Serena Zaccara

Conifer needles as passive biomonitors of the spatial and temporal distribution of DDT from a point source

Needles of two conifer species, Picea abies and Pinus nigra, were used as passive samplers for monitoring air contamination by sampling at increasing distances from a suspected point source of DDT. Needle concentrations declined with increasing distance downwind of the point source allowing to identify spatial and temporal trends of accumulation. This suggested that conifer needles are effective biomonitors of contamination levels in areas characterized by the presence of semi-volatile substances. Differences in uptake were apparent between the species. Needle morphology and structure were studied with scanning electron microscope (SEM) as were dimensional parameters (surface area, volume). The results suggest that the concentrations depend on a mechanism involving the inner structure of the needles, specifically the number and accessibility of resin channels rather than their surface area. Pine needles have more channels with greater accessibility than spruce. The results suggest that spruce is more suitable for short term measurement while pine for determining long term cumulative exposure.

The endangered white-clawed crayfish Austropotamobius pallipes (Decapoda, Astacidae) east and west of the Maritime Alps: A result of human translocation?

The genetic variability among Italian populations of the white-clawed crayfish (Austropotamobius pallipes) was examined to determine their phylogeography and to assess their conservation status as a management unit. A fragment of the mitochondrial DNA COI gene of 107 specimens from ten populations was sequenced, and the phylogenetic relationships were established. Two out of three haplotypes sampled in two French populations from the Rhône basin were shared with Italian populations. Despite a moderate level of genetic variability within the Italian populations of A. pallipes, no genetic structure was revealed. It has been suggested that there have been translocation events throughout the Alpine barrier between the North-Western Italian basins and the Rhône basin. Genetic exchangeability of the French and Italian populations was demonstrated in this study, and a shift of conservation efforts towards the native, congeneric Austropotamobius italicus is recommended.

A northern Italian shallow lake as a case study for eutrophication control

Lake Varese (northern Italy) has shown deterioration in water quality since the 1960s and, as a result of the long duration of direct discharge of untreated sewage into the lake, it was classified as being hypertrophic. To recover the lake water quality, a series of externally and internally remedial actions were implemented in subsequent years. The applied sewage collecting system induced a reduction of the external P loads from 50 t P year−1 to 16t P year−1 and the weighted mean annual TP concentration decreased from 352 μg P l−1 to 85 μg P l−1, typical of eutrophic conditions. The hypolimnetic water withdrawals, adopted in the years 2000–2003, allowed a reduction of the internal P loads of about 3–5 t P. In the same years, 500t O2 were injected at depths of 4.5–8 m during the summer months. In spite of these internal remedial actions, no significant reduction of the weighted mean annual concentration of the TP could be observed, and during the summer stratification period no significant reduction of the volumes of anoxic water and of the duration of the anoxia were detected. The anoxic conditions are still the prevailing force driving the lake P-budget, maintaining the lake in eutrophic status.

Lesser Flamingo Phoeniconaias minor as a nomadic species in African shallow alkaline lakes and pans: Genetic structure and future perspectives

The Lesser Flamingo Phoeniconaias minor is a nomadic species, which inhabits shallow alkaline lakes and pans in sub-Saharan Africa and southern Asia. The extent of genetic diversity and the degree of differentiation within and among populations are important factors to determine in order to help manage and conserve the species, categorised as Near Threatened by the IUCN. This study provides an assessment of the population structure of the two largest African populations of P. minor by genotyping six microsatellite loci from 30 individuals sampled on Lake Bogoria (Kenya) and 11 individuals from Makgadikgadi Sua Pan (Botswana). The alleles detected per locus ranged from four to 13. The Lake Bogoria population harboured 15 specific alleles, whereas the Makgadikgadi Sua Pan population only six alleles. Moderate genetic diversity (He = 0.64–0.69) was comparable with populations that have not suffered from demographic bottlenecks or inbreeding. The populations are genetically similar with little differentiation (FST and RST not significantly different from zero). Small but continuous gene flow (the estimated average number of individuals exchanged is 3–4 per generation) was found, probably reflecting the birds nomadic behaviour and the natural presence of temporary shallow waters between the two sampled populations. The results suggest that inbreeding effects at present are unlikely, and hence that the loss and/or degradation of its specialised habitat remains the primary concern for the species’ continued survival.

