Genetic and morphological divergence in theAndrocymbium gramineum complex (Colchicaceae)

Narrow endemism is a poor predictor of genetic potential in the six taxa that conform theAndrocymbium gramineum complex, as shown by the unexpectedly high values of variability associated with ten allozymic loci and 13 biometrical variables. Although both levels are shown not to be correlated, variability is always concentrated within populations. This result, together with environmental, reproductive and historical data strongly suggests differentiation in local isolates, where changes can be quickly assimilated by stochastic processes. A key implication for conservation is that sampling within the largest population will save effort while neglecting only very low frequency alleles.     

Genetic divergence in the Chorthippus parallelus species group (Orthoptera: Acrididae)

Specimens of Chorthippus parallelus parallelus, C. p. erythropus, C. montanus, C. curtipennis and C. dorsatus were examined electrophoretically. This analysis indicates that C. curtipennis is very closely related to C. p. parallelus and C.p. erythropus (Nei's I = 0.97) while C. montanus is more distantly related ( I = 0.88). The values are consistent with divergence of C. p. erythropus from C. p. parallelus since its separation by the Pyrenean ice sheet during the Pleistocene and of C. curtipennis since invasion of North America by C. parallelus at the same time. A much earlier divergence of C. montanus is implied.     

Genetic divergence and reproductive isolation in the Ochthebius (Calobius) complex (Coleoptera: Hydraenidae)

The reproductive isolation in hydrenid beetles of the Ochthebius complex was studied by analysing gene exchange in natural populations of O. quadricollis, Ochthebius sp. A and O. brevicollis steinbuehleri collected along the Mediterranean coasts. The ranges of these three species are largely allopatric, but sympatric areas were detected between contiguous taxa, ie, O. quadricollis and Ochthebius sp. A; Ochthebius sp. A and O. b. steinbuehleri. Three levels of reproductive isolation and genetic divergence were observed. One level involves extensive intraspecific genetic divergence within the biological species O. quadricollis, Ochthebius sp. A and O. brevicollis, associated with both physical barriers (eg, sea and sand stretches) and the low dispersal capacity of larvae and adults. The finding of transitional samples between the most differentiated population groups should indicate, however, that there is still some gene flow between the populations of the three taxa. Another level is found between Ochthebius sp. A and O. b. steinbuehleri, whose gene pools appear to be fairly distinct in spite of the fact that reproductive isolation is still incomplete: in their few syntopic sites, some F1 hybrids appeared indeed to have lower fitness, since backcrosses or recombinant genotypes were never observed. The final level in the evolution of reproductive isolation (full reproductive isolation) has been achieved by the species O. quadricollis and Ochthebius sp. A. No F1 or F(n) hybrids, nor backcrosses were found in their sympatric areas. The relative importance of ecological factors and evolutionary forces in the prevention of gene exchange between taxa are discussed.     

A duplication of gcyc predates divergence within tribe Coronanthereae (Gesneriaceae): Phylogenetic analysis and evolution

Recent investigations in Gesneriaceae have indicated that the cycloidea homolog, gcyc, remains functional at the DNA level and rates of sequence divergence in this gene are not statistically different across all taxa regardless of floral symmetry. A duplication of gcyc has been detected within Coronanthereae, a tribe that has phylogenetic affinities to subfamily Gesnerioideae and includes two genera with radially symmetrical corollas. Duplication of gcyc has been detected in all Coronanthereae except Sarmienta. All paralogs appear functional at the DNA level. Likewise, there is no increased sequence divergence between the two copies, nor between species with radially symmetrical flowers to those with bilateral symmetry. The duplication of gcyc in Coronanthereae is most likely a result of polyploidy since Coronanthereae have the highest chromosome counts of all Gesneriaceae.     

Genetic divergence among species of the section Strombocarpa,genusProsopis (Leguminosae)

We studied degree of variability and relationships among populations belonging to five species of the section Strombocarpa of the family Leguminosae, namelyProsopis ferox, P. torquata, P. pubescens, P. strombulifera andP. reptans, by isozyme electrophoresis. The genetic similarity betweenP. reptans andP. strombulifera is high enough for the two to be considered subspecies or geographic races ofP. strombulifera instead of good taxonomic species. As expected these species cluster withP. pubescens, all belonging to series Strombocarpae. This group is different isoenzymatically from the remaining species,P. torquata andP. ferox. Comparison of our results with those obtained earlier for species of the section Algarobia showed that genetic variability in the section Strombocarpa is lower than in the section Algarobia, while the species divergence is much higher. These results suggest different adaptive strategies between these sections.     

