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Summary: Sex‐biased gene expression is considered to be an underlying cause of sexually dimorphic traits. Although the nature and degree of sex‐biased expression have been well documented in several animal and plant systems, far less is known about the evolution of sex‐biased genes in more distant eukaryotic groups.Here, we investigate sex‐biased gene expression in two brown algal dioecious species, Fucus serratus and Fucus vesiculosus, where male heterogamety (XX/XY) has recently emerged.We find that in contrast to evolutionary distant plant and animal lineages, male‐biased genes do not experience high turnover rates, but instead reveal remarkable conservation of bias and expression levels between the two species, suggesting their importance in sexual differentiation. Genes with consistent male bias were enriched in functions related to gamete production, along with sperm competition and include three flagellar proteins under positive selection.We present one of the first reports, outside of the animal kingdom, showing that male‐biased genes display accelerated rates of coding sequence evolution compared with female‐biased or unbiased genes. Our results imply that evolutionary forces affect male and female sex‐biased genes differently on structural and regulatory levels, resulting in unique properties of differentially expressed transcripts during reproductive development in Fucus algae. [ABSTRACT FROM AUTHOR]

Due to rising global surface temperatures, Arctic habitats are becoming thermally suitable for temperate species. Whether a temperate species can immigrate into an ice-free Arctic depends on its ability to tolerate extreme seasonal fluctuations in daylength. Thus, understanding adaptations to polar light conditions can improve the realism of models predicting poleward range expansions in response to climate change. Plant adaptations to polar light have rarely been studied and remain unknown in seagrasses. If these ecosystem engineers can migrate polewards, seagrasses will enrich biodiversity, and carbon capture potential in shallow coastal regions of the Arctic. Eelgrass (Zostera marina) is the most widely distributed seagrass in the northern hemisphere. As the only seagrass species growing as far north as 70°N, it is the most likely candidate to first immigrate into an ice-free Arctic. Here, we describe seasonal (and diurnal) changes in photosynthetic characteristics, and in genome-wide gene expression patterns under strong annual fluctuations of daylength. We compared PAM measurements and RNA-seq data between two populations at the longest and shortest day of the year: (1) a Mediterranean population exposed to moderate annual fluctuations of 10–14 h daylength and (2) an Arctic population exposed to high annual fluctuations of 0–24 h daylength. Most of the gene expression specificities of the Arctic population were found in functions of the organelles (chloroplast and mitochondrion). In winter, Arctic eelgrass conserves energy by repressing respiration and reducing photosynthetic energy fluxes. Although light-reactions, and genes involved in carbon capture and carbon storage were upregulated in summer, enzymes involved in CO2 fixation and chlorophyll-synthesis were upregulated in winter, suggesting that winter metabolism relies not only on stored energy resources but also on active use of dim light conditions. Eelgrass is unable to use excessive amounts of light during summer and demonstrates a significant reduction in photosynthetic performance under long daylengths, possibly to prevent photoinhibition constrains. Our study identified key mechanisms that allow eelgrass to survive under Arctic light conditions and paves the way for experimental research to predict whether and up to which latitude eelgrass can potentially migrate polewards in response to climate change. [ABSTRACT FROM AUTHOR]

Genetic affiliation, nuclear DNA content, and gamete functioning were examined in small salt marshFucusfrom three localities in western Ireland. Individuals with small and dioecious receptacles were found at all localities, but production of germlings was only evident at Locality 1. Here, theFucusvegetation formed a morphological cline fromF. vesiculosuswith bladders in the mid-intertidal to smallFucusindividuals lacking bladders in the salt marsh of the upper intertidal. Measurements of nuclear DNA content ranged from 1–1.8 pg at this locality, withF. vesiculosusindividuals in the lower range. At the two other localities, the small salt marshFucusconsisted of distinct morphological entities. Microsatellite analyses revealed that individuals at Locality 2 were derived mainly fromF. vesiculosus, whereas those from Locality 3 were hybrids betweenF. vesiculosusandF. spiraliswith greatest affiliation toF. spiralis. While the small salt marshFucusforms from Locality 2 had high nuclear DNA content (c. 4 pg) and were probably octoploids, the small salt marshFucusfrom Locality 3 formed two groups: one with high (3.9–4.6 pg) and one with low (1.5–1.9 pg) nuclear DNA content. Nuclear DNA content measured in individuals from Locality 3 varied between 1.1–2.8 pg inF. vesiculosusand 2–3.5 pg inF. spiralis, and showed a more or less stepwise increase in both species, consistent with polyploidy. We hypothesize that the small salt marshFucusforms originate from genome size changes in the parental taxa. [ABSTRACT FROM AUTHOR]

