Hybridization studies in Bostrychia. 1: B. radicans (Rhodomelaceae, Rhodophyta) from Pacific and Atlantic North America

Bostrychia radicans(Montagne) Montagne is a pantropical/temperate red alga associated with mangroves and saltmarsh plants. Collections were made from a similar north-south geographic distribution along both the Pacific and Atlantic coasts of North America. Hybridization studies were performed with cultured isolates to assess the extent of interfertility and reproductive isolation along these two coastlines. All male and female gametophytes derived from single tetrasporophytes were intercompatible. Almost all isolates extending over 1500 km of coast line from northern Pacific Mexico are compatible, forming cystocarps that released viable carpospores. Even isolates which morphologically would be placed in two species [B. radicans and B. moritziana(Sender ex Kützing) J. Agardh], based on the presence or absence of monosiphonous branches, were capable of hybridizing. Crosses of isolates from the Atlantic USA showed a greater amount of incompatibility. Certain isolates were not compatible with any other isolates including isolates collected in close proximity (North Carolina isolates), while other isolates from the same locality were compatible (South Carolina). An isolate from South Carolina formed tetrasporophytes with isolates from Pacific Mexico but tetraspores were not viable. Certain incompatible crosses formed ‘pseudocystocarps’ but viable carposporophytes did not develop. Generalizations about reproductive isolation within a species must also consider differences between populations from different biogeographic regions that may reflect different paleoclimatological histories, founder effects and unique dispersal events.     

Biogeography of sexual and asexual populations in Bostrychia moritziana (Rhodomelaceae, Rhodophyta)

Bostrychia moritziana (Sonder ex Kützing) J. Agardh is recorded from many regions around the world. Our laboratory culture investigations have verified a sexual life cycle in isolates from Australia, Venezuela, Colombia, South Africa, Fiji, New Zealand and Indonesia. By contrast, asexual isolates producing successive generations of tetrasporophytes in laboratory culture and, presumably, in the field, are known from Australia. New Caledonia and Japan. In Australia, asexual reproduction is absent only in Victoria. In Western Australia, Northern Territory and Queensland, 99% of the isolates have asexual reproduction. In New South Wales (NSW), asexual and sexual populations are often intermixed. Of the 176 worldwide field collections, 58% were vegetative, 39% were tetrasporic, 2% were female and 1% were male. After several years of observations on the asexual isolates in culture, at least 30 successive asexual tetrasporophytic generations have developed. Only two asexual isolates (3558 and 3575) from NSW have formed a single male and female gametophyte in culture. In a self-cross of 3568, the carpospores developed into tetrasporophytes that recycled asexually. All outcrosses done with normal sexual isolates produced normal carposporophytes and the carpospores developed into tetrasporophytes that also recycled asexually. Asexual populations may arise repeatedly by loss of meiosis in tetrasporangia of sexual populations. Asexual reproduction apparently does not diminish the overall dispersal and abundance in the field. Our present bio-geographic data show that sexually reproducing popuiations of B. moritziana occur worldwide, while asexuaily reproducing populations are confined to the western Pacific. Bostrychia bispora West et Zuccarello, initially described on the basis of its asexual reproduction to distinguish it from B, moritziana, is now reduced to synonymy with B. moritziana.     

MULTIPLE CRYPTIC SPECIES: MOLECULAR DIVERSITY AND REPRODUCTIVE ISOLATION IN THE BOSTRYCHIA RADICANS/B. MORITZIANA COMPLEX (RHODOMELACEAE, RHODOPHYTA) WITH FOCUS ON NORTH AMERICAN ISOLATES

