Genetic diversity and population structure in Vallisneria spinulosa (Hydrocharitaceae)

Vallisneria spinulosa is a dominant submerged macrophyte in lakes of the middle–lower reaches of the Yangtze River. Allozyme variation, clonal diversity and population genetic structure were investigated for a total of 396 individuals sampled from 10 extant populations. V. spinulosa maintained high levels of genetic variation both at the species (P = 46.2, A = 1.69, H_e = 0.23) and at the population level (P = 46.2, A = 1.58, H_e = 0.21). Although aquatic macrophytes commonly exhibit low genetic variation within populations, the obligately outcrossing mating system of V. spinulosa and pervasive gene flow likely account for the high levels of diversity maintained within populations. All V. spinulosa populations contained high clonal diversity with a mean proportion of distinguishable genotypes of 0.57 and a mean Simpson's diversity index of 0.95, indicating that populations were founded sexually or that successful seedling recruitment occurred after initial colonization. Partitioning of genetic diversity revealed a surprisingly low population differentiation (G_ST = 0.06) as compared to other hydrophilous angiosperms. No evidence of isolation-by-distance was found (r = 0.056, P = 0.312), suggesting that gene flow was not restricted geographically. The UPGMA cluster analysis revealed that several widely separated populations grouped together, suggesting long-distance gene flow among populations. The high vagility of V. spinulosa and extensive hydrologic connectivity among populations have facilitated long-distance gene flow and resulted in the pattern of population genetic structure in V. spinulosa.     

Genetic variation and clonal diversity in populations of Nelumbo nucifera (Nelumbonaceae) in central China detected by ISSR markers

To obtain accurate estimates of population structure for purposes of conservation planning for wild lotus (Nelumbo nucifera Gaertn.) in central China, genetic diversity among and within six populations, and clonal diversity within another two populations of the species were analyzed. The genetic diversity was high (percentage of polymorphic bands, PPB = 90.0%; Shannon's information index, I = 0.383 ± 0.234) at the species level, but low within individual study populations (PPB = 35.8%; Shannon's information index I = 0.165 ± 0.241). The mean coefficient of gene differentiation (G_st) was 0.570, indicating that 43.0% of the genetic diversity resided within the population. Analysis of molecular variance (AMOVA) indicated that 50.47% of the genetic diversity among the study populations was attributed to geographical location while 12.3% was attributed to differences in their habitats. An overall value of mean estimated number of gene flow (N_m = 0.377) indicated that there was limited gene flow among the sampled populations. The level of clonal diversity found within the populations was considerably high (Simpson's diversity index, D = 0.985) indicating that clonal diversity contributes to a major extent to the overall genetic variation in the genetic structure of N. nucifera. On the basis of the high G_st and D values detected in this study we recommend that any future conservation plans for this species should be specifically designed to include those representative populations with the highest genetic variation for both in situ conservation and germplasm collection expeditions.     

High allozymic diversity in natural populations of Mycoheterotrophic Orchid Gastrodia elata,an endangered medicinal plant in China

Gastrodia elata Blume, a mycoheterotrophic orchid native to the Far East, is an endangered medicinal plant in China. Genetic variation among 19 natural populations of G. elata was examined in central China by using allozyme polymorphism (16 loci in six enzymatic systems). The species exhibited high level of genetic diversity (P = 56.3%, A = 2.2 and H_E = 0.221), which was mainly attributed to its perennial habit and mixed reproduction system (both sexual and asexual). Evident genetic differentiation in G. elata natural populations was suggested by F_ST = 0.241. AMOVA analysis showed 31.3% of the total molecular variation was attributed to inter-population differentiation. Obvious genetic structure and genetic depauperation of some populations indicate forest fragmentation and over-collection have affected genetic variation of G. elata. A conservation strategy, which is conserving populations with great genetic distinction or high level of genetic variation from four management units, is recommended.     