Rising temperatures are predicted to melt all perennial ice cover in the Arctic by the end of this century, thus opening up suitable habitat for temperate and subarctic species. Canopy-forming seaweeds provide an ideal system to predict the potential impact of climate-change on rocky-shore ecosystems, given their direct dependence on temperature and their key role in the ecological system. Our primary objective was to predict the climate-change induced range-shift of Fucus distichus, the dominant canopy-forming macroalga in the Arctic and subarctic rocky intertidal. More specifically, we asked: which Arctic/subarctic and cold-temperate shores of the northern hemisphere will display the greatest distributional change of F. distichus and how will this affect niche overlap with seaweeds from temperate regions? We used the program MAXENT to develop correlative ecological niche models with dominant range-limiting factors and 169 occurrence records. Using three climate-change scenarios, we projected habitat suitability of F. distichus - and its niche overlap with three dominant temperate macroalgae - until year 2200. Maximum sea surface temperature was identified as the most important factor in limiting the fundamental niche of F. distichus. Rising temperatures were predicted to have low impact on the species' southern distribution limits, but to shift its northern distribution limits poleward into the high Arctic. In cold-temperate to subarctic regions, new areas of niche overlap were predicted between F. distichus and intertidal macroalgae immigrating from the south. While climate-change threatens intertidal seaweeds in warm-temperate regions, seaweed meadows will likely flourish in the Arctic intertidal. Although this enriches biodiversity and opens up new seaweed-harvesting grounds, it will also trigger unpredictable changes in the structure and functioning of the Arctic intertidal ecosystem. [ABSTRACT FROM AUTHOR]

At small spatial and temporal scales, genetic differentiation is largely controlled by constraints on gene flow, while genetic diversity across a species' distribution is shaped on longer temporal and spatial scales. We assess the hypothesis that oceanographic transport and other seascape features explain different scales of genetic structure of giant kelp, Macrocystis pyrifera. We followed a hierarchical approach to perform a microsatellite-based analysis of genetic differentiation in Macrocystis across its distribution in the northeast Pacific. We used seascape genetic approaches to identify large-scale biogeographic population clusters and investigate whether they could be explained by oceanographic transport and other environmental drivers. We then modelled population genetic differentiation within clusters as a function of oceanographic transport and other environmental factors. Five geographic clusters were identified: Alaska/ Canada, central California, continental Santa Barbara, California Channel Islands and mainland southern California/ Baja California peninsula. The strongest break occurred between central and southern California, with mainland Santa Barbara sites forming a transition zone between the two. Breaks between clusters corresponded approximately to previously identified biogeographic breaks, but were not solely explained by oceanographic transport. An isolation-by-environment ( IBE) pattern was observed where the northern and southern Channel Islands clustered together, but not with closer mainland sites, despite the greater distance between them. The strongest environmental association with this IBE pattern was observed with light extinction coefficient, which extends suitable habitat to deeper areas. Within clusters, we found support for previous results showing that oceanographic connectivity plays an important role in the population genetic structure of Macrocystis in the Northern hemisphere. [ABSTRACT FROM AUTHOR]

Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass ( Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top-down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale patterns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top-down control strongly influence functioning of threatened seagrass ecosystems, and suggest that biodiversity is comparably important to global change stressors. [ABSTRACT FROM AUTHOR]

Colpomenia peregrina is an annual brown macroalga found in temperate waters worldwide. To understand population differentiation and to reconstruct pathways of colonization/introduction, we analyzed variation in two mitochondrial protein-coding genes, cytochrome c oxidase subunit III ( cox3) and ATP synthase F0 subunit 6 ( atp6), and cp RuBisCO spacer. A total of 359 cox3, 342 atp6, and 38 RuBisCO spacer sequences from Colpomenia peregrina were obtained for samples collected at 28 sites from 12 countries. The combined cox3 + atp6 sequences (1,231 bp) revealed 99 polymorphic sites and 69 haplotypes. An mt haplotype network revealed four distinct groups, separated by 7 to 26 mutation steps. NW Pacific populations were present in each group (but dominant in one), whereas SW Pacific and the Atlantic populations each were present in one group. The network and phylogenetic analyses, along with patterns of genetic diversity, suggested a NW Pacific center of origin, expanding first to the SW Pacific, then the NE Pacific, and most recently to the north Atlantic. A generalized skyline plot revealed a dramatic population expansion of the species ca. 20 kya. [ABSTRACT FROM AUTHOR]

