Genetic variation in the soil phthiracarid mite, Steganacarus (S.) magnus (Nicolet, 1855) (Acarida, Oribatida) (Notulae Oribatologicae XL)

Genetic divergence and variability at 14 enzyme loci were examined in and between Italian populations of two edaphic Oribatid (Acarida, Oribatida) species, Steganacarus (Steganacarus) magnus (8 populations) and S. (S.) hirsutus (1 population). The seven populations belonging to S. (S.) magnus can be divided into two groups according to their phenotype, form anomala (A) (MON, ARG, AST, CDO) and form magna (M) (MAL, MAM, RIF) while another can be considered as hybrid between the two preceding groups (ZOC). Genetic identity (I) values between the S. (S.) magnus populations in spite of their morphological differences ranged from 0.977 to 1.000 showing the great genetic similarity of simple local populations while those of S. (S.) hirsutus indicated two distinct morphological species. The genetic distances between all the populations examined were very low despite the ecological differences and geographical distances between the collecting sites. Genetic variability estimates in all the populations of both species were very low when compared to those reported for most arthropods. Some explanatory considerations are suggested.     

Isozyme variation inFaidherbia albida (Leguminosae, Mimosoideae)

Genetic variation has been assessed in 30 populations (931 families) ofFaidherbia albida (Leguminosae, Mimosoideae) from across its entire African range, using six isozyme loci identified by five enzyme systems. Among the populations studied a null allele was proposed to explain the absence ofLap-1 activity in populations from southern and eastern Africa. The mean percentage of polymorphic loci per population, the mean number of alleles per locus and the mean genetic diversity within populations were 31.7%, 1.6 and 0.127 respectively. Genetic diversity was greatest in populations from West Africa and lowest in populations from eastern/southern Africa, with Ethiopian/Sudanese populations intermediate. The overall degree of genetic differentiation between populations (G_ST) indicated that approximately 56% of the enzyme variation resided within populations. Clustering of Nei's unbaised genetic distances calculated between all populations produced a dendrogram that generally followed the geographic distribution of the populations. Two major groups were identified that may be considered the eastern/southern African and the Ethiopian/West African clusters. Within the Ethiopian/West African cluster two subclusters could be recognised, one broadly corresponding to those populations from Ethiopia/Sudan and the other to those populations from West Africa. The implications of these results for theories regarding the origin ofF. albida in Africa are discussed.     

Rapid colonization of Belgian breakwaters by the direct developer,Littorina saxatilis (Olivi) (Prosobranchia,Mollusca)

The Belgian coast has no natural rocky sites but a number of man-made constructions are colonized by rocky shore organisms. The rough periwinkle, Littorina saxatilis (Olivi), lacks a planktonic larval stage but is found on most breakwaters along the Belgian coast, a few built as recently as 1986. This indicates a good potential of dispersal along this sandy shallow coast, nearly as good as for the planktonic developer Littorina littorea (L.) which is found on generally the same sites in Belgium. The breakwater populations of L. saxatilis, however, tend to be somewhat less variable (level of heterozygosity about 10% less) than non-Belgian L. saxatilis populations of natural sites. This suggests that the breakwater populations have passed through bottlenecks when founded, but probably restored population sizes fairly rapidly afterwards. No relationship is found between geographic and genetic distances between populations of L. saxatilis.     