Characterization of genetic variance within and among five populations of Sperata seenghala (Skyes, 1839) revealed by random amplified polymorphic DNA markers

The genetic diversity among five populations (Bhadbada reservoir, Mohinisagar reservoir, Bansagar reservoir, Bargi reservoir and Gandhisagar reservoir) was revealed using random amplified polymorphic DNA markers. 10 random primers screened, 5 primers revealed various banding patterns and yielded 71 total loci as an average of which 39.60 (55.77%) were polymorphic between the population and 86.84% within the population of Sperata seenghala. Population wise the highest genetic polymorphism was obtained in Bhadbada reservoir as 67.61% whereas the lowest was in Gandhisagar reservoir as 49.30%. However, Analysis of Molecular Variance indicated low genetic diversity (H_pop = 0.0921 ± 0.1249; I = 0.1584 ± 0.1942) in Bansagar reservoir. Relative genetic differentiation (G_ST = 0.3993) and restricted gene flow (N_m = 0.7523) as an average indicated low gene diversity among the fish populations. The un-weighted pair group method with averages (UPGMA) dendrogram showed 05 major clusters, each cluster representing a population. Fish population of Mohinisagar reservoir showed high genetic distance (0.3981) with respective Bargi reservoir population and highest genetic identity (0.8846) reflected between Bansagar and Gandhisagar reservoir. Highest genetic distance between Mohinisagar and Bargi reservoir fish populations shows no significant correlation between genetic and geographical distance of the genotypes collected from different lentic and geographical isolated water bodies. This investigation indicated that lowest genetic diversity existed in different geographic populations of S. seenghala. All the five populations were found to be low in genetic variation, which is useful information for future conservation measures of S. seenghala confined in natural water bodies of Madhya Pradesh.     

Chloroplast DNA variation and phylogeographic patterns in the Chinese endemic marsh herb Sagittaria potamogetifolia

We examined chloroplast DNA (cpDNA) atpB–rbcL intergenic spacer sequences variation within Sagittaria potamogetifolia, an endangered and endemic marsh herb in China. Sequence data were obtained from 54 individuals in six extant populations of the species. Sequences appeared to evolve neutral (Tajima's criterion D = −1.59826, 0.1 > P > 0.05 and Fu and Li's tests D* = −1.44484, P > 0.1; F* = −1.83446, P > 0.1). Eleven haplotypes were identified in S. potamogetifolia. A relatively high level of haplotype diversity (h = 0.0.699) and low level of nucleotide diversity (pi = 0.0035 ± 0.0020) were detected in S. potamogetifolia. Pairwise comparisons of F_st and Nm deduced from cpDNA variation suggested no significant genetic differentiation between populations of S. potamogetifolia excepted for the WY-1 population. Low genetic differentiation among populations and also among regions was consistently indicated by both hierarchical analyses of molecular variance (AMOVA) and the structure of a neighbor-joining tree. Lack of population differentiation between populations or between regions in cpDNA sequences may be due to effects of lower substitution rates or lineage sorting. In the minimum spanning network, all tip haplotypes except for the haplotype J were unique to a particular population, while the interior nodes except for the haplotype E were widespread (haplotype A). From nested clade analysis (NCA), the evolutionary events such as restricted gene flow with isolation by distance and allopatric fragmentation were inferred to responsible for the current distribution of S. potamogetifolia populations, as well as their genetic diversity.     

Population structure and genetic diversity of Dysosma versipellis (Berberidaceae), a rare endemic from China

Dysosma versipellis (Berberidaceae) is an endangered and endemic species in China. To provide scientific foundation for formulating conservation strategies, we sampled six extant populations of this species and assessed the levels and patterns of genetic diversity using ISSR markers (11 primers). Of 144 bands detected 57.64% were polymorphic, but on average only 20.72% were polymorphic within populations. Our results revealed a low level of intraspecific genetic diversity (at population level: H_pop = 0.082, H_B = 0.177, SI = 0.1194; at species level: H_pop = 0.207, H_B = 0.378, SI = 0.3069). A high level of genetic differentiations among populations was detected based on Nei's genetic diversity analysis (60%), AMOVA analysis (65%), and Bayesian analysis (53%). The low levels of heterozygosity and high genetic differentiation observed in D. versipellis may be the consequence of low rate of natural recruitment, clonal growth, gene drift, and habitat fragmentation. Based on this, we suggest that in situ conservation be an important and practical measure for maintaining the genetic diversity of this species. Ex situ conservation should sample from different populations across the distribution range of the species to conserve high genetic diversity.     

