Recruitment to adult habitats following marine planktonic development in the fiddler crabs, Uca pugilator, U. pugnax, and U. minax

Three congeneric species of fiddler crabs, Uca pugilator (Bosc, 1802), U. pugnax (Smith, 1870), and U. minax (LeConte, 1855), co-occur in estuaries along the east coast of North America, from Cape Cod to northern Florida. Although U. minax adults are generally found at lower salinities than the other two species, the distributions of all three species overlap to some degree. The distribution of megalopae and juvenile fiddler crabs (from first crab stage to those with a carapace width of 3.0 mm) was examined at four sites along a salinity gradient (from 35.0±2.0 to 3.0±3.0; ) in the North Inlet Estuary, South Carolina, USA, in August 2002. A PCR-RFLP technique was developed to identify individuals from the genus Uca to species from first zoea through the early crab stages. An examination of the distribution of early life stages showed that U. minax reinvades low-salinity adult habitats at settlement, following planktonic larval development in the coastal ocean. Also, juveniles of U. pugilator were found to occupy Spartina alterniflora stands, where adult conspecifics rarely occur. Species frequencies were different for adults compared to early life stages in low-salinity areas of the marsh, where populations overlap. Settlement and survival dynamics of early life-history stages in wet and dry years likely determine the distribution of adult Uca spp. populations along salinity gradients in estuarine ecosystems.Communicated by J.P. Grassle, New Brunswick     

Genetic divergence between colour morphs in populations of the common intertidal sea anemones Actinia equina and A. prasina (Anthozoa: Actiniaria) in the Isle of Man

A distinctive morph ofActinia equina (L.) is found at low frequency among populations on intertidal hard substrata on some shores on the Isle of Man. This morph is red with rows of green oval spots or elongate markings running longitudinally down the column. Starch gel electrophoresis of 21 allozyme loci was used to compare samples of this morph from two localities with other sympatricActinia spp. Collections were made in early summer 1986. For one sampling site the comparison was with redA. equina and greenA. prasina Gosse, whilst at the other site with redA. equina only. At both sites significant genetic differences in allele frequencies at several loci were found between the new morph and sympatricA. equina andA. prasina. The results also confirm the reproductive isolation ofA. prasina. As with much previous work on sea anemones, levels of mean heterozygosity per locus (H) were found to be high (H=0.157 to 0.342). A surprising feature of the results, although bearing out earlier unpublished data, is that high levels of genetic differentiation are found between populations of what appear to be the same morphs collected from shores only a few km apart. Among theActinia spp. studied, differentiation between populations of the same morph on different shores was of the same order as between sympatric, reproductively isolated populations.     

Population differentiation and taxonomic status of the exploited limpet Patella candei in the Macaronesian islands (Azores,Madeira, Canaries)

There has been considerable confusion in the taxonomy of limpets of the North East Atlantic Ocean and Mediterranean Sea, particularly those from the Macaronesian islands. The present study compared populations of the intertidal limpet Patella candei d'Orbigny from the Azores, Madeira and the Canaries with those of P. caerulea Linnaeus and P. depressa Pennant from the European and African continental coasts. No major differences in radular morphology were detected between the three species. However, electrophoretic analysis of 15 enzyme loci gave overall genetic identity (I) values of 0.5 between the three species, indicating that they cannot be regarded as conspecific as previously thought, and suggesting that P. candei is endemic to the Macaronesian islands. Comparisons of P. candei within these islands showed that, although populations did not differ with respect to radular morphology and soft-body parts, populations from the Azores were distinct from those in Madeira and the Canaries in shell shape and gene frequencies. Individuals from the Azores had, no average, taller shells and longer radulae, while those in Madeira and the Canaries had a shallow, depressed and stellate shell form. This was interpreted as being due to the wider habitat distribution of the species in the Azores compared to Madeira and the Canaries. Electrophoretic results showed that P. candei from the Azores differed from P. candei in Madeira and the Canaries by almost 40% of the loci investigated (I=0.660), suggesting that the former is a separate endemic species. An I value of 0.969 between populations in Madeira and the Canaries was typical of conspecific populations.     