Genetic and phenotypic variation in central and northern European populations of Aedes (Aedimorphus) vexans (Meigen, 1830) (Diptera,Culicidae)

The floodwater mosquito Aedes vexans can be a massive nuisance in the flood plain areas of mainland Europe, and is the vector of Tahyna virus and a potential vector of Dirofilaria immitis. This epidemiologically important species forms three subspecies worldwide, of which Aedes vexans arabiensis has a wide distribution in Europe and Africa. We quantified the genetic and phenotypic variation in Ae. vexans arabiensis in populations from Sweden (northern Europe), Hungary, and Serbia (central Europe). A landscape genetics approach (F_ST, STRUCTURE, BAPS, GENELAND) revealed significant differentiation between northern and southern populations. Similar to genetic data, wing geometric morphometrics revealed two different clusters, one made by Swedish populations, while another included Hungarian and Serbian populations. Moreover, integrated genetic and morphometric data from the spatial analysis suggested groupings of populations into three clusters, one of which was from Swedish and Hungarian populations. Data on spatial analysis regarding an intermediate status of the Hungarian population was supported by observed Isolation‐by‐Distance patterns. Furthermore, a low proportion of interpopulation vs intrapopulation variance revealed by AMOVA and low‐to‐moderate F_ST values on a broader geographical scale indicate a continuous between‐population exchange of individuals, including considerable gene flow on the regional scale, are likely to be responsible for the maintenance of the observed population similarity in Aе. vexans. We discussed data considering population structure in the light of vector control strategies of the mosquito from public health importance.     

mtDNA analysis reveals the ongoing speciation on Greek populations of Microtus (Terricola) thomasi (Arvicolidae,Rodentia)

The present article extends our previous work on the phylogenetic history of Microtus (Terricola) thomasi, analysing cytochrome b, 12S rRNA, 16S rRNA and the control region in 65 Greek populations. The analysis revealed three clades: one grouping the populations from Peloponnisos (Southern Greece); the second, the populations from Agios (Ag.) Stefanos and Evvoia island (Central East Greece); and the third, all the remaining populations with no geographical substructure. Genetic distances were low for most populations, with only the populations of Evvoia and Ag. Stefanos being substantially distant. Thus, although this species has a recent colonization history and probably descends from a highly polymorphic ancestor, a monophyletic and highly differentiated lineage is formed in Greece and is distributed in Ag. Stefanos and Evvoia. Molecular differentiation, distinct geographical distribution and restriction of gene flow between this lineage and the rest of the Greek populations provide evidence for its probable subspecific status, Microtus (Tericola) thomasi atticus. A possible mechanism leading the differentiation process of the proposed subspecies is suggested, based on the displacement of this species in central Greece by its congeneric, probably better‐fitted Microtus (Microtus) guentheri and the subsequent separation of Ag. Stefanos and Evvoia from the remaining Greek populations. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 117–130.     

Phylogeography of the African catfish,Chrysichthys maurus (Valenciennes, 1839)

Polymorphism at 19 allozyme loci was studied in 227 individuals of the catfish, Chrysichthys maurus (Valenciennes, 1839), collected from ten populations representing nine different river basins in west Africa. Eleven of the loci studied were polymorphic. Analysis showed that populations clustered according to their geographical origin: eastern populations close to the root represented by a population of a closely related species (C. auratus); then populations from the centre of the species' range, followed by the more western populations. Networks observed, regression of genetic distances versus geographical distances, results of the Mantel test as well as the apomorphic status of two alleles suggested that the genetic differentiation corresponds to an isolation by distance model. These results strongly suggest that the populations initially occurred in the lagoons and rivers of Ivory Coast and from here spread to the western part of the species' range by progressively colonising basins from east to west.     

Identification and characterization of microsatellites loci in Brycon opalinus (Cuvier, 1819) (Characiforme,Characidae, Bryconiae)

Brycon species are present in various basins in Brazil and were or still are part of commercial fisheries and aquaculture activities ( Ferreira et al. 1996 , Mendonça 1994 ). Despite the importance of this group of fish, natural populations of some Brycon species are endangered ( Lins et al. 1997 ). Here, we describe the characterization of seven microsatellite loci that will be useful for the genetic studies in natural and captive populations for these and other species of Brycon.     