Red algae of the Bostrychia radicans/B. moritziana complex are common in warm temperate areas of North America. Phylogenetic analysis of both plastid and mitochondrial DNA sequence data revealed seven distinct evolutionary lineages among worldwide samples. Although only two haplotypes (plastid and mitochondrial) were found in Pacific Mexico, four plastid and 11 mitochondrial haplotypes were found in a similar latitudinal spread along the Atlantic coast of the United States. On the U.S. Atlantic coast only one plastid haplotype was found in northern samples (Connecticut to North Carolina), whereas further south several plastid haplotypes were found. Phylogenetic analyses suggested that this single plastid haplotype found among northern samples could be the result of a northward range expansion possibly since the last glacial maximum. Crossing data of samples within the same evolutionary lineage showed that samples with the same plastid haplotypes were generally sexually compatible; samples with different plastid haplotypes were reproductively isolated. Samples from Pacific Mexico were partially reproductively compatible with some samples from the Atlantic USA (plastid haplotype C) and were more closely related to these samples than these U.S. samples were to other U.S. Atlantic samples. Compatible solute types mirrored the plastid haplotype, with plastid haplotype B having only sorbitol, whereas all other haplotypes also contained dulcitol. Samples from Atlantic USA, with different plastid haplotypes (e.g. B vs. C), but within the same evolutionary lineage, were reproductively isolated from each other. Data indicate that reproductive isolation occurs between and within supported evolutionary lineages and that the number of cryptic species is high.     

Global population genetic structure of the starlet anemone <Emphasis Type="Italic">Nematostella vectensis</Emphasis>: multiple introductions and implications for conservation policy

Distinguishing natural versus anthropogenic dispersal of organisms is essential for determining the native range of a species and implementing an effective conservation strategy. For cryptogenic species with limited historical records, molecular data can help to identify introductions. Nematostella vectensis is a small, burrowing estuarine sea anemone found in tidally restricted salt marsh pools. This species’ current distribution extends over three coast lines: (i) the Atlantic coast of North America from Nova Scotia to Georgia, (ii) the Pacific coast of North America from Washington to central California, and (iii) the southeast coast of England. The 1996 IUCN Red List designates N. vectensis as “vulnerable” in England. Amplified fragment length polymorphism (AFLP) fingerprinting of 516 individuals from 24 N. vectensis populations throughout its range and mtDNA sequencing of a subsample of these individuals strongly suggest that anthropogenic dispersal has played a significant role in its current distribution. Certain western Atlantic populations of N. vectensis exhibit greater genetic similarity to Pacific populations or English populations than to other western Atlantic populations. At the same time, F-statistics showing high degrees of genetic differentiation between geographically proximate populations support a low likelihood for natural dispersal between salt marshes. Furthermore, the western Atlantic harbors greater genetic diversity than either England or the eastern Pacific. Collectively, these data clearly imply that N. vectensis is native to the Atlantic coast of North America and that populations along the Pacific coast and in England are cases of successful introduction.     

Land barriers and open oceans: effects on gene diversity and population structure in Avicennia germinans L. (Avicenniaceae)

Avicennia germinans L. is a widespread mangrove species occupying the west coast of Africa and the Atlantic and Pacific coasts of the Americas from the Bahamas to Brazil and Baja California to Peru. An amplified fragment length polymorphism (AFLP) molecular analysis was carried out to assess genetic architecture within this species and to evaluate the effects of the Atlantic Ocean and the Central American Isthmus (CAI) on population and regional genetic diversity and differentiation. In total, 349 polymorphic AFLP fragments were identified among 144 individuals from 14 populations from the east Atlantic, west Atlantic and east Pacific. Levels of genetic diversity varied considerably among populations, but were generally higher in populations from the east Atlantic. Regional differentiation between the Pacific coast and Atlantic populations was greater than between east and west Atlantic populations, suggesting that the CAI has had an important influence on population genetic structure in this species. The lower level of divergence of east Atlantic from west Atlantic populations suggests some dispersal across the Atlantic Ocean, although migration rates are probably low; Nm from GST equal to 0.41 and accumulation of private and rare alleles in the east Atlantic. Population differentiation did not appear to follow an isolation by distance model and has probably resulted from complex patterns of population bottlenecks, and founder events due to landscape changes during the Pleistocene, particularly in the west Atlantic. The molecular data provide no support for the treatment of east Atlantic populations as a separate species A. africana.     