Genetic structure of<Emphasis Type="Italic"> Linckia laevigata</Emphasis> and<Emphasis Type="Italic"> Tridacna crocea</Emphasis> populations in the Palawan shelf and shoal reefs

Allozyme variation of 10 populations of Linckia laevigata at 8 polymorphic loci and 13 populations of Tridacna crocea at 6 polymorphic loci were analyzed to compare genetic variability and genetic affinities among reefs in Palawan, Philippines. Two to five populations were sampled from each of four regions: the shelf reefs in (1) northern Palawan and (2) southern Palawan and the offshore reefs in (3) the Kalayaan island group (KIG) in the South China Sea and (4) the Tubbataha shoals in the Sulu Sea. Heterozygosity was highest in populations of L. laevigata from the south shelf of Palawan and populations of T. crocea from the Tubbataha shoals of the Sulu Sea. The lowest heterozygosity estimates were from the reefs of the KIG in the South China Sea, for both species. Overall F _ST values for both species were significant, with an estimated average number of effective migrants per generation (N _EM) of 4.85 (~5 individuals) for L. laevigata and 3.54 (~4 individuals) for T. crocea. Within-region comparisons showed N_EM ranging from 6.29 to 92.34 for L. laevigata and from 3.40 to 6.30 for T. crocea. The higher gene flow among L. laevigata populations relative to T. crocea is consistent with the greater dispersal potential of the former species. Finer scale genetic structuring was evident in T. crocea populations. For both species, the Tubbataha reefs in the Sulu Sea have higher genetic affinity with the populations from the southern shelf of Palawan, while the reefs in the KIG had higher affinity with the northern Palawan shelf reefs. The north and south shelf populations have the least genetic affinity. Genetic patchiness among reefs within regions suggests the importance of small-scale physical factors that affect recruitment success in structuring populations in small island and shoal reef systems in Palawan.     

Nuclear and mitochondrial DNA markers indicate unidirectional gene flow of Indo-Pacific to Atlantic bigeye tuna (<Emphasis Type="Italic">Thunnus obesus</Emphasis>) populations,and their admixture off southern Africa

A sharp genetic break separates Atlantic from Indo-Pacific bigeye tuna (Thunnus obesus) populations, as the frequencies of two major mitochondrial (mt) DNA types ( and ) found in this species are different across the tip of southern Africa. The level of nucleotide divergence between mtDNA types and is of the same order as that between reproductively isolated taxa. To further investigate the genetic structure of bigeye tuna over its distribution range and in the contact zone off southern Africa, bigeye tuna samples collected between 1992 and 2001 (including samples from a previous mtDNA survey) were characterized for four nuclear DNA loci and for mtDNA. Nuclear markers did not support the hypothesis that and mitochondria characterize sibling species. Significant allele-frequency differences at one intronic locus (GH2) and one microsatellite locus (µ208) were found between Atlantic and Indo-Pacific samples, although the level of nuclear genetic differentiation (Weir and Cockerhams =0.025 to 0.042) was much lower than in mtDNA ( =0.664 to 0.807). Probabilistic Bayesian assignment of individuals to a population confirmed that southern African bigeye tuna samples represent a simple mixture of individuals from Atlantic and Indian stocks that do not interbreed, with a higher contribution from Indian Ocean individuals (about 2/3 vs. 1/3).Communicated by M.S. Johnson, Crawley     

Evolution of coral reef fish<Emphasis Type="Italic"> Thalassoma</Emphasis> spp. (Labridae). 2. Evolution of the eastern Atlantic species

The genetic relationships within and among congeneric species of marine fish from the Atlantic and the Mediterranean are poorly known. Relationships among all five species of the wrasse genus Thalassoma present in the Atlantic and the Mediterranean were examined using sequence data from the mitochondrial control region. Sampling was focused on the mid-Atlantic T. sanctaehelenae (Valenciennes, 1839) and T. ascensionis (Quoy & Gaimard, 1834), the eastern Atlantic T. newtoni (Osório, 1891) from Sao Tome, and the eastern Atlantic/Mediterranean T. pavo (Linnaeus, 1758). Two western Atlantic species T. bifasciatum (Bloch, 1791) from the Caribbean and T. noronhanum (Boulenger, 1890) from Brazil served as outgroups. Tissues from a total of 132 individuals were sequenced. T. newtoni from Sao Tome preferentially grouped with the central Atlantic T. sanctaehelenae and T. ascensionis. T. pavo exhibits two distinct coloration patterns, one in the Cape Verde Islands and one in the eastern Atlantic Islands and Mediterranean. However, no genetic discontinuities between the Cape Verde Islands and the remaining samples or between Atlantic and Mediterranean individuals were found. Within Mediterranean populations of T. pavo, our data suggested the presence of a genetic break between eastern and western regions.Communicated by J.P. Grassle, New Brunswick     