Genetic divergence is not the same as phenotypic divergence

Far too often, phenotypic divergence has been misinterpreted as genetic divergence, and based on phenotypic divergence, genetic divergence has been indicated. We have attempted to disprove this statement and call for the differentiation of phenotypic and genotypic variation.     

Genetic and morphological divergence within the Sebastes pachycephalus complex (Scorpaeniformes: Scorpaenidae)

Genetic and morphological divergence among the four subspecies in the Sebastes pachycephalus complex (S. pachycephalus pachycephalus, S. p. nigricans, S. p. nudus and S. p. chalcogrammus) was clarified. Principal coordinate analysis (PCoA) based on AFLP clearly divided 55 specimens of the complex into two groups, the S. p. pachycephalus?CS. p. nigricans group (P-Ni group) and the S. p. nudus?CS. p. chalcogrammus group (Nu-C group), although three specimens occupied intermediate positions. The minimum spanning network (MSN) based on partial sequences of the mitochondrial control region (mtCR) failed to separate either the P-Ni and Nu-C groups or the four subspecies into distinct clades, although restricted gene flow and genetic differentiation between the former were indicated by the F _ST estimation. Differences in morphological characters, including counts of pectoral fin rays and counts of dorsal fin spines lacking basal scales, were also evident between the two groups. However, little or no genetic or morphological difference was found between the two subspecies within each group. It was concluded that the P-Ni and Nu-C groups of the S. pachycephalus complex actually represent two different species, which is further supported by their sympatric distribution. Differences in dorsal body coloration and the presence or absence of brown spots on the ventral surface, which were formerly used to discriminate between four ??subspecies,?? may simply represent intraspecific variation. The three specimens occupying intermediate positions in the AFLP PCoA also occupied equivocal positions between the two species in the principal component analysis (PCA) based on morphometric characters, suggesting that they were hybrids between the two species. The star-shaped MSN of mtCR, which lacks distinct clades representing the two species, may be due to not only interspecific hybridization but also the sharing of ancestral haplotypes.     

The trophodynamics of Southern Ocean Electrona (Myctophidae) in the Scotia Sea

The Scotia Sea is one of the most productive regions of the Southern Ocean, but its surface waters are experiencing a rapid increase in temperature, which may be changing the behaviour and distribution of many myctophids and their prey species. Electrona antarctica and Electrona carlsbergi are two of the most abundant myctophids in the region, but their ecology is poorly understood and their response to ongoing environmental change is difficult to determine. This study investigated spatial and temporal patterns in their abundance, population structure and diets using mid-water trawl nets deployed across the Scotia Sea during spring, summer and autumn. E. antarctica was the most numerically abundant species (0.09–0.21 ind. 1,000 m^?3), with greatest concentrations occurring in the sea-ice sectors. E. carlsbergi occurred in more northern regions, comprising densities of 0.02–0.11 ind. 1,000 m^?3. There was evidence of seasonal variation in depth distribution, size-related sexual dimorphism and size-specific vertical stratification for both species. Latitudinal trends in sex ratio and female body size were apparent for E. antarctica. Its diet varied between regions, seasons and size classes, but overall, Euphausia superba, Metridia spp. and Themisto gaudichaudii were the dominant prey items. E. carlsbergi appeared not to recruit in the Scotia Sea. Its diet was dominated by copepods, particularly Rhincalanus gigas and Metridia spp., but regional, seasonal and ontogenetic variations were evident. This study contributes to our understanding of how mid-water food webs are structured in the Southern Ocean and their sensitivity to ongoing environmental change.     

Genetic divergence and larval dispersal in two spider crabs (Crustacea: Decapoda)

The spider crabs Inachus dorsettensis (Pennant) and Hyas coarctatus Leach are widespread in subtidal areas of muddy sand or gravel around western Europe. Both species have a life cycle with an obligatory planktonic larval phase of several weeks, which might be expected to cause widespread larval dispersal and consequent genetic homogeneity over considerable distances. However, earlier work on both taxa has indicated differences in growth pattern between populations separated by tens of kilometres. This study was undertaken to determine whether these differences were purely environmental or whether, despite the short distances involved, differences may have a genetic basis. A study of gene frequencies, as indicated by allozymes in samples of adults collected off the Isle of Man (northern Irish Sea), indicates significant genetic differentiation between populations over a geographical distance of only about 40 km in both Inachus dorsettensis ( = 0.086 ± 0.048) and Hyas coarctatus ( = 0.023 ± 0.017). Variability measures differed between species, showing I. dorsettensis to have a mean number of alleles per locus of 2.5–2.6 and a range of gene diversity of 0.216–0.241, while H. coarctatus showed lower values of mean number of alleles (1.9–2.0) and a range of gene diversity from 0.122 to 0.124. Given the high expected larval mobility of the two species the results are most surprising. Possible explanations are discussed in relation to population discontinuities and patterns of larval drift.     