Dung beetles in pasture landscapes of Central America: proliferation of synanthropogenic species and decline of forest specialists

This study examines the spread of synanthropogenic dung beetles (species favoured by human activities) in pasture landscapes in Central America, and evaluates the role of forest fragments and regenerating patches of native vegetation in maintaining beetle diversity. Pitfall trapping was carried out at nine locations in El Salvador and seven in Atlantic Nicaragua that included both pasture and remnant or regenerating native vegetation. More dung beetle species occurred in forest fragments than in pastures. Community composition differed considerably between forest fragments from El Salvador and Nicaragua with many species restricted to either the Caribbean or Pacific regions. In contrast, dung beetle community composition and structure were largely the same in the pastures of El Salvador and Nicaragua, regardless of region or original habitat-type, and were similar to published results from pastures in Mexico and elsewhere on the Isthmus. Very small patches of native shrubs and tree stands (<2.5 ha) maintained no forest specialists in Nicaragua, whereas, in El Salvador, some forest specialists occurred even in the smallest stands of trees (ca. 0.25 ha). The study indicates that the expansion of cattle pastures has caused a regional decline in dung beetle diversity. Forest fragments and small isolated patches of native trees and shrubs maintain some of the diversity of the original landscape but their conservation value for dung beetles will depend on the biogeographical history of the sites.     

Possible Ballast Water Transfer of Lionfish to the Eastern Pacific Ocean

The Indo-Pacific Red Lionfish was first reported off the Florida coast in 1985, following which it has spread across much of the SE USA, Gulf of Mexico, and Caribbean Sea. Lionfish negatively impact fish and invertebrate assemblages and abundances, thus further spread is cause for concern. To date, the fish has not been reported on the Pacific coast of North or Central America. Here we examine the possibility of ballast water transfer of lionfish from colonized areas in the Atlantic Ocean to USA ports on the Pacific coast. Over an eight-year period, we documented 27 commercial vessel-trips in which ballast water was loaded in colonized sites and later discharged untreated into Pacific coast ports in the USA. California had the highest number of discharges including San Francisco Bay and Los Angeles-Long Beach. A species distribution model suggests that the probability of lionfish establishment is low for the western USA, Colombia and Panama, low to medium for Costa Rica, Nicaragua, El Salvador and Guatemala, medium to high for mainland Ecuador, and very high for western Mexico, Peru and the Galapagos Islands. Given the species’ intolerance of freshwater conditions, we propose that ballast water exchange be conducted in Gatún Lake, Panama for western-bound vessels carrying ‘risky’ ballast water to prevent invasion of the eastern Pacific Ocean.     

Population genetics of Cordia alliodora (Boraginaceae), a neotropical tree. 1. Genetic variation in natural populations

We provide an estimate of genetic differentiation within and among 11 populations of Cordia alliodora, an economically important timber tree Cordia alliodora is a widespread species that is distributed throughout Central and South America. Our survey of isozyme variation was conducted on material gathered for international provenance trials over approximately 1,000 km in Central America. Results from provenance trials indicate that there are significant differences between Atlantic and Pacific coast provenances for quantitative characters. Genetic data support some of these findings. Populations of C. alliodora show significant differences in allele frequency at various loci. Significant differences in multilocus allele frequencies occur at 13 of the 55 possible combinations. Eight of these 13 populations are situated on opposite coasts. This physical separation corresponds well with the results of provenance trials that indicate differentiation among the Atlantic and Pacific populations in quantitative morphological traits. We also found a significant negative correlation between levels of heterozygosity and the amount of rainfall, indicating that populations from the drier zone are genetically more heterogenous than populations from the wet zone. Our study indicates that in situ and ex situ conservation should accord high priority to the dry zone populations; furthermore, conservation of this widespread species would require preservation of multiple populations.     