Investigations of carotenoids in some fauna of the Adriatic Sea. II. Anemonia sulcata and Actinia equina (Coelenterata: Anthozoa)

Investigations have been carried out on the carotenoids in Anemonia sulcata (Pennant) and Actinia equina (L.) (Coelenterata: Anthozoa) from the Adriatic Sea. The presence of the carotenoids was determined by means of columnar and thin-layer chromatography. The following carotenoids were found: Anemonia sulcata: β-carotene, lutein-like (epoxy and free) and astaxanthin; Actinia equina: α-carotene, β-carotene, actinioerythrin, lutein-like (?) and astaxanthin (ester and free).     

Ancient divergences and recent connections in two tropical Atlantic reef fishes<Emphasis Type="Italic"> Epinephelus adscensionis</Emphasis> and<Emphasis Type="Italic"> Rypticus saponaceous</Emphasis> (Percoidei: Serranidae)

Reef habitats of the tropical Atlantic are separated by river outflows and oceanic expanses that may preclude larval dispersal or other population connections in shorefishes. To examine the impact of these habitat discontinuities on the intraspecific phylogeography of reef-associated species we conducted range-wide surveys of two amphi-Atlantic reef fishes that have dispersive pelagic larval stages. Based on 593 bp of mtDNA cytochrome b from the rock hind Epinephelus adscensionis and 682 bp from the greater soapfish Rypticus saponaceous (n=109 and 86, respectively), we found evidence of relatively ancient separations as well as recent surmounting of biogeographic barriers by dispersal or colonization. Rock hind showed slight but significant population genetic differentiation across much of the tropical Atlantic Ocean (_ST=0.056), but deep divergence between the southeastern United States and seven other localities from the Bahamas to the south, central and east Atlantic (mean pairwise d=0.040, overall _ST=0.867). The geographic distribution of the two rock hind lineages is highly unusual in genetic studies of Caribbean Sea reef fishes, because those lineages are separated by less than 250 km of open water within a major biogeographic region. In contrast, highly significant population genetic structure was observed among greater soapfish from the SW Caribbean, Brazil, and mid-Atlantic ridge (_ST=0.372), with a deep evolutionary separation distinguishing putative R. saponaceous from West Africa (mean pairwise d=0.044, overall _ST=0.929). Both species show evidence for a potential connection between the Caribbean and Brazilian provinces. While widespread haplotype sharing in rock hind indicates that larvae of this species cross oceanic expanses of as much as 2000 km, such a situation is difficult to reconcile with the isolation of populations in Florida and the Bahamas separated by only 250 km. These findings indicate that populations of some species in disjunct biogeographic zones may be isolated for long periods, perhaps sufficient for allopatric speciation, but rare gene flow between zones may preclude such evolutionary divergence in other species.Communicated by P.W. Sammarco, Chauvin     

Individual growth and somatic production in<Emphasis Type="Italic"> Adelomelon brasiliana</Emphasis> (Gastropoda; Volutidae) off Argentina

Growth, age and somatic production of the benthic predator Adelomelon brasiliana were studied at the southern limit of its distribution on the South American Atlantic shelf. Stable oxygen isotope ratios confirmed annual formation of internal shell growth marks. Modal shell length of the population was 140 mm, while modal shell-free wet mass was 255 g. A logistics growth function (SL=186.28 mm, K=0.185, t₀=4.601) fitted 131 pairs of size-at-age data (25 shells) best. A. brasiliana is a very long-lived species, reaching up to 20 years of age. The maximum individual somatic production of 46 g shell-free wet mass year^–1 is attained at 145 mm shell length, which corresponds to about 12 years of age.Communicated by O. Kinne, Oldendorf/Luhe     