Although benthic marine algae are essential components of marine coastal systems that have been influenced profoundly by past and present climate change, our knowledge of seaweed phylogeography is limited. The brown alga Ishige okamurae Yendo occurs in the northwest Pacific, where it occupies a characteristic belt in the exposed intertidal zone. To understand the patterns of genetic diversity and the evolutionary history of this species, we analyzed mitochondrial cox3 from 14 populations (221 individuals) throughout its range. The 17 haplotypes found in this study formed five distinct clades, indicating significant genetic structure. The high differentiation and number of unique (private) haplotypes may result from the recolonization of the species from glacial refugia. Three putative refugia, each with high genetic diversity, were identified: southern Korea (including Jeju Island), northern Taiwan, and central Pacific Japan. Recolonization of I. okamurae was probably determined by ocean currents and changes in sea level during the last glacial period. [ABSTRACT FROM AUTHOR]

We examined the phylogeography of the cold-temperate macroalgal species Fucus distichus L., a key foundation species in rocky intertidal shores and the only Fucus species to occur naturally in both the North Pacific and the North Atlantic. North Pacific and North Atlantic oceans (42° to 77° N). We genotyped individuals from 23 populations for a mitochondrial DNA (mtDNA) intergenic spacer (IGS) ( n = 608) and the cytochrome c oxidase subunit I (COI) region ( n = 276), as well as for six nuclear microsatellite loci ( n = 592). Phylogeographic structure and connectivity were assessed using population genetic and phylogenetic network analyses. IGS mtDNA haplotype diversity was highest in the North Pacific, and divergence between Pacific haplotypes was much older than that of the single cluster of Atlantic haplotypes. Two ancestral Pacific IGS/COI clusters led to a widespread Atlantic cluster. High mtDNA and microsatellite diversities were observed in Prince William Sound, Alaska, 11 years after severe disturbance by the 1989 Exxon Valdez oil spill. At least two colonizations occurred from the older North Pacific populations to the North Atlantic between the opening of the Bering Strait and the onset of the Last Glacial Maximum. One colonization event was from the Japanese Archipelago/eastern Aleutians, and a second was from the Alaskan mainland around the Gulf of Alaska. Japanese populations probably arose from a single recolonization event from the eastern Aleutian Islands before the North Pacific-North Atlantic colonization. In the North Atlantic, the Last Glacial Maximum forced the species into at least two known glacial refugia: the Nova Scotia/Newfoundland (Canada) region and Andøya (northern Norway). The presence of two private haplotypes in the central Atlantic suggests the possibility of colonization from other refugia that are now too warm to support F. distichus. With the continuing decline in Arctic ice cover as a result of global climate change, renewed contact between North Pacific and North Atlantic populations of Fucus species is expected. [ABSTRACT FROM AUTHOR]

Background and Aims The dwarf eelgrass, Zostera noltii, is a predominant inhabitant of soft-bottom intertidal regions along the coasts of northern Europe. It is a monoecious, protogynous angiosperm in which the potential for self-fertilization and inbreeding are high, especially if clone sizes exceed pollen dispersal distances. The aim of the present study was to determine the relationship between mating system and clonal structure, examine the relative roles of geitonogamous selfing and biparental inbreeding, measure pollen availability (multiple paternities) and estimate pollen dispersal. Methods A 100-m2 plot was established in a large, intertidal Z. noltii meadow on the island of Sylt in the German Wadden Sea. A total of 256 adult shoots was sampled: one from the centre of 100 fixed 1-m2 quadrats (large scale resolution) and an additional 156 from within eight randomly selected 1-m2 sub-quadrats (small-scale resolution). DNA was extracted from seeds and leaf tissue of all samples and genotyped with nine microsatellite loci. Key Results Mating system analysis revealed high multilocus and single locus outcrossing rates. Average pollen dispersal distance was nearly the same as the average genet (clone) size. Multiple paternity was common and 20–30 % of mature seeds originated from matings within the plot. Among inbred seeds, most resulted from geitonogamy rather than biparental inbreeding. Conclusions Moderate disturbances intrinsic to the intertidal habitat appear to facilitate seed recruitment by gap formation. Pollen dispersal distances are sufficient to maintain outcrossing and high clonal diversity. [ABSTRACT FROM AUTHOR]

