Opportunistic Colonization Research Articles

New and rare coastal fishes in the Azores islands: occasional events or tropicalization process?

Seven coastal fish species are newly reported for the remote north Atlantic archipelago of the Azores: Mediterranean sand eel Gymnammodytes cicerelus, bar jack Caranx ruber, two-banded seabream Diplodus vulgaris, bastard grunt Pomadasys incisus, unicorn leatherjacket filefish Aluterus scriptus and longspined porcupinefish Diodon holacanthus. The occurrence is also confirmed for 19 species that had been hitherto cited occasionally for the region, totalling a list of two elasmobranchs and 23 teleosts. Diplodus vulgaris, which appears to have recently colonized the islands, as well as roughtail stingray Dasyatis centroura and golden grey mullet Liza aurata, re-cited based on new records, are frequent or common coastal species in the Azores. The remaining 22 species, exceptional or rare in the region, are of tropical or subtropical affinity and find their northernmost distribution limit within the central and north-east Atlantic Ocean precisely in the Azores. This biogeographical pattern contrasts with that of the Azorean coastal fish community and suggests a tropicalization process in the region in line with previous findings of similar patterns across the north-east Atlantic Ocean and the Mediterranean Sea. These novel data from the most isolated archipelago of the North Atlantic Ocean, located in a biogeographic boundary area where colonization opportunities are reduced, reinforce the need for long-term monitoring programmes of coastal fish communities and, in particular, of indicator species groups to improve understanding of the effects of climate change on marine communities.

Structural development of vegetation on rehabilitated North Stradbroke Island: Above/belowground feedback may facilitate alternative ecological outcomes

This study depicts broad-scale revegetation patterns following sand mining on North Stradbroke Island, south-eastern Queensland, Australia. Based on an ecological timeline spanning 4–20 years post-rehabilitation, the structure of these ecosystems (n = 146) was assessed by distinguishing between periods of ‘older’ (pre-1995) and ‘younger’ (post-1995) rehabilitation practices. The general rehabilitation outlook appeared promising, whereby an adequate forest composition and suitable levels of native biodiversity (consisting of mixed-eucalypt communities) were achieved across the majority of rehabilitated sites over a relatively short time. Still, older sites (n = 36) appeared to deviate relative to natural analogues as indicated by their lack of under-storey heath and simplified canopy composition now characterised by mono-dominant black sheoak (Allocasuarina littoralis) reaching up to 60% of the total tree density. These changes coincided with lower soil fertility parameters (e.g., total carbon, total nitrogen, and nutrient holding capacity) leading us to believe that altered growth conditions associated with the initial mining disturbance could have facilitated an opportunistic colonisation by this species. Once established, it is suspected that the black sheoak’s above/belowground ecological behaviour (i.e., relating to its leaf-litter allelopathy and potential for soil-nitrogen fixation) further exacerbated its mono-dominant distribution by inhibiting the development of other native species. Although rehabilitation techniques on-site have undergone refinements to improve site management, our findings support that putative changes in edaphic conditions in combination with the competitive characteristics of some plant species can facilitate conditions leading to alternative ecological outcomes among rehabilitated ecosystems. Based on these outcomes, future studies would benefit from in depth spatio-temporal analyses to verify these mechanisms at finer investigative scales.

A role for indirect facilitation in maintaining diversity in a guild of African acacia ants

Determining how competing species coexist is essential to understanding patterns of biodiversity. Indirect facilitation, in which a competitively dominant species exerts a positive effect on one competitor by more strongly suppressing a third, shared competitor, is a potentially potent yet understudied mechanism for competitive coexistence. Here we provide evidence for indirect facilitation in a guild of four African Acacia ant species that compete for nesting space on the host plant Acacia drepanolobium, showing that a competitively dominant acacia ant species indirectly creates establishment opportunities for the most subordinate species that may help to maintain diversity. Using long-term observational data and field experiments, we demonstrate that the competitively dominant ant species outcompetes two competitively intermediate species, while tolerating colonies of the subordinate competitor; this creates opportunities for local colonization and establishment of colonies of the subordinate species within the dominant species' territories. Host plants occupied by this subordinate species are then more likely to be colonized by the intermediate species, which in turn are more likely to be displaced by the dominant species. This process has the potential to generate a cyclical succession of ant species on host trees, contributing to stable coexistence within this highly competitive community.