Spatial heterogeneity of photosynthesis and the effect of temperature-induced bleaching conditions in three species of corals

Heterogeneity in photosynthetic performance between polyp and coenosarc tissue in corals was shown using a new variable fluorescence imaging system (Imaging-PAM) with three species of coral, Acropora nobilis, Cyphastrea serailia and Pocillopora damicornis. In comparison to earlier studies with fibre-optic microprobes for fluorescence analysis, the Imaging-PAM enables greater accuracy by allowing different tissues to be better defined and by providing many more data points within a given time. Spatial variability of photosynthetic performance from the tip to the distal parts was revealed in one species of branching coral, A. nobilis. The effect of bleaching conditions (33°C vs. 27°C) was studied over a period of 8 h. Marked changes in fluorescence parameters were observed for all three species. Although a decline in _PSII (effective quantum yield) and Yi (the first effective quantum yield obtained from a rapid light curve) were observed, P. damicornis showed no visual signs of bleaching on the Imaging-PAM after this time. In A. nobilis and C. serailia, visual signs of bleaching over the 8 h period were accompanied by marked changes in F (light-adapted fluorescence yield), NPQ (non-photochemical quenching) and E _k (minimum saturating irradiance), as well as _PSII and Yi. These changes were most marked over the first 5 h. The most sensitive species was A. nobilis, which after 8 h at 33°C had reached a _PSII value of almost zero across its whole surface. Differential bleaching responses between polyps and coenosarc tissue were found in P. damicornis, but not in A. nobilis and C. serailia. NPQ increased with exposure time to 33°C in both the latter species, accompanied by a decreasing E _k, suggesting that the xanthophyll cycle is entrained as a mechanism for reducing the effects of the bleaching conditions.Communicated by L. Hagerman, Helsingør     

Gonadal development in the coral reef damselfish<Emphasis Type="Italic"> Dascyllus flavicaudus</Emphasis> from Moorea,French Polynesia

The present study investigated the sexual pattern of the yellow-tailed dascyllus, Dascyllus flavicaudus (Randall and Allen), through histological examination of the process of gonadal differentiation and maturation and through male-removal experiments in the laboratory. The study was conducted in Moorea, French Polynesia (17°32S; 149°50W), from 31 December 1994 to 11 March 1995. For gonadal histology, two populations were sampled, one consisting of large aggregations (n=54) and the other consisting of small- to medium-sized groups around isolated corals (n=55). An additional small sample (n=21) was also collected from a population that consisted of small groups around isolated corals. After an initially undifferentiated state, gonads of D. flavicaudus developed an ovarian lumen, followed by oocytes in the primary growth stage. From this ovarian state or from more developed ovaries with cortical-alveolus stage oocytes, some gonads developed into testes through degeneration of oocytes and development of spermatogenic tissue. In all three populations, spermatogenic tissue developed only in gonads that contained pre-vitellogenic oocytes (termed as mixed stage 1–2 gonads). The two main populations did not differ in their expression of sex change despite differences in their social organization. In both populations, size of individuals with mixed stage 1–2 gonads overlapped mainly with the size range of immature females, which suggests that functional female-to-male sex change was rare. The hypothesis that D. flavicaudus is primarily gonochoristic is further supported by removal experiments in laboratory groups, in which removal of a dominant male(s) failed to induce sex change in any of the high-ranking females. Yet, in all three field populations, some fish with mixed stage 1–2 gonads were found within the size ranges of mature females, which indicates possible occurrences of functional sex change. These conflicting results indicate that it may be premature to draw any definitive conclusions about the sexual pattern of D. flavicaudus.Communicated by T. Ikeda, Hakodate     

Spatio-temporal patterns in the genetic structure of recently settled blue mussels (<Emphasis Type="Italic">Mytilus</Emphasis> spp.) across a hybrid zone