Aim Ascophyllum nodosum (L.) Le Jolis is a dominant fucoid seaweed occurring along sheltered, rocky shores throughout the North Atlantic (but not in the Pacific), where it is a foundational species of the intertidal community. Its large size and vulnerability to ice-scour have led to the hypothesis that contemporary populations in the north-west Atlantic may be the result of de novo recolonization from the north-east Atlantic since the Last Glacial Maximum (LGM) ( c. 20 ka). We tested this hypothesis. Location Temperate North Atlantic rocky intertidal between c. 42 and 65° N latitude. Methods More than 1300 individuals from 28 populations were sampled from across the entire range of A. nodosum and genotyped for six microsatellite loci, and > 500 individuals were genotyped for two mitochondrial loci, an intergenic spacer (IGS) and the tRNA (W) gene ( trnW). Population structure and historical demography were analysed in a standard population genetics and coalescence framework. Results Based on the presence of private alleles and haplotypes, we found that A. nodosum has survived on both sides of the Atlantic (since before the LGM, dating back to at least the penultimate Eemian interglacial) with similar effective population sizes and divergence times (1.2 and 0.8 Ma). Dispersal has been predominantly from Europe to North America, and there is very weak present-day population differentiation across the North Atlantic. Diversity measures provided additional support for determining the location of refugia. Main conclusions Ascophyllum nodosum was apparently little affected by the LGM, although contemporary climate change is likely to have major effects on its latitudinal distribution on both sides of the North Atlantic. It is a very long-lived species, analogous in virtually all demographic aspects to a tree – resistant to extinction but vulnerable to catastrophic events. The Brittany peninsula is a hotspot of genetic diversity worthy of conservation. [ABSTRACT FROM AUTHOR]

In order to aid gene discovery and uncover genes responding to abiotic stressors in stress-tolerant brown algae of the genus Fucus, expressed sequence tags (ESTs) were studied in two species, Fucus serratus and Fucus vesiculosus. Clustering of over 12,000 ESTs from three libraries for heat shock/recovery and desiccation/rehydration resulted in identification of 2,503, 1,290, and 2,409 unigenes from heat-shocked F. serratus, desiccated F. serratus, and desiccated F. vesiculosus, respectively. Low overall annotation rates (18–31%) were strongly associated with the presence of long 3′ untranslated regions in Fucus transcripts, as shown by analyses of predicted protein-coding sequence in annotated and nonannotated tentative consensus sequences. Posttranslational modification genes were overrepresented in the heat shock/recovery library, including many chaperones, the most abundant of which were a family of small heat shock protein transcripts, Hsp90 and Hsp70 members. Transcripts of LI818-like light-harvesting genes implicated in photoprotection were also expressed during heat shock in high light. The expression of several heat-shock-responsive genes was confirmed by quantitative reverse transcription polymerase chain reaction. However, candidate genes were notably absent from both desiccation/rehydration libraries, while the responses of the two species to desiccation were divergent, perhaps reflecting the species-specific physiological differences in stress tolerance previously established. Desiccation-tolerant F. vesiculosus overexpressed at least 17 ribosomal protein genes and two ubiquitin-ribosomal protein fusion genes, suggesting that ribosome function and/or biogenesis are important during cycles of rapid desiccation and rehydration in the intertidal zone and possibly indicate parallels with other poikilohydric organisms such as desiccation-tolerant bryophytes. [ABSTRACT FROM AUTHOR]

Genotypic structure and temporal dynamics of the dwarf seagrass, Zostera noltii, were studied in an intertidal meadow that has persisted since prior to 1936 near the Wadden Sea island of Sylt. Samples were collected from two 10 × 10 m plots separated by 250 m from May 2002 to June 2005 and from four 1 × 1 m plots from June 2003 to September 2004. All the samples were genotyped with nine microsatellite loci. No genotypes were shared between the plots separated by 250 m. Genetic diversity was higher in the Wadden Sea than in the other regions of its geographic range. The average clone size (genets) (SD) in the two plots was 1.38 (0.26) and 1.46 (0.4) m², respectively, with a range up to 9 m² and <20% persisted for >4 years. A high genetic and genotypic diversity was maintained by annual recruitment of seedlings despite a dramatic decrease in ramet density that coincided with the severe heat stress event of 2003. Fine-scale (1 m²) analysis suggested that extensive loss of seagrass cover precluded space competition among the genets, while a persistent seed bank prevented local extinction. Long-term persistence of Z. noltii meadows in the intertidal Wadden Sea was achieved by high genet turnover and frequent seedling recruitment from a seed bank, in contrast to the low diversity observed in large and long-living clones of Z. noltii and other seagrasses in subtidal habitats. [ABSTRACT FROM AUTHOR]