Population genetics and conservation of the Azorean tree Picconia azorica

Picconia azorica (Tutin) Knobl. (Oleaceae) is an endangered species, endemic to the Azores. Samples from 31 populations in 8 islands were genotyped using 8 newly developed nuclear microsatellite markers. From the amplified loci, 81% were polymorphic across all populations and the species showed a relatively high total genetic diversity (H_T = 0.7). Several populations were close to Hardy–Weinberg equilibrium while others presented positive F_IS values (0.02–0.2). The largest proportion of genetic variation (98%) occurred within populations and the level of differentiation between populations, was generally low, although 27% of the population pairwise comparisons showed relatively high differentiation values (0.25 ≤ R_ST ≤ 0.65). Relatively high levels of gene flow were also found among most populations. Using the Bayesian clustering method implemented in STRUCTURE we found a particular genetic pattern in Corvo samples, and also similarities between Santa Maria, São Miguel and Flores populations. Considerable levels of genetic admixture within P. azorica populations might have resulted from: (i) fruit dispersal by native birds; and/or (ii) human mediated dispersal between islands. Our results revealed the existence of some genetically depauperate populations needing specific conservation measures, and indicate that arbitrary translocation of individuals between islands should be avoided.     

Genetic structure of expanding wolf (Canis lupus) populations in Italy and Croatia,and the early steps of the recolonization of the Eastern Alps

After centuries of range contraction and demographic declines wolves are now expanding in Europe, colonizing regions from where they have been absent for centuries. Wolf colonizing the western Alps originate by the expansion of the Italian population. Vagrant wolves of Italian and Dinaric-Balkan origins have been recently observed in the Eastern Alps. In this study we compared the genetic structure of wolf populations in Italy and Croatia, aiming to identify the sources of the ongoing recolonization of the Eastern Alps. DNA samples, extracted from 282 Italian and 152 Croatian wolves, were genotyped at 12 autosomal microsatellites (STR), four Y-linked STR and at the hypervariable part of the mitochondrial DNA control-region (mtDNA CR1). Wolves in Croatia and Italy underwent recent demographic bottlenecks, but they differ in genetic diversity and population structure. Wolves in Croatia were more variable at STR loci (N_A = 7.4, H_O = 0.66, H_E = 0.72; n = 152) than wolves in Italy (N_A = 5.3, H_O = 0.57, H_E = 0.58; n = 282). We found four mitochondrial DNA (mtDNA CR1) and 11 Y-STR haplotypes in Croatian wolves, but only one mtDNA CR1 and three Y-STR haplotypes in Italy. Wolves in Croatia were subdivided into three genetically distinct subpopulations (in Dalmatia, Gorski kotar and Lika regions), while Italian wolves were not sub-structured. Assignment testing shows that the eastern and central Alps are recolonized by wolves dispersing from both the Italian and Dinaric populations. The recolonization of the Alps will predictably continue in the future and the new population will be genetically admixed and very variable with greater opportunities for local adaptations and survival.     

High genetic diversity in fragmented Iris pumila L. populations in Ukrainian steppe enclaves

Habitat fragmentation can prevent gene flow between plant populations and lead to a loss of genetic diversity. However, such impact of fragmentation has not always been consistently confirmed by previous studies and the issue still needs further research. Particularly little is known about the impact of fragmentation on steppe plants. Steppe once covered vast, continuous areas, and nowadays is among the most fragmented biomes. In Ukraine, remnants of this habitat survived in large but few nature reserves and loess ravines as well as on kurgans (burial mounds of ancient nomadic people), which, despite their small size, are still numerous and scattered throughout the landscape.We studied the impact of fragmentation on the genetic diversity and structure of Iris pumila, a typical species of European steppes. Our main focus was to compare the genetic characteristics between kurgan populations (n = 8), and populations from larger refugia (n = 6). We assessed the genetic diversity of the studied populations with Universal Rice Primers.Our analyses revealed high genetic diversity across all investigated populations (mean He: 0.233; mean PPB: 58.57). However in kurgan populations genetic diversity was significantly higher than in larger refugia. Genetic diversity (He) was negatively correlated with population size. Most of the molecular variance (82%) was represented within populations, whereas genetic differentiation among populations was moderate (Φ_ST = 0.160), and low among refugia types (Φ_RT = 0.026).The maintenance of high genetic diversity despite two centuries of fragmentation may be related to the moderate disturbance occurring on kurgans, which enhances the sexual reproduction of the species. Moreover, we assume that species traits such as longevity and polyploidy might counterbalance genetic drift, while its self-incompatibility and presence of a soil seed bank allows for the replenishment of the gene pool. Overall, our results suggest that kurgans can protect genetic diversity of steppe species.     