Previous studies of a hybrid zone between the mussels Mytilus edulis Linnaeus and M. galloprovincialis Lamarck have not resolved the relative importance of the genetic composition of settling larval cohorts versus post-settlement selection in determining the distribution of the parental species and their hybrids. In the present study, recently settled mussels (spat) were collected from 20 sites in southwest England throughout the summer and fall (May–October) in 1998 and 1999. This study investigated the spatio-temporal patterns of settlement and genetics of mussel spat by genetically identifying M. edulis, M. galloprovincialis and their hybrids using the diagnostic PCR marker Glu-5. Settlement was observed earlier in populations of M. edulis than in populations of M. galloprovincialis. Settlement occurred in hybrid populations at times intermediate to and overlapping with both of the parental populations. Temporal genetic variation within years was rare at most sites, while there was some variation between the two years. Spatial genetic variation, however, was common among spat settling within the hybrid populations and matched that observed in small, sub-adults at the same sites. No consistent directional changes in allele frequency were observed over the course of several weeks after settlement. These data suggest that the observed spatial variation in the adult populations is the result of spatial variation in settling larval cohorts and not of either temporal genetic variation or of selection soon after settlement.Communicated by J.P. Grassle, New Brunswick     

<Emphasis Type="Italic">Acropora austera</Emphasis> connectivity in the south-western Indian Ocean assessed using nuclear intron sequence data

The hypervariable carbonic anhydrase 3/550 intron marker was sequenced in order to ascertain the levels of genetic variability and connectivity within and between reefal populations of the hard coral, Acropora austera, on the south-east African coastline. Populations were sampled from (north to south) Bazaruto and Inhaca islands (Mozambique), Rabbit Rock, Two-mile and Red Sands Reefs and Leadsman Shoal (Maputaland, South Africa). Populations at Inhaca Island contained two private alleles, part of the only monophyletic clade with fixed differences between populations in this study. Haplotype and nucleotide diversity were higher in the north of the study area. Indices of migration and haplotype sharing supported significant connectivity between populations in South Africa and Mozambique, which may be important in sustaining genetic diversity in the down-current South African A. austera populations. Measures of population subdivision indicated a significant amount of fixation of allele frequencies amongst populations. Although fine, such differentiation in a marker from the nuclear genome of a hard coral is consistent with some demographic isolation between A. austera populations in southern Mozambique and South Africa. Populations at Rabbit Rock and Inhaca Island were found to be significantly isolated from, and thus less connected to, A. austera populations at other reefs.     

Geographic and reproductive isolation in the marine Harpacticoid Copepod Tisbe

Within the genus Tisbe (Copepoda: Harpacticoida), there is a wide range of reproductive isolation. In the European area, in addition to species where (between geographic populations) the reproductive barrier is practically absent, there are others which show a varying degree of incompatibility. The present paper deals with the results of cross-breeding experiments carried out between American and European populations. The respective intrapopulation crosses served as controls. Transatlantic crosses have been attempted with the following species: T. lagunaris, T. bulbisetosa, T. holothuriae, T. battagliai, and T. clodiensis. The American and European populations of the first 4 species are interfertile, and the F₁ hybrids produce viable offspring. Moreover, the interpopulation crosses, compared to the controls, exhibit a slight superiority whose nature is, however, still unclear. The fifth species, T. clodiensis, behaves differently. The absence of viable offspring from interpopulation crosses, or the death of the hybrids before reaching the adult stage, indicate that, in this species, the barrier to gene flow is complete. Populations of T. clodiensis show, in addition, signs of relative intraspecific incompatibility. The problem of the different degree of reproductive isolation in the genus Tisbe, with special regard to the role played by ecological factors in determining the isolation patterns, is discussed.     