Eukaryotic mitochondria are mostly uniparentally (maternally) inherited, although mtDNA heteroplasmy has been reported in all major lineages. Heteroplasmy, the presence of more than one mitochondrial genome in an individual, can arise from recombination, point mutations, or by occasional transmission of the paternal mtDNA (=paternal leakage). Here, we report the first evidence of mtDNA paternal leakage in brown algae. In Denmark, where Fucus serratus L. and Fucus evanescens C. Agardh have hybridized for years, we found eight introgressed individuals that possessed the very distinct haplotypes of each parental species. The finding of heteroplasmy in individuals resulting from several generations of backcrosses suggests that paternal leakage occurred in earlier generations and has persisted through several meiotic bottlenecks. [ABSTRACT FROM AUTHOR]

Early invasions of the North American shore occurred mainly via deposition of ballast rock, which effectively transported pieces of the intertidal zone across the Atlantic. From 1773-1861, >880 European ships entered Pictou Harbor, Nova Scotia, as a result of emigration and trade from Europe. The rockweed Fucus serratus (1868) and the snail Littorina littorea (≈1840) were found in Pictou during this same period. With shipping records (a proxy for propagule pressure) to guide sampling, we used F. serratus as a model to examine the introductions because of its relatively low genetic diversity and dispersal capability. Microsatellite markers and assignment tests revealed 2 introductions of the rockweed into Nova Scotia: 1 from Galway (Ireland) to Pictou and the other from Greenock (Scotland) to western' Cape Breton Island. To examine whether a high-diversity, high-dispersing species might have similar pathways of introduction, we analyzed L. littorea, using cytochrome b haplotypes. Eight of the 9 Pictou haplotypes were found in snails collected from Ireland and Scotland. Our results contribute to a broader understanding of marine communities, because these 2 conspicuous species are likely to be the tip of an "invasion iceberg" to the NW Atlantic from Great Britain and Ireland in the 19th Century. [ABSTRACT FROM AUTHOR]

As the most widespread seagrass in temperate waters of the Northern Hemisphere, Zostera marina provides a unique opportunity to investigate the extent to which the historical legacy of the last glacial maximum (LGM18 000–10 000 years bp) is detectable in modern population genetic structure. We used sequences from the nuclear rDNA–internal transcribed spacer (ITS) and chloroplast matK-intron, and nine microsatellite loci to survey 49 populations (> 2000 individuals) from throughout the species’ range. Minimal sequence variation between Pacific and Atlantic populations combined with biogeographical groupings derived from the microsatellite data, suggest that the trans-Arctic connection is currently open. The east Pacific and west Atlantic are more connected than either is to the east Atlantic. Allelic richness was almost two-fold higher in the Pacific. Populations from putative Atlantic refugia now represent the southern edges of the distribution and are not genetically diverse. Unexpectedly, the highest allelic diversity was observed in the North Sea–Wadden Sea–southwest Baltic region. Except for the Mediterranean and Black Seas, significant isolation-by-distance was found from ~150 to 5000 km. A transition from weak to strong isolation-by-distance occurred at ~150 km among northern European populations suggesting this scale as the natural limit for dispersal within the metapopulation. Links between historical and contemporary processes are discussed in terms of the projected effects of climate change on coastal marine plants. The identification of a high genetic diversity hotspot in Northern Europe provides a basis for restoration decisions. [ABSTRACT FROM AUTHOR]

The photosynthetic performance, pigmentation, and growth of a Halimeda community were studied over a depth gradient on Conch Reef, Florida Keys, USA during summer–fall periods of 5 consecutive years. The physiology and growth of H. tuna (Ellis & Solander) Lamouroux and H. opuntia (L.) Lamouroux on this algal dominated reef were highly variable. Maximum rate of net photosynthesis (Pmax ), respiration rate, and quantum efficiency (α) did not differ between populations of either species at 7 versus 21 m, even though the 21-m site received a 66% lower photon flux density (PFD). Physiological parameters, as well as levels of photosynthetic pigments, varied temporally. Pmax , saturation irradiance, compensation irradiance, and growth were greatest in summer months, whereas α, chl a , chl b , and carotenoid concentrations were elevated each fall. Halimeda tuna growth rates were higher at 7 m compared with 21 m for only two of five growth trials. This may have arisen from variability in light and nutrient availability. Individuals growing at 7 m received a 29% greater PFD in August 2001 than in 1999. In August 1999 and 2001 seawater temperatures were uniform over the 14-m gradient, whereas in August 2000 cold water regularly intruded upon the 21-m but not the 7-m site. These results illustrate the potentially dynamic relationship between nutrients, irradiance, and algal productivity. This suggests the necessity of long-term monitoring over spatial and temporal gradients to accurately characterize factors that impact productivity. [ABSTRACT FROM AUTHOR]