Phylogeographical structure of vairone Telestes muticellus (Teleostei, Cyprinidae) within three European peri‐Mediterranean districts

The phylogeographical pattern of vairone (Telestes muticellus) populations was assessed to test the biogeographical distinction of three peri‐Mediterranean ichthyogeographical districts: Padano‐Venetian (PV), Tuscano‐Latium (TL) and southern France (SF), evaluating the role of Alpine and Apennine barriers in shaping distinct evolutionary lineages. A fragment of mitochondrial DNA (mtDNA) cytochrome b (cytb) was sequenced in 153 specimens from 14 north‐western Italian populations, collected in 10 tributaries of Po River and in four rivers on the Tyrrhenian slope of Ligury, and 32 haplotypes were identified. The phylogenetic analyses confirmed the presence of two distinct clades, an ‘Italian clade’ (T. muticellus) and a ‘French clade’ (T. souffia), showing an average genetic distance of 12.9% (± 1.3 SD) and allopatric distribution. The Nested Clade Analysis (NCA) and the Analysis of Molecular Variance (amova) revealed an isolated gene pool in eastern basins on the Tyrrhenian slope of Ligury. The phylogeographical findings suggest: (i) the lack of permeability of Alpine barrier towards the dispersion across Italian and French hydrographical systems; and (ii) partial permeability of Mediterranean Alps and Apennines through river captures crossing lower watersheds.

Loss of genetic integrity and biological invasions result from stocking and introductions of Barbus barbus: insights from rivers in England.

Abstract Anthropogenic activities, including the intentional releases of fish for enhancing populations (stocking), are recognized as adversely impacting the adaptive potential of wild populations. Here, the genetic characteristics of European barbel Barbus barbus were investigated using 18 populations in England, where it is indigenous to eastern‐flowing rivers and where stocking has been used to enhance these populations. Invasive populations are also present in western‐flowing rivers following introductions of translocated fish. Two genetic clusters were evident in the indigenous range, centered on catchments in northeast and southeast England. However, stocking activities, including the release of hatchery‐reared fish, have significantly reduced the genetic differentiation across the majority of this range. In addition, in smaller indigenous rivers, populations appeared to mainly comprise fish of hatchery origin. In the nonindigenous range, genetic data largely aligned to historical stocking records, corroborating information that one particular river (Kennet) in southeast England was the original source of most invasive B. barbus in England. It is recommended that these genetic outputs inform management measures to either restore or maintain the original genetic diversity of the indigenous rivers, as this should help ensure populations can maintain their ability to adapt to changing environmental conditions. Where stocking is considered necessary, it is recommended that only broodstock from within the catchment is used.

Intrinsic and extrinsic factors act at different spatial and temporal scales to shape population structure, distribution and speciation in Italian Barbus (Osteichthyes: Cyprinidae).

Previous studies have given substantial attention to external factors that affect the distribution and diversification of freshwater fish in Europe and North America, in particular Pleistocene and Holocene glacial cycles. In the present paper we examine sequence variation at one mitochondrial and four nuclear loci (over 3 kbp) from populations sampled across several drainages of all species of Barbus known to inhabit Italian freshwaters (introduced B. barbus and native B. balcanicus, B. caninus, B. plebejus and B. tyberinus). By comparing species with distinct ecological preferences (rheophilic and fluvio-lacustrine) and using a fossil-calibrated phylogeny we gained considerable insight about the intrinsic and extrinsic processes shaping barbel distribution, population structure and speciation. We found that timescales of Italian barbel diversification are older than previously thought, starting in the Early Miocene, and involving local and regional tectonism and basin paleo-evolution rather than Pleistocene glacial cycles. Conversely, more recent environmental factors associated with glaciation-deglaciation cycles have influenced species distributions. These events had a more marked impact on fluvio-lacustrine than on rheophilic species by means of river confluence at low sea levels. We show that genetic structure is influenced by species ecology: populations of small rheophilic species inhabiting upper river stretches of large basins are less connected and more differentiated than large fluvio-lacustrine species that inhabit lower river courses. We report the existence of both natural and human-induced interspecific gene flow, which could have great impacts on the evolution and persistence of species involved. In addition, we provide evidence that B. tyberinus is genetically distinguishable from all other Italian taxa and that its morphological similarity to B. plebejus and intermediacy with B. caninus are best explained by recent common ancestry and similar ecology with the former, rather than by hybrid origin involving these two species as previously hypothesized.