Genetic divergence and geographic variation in the deep-water Conus orbignyi complex (Mollusca: Conoidea)

Puillandre, N. et al. (2010) Genetic divergence and geographic variation in a deep-water cone lineage: molecular and morphological analyses of the Conus orbignyi complex (Mollusca: Conoidea).The cone snails (family Conidae) are a hyperdiverse lineage of venomous gastropods. Two standard markers, COI and ITS2, were used to define six genetically-divergent groups within a subclade of Conidae that includes Conus orbignyi; each of these was then evaluated based on their shell morphology. We conclude that three forms, previously regarded as subspecies of Conus orbignyi are distinct species, now recognized as Conus orbignyi, Conus elokismenos and Conus coriolisi. In addition, three additional species (Conus pseudorbignyi, Conus joliveti and Conus comatosa) belong to this clade. Some of the proposed species (e.g., Conus elokismenos) are possibly in turn complexes comprising multiple species. Groups such as Conidae illustrate the challenges generally faced in species delimitation in biodiverse lineages. In the case of the Conus orbignyi complex, not only are there definable, genetically divergent lineages, but also considerable geographic variation within each group. Our study suggests that an intensive analysis of multiple specimens within a single locality helps to minimize the confounding effects of geographic variation and can be a useful starting point for circumscribing different species within such a confusing complex.     

Myctophid (Myctophidae) Abundance and Ecology in the Gulf of Alaska in Winter

Russian Journal of Marine Biology - The distribution and abundance of four common myctophid fish species in the upper epipelagic layer of the northeastern North Pacific in winter were analyzed...     

A smaller Macadamia from a more vagile tribe: inference of phylogenetic relationships, divergence times, and diaspore evolution in Macadamia and relatives (tribe Macadamieae; Proteaceae)

Tribe Macadamieae (91 spp., 16 genera; Proteaceae) is widespread across the southern hemisphere on all major fragments of Gondwana except New Zealand and India. Macadamia is cultivated outside its natural range as a "nut" crop (notably in Hawaii, where it is the principal orchard crop). We sampled seven DNA regions and 53 morphological characters from the tribe to infer its phylogeny and address the common assumption that the distribution of the extant diversity of the tribe arose by the rafting of ancestors on Gondwanan fragments. Macadamia proves to be paraphyletic with respect to the African genus Brabejum, the South American genus Panopsis, and the Australian species Orites megacarpus. We erect two new generic names, Nothorites and Lasjia, to produce monophyly at that rank. The earliest disjunctions in the tribe are inferred to be the result of long-distance dispersal out of Australia (with one possible exception), rather than vicariance. Evolution of tardy fruit dehiscence is correlated with these dispersals, and the onset of the Antarctic Circumpolar Current (ACC) precedes them. We suggest that the ancestors of extant diversity arrived on their respective continents via the ACC, and we recognize that this is a mechanism precluded, rather than facilitated, by Gondwana's terrestrial continuity.     

Genetic divergence of sympatric charrs of the genus Salvelinus from Nachikinskoe Lake (Kamchatka)

We studied genetic differentiation of two charr species, Dolly Varden Salvelinus malma malma Walbaum and resident lacustrine charr Salvelinus sp., which sympatrically inhabit Nachikinskoe Lake (the Bol'shaya River basin) in southwestern Kamchatka Peninsula. Using restriction analysis (RFLP), three mitochondrial DNA fragments (ND1/ND2, ND5/ND6, and Cytb/D loop) amplified in polymerase chain reaction (PCR) were compared. The divergence of the mtDNA sequences between Salvelinus sp. and S. malma malma was 2.8%; Salvelinus sp. and S. taranetzi, 0.36%; Salvelinus sp. and S. krogiusae, 0.21%; Salvelinus sp. and S. alpinus, 3.0%. These results point to reproductive isolation of charrs in Nachikinskoe Lake and support the earlier suggestion on a close relationship between Salvelinus sp., S. taranetzi, and S. krogiusae.     