Growth, survivorship, recruitment, and reproduction of Halimeda tuna, a dominant green alga in many reef systems of the Florida Keys, were monitored at a shallow back reef (4–7m) and deep reef slope (15–22 m) on Conch Reef. Despite lower light intensities and similar grazing pressures, amphipod infestations, and epiphyte loads at both sites, the deeper site exhibited significantly higher growth rates in summer months over a 4-year period than found for the shallow population, possibly because of higher nutrient levels at depth and photoinhibition of shallow plants. Sexual reproductive events occurred simultaneously across the entire reef, with up to 5% of the population at both sites developing gametangia. New upright axes formed from zygotes, asexual fragmentation, or vegetative runners. Plants appear to have persistent basal stumps that survive harsh environmental conditions, even if upright, photosynthetic axes are removed. Sexual reproduction and `smothering' by epiphyte overgrowth are hypothesized to be two causes of death for individuals. [ABSTRACT FROM AUTHOR]

Ecological interactions among invading species are common and may often be important in facilitating invasions. Indeed, the presence of one nonindigenous species can act as an agent of disturbance that facilitates the invasion of a second species. However, most studies of nonindigenous species are anecdotal and do not provide substantive evidence that interactions among nonindigenous species have any community-level effects. Here, using a combination of field experiments and observations we examine interactions among introduced species in New England kelp forests and ask whether these interactions have altered paradigms describing subtidal communities in the Gulf of Maine. The green alga Codium fragile was observed at the Isles of Shoals, Maine, USA, in 1983 and has since replaced the native kelp as the dominant seaweed on leeward shores. Experiments manipulating kelp and Codium reveal that Codium does not directly inhibit growth or survival of kelp. Codium does, however, successfully recruit to gaps in the kelp bed and, once established, inhibits recruitment of kelp. A second nonindigenous species, Membranipora membranacea, grows epiphytically on kelp, and experiments reveal that the presence of Membranipora reduces growth and survival of kelp, resulting in defoliation of kelp plants and gap formation in kelp beds. In the absence of Codium, kelp recolonizes these gaps, but when present, Codium colonizes and prevents kelp recolonization. Manipulations of herbivores demonstrate that herbivory will reinforce Codium dominance. Thus, the demise of New England kelp beds appears to result from one invasive species facilitating the spread of a second nonindigenous species. [ABSTRACT FROM AUTHOR]

Macrocystis (Lessoniaceae) displays an antitropical distribution, occurring in temperate subtidal regions along western North America in the northern hemisphere and throughout the southern hemisphere. We used the noncoding rDNA internal transcribed spacer regions (ITS1 and ITS2) to examine relatedness among (1) Macrocystis and several genera of Laminariales, (2) four species of Macrocystis (M. integrifolia Bory from the northern hemisphere, M. angustifolia Bory and M. laevis Hay from the southern hemisphere, and M. pyrifera [L.] C. Ag. from both hemispheres), and (3) multiple clones of several individuals. Of the taxa included in our phylogenetic analysis, the elk kelp, Pelagophycus porra (Lem.) Setch., was the sister taxon to Macrocystis spp. Macrocystis individuals from the southern hemisphere (representing three species) formed a strongly to moderately supported clade, respectively, when the ITS1 and ITS2 sequences were analyzed separately. No distinction was detected between the two species in the northern hemisphere. Thus, Macrocystis may be a monospecific genus (M. pyrifera). A northern-hemisphere-to-southern-hemisphere pattern of dispersal was inferred, because northern-hemisphere individuals were more diverse and displayed paraphyletic clades, whereas southern-hemisphere individuals were less diverse and formed a monophyletic clade. High intraindividual variation in ITS1 sequences was observed in one individual from Santa Catalina Island (CA), suggesting very recent and rapid mixing of genotypes from areas to the north and Baja California (Mexico) or introgressive hybridization with Pelagophycus. [ABSTRACT FROM AUTHOR]

Postelsia palmaeformis Ruprecht is an annual species, occurring from southern California to Vancouver Island, Canada, in upper interidal sites exposed to extreme wave shock. Because of its limited spore dispersal, discrete and inbred populations are likely on the local scale, yet dispersal of drifting and fertile thalli raises the possibility of outbred populations on a regional scale M13 minisatellite DNA fingerprinting and random amplified polymarphic DNA (RAPD) markers were used in a complementary fashion to investigate genetic variability among 24 individuals on scales of clusters (= coalesced holdfasts). <1 m, 10 m, 25 m, 16 km, and 250 km. Based on M13 fingerprinting, genetic relatedness within clusters was extremely high. Three of six clusters had at least two identical individuals, and similarity values within five clusters were ≥0.90. Similarities between two of three clusters separated by <1 m were significantly higher than between cluster pairs separated by 25 m and 250 km: however, the similarity between two clusters separated by 25 m was equivalent to the similarity between two clusters separated by 250 km. Thus, genetic relatedness as determined by M13 fingerprinting generally decreased as distance increased to 25 m. Conversely, RAPD data easily discriminated populations separated by 16 and 250 km but were not useful in discriminating individuals from <1 to 25 m. Results from the complementary data sets suggest that most dispersal occurs over distances of 1-5 m, individuals within a cluster are siblings, and distinguishable biogeographic populations are present along the coast. [ABSTRACT FROM AUTHOR]