Conservation genetics of Leucadendron argenteum (Silvertree) — A flag ship species of the Cape Peninsula

The Silvertree (Leucadendron argenteum (L.) R.Br.) is an iconic tree to South Africans and tourists alike. This endangered species is endemic to the Cape Peninsula, the most southwestern part of Africa. Despite its visual presence, no population genetic data of L. argenteum are currently available, but such information is crucial for effective conservation management. A historical question is whether the inland populations are natural or planted? This study aimed to reveal the genetic structure and possible differences of L. argenteum populations on the Cape Peninsula and inland at Helderberg, Paarl Mountain and Simonsberg. It was expected that inland populations would exhibit reduced genetic variation due to their isolation from each other and the main Cape Peninsula gene pool. Furthermore, genetic differences between populations were expected to be higher at inland populations because they are further apart from each other, relative to the Peninsula populations. Plant leaf material was collected and AFLP was used to assess the genetic variation. In general, low genetic variation was present within all populations (mean Nei's gene diversity 0.11 ± 0.01) and no significant differences between Peninsula and inland populations were found. Minor differences in molecular variances were found between Peninsula and inland populations (PhiPt = 0.11), being double between Peninsula populations (PhiPt = 0.08) than between inland populations (PhiPt = 0.04). This supports a possible anthropogenic origin of inland populations. Although the genetic variation of populations is very similar, they should not be managed as a single gene pool. Inland populations are more similar to each other compared to the Peninsula ones and therefore might be managed as one genetic entity. In contrast, Peninsula populations show a higher degree of differentiation and should be managed to maintain genetic integrity by minimizing further cross planting.     

Micro-geographic landscape features demarcate seedling genetic structure in the stream lily,Helmholtzia glaberrima

In this study, 169 stream lily (Helmholtzia glaberrima) seedlings from six micro-drainages were genotyped with AFLP markers to quantify the impact that topographic landscape features and altitude may have in shaping patterns of genetic diversity within individual populations. A global analysis of genetic diversity detected significant genetic differentiation among micro-drainages (F_ST = 0.22, P < 0.01). The observed genetic structure of sampled sites conformed to a hierarchical model of gene flow. Assignment tests also supported a hierarchical model of gene flow as only one dispersal event among the sampled micro-drainages was detected. This suggests that opportunities for seed dispersal in H. glaberrima are highly constrained by patterns of hydrographic networks even at a local scale. In contrast, altitude had little impact on partitioning of genetic diversity as no increase in genetic diversity was evident among individuals in the upper (0.18 ± 0.02), and lower (0.17 ± 0.02) areas of micro-drainages. Overall these results suggest that the influence of freshwater landscape features can vary widely the effect on the patterns of genetic diversity of seedlings in stream lily populations.     

Noninvasive genetic assessment of brown bear population structure in Bulgarian mountain regions

The Balkans are one of the last large refugia for brown bear (Ursus arctos) populations in Europe, and Bulgaria, in particular, contains relatively large areas of suitable brown bear habitat and a potential population of more than 600 individuals. Despite this, the majority of brown bear research remains focused on bear populations in Central and Western Europe. We provide the first assessment of genetic population structure of brown bears in Bulgaria by analysing tissue samples (n = 16) as well as samples collected with noninvasive genetic methods, including hair and faecal samples (n = 189 and n = 163, respectively). Sequence analysis of a 248 base pair fragment of the mitochondrial control region showed that two highly divergent mitochondrial European brown bear lineages form a contact zone in central Bulgaria. Furthermore, the analysis of 13 polymorphic microsatellite markers identified 136 individuals and found substantial genetic variability (H_e = 0.74; N_A = 8.9). The combination of both genetic markers revealed the presence of weak genetic substructure in the study area with considerable degrees of genetic admixture and the likely presence of migration corridors between the two subpopulation in the Rhodope Mountains and Stara Planina as evidenced from the genetic detection of two male long-distance dispersers. A detailed assessment from densely collected samples in the Rhodope Mountains resulted in a population size estimate of 315 (95% CI = 206–334) individuals, indicating that not all available habitat is presently occupied by bears in this region. Efficient management plans should focus on preserving connectivity of suitable habitats in order to maintain gene flow between the two Bulgarian brown bear subpopulations.     