Genetic divergence of chars of the genus Salvelinus from Kronotsky Lake (Kamchatka Peninsula)

Chars from the genus Salvelinus, inhabiting lakes and lake-river systems, belong to morphologically and ecologically different forms whose taxonomic status is under dispute. In the present work, we have examined genetic variation and divergence in various chars from the Kronotsky lake basin: the lacustrine chars (white, nose, and long-head) and Dolly Varden char Salvelinus malma. The study was conducted using analysis of allozyme and microsatellite loci, myogens, RAPD, and restriction analysis of two mtDNA segments. The estimates of heterozygoisty at allozyme and microsatellite loci were similar to the corresponding parameters in populations of northern Dolly Varden and Arctic char. Heterozygote deficit was recorded in both samples of individual forms, and in the combined sample of all chars from Kronotsky Lake. For both markers, appreciable genetic differentiation among the samples of different char forms was found, which was comparable to that among the spatially isolated populations of northern Dolly Varden. This result indicates reproductive isolation among the char forms examined. However, this isolation is not complete, because no fixed differences between the forms by any of the genetic systems analyzed was found. The genetic differentiation among different forms of lacustrine chars, which corresponds to the interpopulation rather than interspecies level, is thought to be explained by their comparatively recent divergence.     

Genetic and morphological divergence between populations of the flatfish Platichthys flesus (L.) (Pleuronectidae)

Populations of the flounder, Platichthys flesus , were screened for electrophoretically detectable protein variation at up to 37 loci. Atlantic and North Sea populations (subspecies flesus ) were genetically very similar to one another ( I >0.99) but different from Adriatic (subspecies italicus ) and Black Sea (subspecies luscus ) populations. The values for genetic identity between subspecies were around 0.9. Diagnostic loci enabled specimens of flesus, italicus and luscus to be differentiated from one another. Samples of flesus showed two to three times the heterozygosity levels of italicus or luscus , consistent with the greater population size of flesus . Morphological comparisons enabled populations to be categorized to subspecies. Platichthys flesus italicus and luscus are valid subspecies: the terms are not synonyms. The genetic distance data provide an estimate of divergence time of the three subspecies at about 2 My ago, an estimate that seems reasonable in the light of present knowledge concerning the recent geological histories of the Mediterranean and Black Sea basins.     

Genetic divergence, speciation and biogeography of Mustelus (sharks) in the central Indo-Pacific and Australasia

The shark genus Mustelus is speciose, commercially important and systematically troublesome. We use a molecular approach combining inter and intra-specific data to investigate Mustelus species in the central Indo-Pacific and Australasia. Our analysis supports two Mustelus clades, one comprising species with no white spots and a placental reproductive mode and a second clade of white spotted, aplacental species. Levels of genetic divergence are low, especially among species in the white spotted, aplacental clade and this should be taken into account when employing molecular data to delineate species. Our data support the hypothesis of a radiation following dispersal from a northern hemisphere ancestor. Molecular dating suggests that localised speciation in Australasia may have occurred during the Pleistocene. We propose that some of the difficulties associated with Mustelus systematics relate to a recent radiation, particularly in the Australasian region.     

A revision of the tribe Forsskaoleae (Urticaceae)

Friis, I. & Wilmot-Dear, C.M. 1988. A revision of the tribe Forsskaoleae (Urticaceae). - Nord. J. Bot. 8: 25–59. Copenhagen. ISSN 0107–055X.
The tribe Forsskaoleae has been revised and the inflorescence and floral structure reinvestigated. The alternative interpretation of the flowers and inflorescences of Forsskaoleae proposed by Rivieres is rejected. A division of the tribe into two subtribes is tentatively maintained. The study of all genera is based on the total available material, with exception of Forsskaolea , of which only the types and some additional material have been studied, and an annotated survey of the six recognized species is presented. In Droguetia seven species are recognized, distributed from tropical and South Africa to Madagascar, the Mascarenes, Java, and India. An infrageneric division of the genus is not tenable. The genus Didymodoxa , for the last hundred years united with Australina , is reestablished with two species, both restricted to eastern and southern Africa. The genus Australina is, within the new delimitation, disjunct between Australia, Tasmania and New Zealand on the one hand and Ethiopia and Kenya on the other. In view of the considerable differences between them, each of the two species is placed in a separate section, sect. Australina and sect. Sarmentago . The lectotypification of Urtica capensis made by Prain is shown to be in conflict with the protologue; a new lectotype is selected, with consequence for the nomenclature of a South African Acalypha species (Euphorbiaceae). All taxa are keyed out and described; distribution maps and illustrations are provided for most taxa.