crescent gunnel Pholis laeta based on cleared-and-stained specimens and X-rays to help provide sufficient morphological data to generate a robust phylogeny for the family Pholidae. Pholis laeta exhibits high variation in the structure of its caudal skeleton. The length of the preural (pu)2 neural spine is variably reduced (most common) or elongated (i.e. of similar length to that of pu3). Additionally, the neural spine of pu3 is either bifurcated or single. These results document and describe characters useful for phylogenetic inference of the family, including the insertion pattern of anal-fin pterygiophores between haemal spines. Pholidae was recovered as monophyletic (synapomorphies: ribs absent, haemonephropophyses present, gill membranes broadly joined, first neural arch fused to centrum, first anal-fin spine very robust, the dorsal fin comprises only spines and the presence of five branchiostegals), with monophyletic genera Pholis and Apodichthys (Rhodymenichthys is monotypic) and Apodichthys and Rhodymenichthys as sister taxa. The elongation of its pu2 neural spine defines Pholis and synapomorphies for Apodichthys include five infraorbital bones, no pelvic fin, a hypertrophied first anal-fin spine, the presence of two or three empty interhaemal spaces after the anteriormost anal-fin spine and having 35-46 abdominal vertebrae. Apodichthys and Rhodymenichthys are sister taxa based on the continuity of the caudal fin with the dorsal and anal fins and uniform colouration. Future study is needed to more fully resolve the interrelationships of species within Pholidae (especially the genus Pholis) and solidify the position of Pholidae within the Zoarcoidei.

Phylogeography of 3 North Atlantic Wolffish species (Anarhichas spp.) with phylogenetic relationships within the family Anarhichadidae

Phylogenetic analyses of all 4 wolffish species (Atlantic, Spotted, Northern, and Bering wolffishes) and the Wolfeel were assessed with both mitochondrial (D-loop and ND1) and nuclear (amplified fragment length polymorphism) DNA to resolve relationships within the family Anarhichadidae. Species-specific mitochondrial DNA (mtDNA) mutation rates were estimated based on 2 possible dates of divergence between the Pacific and Atlantic lineages. Phylogeographic patterns within each of the 3 North Atlantic wolffishes were investigated with Markov chain Monte Carlo simulations based on mtDNA to determine whether population size changes occurred following the last glaciation and where wolffishes likely survived glaciation. All 3 species of North Atlantic wolffishes showed evidence of postglacial expansion but did not show evidence of persistence in multiple refugia in both the eastern and western Atlantic Ocean. Rather, the data supported persistence in a single refuge, with postglacial expansion into the rest of the range. Nucleotide diversity, in particular, was low in wolffishes compared with other marine fishes, possibly related to reductions in population sizes during the last glaciation.

CRYPTIC DIVERSITY AND PHYLOGENETIC RELATIONSHIPS WITHIN THE MASTOCARPUS PAPILLATUS SPECIES COMPLEX (RHODOPHYTA, PHYLLOPHORACEAE)(1)

Mastocarpus papillatus (C. Agardh) Kütz. is a common intertidal red alga occurring along the west coast of North America from Baja California to Alaska. Sequencing of both the chloroplast-encoded rbcL gene and the nuclear ribosomal internal transcribed spacer (ITS) regions of ∼200 specimens from California to Alaska revealed that M. papillatus is actually a complex of at least five species. All five species have high bootstrap support in phylogenetic analyses of both genetic regions, and in the case of the ITS marker, the species also have distinctive patterns of indels. Three of the species are localized in the mid- to upper intertidal, whereas two of the species occur in the low intertidal. The species also have different geographic ranges that overlap in the Vancouver Island area of British Columbia. No distinctive, reliable morphological differences were observed among the species. Although a variety of names are available for species in the complex, it is not yet clear which name goes with which species. As part of the survey, I also sequenced other species of Mastocarpus in the northeast Pacific region, and I provide new distribution records for M. jardinii ( J. Agardh) J. A. West and for a nonpapillate and probably undescribed species of Mastocarpus.

Mitochondrial DNA phylogeography of the three-spined stickleback (Gasterosteus aculeatus) in Europe-evidence for multiple glacial refugia

An analysis of mitochondrial DNA sequence variation in 172 three-spined sticklebacks (Gasterosteus aculeatus) sampled across the European distribution range revealed three major evolutionary lineages occupying relatively large and separate geographic areas. The trans-Atlantic lineage comprised of populations spanning from the East Coast of USA to the continental Europe and was basal group to the other European lineages in the phylogeny. The European lineage included populations located in the Western and Eastern Europe, British Isles, Scandinavia as well as some parts of the Mediterranean region. The third lineage was specific to the Black Sea drainages. The within lineage structure was characterized by significant excess of low frequency haplotypes and star-like mtDNA genealogies, which suggest a recent population expansions to the formerly glaciated marine and freshwater environments. A coalescent-based method dated the splits between the major lineages to have occurred during the Saalian and Weichselian glaciations in the late Pleistocene, depending on the molecular clock calibration. The coalescent simulations further indicate high degree of genetic diversity within the lineages and a substantial increase in the genetic diversity in the European lineage relative to the ancestral level. In addition to the three major lineages, the freshwater populations in R. Neretva and L. Skadar in the Adriatic Sea coast region harboured unique and highly divergent haplotypes suggesting long independent histories of these populations. Evidence from mtDNA analyses suggests that these populations deserve a status of an evolutionary significant unit.