Geometric morphometrics on Greek house mouse populations (Mus musculus domesticus) with Robertsonian and all-acrocentric chromosomal arrangements

This work aims to give the first comprehensive morphometric analysis of intraspecific variation for the different populations of the western house mouse (Mus musculus domesticus), in the Robertsonian (Rb) system of the N-NW Peloponnisos. Furthermore, we study all-acrocentric karyotype populations (2n = 40) of the species coming from several localities of Greece. We apply 2D shape analysis, i.e. landmark analysis and Elliptic Fourier Analysis, on the dorsal and ventral side of skull and the occlusal view of the first upper molar (M¹), respectively. Although significant genetic divergence between typical and Rb populations and even ongoing speciation processes have been reported for this species, this was not the case for the Greek populations studied. However, our analyses herein reveal morphologically differentiated chromosome groups in N-NW Peloponnisos Rb system and a clear geographical discrimination of the all-acrocentric (2n = 40) populations for all characters studied. We suggest that in all-acrocentric (2n = 40) karyotype mice the geographical distance drives their differentiation while within the Rb system of N-NW Peloponnisos, karyotype is the key factor that acts on their phenotypic variation.     

Mitochondrial DNA sequence variation of the bumblebee,Bombus ardens (Hymenoptera: Apidae)

The bumblebee, Bombus ardens, is a valuable natural resource, and is most notably utilized for greenhouse pollination. In order to gain a greater understanding of the population genetic structure and the genetic diversity of this species, we sequenced a portion of the mitochondrial COI gene corresponding to the “DNA Barcode” region (658 bp) from 160 individuals collected over 15 Korean localities. Uncorrected pairwise distances among the eight haplotypes suggested low intraspecific genetic diversity, with a maximum sequence divergence of 0.3%. Such a low level of intraspecific genetic diversity was further reflected in local populations, particularly to islet populations, such as those of Youngheungdo, Jakyakdo, and Ulleugdo, which had zero genetic diversity. Geographically, one haplotype (BARBA01) was widespread and dominant, with a frequency of 90.6% (145 among 160 individuals). Other haplotypes were restricted to one to three localities and had low frequency. Overall, a very high rate of per generation female migration ratio (Nm = 4.6 to infinite) and a very low level of genetic fixation (F_ST = 0 to 0.099) were detected between pairs of localities, suggesting that the B. ardens populations on the Korean peninsula are panmictic, which is consistent with our understanding of their dispersal capability.     

High genetic differentiation revealed by RAPD analysis of narrowly endemic Sinocalycanthus chinensis Cheng et S.Y. Chang,an endangered species of China

Genetic diversity and genetic differentiation of narrowly endemic Sinocalycanthus chinensis Cheng et S.Y. Chang, an endangered species of China, were analyzed using random amplified polymorphic DNA (RAPD) markers. Totally, 165 stable and clearly scored RAPD bands were achieved from 12 primers. The genetic diversity of S. chinensis was high (P% = 68.84; h = 0.2421 ± 0.1978; I = 0.3615 ± 0.2789), whereas that at the population level was relatively low (P% = 14.49; h = 0.0578 ± 0.0167; I = 0.0843 ± 0.0236). High genetic differentiation among populations was detected based on Shannon's information index (0.7668), Nei's gene diversity (0.7613) and AMOVA (0.8183). This might be explained by its survival in refugia during the last glaciation in southeastern China with origin from a widespread continental progenitor. The 10 populations from different geographical sites could be clustered into two groups. Low gene flow due to mixed mating system and anthropogenic activities likely played important roles in shaping the population genetic structure of the species.     