High migration rates shape the postglacial history of amphi‐Atlantic bryophytes

Paleontological evidence and current patterns of angiosperm species richness suggest that European biota experienced more severe bottlenecks than North American ones during the last glacial maximum. How well this pattern fits other plant species is less clear. Bryophytes offer a unique opportunity to contrast the impact of the last glacial maximum in North America and Europe because about 60% of the European bryoflora is shared with North America. Here, we use population genetic analyses based on approximate Bayesian computation on eight amphi‐Atlantic species to test the hypothesis that North American populations were less impacted by the last glacial maximum, exhibiting higher levels of genetic diversity than European ones and ultimately serving as a refugium for the postglacial recolonization of Europe. In contrast with this hypothesis, the best‐fit demographic model involved similar patterns of population size contractions, comparable levels of genetic diversity and balanced migration rates between European and North American populations. Our results thus suggest that bryophytes have experienced comparable demographic glacial histories on both sides of the Atlantic. Although a weak, but significant genetic structure was systematically recovered between European and North American populations, evidence for migration from and towards both continents suggests that amphi‐Atlantic bryophyte population may function as a metapopulation network. Reconstructing the biogeographic history of either North American or European bryophyte populations therefore requires a large, trans‐Atlantic geographic framework.     

When physical oceanography meets population genetics: The case study of the genetic/evolutionary discontinuity in the endangered goliath grouper (Epinephelus itajara; Perciformes: Epinephelidae) with comments on the conservation of the species

Epinephelus itajara is one of the marine fish species most threatened for extinction and it is considered to be “critically endangered” by the IUCN. The present study evaluated the genetic diversity of the species and the genetic/evolutionary relationships of its populations along the Atlantic coast of South America. The results indicate relatively reduced genetic variation, re-emphasizing the low adaptive potential of the species. One of the populations presented relatively high degrees of genetic diversity and it is evolutionary isolated from the all other populations. The evidences indicate the existence of two Evolutionarily Significant Units comprising E. itajara in the Atlantic coast of South America and the conservation prospects for the species must take these evidences into account.     

BIODIVERSITY RESEARCH: Genetic diversity in two introduced biofouling amphipods (Ampithoe valida & Jassa marmorata) along the Pacific North American coast: investigation into molecular identification and cryptic diversity

Aim We investigated patterns of genetic diversity among invasive populations of Ampithoe valida and Jassa marmorata from the Pacific North American coast to assess the accuracy of morphological identification and determine whether or not cryptic diversity and multiple introductions contribute to the contemporary distribution of these species in the region. Location Native range: Atlantic North American coast; Invaded range: Pacific North American coast. Methods We assessed indices of genetic diversity based on DNA sequence data from the mitochondrial cytochrome c oxidase subunit I (COI) gene, determined the distribution of COI haplotypes among populations in both the invasive and putative native ranges of A. valida and J. marmorata and reconstructed phylogenetic relationships among COI haplotypes using both maximum parsimony and Bayesian approaches. Results Phylogenetic inference indicates that inaccurate species‐level identifications by morphological criteria are common among Jassa specimens. In addition, our data reveal the presence of three well supported but previously unrecognized clades of A. valida among specimens in the north‐eastern Pacific. Different species of Jassa and different genetic lineages of Ampithoe exhibit striking disparity in geographic distribution across the region as well as substantial differences in genetic diversity indices. Main conclusions Molecular genetic methods greatly improve the accuracy and resolution of identifications for invasive benthic marine amphipods at the species level and below. Our data suggest that multiple cryptic introductions of Ampithoe have occurred in the north‐eastern Pacific and highlight uncertainty regarding the origin and invasion histories of both Jassa and Ampithoe species. Additional morphological and genetic analyses are necessary to clarify the taxonomy and native biogeography of both amphipod genera.     

Invasion by the marine gastropod Ocinebrellus inornatus in France: I. Scenario for the source of introduction

The rate of introduction of exotic marine species has dramatically increased during the 19th and 20th centuries. Exemplifying this trend, the marine gastropod Ocinebrellus inornatus was first detected outside its native range in 1924 on the American Pacific coast, then in 1995 on the French Atlantic coast. To determine the origin of the French populations of this invasive species, we compared a French population with populations collected in Asia—the native range—and with a population collected in the United States. Analyses of mitochondrial DNA and allozyme polymorphism revealed that the French and American populations were closely related and substantially differentiated from the Asian populations. According to our results, the most likely scenario is that the source population of the French Atlantic coast populations was located in the United States. Indeed, taken altogether, the genetic structure of Asian populations, the time lag separating the introduction on the American Pacific coast from the introduction on the French Atlantic coast and the high level of genetic diversity in the two introduced areas (indicating an absence of major founder events) are hardly compatible with a scenario in which French population resulting only from primary introduction events from the native area. Finally, although similar, the French and American populations were not identical. Thus, even if the main source population of the French populations was located in the United States, the genetic structure of French populations may have been modified by cryptic and recurrent introduction events directly from Asia.     