Molecular evidence for multiple lineages in the gorgonian family Plexauridae (Anthozoa: Octocorallia)

Octocorals are diverse and abundant on many marine hard substrates, and, within this group, members of the family Plexauridae are an important component of tropical reef assemblages, especially in the Caribbean. To understand historical relationships within this large and diverse assemblage, and to test the monophyly of the family and some of its genera, DNA sequences of two mitochondrial loci (msh1 and ND2, ~1,185 bp) were analyzed from 46 species in 21 genera from deep and shallow waters in the tropical western Atlantic and in the tropical western and eastern Pacific (plus 9 taxa in the closely related Gorgoniidae and 1 species of the more distantly related Alcyoniidae). Five strongly supported clades were recovered. Three large clades correspond roughly to the Plexauridae, Paramuriceidae, and Gorgoniidae, and two smaller clades were comprised of taxa previously assigned to several families. Astrogorgia sp. did not group with any of the clades. The mutual relationships among the five clades remain unclear. Several genera previously regarded as unrelated appear to be grouped among the three families; e.g. Hypnogorgia sp. (Paramuriceidae) falls within a clade consisting of both Pacific and Atlantic Muricea spp. (Plexauridae), while Swiftia sp., Scleracis sp., and an Atlantic Thesea sp. (all Paramuriceidae) group with the gorgoniids. In several instances, genera containing Atlantic and Pacific species were recovered as monophyletic (Muricea spp., Bebryce spp.). However, in at least three cases (Echinomuricea spp., Thesea spp., Villogorgia spp.), placement of Atlantic and Pacific species in the same genus may reflect convergence of sclerite morphology. The results indicate a strong need for reexamination of octocoral taxonomy using a combination of molecular, morphological, and chemical evidence.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00227-005-1592-y.Communicated by J.P. Grassle, New Brunswick     

Effects of temperature on activity,food consumption rates,and gut passage times of seaweed-eating<Emphasis Type="Italic"> Tegula</Emphasis> species (Trochidae) from California

Previous feeding studies on herbivorous marine snails rarely have focused on temperature effects on food intake. If temperature affects food intake, ectothermic snails may experience difficulty obtaining sufficient nutritional resources, limiting their ability to sustain populations at suboptimal temperatures. We hypothesized that the feeding responses of Tegula species would correspond with temperatures characteristic of their geographic distributions. We determined activity, consumption rates, and gut passage times at 11°C, 15°C, 19°C, and 23°C for three Tegula species with distinct thermal distributions: T. brunnea (cold water), T. aureotincta (warm water), and individuals from warm- and cold-water populations of T. funebralis, a broadly distributed species. Activity and consumption rates of T. aureotincta increased with increasing temperature, but were highest for T. brunnea at 19°C, a temperature rarely achieved in habitats occupied by this species, and lowest at 11°C. Warm-water T. funebralis showed significantly lower activity and consumption rates at 11°C, whereas cold-water T. funebralis consumed food fastest at 15°C and were most active at 23°C. Temperature affected gut passage time only in T. aureotincta. These data suggest that temperature might influence the northern limit of T. aureotincta by affecting activity and food consumption rates. T. brunneas activity and ability to consume food were not hindered by warmer temperatures despite the present day restriction of this species to colder waters. Also, widely separated (>300 km) T. funebralis populations may be adapted to regional conditions based on the different temperature responses of northern and southern snails.Communicated by P.W. Sammarco, Chauvin     

Sibling species in interstitial flatworms: a case study using<Emphasis Type="Italic"> Monocelis lineata</Emphasis> (Proseriata: Monocelididae)

The genetic relationships between morphologically indistinguishable marine and brackish-water populations of Monocelis lineata (O.F. Müller, 1774) (Proseriata: Monocelididae) were analysed by means of allozyme electrophoresis. Fifteen samples of M. lineata (13 from the Mediterranean and two from the Atlantic) from coastal marine and brackish-water habitats were examined for variation at 18 loci. Eleven loci were polymorphic in at least one population of M. lineata. Low levels of within-population genetic variability were found, with average observed and expected heterozygosity values ranging from H_o=0.015±0.015 to 0.113±0.044, and from H_e=0.028±0.028 to 0.138±0.054, respectively. The occurrence of a number of private alleles indicated a marked genetic divergence among populations of M. lineata, with Rogers genetic distances ranging from D_R=0.003 to 0.676 and a highly significant F_ST value (0.918±0.012, P<0.001). UPGMA (unweighted pair-group method using arithmetic average) cluster analysis and multidimensional scaling showed a clear genetic divergence between marine and brackish-water populations. Moreover, Atlantic and Mediterranean populations were sharply separated. Our results suggest that M. lineata is a complex of sibling species.Communicated by R. Cattaneo-Vietti, Genova     