Multivariate analyses of morphometrical features from Apatemon gracilis (Rudolphi, 1819) Szidat, 1928 and A. annuligerum (v. Nordmann, 1832) (Digenea: Strigeidae) metacercariae

Only two species of the strigeid subgenus Apatemon (Apatemon) sensu Sudarikov (1959), Apatemon gracilis (Rudolhi, 1819) and A. annuligerum (von Nordmann, 1832), are known to infect British fishes. A. annuligerum is poorly characterised, with few life-cycle data available, since only the adult and metacercarial stages have been described. Both of these life-stages demonstrate only minor morphological differences from those of A. gracilis. The multidimensional approach of principal components analysis (PCA) was employed to determine the intra- and inter-specific morphological variation that exists for metacercariae of these species. Analyses revealed that metacercarial morphometrics cannot confidently discriminate between Apatemon gracilis and A. annuligerum specimens. Indeed, levels of intra-specific variation present between A. gracilis metacercariae originating from different piscine hosts were as marked for certain populations as those between the two nominal species. Individual populations of A. gracilis metacercariae differed most in the relative dimensions of their internal organs, whereas variation between the two nominal species was primarily in length-related variables. A. gracilis specimens originating from Welsh and Scottish stoneloach represented two populations with the most comparable total body lengths, yet clustered separately. Conversely, A. gracilis metacercariae infecting rainbow trout and salmon parr differed markedly in size, but demonstrated minimal composite morphological variation. Much, if not all, of the variation described between populations and species of parasites can be attributed to host or to metacercarial location within a particular host. These findings and the lack of strong life-cycle data for A. annuligerum place some doubt on its validity as a species discrete from A. gracilis.     

Advertisement calls of the midwife toads Alytes (Amphibia, Anura, Discoglossidae) in continental Spain

The advertisement calls of six Spanish populations of midwife toads (genus Alytes) are described presenting characteristic audiospectrograms and oscillograms of the calls. Numerical data concerning the spectral and temporal features of the calls in relation to caller size (SVL) and temperature are also compared. The regression temperature vs. call duration groups the different populations according to the extant recognized phylogeny of the genus. Based on this character, the montane population of A. obstetricans from Penalara (Madrid) appears to be more closely related to the Pyrenean populations of A. o. almogavarü than to the more western populations of A. oboscai in Central Spain, which are closer geographically.     

Host Suitability of Four Cereal Stem Borers (Lepidoptera: Crambidae, Noctuidae) for Different Geographic Populations of Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) in Kenya

This study focused on the suitability of four species of cereal stem borers for the development of five geographic populations of Cotesia sesamiae (Cameron). C. sesamiae, an indigenous larval parasitoid of gramineous stem borers, is widespread in Africa. Four stem borers, Chilo partellus (Swinhoe), Chilo orichalcociliellus Strand (Lepidoptera: Crambidae), Busseola fusca Fuller, and Sesamia calamistis Hampson (Lepidoptera: Noctuidae), were offered to C. sesamiae for oviposition. Parasitoid individuals originated from five locations in Kenya. Biological parameters such as developmental time, percentage parasitism, progeny production, mortality of immature parasitoids, and proportion of female progeny were compared across host species. The two populations from western Kenya developed well on B. fusca. However, populations from the coast and the Eastern Province could not successfully parasitize B. fusca. With the exception of B. fusca, the percentage of hosts successfully parasitized by the different C. sesamiae populations was not different. The size of the host appeared to be an important factor influencing the development and reproductive potential of the parasitoid. We conclude that the different parasitoid populations were adapted to location-specific characteristics. Parasitoid–host compatibility must be evaluated before release for better establishment and colonization.     