Multi-locus DNA fingerprints using an M 13 probe were obtained for two individuals of Macrocystis pyrifera (L.) C. Ag. collected from Monterey.' Bay, California, and their laboratory-reared offspring. DNA was extracted from each of two field-collected individuals (= parents), their selffertilized diploid offspring (three and seven individuals), and one diploid individual resulting from spores of the two parents. A total of 20 bands (4-19 kb) was detected among all individuals, ranging from 7 to 14 bands for any one individual. Two bands were present in all individuals, and three bands were unique to one parent and its three progeny. Ten bands were observed in the outcrossed individual, of which three were inherited from one parent, two from the other parent, and five were present in both parents. Genetic similarity between each parent and their self-fertilized offspring was significantly higher than similarity between the two self-fertilized groups. The data show that multi-locus DNA fingerprints can be used to assess parentage in the giant kelp and that there is consistent agreement between genetic similarity and known genetic relatedness among parents and offspring. [ABSTRACT FROM AUTHOR]

A method for extracting DNA from laminarialean algae resulting in Dna of sufficient quantity and purity for DNA fingerprints is presented. The method both eliminates the use of liquid N[sub2] and delays the use of toxic chemicals in the initial extraction steps, thus, it is appropriate for use in remote field locations. The algal samples were ground in a solution of hexaderyltrimethylammonium bromide (CTAB) and polyvinlpyrrolidone (PVPP) at room temperature and then stored for 1 week in the CTAB-PVPP solution at room temperature before extraction with chloroformisoamyl alcohol and purification by cesium chloride ultra centrifugation. No degradation of DNA was observed. Hybridization of Rsal-digested Macrocystis pyrifera (L.) C. Ag. DNA with the M13 repeat probe yielded a DNA fingerprint with 12 discrete bands 4-19 kb in molecular size. [ABSTRACT FROM AUTHOR]

Multi-locus DNA fingerprints using an M13 probe were obtained for eight individuals of giant kelp Macrocystis pyrifera (L.) C. Ag. Collected from Monterey Bay, California. For each individual, DNA was extracted from a diploid blade and from ca. 10[SUP9] haploid spores that were released from four to five sporophylls. Viable or swimming released from one individual were pooled and referred to as a spore group. A total of 34 bands (4-19 kb) was detected in DNA fingerprints from the eight blades and eight spore groups, with individual blads or spore groups exhibiting 7-18 bands (mean = 12.6). One band (4.5 kb) was present in all 16 samples. Similarity indices were detected in 11-14 of the 16 samples. Similarity indices were calculated for all pairwise comparisons of fingerprints bands among all possible combinations of blades and spore groups. Mean similarity indices for the eight comparisons of the blades and spore groups. Mean similarity indices for the eight blades (0.51, SE = 0.032) and spore groups (0.56, SE = 0.031) were significantly lower than for the eight comparisons of the blade and spore groups from a single individual (0.86, SE = 0.052). The data indicate that DNA fingerprints can be used to measure genetic variation within populations of M. pyrifera because variation of DNA fingerprints associated with meiotic products (spores) of a given individual is small relative to variation observed among individuals within the population. Additionally, fingerprint variation between diploid vegetative tissue and haploid meiotic products may be a measure of genetic change due to recombination or DNA turnover mechanisms. [ABSTRACT FROM AUTHOR]

Discusses the discovery of a fertile putative hybrid of Pelagophycus porra (Lem.) Setch. x Macrocystis pyrifera (L.) in Big Fisherman Cove, Santa Catalina Island, California. Plant's possession of a single, solid primary stipe that bifurcated into two secondary stipes; Number of blades that were produced on two or three dichotomies above and below each pneumatocyst.