Prevalence,distribution and intraspecific variation of Heterodera schachtii populations from semiarid environment

A two-year survey study was carried-out to identify and determine the distribution, community characteristics and intraspecific variation of the sugar beet cyst nematode, Heterodera schachtii populations collected from the six major sugar beet-producing governorates in Syria, west Asia. A total of 178 composite rhizosphere soil samples were collected from the six governorates during 2009 and 2010 growing seasons as follows: Aleppo (26), Ar Raqqah (17), Dayr az Zawr (33), Idlib (34), Hamah (41) and Homs (27 samples). The nematode was originally identified on the basis of morphometrics and morphological features of the cyst vulvar cones and second-stage juveniles (J₂). The communities of H. schachtii were then analyzed using the criteria of frequency of occurrence (FO%), mean population density (PD) and prominence value (PV). Results showed that H. schachtii was the most frequent and prominent in Homs (FO% = 70.37% and PV = 23472.37) and the least frequent and prominent in Ar Raqqah (FO% = 5.88% and PV = 28.86). The highest nematode population density was also recorded in Homs in 2009 (50,545 J₂ + eggs/100 g soil) while the least was recorded in Ar Raqqah in 2010 (119 J₂ + eggs/100 g soil). The morphometric data of cyst vulvar cone, second-stage juveniles (J₂) and eggs were also subjected to a multivariate principal component analysis to analyze the relationships between the studied populations, and to identify the variables that show the highest multiple correlations with these populations. Results showed that at the high order of hierarchical cluster analysis, four populations (Idlib, Hamah, Homs and Aleppo) formed one main cluster, while Dair az Zawr and Ar Raqqah failed to form clusters and separated individually. However, at low distance value, the main cluster further subdivided to separate the Aleppo population from Idlib, Hamah and Homs populations. The morphometric distance values ranged from 0.07 to 0.61. Hamah and Homs were the closest populations while Dair az Zawr showed the most diverse population. This study also revealed the value of J₂ body length, egg length and width, fenestral length and width and the number of bullae inside the cyst vulvar cone in determining the intraspecific variations among the Syrian populations of H. schachtii.     

Genetic diversity and population structure of Sicilian sheep breeds using microsatellite markers

Genetic diversity studies in domestic animals aim at evaluating genetic variation within and across breeds mainly for conservation purposes. In Sicily, dairy sheep production represents an important resource for hilly and mountain areas economy. Their milk is used for the production of traditional raw milk cheeses, sometimes protected designation of origin (PDO) cheeses. In some cases, the quality of these products is linked to a specific breed, i.e. mono-breed labelled cheeses and it is therefore important to be able to distinguish the milk of a breed from that of others, in order to guarantee both the consumer and the breed itself. In order to investigate the genetic structure and to perform an assignment test, a total of 331 individuals (Barbaresca, BAR n = 57, Comisana, COM n = 65, Pinzirita, PIN n = 75, Sarda, SAR n = 64, and Valle del Belice, VDB n = 70) were analysed using a panel of 20 microsatellite markers. A total of 259 alleles were observed with average polymorphic information content equal to 0.76, showing that the microsatellites panel used was highly informative. Estimates of observed heterozygosity ranged from 0.65 in the BAR breed to 0.75 in the COM breed. The low value of genetic differentiation among breeds (F_st = 0.049) may indicate that these breeds are little differentiated probably due to common history and breeding practices. The low F_is and F_it values indicated low level of inbreeding within and among breeds. The unrooted neighbor-joining dendrogram obtained from the Reynold's genetic distances, and factorial correspondence analysis revealed a separation between BAR and the other sheep breeds. Recent migration rates were estimated, showing that four out of the five breeds have not received a significant proportion of migrants. Only for the PIN breed a recent introgression rate from the VDB breed (7.2%) was observed. The Bayesian assignment test showed that BAR and SAR breeds had a more definite genetic structure (proportion of assignment of 92% and 86.6%, respectively), whereas the lowest assignment value was found in the PIN breed (67.1%). Our results indicated high genetic variability, low inbreeding and low genetic differentiation, except for BAR breed, and were in accordance with geographical location, history, and breeding practices. The low robustness of the assignment test makes it unfeasible for traceability purposes, due to the high level of admixture, in particular for COM, PIN and VDB.     