Reproductive strategy of<Emphasis Type="Italic"> Calanoides carinatus</Emphasis> and<Emphasis Type="Italic"> Calanus helgolandicus</Emphasis> during a summer upwelling event off NW Spain

Reproductive activity and production of the calanoid copepods Calanus helgolandicus and Calanoides carinatus were measured during a summer upwelling event off the coast of NW Spain. The upwelling pattern affected the distribution and fecundity of both species in the study area. The demographic composition of both populations and the stage of gonad maturation (e.g. the high abundance of fertilised females with mature ova) indicated active reproduction. C. carinatus, a highly fecund species associated with the African upwelling zones and considered as an upwelling specialist, showed low production rates (overall means of 15 eggs female^–1 day^–1 and 3% body C day^–1), despite the fact that the food conditions (high phytoplankton biomass dominated by diatoms) seemed to be optimal for this species. By contrast, C. helgolandicus, a temperate species that shows a strong link between spring phytoplankton blooms and reproduction time, seems to be flexible enough to take full advantage of shorter-term, enhanced feeding conditions associated with the pulsed nature of the summer coastal upwelling. Both the egg and carbon-specific production rates attained by this species (overall means of 26 eggs female^–1 day^–1 and 12% body C day^–1) were similar to values reported for a spring bloom situation. This high production would imply a long spring–summer recruitment event of C. helgolandicus in these waters. For both species the stage of gonad maturation was significantly correlated with their egg production rates and likely influenced by the food conditions; a species-specific nutritional requirement for final oogenesis is suggested. The carbon condition factor (carbon weight/prosome volume) of C. carinatus females was higher than that of C. helgolandicus, suggesting differential use of the carbon ingested; C. helgolandicus seems to use all ingested carbon to produce eggs at a high rates, whereas C. carinatus seems to store part of the ingested carbon as lipid reserves to ensure female survival and to support production during subsequent unfavourable food conditions.Communicated by S.A. Poulet, Roscoff     

Tropical fishes in a temperate sea: evolution of the wrasse <Emphasis Type="Italic">Thalassoma pavo</Emphasis> and the parrotfish <Emphasis Type="Italic">Sparisoma cretense</Emphasis> in the Mediterranean and the adjacent Macaronesian and Cape Verde Archipelagos

The northeastern Atlantic and the Mediterranean Sea share geological histories and display great faunal affinities. The majority of the Mediterranean species have Atlantic origins, with a few species with tropical affinities. These include the parrotfish Sparisoma cretense and the wrasse Thalassoma pavo that are restricted to the subtropical northeastern Atlantic, the Macaronesian archipelagos (Azores, Madeira, and Canaries) and the southern Mediterranean. The Pleistocene glaciations have been described as having different effects on the fauna of the two regions. During glacial peaks, Mediterranean waters remained warmer than those of the adjacent Atlantic. Within the eastern Atlantic, the effects of Pleistocene glaciations were differentiated. Here, we perform a comparative analysis focusing on T. pavo and S. cretense populations from the northeastern Atlantic and the Mediterranean to assess the effects of Pleistocene glaciations in these two species. Sequences from the mitochondrial control region were obtained and analyzed combining phylogeographic and demographic approaches. Gene flow between Atlantic and Mediterranean populations was shown to be very high. The Mediterranean populations of T. pavo and S. cretense showed high levels of genetic diversity, even in the eastern basin, pointing to an ancient colonization event. This suggests that both species must have been able to persist in the Mediterranean during the cold Pleistocene periods. Historical migration estimates revealed a Mediterranean towards Atlantic trend in the case of T. pavo, which may reflect the re-colonization of areas in the Atlantic by fish that survived the cold phases in relatively warmer Mediterranean refugia. Our data also showed that within the Macaronesian Archipelagos, migrations occurred from Madeira towards the Azores, for both T. pavo and S. cretense, thus supporting a post-glacial colonization of the Azores by fish that persisted in the warmer region of Madeira. Similar geographic distributions, thermal affinities, and means of dispersion for T. pavo and S. cretense resulted in a similar response to the effects of Pleistocene glaciations, as evidenced by identical phylogeographic patterns.