Characteristics of the diet of black surfperch, Embiotoca jacksoni (Embiotocidae), were compared between islands where it occurs with and without a congener, the striped surfperch, Embiotoca lateralis. Several hypotheses were considered to explain observed dietary differences between allopatric and sympatric populations of black surfperch. Some differences could be readily attributed to interisland differences in the availability of prey items. Remaining dietary differences were examined in view of optimal foraging and competition hypotheses. Observations did not conform to predictions of optimal foraging theory, but did fit predictions regarding interspecific competition. There was a shift in the types and sizes of gammarid amphipods consumed between allpatric and sympatric populations of black surfperch. Gammarid amphipods are the most important prey taxon to both Embiotoca species, comprising more than 70% by number of all prey items in the diet. Further, allopatric E. jacksoni displayed patterns of selectivity for prey of various sizes that were qualitatively different from those displayed by black surfperch sympatric with E. lateralis. The prey size selectivity of allopatric black surfperch was qualitatively very similar to that found for E. lateralis. The differences in black surfperch diet that were not explained by differences in resource bases among islands were in the direction predicted by competition theory. The dietary breadth of E. jacksoni was also broader in allopatry than in sympatry. As a result of these dietary differences, there was an apparant divergence in prey use by co-occurring Embiotoca species. [ABSTRACT FROM AUTHOR]

The article discusses the genetic diversity and effective population size in the brown alga Fucus serratus species. In the study conducted on brown alga species off the coast of southern Norway, it showed that being abundant could not guarantee the species' ability to survive future environmental changes.

Here we describe a rapid method for extracting DNA from dried brown algae material using a microtitre plate system in conjunction with a milling instrument. The method allows the preparation of nuclear and organelle DNA of quality suitable for polymerase chain reaction amplification. It combines high throughput with low cost per sample: DNA from 192 samples can be extracted in c. 3 h for < €0.40 per sample, nearly tenfold cheaper than commercially available kits. Furthermore, by using microtitre plates, efficient storage and downstream processing is facilitated. [ABSTRACT FROM AUTHOR]

Background: The spatial distribution of genetic diversity and structure has important implications for conservation as it reveals a species' strong and weak points with regard to stability and evolutionary capacity. Temporal genetic stability is rarely tested in marine species other than commercially important fishes, but is crucial for the utility of temporal snapshots in conservation management. High and stable diversity can help to mitigate the predicted northward range shift of seaweeds under the impact of climate change. Given the key ecological role of fucoid seaweeds along rocky shores, the positive effect of genetic diversity may reach beyond the species level to stabilize the entire intertidal ecosystem along the temperate North Atlantic. In this study, we estimated the effective population size, as well as temporal changes in genetic structure and diversity of the seaweed F. serratus using 22 microsatellite markers. Samples were taken across latitudes and a range of temperature regimes at seven locations with decadal sampling (2000 and 2010). Results: Across latitudes, genetic structure and diversity remained stable over 5–10 generations. Stable small-scale structure enhanced regional diversity throughout the species' range. In accordance with its biogeographic history, effective population size and diversity peaked in the species' mid-range in Brittany (France), and declined towards its leading and trailing edge to the north and south. At the species' southern edge, multi-locus-heterozygosity displayed a strong decline from 1999 to 2010. Conclusion: Temporally stable genetic structure over small spatial scales is a potential driver for local adaptation and species radiation in the genus Fucus. Survival and adaptation of the low-diversity leading edge of F. serratus may be enhanced by regional gene flow and 'surfing' of favorable mutations or impaired by the accumulation of deleterious mutations. Our results have clear implications for the conservation of F. serratus at its genetically unique southern edge in Northwest Iberia, where increasing temperatures are likely the major cause for the decline not only of F. serratus, but also other intertidal and subtidal macroalgae. We expect that F. serratus will disappear from Northwest Iberia by 2100 if genetic rescue is not induced by the influx of genetic variation from Brittany. [ABSTRACT FROM AUTHOR]

The article focuses on the reply by the authors for comments on their article on Phylogeography of the seaweed Ishige (I.) okamurae (Phaeophyceae). It informs that samples of glacial refugia collected from Taiwan and off the Jeju Island in South Korea showed refugial derived populations with little or no contact. It also states that the number of samples collected of I. okamurae, off the coast of Taiwan and Jeju Island, were adequate to establish that brown algal were glacial refugia.

Eleven microsatellites were characterized for Semicossyphus pulcher (California sheephead) using an enrichment protocol. The number of alleles varied from three to 14 for a sample of 40 individuals from two populations. Expected heterozygosities ranged from 0.311 to 0.891. All loci but one were in Hardy-Weinberg equilibrium. No evidence for linkage disequilibrium was observed. These polymorphic microsatellites will be useful for genetic diversity and connectivity analyses of S. pulcher. [ABSTRACT FROM AUTHOR]