Lesser Flamingo Phoenicopterus minor populations in eastern and southern Africa are not genetically isolated

A preliminary analysis of the phylogeographic pattern of the two main African populations of Lesser Flamingo Phoenicopterus minor from East and southern Africa was carried out to evaluate possible gene flow. A fragment of mitochondrial DNA encoding the NADH dehydrogenase subunit 2 gene (ND2) was sequenced in 27 specimens from these two populations and 11 haplotypes were identified. The phylogenetic analyses, based both on distance and parsimonious methods (neighbour joining and maximum parsimony), showed a homogeneous clade with a low level of genetic distance (0.26% ± 0.12 SD), which was also evidenced by the minimum spanning network method. The mismatch distribution analysis suggested a sudden demographic expansion from a single ancestral population. This latter result is also reinforced by the presence of few ancestral haplotypes, by the high level of haplotype diversity (0.83) and the low level of nucleotide diversity (0.0015–0.0017). These data support the belief of field ornithologists for restricted interchange between the two populations determined by the geographical distance between the two populations and lack of any observations of movement between them, but with evidence of changes in each populations numbers, giving the concept of a permeable geographic barrier.

Morphological and genetic characterization of Sardinian trout Salmo cettii Rafinesque, 1810 and their conservation implications

AbstractThe morphological and genetic structure of Western Mediterranean trout Salmo cettii inhabiting basins in Sardinia was completed to assist the design of its conservation programmes. Genetic analysis of protein-coding LDH-C1 plus sequencing mitochondrial control region gene and analyses of morphological characters described 253 specimens from seven localities in two basins in Southwest Sardinia. Nuclear and mitochondrial analyses revealed all of the fish were pure-bred native S. cettii, with no introgression from allochthonous S. trutta. The novel 18 mtDNA control region haplotypes were clustered in an ‘insular’ clade, strictly related to the Adriatic haplogroup, and depicted a radial network around two ancestral haplotypes. Completion of discriminant analysis using data on body pigmentation and quantitative morphologic parameters revealed three phenotypic groups within the fish. Each population and phenotype, characterised by high values of nucleotide and haplotype diversity, were not genetically differentiated and not geographically structured according to the two hydrological basins. Geometric morphometric analysis, based on 15 landmarkers, revealed pronounced and highly significant differences in body shape morphology between populations, suggesting S. cettii is locally adapting to extreme environmental conditions and so future management plans for these populations should treat the two basins as distinct morphological units.

Human-mediated contact zone between endemic and invasive Barbus species (Osteichthyes: Cyprinidae) in a regulated lowland river: genetic inferences and conservation implications

Abstract Genetic surveys of the endemic Padanian barbel Barbus plebejus (Osteichthyes: Cyprinidae) were completed on the lowland Adda River, a heavily regulated Italian Alpine river in which the European Barbus barbus is invasive. Both Barbus species are of the large fluvio-lacustrine ecophenotype and thus they share habitats in the river. Mitochondrial (N = 35) and nuclear (N = 256) DNA sequences were completed with the aim of estimating the extent and genetic consequences of the B. barbus invasion. The phylogenetic analyses, based on cyt b mtDNA, S7 ribosomal protein and growth hormone (GH) nuclear genes, revealed 59 haplotypes as B. plebejus and 37 as B. barbus. Genetic diversity values (H and π) and the mismatch distribution analyses indicated B. plebejus was still experiencing demographic radiation from a modest number of founders. The B. barbus cyt b haplotypes suggested their original source was the River Danube. Through analysing the nuclear paralog sequences, evidence was provided of consistent genetic admixture between B. plebejus and B. barbus, being recorded in over 40% of the sampled fishes, indicating that their ecological and biological interactions are disrupting the genetic integrity of B. plebejus. Bayesian analysis and factorial correspondence analysis then revealed that the habitat fragmentation of the Adda River is not limiting population connectivity. It was apparent there has been recent and rapid upstream dispersion of B. barbus, with individuals overcoming barriers to their migration through using fish passes and/or through translocation between impounded sections by anglers. The potential conservation implications of this for the endemic Barbus species are discussed.