Genetic diversity and differentiation between Palearctic and Nearctic populations of Aedimorphus (=Aedes) vexans (Meigen, 1830) (Diptera,Culicidae)

Genetic diversity was studied at allozyme loci in two Palearctic and one Nearctic population of Aedimorphus (=Aedes) vexans, a species of public health and veterinary importance. The population from Serbia was the most polymorphic (P= 35%) with the highest observed heterozygosity (H_o= 0.027). The lowest observed heterozygosity (H_o= 0.010) was obtained for the Nearctic population. All analyses based on individual (STRUCTURE analysis) and population level (pairwise F_ST,Nm values, AMOVA, Nei's D value) revealed significant structuring between Nearctic and Palearctic populations, indicating a lack of gene flow and thus, the presence of independent gene pools. Taxon‐specific alleles at the diagnostic Ao, Hk‐2, Hk‐3, Hk‐4, Idh‐1, and Idh‐2 loci were used for identification and separation of Nearctic and Palearctic populations. Population genetics study provided valuable information on the correct distinction of Am. vexans populations and their adaptive potential that could find a future use in the studies of vector competence and development of vector‐control strategies.     

Genetic structure of Amphioctopus fangsiao (Mollusca,Cephalopoda) in Chinese waters inferred from variation in three mtDNA genes (ATPase 6, ND2, and ND5)

Amphioctopus fangsiao is an economically important resource found in Chinese coastal waters. Three mitochondrial DNA genes were used to assess the genetic structure among nine populations spanning the northern to southern regions of the Chinese coast. Fragments of 575, 639, and 640 bp in length representing three genes (ATPase 6, ND2, and ND5) were amplified from 183, 170, and 167 individuals, respectively. Overall, ATPase 6, ND2, and ND5 showed high haplotype diversity and low nucleotide diversity (HD: 0.683–0.896; −π: 0.021–0.033). All three mtDNA genes revealed high molecular variance among populations and low variance within populations. Φ_ST values obtained for ATPase 6 (Φ_ST = 0.000 to 0.997), ND2 (Φ_ST = 0.000 to 0.997), and ND5 (Φ_ST = 0.125 to 0.983) showed differentiation among the populations. The constructed phylogeographic tree and haplotype network separated the nine populations into two clades representing the northern and southern populations. Low salinity in the Changjiang River estuary may act as a barrier to promote the differentiation between the two clades. These results enhance our understanding of the genetic structure of A. fangsiao and can promote the management of its genetic resources.

     

Genetic diversity of Mexican brook lamprey <Emphasis Type="Italic">Lampetra (Tetrapleurodon) geminis</Emphasis> (Alvarez del Villar, 1966)

Lampreys are the only surviving representatives of the oldest known vertebrates. The Mexican lamprey L. geminis (nonparasitic), is particularly interesting, because it is an endemic, biogeographical relict, and a threatened species. RAPD markers were used to describe genetic diversity in L. geminis A total of 77 specimens were collected from five populations, three in the R'o Grande de Morelia-Cuitzeo basin and two in the R'o Duero-Lerma-Chapala basin, Mexico. Eighty-eight RAPD markers were obtained from eight primers. Genetic diversity within each population was estimated using Shannon's index (S), heterozygosity (H) and gene diversity (h). These estimates revealed significant variation within populations, although a variance homogeneity test (HOMOVA) showed no significant differences among populations or between basins. Nei genetic distance values indicate a low genetic differentiation among populations. Analysis of molecular variance (AMOVA) indicates that most of the genetic diversity occurs within populations (91.4%), but that a statistically significant amount is found among populations (P0.001). Principal coordinates and cluster analyses of RAPD phenotypes show that specimens are not grouped by geographical origin. The genetic diversity found within L. geminispopulations may be explained by its breeding system and an overlapping of generations. The scarce genetic differentiation among populations is likely to the low rate of DNA change that characterizes the lamprey group.     