An introduced population of Chorda asiatica (Chordaceae,Laminariales) in Puget Sound,Pacific coast of North America

Northeastern Pacific Ocean and northwestern Atlantic Ocean populations of Chorda species, which have not been examined in previous phylogenetic studies, were investigated. All specimens that were collected in Hood Canal, Puget Sound, WA, USA, Pacific coast of North America, showed identical ITS‐5.8S rDNA sequences, and they were included in the clade of Japanese Chorda asiatica. With morphological data added to the molecular data, they were identified as C. asiatica and were concluded to be non‐indigenous populations, most likely introduced with oyster spat together with Sargassum muticum. Specimens collected in New York, NY, USA, Atlantic coast of North America, were genetically closest to C. filum from Newfoundland and were identified as C. filum. The genetic divergence of the North Atlantic populations of C. filum was relatively small compared to that of Japanese C. asiatica considering their broader distributional ranges on both sides of the Atlantic.     

Genetic diversity of the black mangrove (Avicennia germinans L.) in Colombia

This study analyzed the genetic diversity and patterns of genetic structure in Colombian populations of Avicennia germinans L. using microsatellite loci. A lower genetic diversity was found on both the Caribbean (Ho = 0.439) and the Pacific coasts (Ho = 0.277) than reported for the same species in other locations of Central American Pacific, suggesting the deterioration of genetic diversity. All the populations showed high inbreeding coefficients (0.131–0.462) indicating heterozygotes deficience. The genetic structure between the Colombian coasts separated by Central American Isthmus was high (F_RT = 0.39) and the analyses of the genetic patterns of A. germinans revealed a clear differentiation of populations and no-recent gene flow evidence between coasts. Genetic structure was found within each coast (F_ST = 0.10 for the Caribbean coast and F_ST = 0.22 for the Pacific coast). The genetic patterns along the two coasts appear to reflect a forcing by local geomorphology and marine currents. Both coasts constitute a different Evolutionary Significant Unit, so we suggest for future transplantations plans that propagules or saplings of the populations of the Caribbean coast should not be mixed with those of the Pacific Colombian coast. Besides, we suggest that reforestation efforts should carefully distinguish propagules sources within each coast.     

Geographic structure, genetic diversity and source tracking of Spartina alterniflora

Aim To examine the distribution and structure of genetic variation among native Spartina alterniflora and to characterize the evolutionary mechanisms underlying the success of non‐native S. alterniflora. Location Intertidal marshes along the Atlantic, Gulf and Pacific coasts of North America. Methods amova , parsimony analysis, haplotype networks of chloroplast DNA (cpDNA) sequences, neighbour‐joining analysis, Bayesian analysis of population structure, and individual assignment testing were used. Results Low levels of gene flow and geographic patterns of genetic variation were found among native S. alterniflora from the Atlantic and Gulf coasts of North America. The distribution of cpDNA haplotypes indicates that Atlantic coast S. alterniflora are subdivided into ‘northern’ and ‘southern’ groups. Variation observed at microsatellite loci further suggests that mid‐Atlantic S. alterniflora are differentiated from S. alterniflora found in southern Atlantic and New England coastal marshes. Comparisons between native populations on the Atlantic and Gulf coasts and non‐native Pacific coast populations substantiate prior studies demonstrating reciprocal interspecific hybridization in San Francisco Bay. Our results corroborate historical evidence that S. alterniflora was introduced into Willapa Bay from multiple source populations. However, we found that some Willapa Bay S. alterniflora are genetically divergent from putative sources, probably as a result of admixture following secondary contact among previously allopatric native populations. We further recovered evidence in support of models suggesting that S. alterniflora has secondarily spread within Washington State, from Willapa Bay to Grays Harbor. Main conclusions Underlying genetic structure has often been cited as a factor contributing to ecological variation of native S. alterniflora. Patterns of genetic structure within native S. alterniflora may be the result of environmental differences among biogeographical provinces, of migration barriers, or of responses to historical conditions. Interactions among these factors, rather than one single factor, may best explain the distribution of genetic variation among native S. alterniflora. Comprehensive genetic comparisons of native and introduced populations can illustrate how biological invasions may result from dramatically different underlying factors – some of which might otherwise go unrecognized. Demonstrating that invasions can result from several independent or interacting mechanisms is important for improving risk assessment and future forecasting. Further research on S. alterniflora not only may clarify what forces structure native populations, but also may improve the management of non‐native populations by enabling post‐introduction genetic changes and the rapid evolution of life‐history traits to be more successfully exploited.     