Nutrient concentrations in tidal creeks as indicators of the water quality role of mangrove wetlands in Southwest Florida

Coastal mangroves have the potential to improve the water quality of urban and rural runoff before it is discharged into adjacent coastal bays and oceans; but they also can be impaired by excessive pollutants from upstream. Nutrients (phosphorus and nitrogen), salinity, and other water quality parameters were measured in five mangrove tidal creeks in different hydrogeomorphic and urbanization settings during high and low tides over a calendar year of wet (June and August 2015) and dry (February and April 2016) seasons in the Greater Naples Bay area in Southwest Florida, USA. Nutrient concentrations (ave. ± std error) in the tidal creeks were 0.055 ± 0.008 mg-P/L for total phosphorus (TP) and 0.610 ± 0.020 mg-N/L for total nitrogen (TN), with an average N:P ratio of 11.4:1. Average wet season TP (0.075 ± 0.010 mg-P/L) was significantly higher than the dry season TP (0.033 ± 0.003 mg-P/L; p < 0.01, f = 15.17, f_crit = 3.89) and the average wet season TN (0.75 ± 0.03 mg-N/L) was significantly higher than dry season TN (0.52 ± 0.02 mg/L; p < 0.01, f = 64.14, f_crit = 3.89), suggesting that urban stormwater runoff is directly or indirectly affecting the nutrient conditions in these mangroves. Significant differences in nutrient concentrations between low tide and high tide were not found for either TP (p = 0.43, f = .63, f_crit = 3.88) or TN (p = 0.20, f = 1.66, f_crit = 3.89). These differences were confirmed by a PCA and cluster analyses, which found differences to be seasonal. We could not conclude from these results whether these five mangrove wetlands were sources nor sinks of nutrients based simply on the measurement of nutrient concentrations. But we illustrated that nutrient concentrations were indicators of the mangroves’ hydrogeomorphic settings, their tidal fluxes from Naples Bay, and the Bay's upstream watersheds, and less by direct urban runoff.     

Genetic differentiation in Pyrenophora teres populations measured with AFLP markers

The genetic structure and occurrence of mating types and forms of Pyrenophora teres, the causal agent of net blotch on barley, was studied among 278 isolates collected from the northern hemisphere and from Australia. Genetic differentiation was high (F_CT 0.238, P = 0.002) between P. teres f. teres (PTT) isolates originating from Northern Europe, North America, Russia and Australia. The P. teres population in Australia was clearly divided into two subgroups (F_CT 0.793, P < 0.001) according to the form identity: PTT and P. teres f. maculata (PTM), with the PTT samples showing a greater degree of differentiation (F_ST 0.573, P < 0.001) among Australian states than the PTM samples (F_CT 0.219, P < 0.001). No differentiation was found among locations within Australian states. Both mating types (MAT1 and MAT2) were equally common (1:1) in several locations in Australia and in Finland. The only exception was Krasnodar, Russia, where only MAT2 was identified. Our results show that the prevalence of sexual reproduction, occurrence of forms of P. teres, and genetic differentiation between geographical regions are highly variable. The paper discusses the various effects and outcomes of population selection in Australia and in the northern barley growing regions.     

Crossing the border? Structure of the red deer (Cervus elaphus) population from the Bavarian–Bohemian forest ecosystem

Anthropogenic impact such as overhunting and habitat fragmentation has reduced the total red deer population (Cervus elaphus) across Europe. In Germany remaining subpopulations are even confined to designated areas with limited or no gene flow among them. Red deer populations inhabiting the Bavarian–Bohemian forest ecosystem had been divided by a fortified State border between Germany and former Czechoslovakia. To assess red deer genetic diversity more than two decades after the removal of the fortifications, we analysed a population from the Bavarian Forest National Park, Germany, and one from the National Park ?umava, Czech Republic, using 11 microsatellite loci and a 910 bp long section of the mitochondrial control region (mtDNA). Bayesian analyses of microsatellite allele frequencies favoured the presence of a single population in the Bavarian-Bohemian forest ecosystem over other population genetic structures. This admixture was supported by a lack of population pairwise differentiation between German and Czech red deer microsatellite genotypes in the analysis of molecular variance (AMOVA, F_ST = 0.009, p = 0.383). Contrastingly, AMOVA revealed a highly significant matrilinear differentiation of mtDNA between the two samples (Φ_ST = 0.285, p = 0.002), whereby German red deer belonged predominantly to haplogroup A (western Europe) and Czech red deer predominantly to haplogroup C (eastern Europe). In combination, these findings indicated a high degree of philopatry by does and extensive gene flow across the former border mediated by stags. They also identified the Bavarian–Bohemian forest ecosystem as part of a suture zone between western and eastern European red deer matrilines.