Genetic Diversity of Populations of Monilinia fructicola (Fungi,Ascomycota, Helotiales) from China

ABSTRACT. The genetic variation among 128 isolates of Monilinia fructicola (Fungi, Ascomycota, Helotiales) from China was analyzed using Inter‐Simple Sequence Repeat (ISSR) markers and compared with those of samples from California, USA and New Zealand. A total of 72 reproducible DNA fragments were scored, of which 87.5% (63/72) were polymorphic. The Nei's gene diversity and Shannon's diversity indices of three Chinese regional populations were very similar to that from California. However, several differences were observed among geographic populations of M. fructicola from both within China and between China and California. The analysis of molecular variance (AMOVA) of isolates from different geographic locations suggested that most of the observed genetic variation was found within populations. Results of this study are inconsistent with the hypothesis that the Chinese populations of M. fructicola were derived from a single or few recent migrants from other countries. Instead, our results suggest that M. fructicola has been in China long before its first official recording in 2003.     

Eurycercus glacialis in Ireland (Cladocera,Chydoridae)

The taxon Eurycercus glacialis of Western Europe has been discovered living in the turloughs (tuar loch = dry lake) of Western Ireland. Only four populations were found during three field excursions, but because of the multitude of these waterbodies in the region, there must be many populations present. Turloughs are mainly periodic waterbodies occupying depressions in the drift overlying limestone. Most of them dry every year, and the bottoms are then used for grazing cattle. This periodicity prevents the establishment of fish populations, which would rapidly eliminate the cladoceran by size-selective predation. Only one of the many populations known from Western Europe survives in the presence of fishes. A species of the glacialis group in Newfoundland (not yet described), which is the southernmost known location of E. glacialis sens. lat. in the world, occurs commonly with salmonid or gasterosteid fishes, but this is a completely different species. Scanning electron micrographs of E. glacialis and E. lamellatus in Western Europe will aid in understanding their morphological differences.     

GENETIC STRUCTURE OF NATURAL POPULATIONS IN THE RED ALGAE GELIDIUM CANARIENSE (GELIDIALES,RHODOPHYTA) INVESTIGATED BY RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) MARKERS1

Random amplified polymorphic DNA (RAPD) marker variation was analyzed in female gametophytes in natural populations of Gelidium canariense (Grunow) Seoane‐Camba ex Haroun, Gil‐Rodríguez, Diaz de Castro et Prud'Homme van Reine from the Canary Islands to estimate the degree and distribution of genetic variability and differentiation. A total of 190 haploid individuals were analyzed with 60 polymorphic RAPDs bands which produced 190 distinct multilocus genotypes. A high level of polymorphism was detected in all populations analyzed. Within‐population gene diversity ranged from 0.156 to 0.264. The populations on the island of Gran Canaria showed higher genetic variation than the other populations analyzed. The partitioning of molecular variance by analysis of molecular variance showed that most genetic variation resides within populations (68.85%). These results suggest that sexual reproduction is the predominant mode of reproduction for G. canariense gametophytic populations, and the main determinant in reaching high levels of genetic diversity. The Neighbor‐Joining tree and FCA analysis displayed two subclusters that correspond to the populations from the western islands (Tenerife, La Palma, Gomera) and the eastern island (Gran Canaria). In addition, we have detected a significant relationship between F_ST/(1?F_ST) and geographical distance consistent with data on water circulation and age of islands. The results obtained agree with an isolation by distance model, with gene flow from eastern to the western islands, and a high level of genetic differentiation between populations (F_ST=0.311, P<0.001).     

Sesquiterpenoids of Laurencia majuscula (Ceramiales, Rhodophyta) from the Ryukyu Islands, Japan

Two populations of the red alga Laurencia majuscula (Harvey) Lucas (Rhodomelaceae, Ceramiales) from Taketomi Island and Hateruma Island, the Ryukyu Islands, Japan, have been characterized on the basis of both morphological features and halogenated secondary metabolite content. These populations have smaller and more slender thalli than those of other regions. Furthermore, the populations contain two chamigrane-type Sesquiterpenoids, (2R, 3R, 5S)-5-acetoxy-2-bromo-3-chlorochamigra-7(14),9-dien-8-one and (2R, 3R)-2-bromo-3-chlorochamigra-7(14), 9-dien-8-one, and a laurane-type sesquiterpenoid, debromoisolaurinterol, as secondary metabolites which are different from those previously reported from other populations. These results are consistent with the concept of ‘chemical races’ within a single species of Laurencia.     