Contrasting patterns of population structure and demographic history in cryptic species of Bostrychia intricata (Rhodomelaceae,Rhodophyta) from New Zealand

Spatial patterns of genetic diversity provide insight into the demography and history of species. Morphologically similar but genetically distinct “cryptic” species are increasingly being recognized in marine organisms through molecular analyses. Such species are, on closer inspection, often discovered to display contrasting life histories or occasionally minor morphological differences; molecular tools can thus be useful indicators of diversity. Bostrychia intricata, a marine red alga, is widely distributed throughout the Southern Hemisphere and comprises many cryptic species. We used mitochondrial cytochrome c oxidase I gene sequences to assess the genetic variation, population genetic structure, and demographic history of B. intricata in New Zealand. Our results supported the existence of three cryptic species of B. intricata (N2, N4, and N5) in New Zealand. Cryptic species N4, which was found throughout New Zealand, showed a higher genetic diversity and wider distribution than the other two species, which were only found in the North Island and northern South Island. Our analyses showed low to moderate genetic differentiation among eastern North Island populations for cryptic species N2, but high differentiation among North and South Island populations for N4, suggesting different population structure between these cryptic species. Data also indicated that N2 has recently undergone population expansion, probably since the Last Glacial Maximum (LGM), while the higher genetic diversity in N4 populations suggests persistence in situ through the LGM. The contrasting population structures and inferred demographic histories of these species highlight that life history can vary greatly even among morphologically indistinguishable taxa.     

Worldwide patterns of mitochondrial DNA differentiation in the harbor seal (Phoca vitulina)

The harbor seal (Phoca vitulina) has one of the broadest geographic distributions of any pinniped, stretching from the east Baltic, west across the Atlantic and Pacific Oceans to southern Japan. Although individuals may travel several hundred kilometers on annual feeding migrations, harbor seals are generally believed to be philopatric, returning to the same areas each year to breed. Consequently, seals from different areas are likely to be genetically differentiated, with levels of genetic divergence increasing with distance. Differentiation may also be caused by long-standing topographic barriers such as the polar sea ice. We analyzed samples of 227 harbor seals from 24 localities and defined 34 genotypes based on 435 bp of control region sequence. Phylogenetic analysis and analysis of molecular variance showed that populations in the Atlantic and Pacific Oceans and east and west coast populations of these oceans are significantly differentiated. Within these four regions, populations that are geographically farthest apart generally are the most differentiated and often do not share genotypes or differ in genotype frequency. The average corrected sequence divergence between populations in the Atlantic and Pacific Oceans is 3.28% +/- 0.38% and those among populations within each of these oceans are 0.75% +/- 0.69% and 1.19% +/- 0.65%, respectively. Our results suggest that harbor seals are regionally philopatric, on the scale of several hundred kilometers. However, genetic discontinuities may exist, even between neighboring populations such as those on the Scottish and east English coasts or the east and west Baltic. The mitochondrial data are consistent with an ancient isolation of populations in both oceans, due to the development of polar sea ice. In the Atlantic and Pacific, populations appear to have been colonized from west to east with the European populations showing the most recent common ancestry. We suggest the recent ancestry of European seal populations may reflect recolonization from Ice Age refugia after the last glaciation.      