The Reproductive Behavior of Acanthurus nigrofuscus (Forskal) and other Surgeonfishes (Fam. Acanthuridae) off Eilat,Israel (Gulf of Aqaba,Red Sea)

The reproductive behavior of Acanthurus nigrofuscus, a common surgeonfish of the Red Sea, is described for two overlapping populations inhabiting the coral reefs off Eilat, Israel (Gulf of Aqaba). The spectacular daily spawning activities, often involving aggregations of thousands of individuals, as well as the often long distance migrations to and from the spawning grounds by groups in highly organized formations are characterized in detail. Evidence is provided that the precise timing of these various phenomena is controlled by ambient light levels during the late afternoon. Less detailed information is also provided on comparable activities of two other surgeonfishes from the same reefs: Ctenochaetus striatus and Zebrasoma xanthurum. Finally, comparisons are made of reproduction and its associated environmental controls among populations of the same and related species of surgeonfishes at widely distributed locations in the Indo-Pacific.     

GEOGRAPHICAL CORRELATION OF MORPHOLOGICAL VARIATION IN SILVETIA COMPRESSA (FUCACEAE,FUCALES, PHAEOPHYCEAE)

Silvetia compressa ( J. Agardh) Serrão et al. is a common member of the upper intertidal fucoid community on the Pacific coast of America from Humboldt County, California, to Punta Baja, Baja California, Mexico. A relatively narrow range of morphological variability is exhibited by most mainland populations, regardless of latitude, but some mainland populations and all insular populations participate in a complex pattern that we have attempted to analyze. A few populations on the Monterey Peninsula in which the fronds are atypically delicate were described by Setchell & Gardner as f. gracilis, to which was assigned a population from Santa Catalina Island. After comparing populations from various parts of the range of the species, including all of the Channel Islands, we conclude that two subspecies may be recognized. In subsp. compressa, which includes f. gracilis as a growth form and occurs chiefly on the mainland, the frond is robust with long tapered receptacles. In the variant subspecies, which is chiefly insular but also occurs on the coast of northern Baja California, the typical frond has slender axes as in f. gracilis, but is more densely branched and has short ellipsoidal receptacles. Comparison of nucleotide sequences from the ITS regions of rDNA revealed an identical pattern for subsp. compressa from Baja California and central California, including populations assignable to f. gracilis. By contrast, the pattern for the variant subspecies differed by 2 bp (0.3%) from that of subsp. compressa.     

Distribution and population dynamics of Porphyra (Bangiales, Rhodophyta) in the southern Western Cape, South Africa

Although Porphyra is commercially farmed in many countries, in South Africa only small harvests of wild populations for sale as nori have been carried out. The discovery that Porphyra improves growth of South African abalone (Haliotis midae) farmed inland-based tanks has led to increased pressure to harvest wild populations. This paper reports on a survey of the distribution and seasonality of Porphyra in the southern Western Cape. Porphyrawas present at all sites surveyed, and showed considerable temporal variation. A significant amount of the Porphyra present is in reserves and therefore protected from harvesting. Close rexamination of one site revealed seasonal populations of Porphyra that occupied different niches dependent on season. Recruitment peaked in spring and autumn, leading to dense summer and winter populations. Summer populations generally grew lower in the eulittoral than winter populations. No pattern in the mortality of larger thalli wasde tected, though sporeling mortality was high following recruitment peaks. Although it seems that most sites in the southern Western Cape are suitable for harvesting, the taxonomy of the genus in the region urgently needs revision if populations are to be appropriately managed. This revised version was published online in August 2006 with corrections to the Cover Date.