Hierarchical modeling of genome‐wide Short Tandem Repeat (STR) markers infers native American prehistory

This study examines a genome‐wide dataset of 678 Short Tandem Repeat loci characterized in 444 individuals representing 29 Native American populations as well as the Tundra Netsi and Yakut populations from Siberia. Using these data, the study tests four current hypotheses regarding the hierarchical distribution of neutral genetic variation in native South American populations: (1) the western region of South America harbors more variation than the eastern region of South America, (2) Central American and western South American populations cluster exclusively, (3) populations speaking the Chibchan‐Paezan and Equatorial‐Tucanoan language stock emerge as a group within an otherwise South American clade, (4) Chibchan‐Paezan populations in Central America emerge together at the tips of the Chibchan‐Paezan cluster. This study finds that hierarchical models with the best fit place Central American populations, and populations speaking the Chibchan‐Paezan language stock, at a basal position or separated from the South American group, which is more consistent with a serial founder effect into South America than that previously described. Western (Andean) South America is found to harbor similar levels of variation as eastern (Equatorial‐Tucanoan and Ge‐Pano‐Carib) South America, which is inconsistent with an initial west coast migration into South America. Moreover, in all relevant models, the estimates of genetic diversity within geographic regions suggest a major bottleneck or founder effect occurring within the North American subcontinent, before the peopling of Central and South America. Am J Phys Anthropol 2010. © 2009 Wiley‐Liss, Inc.     

Translocations maintain genetic diversity and increase connectivity in sea otters,Enhydra lutris

Sea otters, Enhydra lutris, were once abundant along the nearshore areas of the North Pacific. The international maritime fur trade that ended in 1911 left 13 small remnant populations with low genetic diversity. Subsequent translocations into previously occupied habitat resulted in several reintroduced populations along the coast of North America. We sampled sea otters between 2008 and 2011 throughout much of their current range and used 19 nuclear microsatellite markers to evaluate genetic diversity, population structure, and connectivity between remnant and reintroduced populations. Average genetic diversity within populations was similar: observed heterozygosity 0.55 and 0.53, expected heterozygosity 0.56 and 0.52, unbiased expected heterozygosity 0.57 and 0.52, for reintroduced and remnant populations, respectively. Sea otter population structure was greatest between the Northern and Southern sea otters with further structuring in Northern sea otters into Western, Central, and Southeast populations (including the reintroduced populations). Migrant analyses suggest the successful reintroductions and growth of remnant groups have enhanced connectivity and gene flow between populations throughout many of the sampled Northern populations. We recommend that future management actions for the Southern sea otter focus on future reintroductions to fill the gap between the California and Washington populations ultimately restoring gene flow to the isolated California population.     

Observations on Bostrychia radicosa comb. nov. (Rhodomelaceae, Rhodophyta)

Only two genera in the Rhodomelaceae share the morphological character of transverse division of periaxial cells into two or more tier cells in which the pit connection is retained between the lower cell and the axial cell: Bostrychia and Rhodolachne. One species, Rhodolachne radicosa Itono, has been reported from mangroves, a common habitat for Bostrychia. Many collections of an entity similar to Rhodolachne radicosa have been made from localities around the Indo‐Pacific. Culture observations show a Polysiphonia‐type sexual life history in Malaysia and New Caledonia isolates that produce self‐compatible bisexual gametophytes. The New Caledonia isolate also has unisexual gametophytes. An isolate from New South Wales (Australia) reproduces asexually through successive generations of tetrasporophytes. The Thailand isolate has successive generations of mixed‐phase tetrasporophytes. The tetrasporangial stichidia also bear male spermatangial sectors, but female structures are lacking. Western Australia and Madagascar isolates do not reproduce in culture. Molecular evidence, based on sequencing of the rbcL and the large subunit ribosomal RNA genes, shows that these isolates belong to the genus Bostrychia. Low molecular weight carbohydrate analysis reveals high levels of digeneaside in all isolates. The sugar hexitol sorbitol, an osmolyte characteristic of Bostrychia, occurs in all isolates, whereas the Madagascar and New Caledonia isolates have very low levels of dulcitol. Molecular, low molecular weight carbohydrate and morphological evidence show that Rhodolachne radicosa belongs within the genus Bostrychia. We transfer Rhodolachne radicosa to Bostrychia radicosa (Itono) West, Zuccarello and Hommersand.