Factors affecting woody plant species diversity of fragmented seasonally dry oak forests in the Mixteca Alta, Oaxaca, Mexico

We explored the relationship between fragment area, topographic heterogeneity, and disturbance intensity with tree and shrub species diversity in seasonally dry oak forest remnants in the Mixteca Alta, Oaxaca, Mexico. The fragments are distributed in a matrix of eroded lands and crop fields, have a complex topography, and are disturbed by plant extraction and trail opening. Sampling was conducted in 12 fragments from 12-3 211 ha. Topographic heterogeneity was estimated by the fragment's standard deviation in slope-aspect, slope, and altitude. The density of stumps and roads were used as estimators of disturbance intensity. Fisher's α diversity ranked from 0.95 to 4.55 for the tree layer; and 2.99 to 8.51, for the shrub layer. A structural equation model showed that the diversity of woody plants increases with topographic heterogeneity and disturbance in the remnants. When these 2 variables were considered, diversity tended to decrease with fragment size probably because smaller fragments have a greater perimeter-to-area ratio and therefore proportionally offer more opportunities for pioneer species colonization. Indeed, the tree-to shrub-layer diversity ratio increased with fragment size. Conservation strategies in fragmented forests must consider the fragment's environmental heterogeneity, the disturbance type and intensity, and the species to be preserved.

Laboratory crosses and genetic analysis of natural populations demonstrate sexual viability of invasive hybrid watermilfoils (Myriophyllum spicatum × M. sibiricum)

The hybrid offspring of invasive Eurasian watermilfoil (Myriophyllum spicatum) and native northern watermilfoil (Myriophyllum sibiricum) are highly invasive and have recently been considered to be of special management concern. Hybrid watermilfoils can reproduce asexually via fragmentation, but it is unknown if they can reproduce sexually. Here, we use laboratory crosses of hybrid watermilfoil genotypes to demonstrate that they can be sexually viable. In addition, a Bayesian analysis of Amplified Fragment Length Polymorphism (AFLP) data from natural populations of parental and hybrid watermilfoils was used to determine whether there was evidence for sexual reproduction by hybrid watermilfoils in natural populations. While many hybrid genotypes were estimated to be first generation hybrids, we found strong evidence for sexual reproduction in the form of later generation hybrids (F2 backcrosses, or later generation hybrids). Our study provides strong evidence that hybrids can, and frequently do, reproduce via sexual reproduction in natural populations. The capacity for sexual reproduction by hybrid watermilfoils has important management implications. The production of viable seeds may serve as an important source for the recolonization of previously treated lakes or areas within lakes. In addition, seeds may provide opportunities for colonization of new lakes (e.g., through water fowl). Thus, managers may consider practices that limit the production of seeds. In addition, sexual reproduction by hybrids may provide opportunities for the generation of unique genotypes through genetic recombination, some of which may be more invasive than their parental genotypes. Therefore, further consideration of sexual reproduction by hybrid watermilfoils is warranted.

The Role of Diminishing Appetite and Serum Nesfatin-1 Level in Patients with Burn Wound Infection

BackgroundThe burn wound represents a susceptible site for opportunistic colonization by organisms of endogenous and exogenous origin. Diminishing appetite is known to occur in patients with burn infection, yet its underlying reason is not fully understood. We have examined the levels of nesfatin 1, a protein that we consider to be a potential new treatment target for the solution of appetite and nutrition problem in patients with burn infection.ObjectivesThe aim of the present study was therefore to examine nesfatin levels in patients with burn infection.Material and MethodsLaboratory values, medication and dietary records, and patient notes with diagnostic information of burn wounds patients who were admitted to the Division of Burn Treatment Center were obtained from the Erzurum Region Education and Research Hospital electronic database. Post-burn wound infection was objectively assessed by culturing wound homogenates from skin tissue. The main immediate inflammatory stress response parameters assessed were serum CRP concentrations, WBC counts, and blood nesfatin concentrations.ResultsScalding was the predominant cause of burns in both categories of patients. In 19 (61.3%) burn wound infection patients, the burns were due to a scald. A significant difference was found for the nesfatin, CRP, and WBC levels between the patients and the control group (P = 0.000). A significant difference was also determined between the nesfatin, CRP, and WBC figures at the time of hospitalization and at discharge from the hospital (P = 0.000). The most predominant bacterial isolate was Pseudomonas aeruginosa 16 (51.6%) followed by Methicilline resistant Staphylococcus aureus (MRSA) 7 (22.6%).ConclusionsWe showed that the serum nesfatin 1 level was significantly lower in the patients with burn than in the control group in our study. We considered that the central nesfatin 1 system should be taken into consideration, rather than the peripheric nesfatin 1 system, when considering the regulation of appetite in patients with burns and particularly those accompanied by infection. In other explanation of the observed negative correlation between nesfatin 1 and burn wound infection suggests that nesfatin 1 may indicate the possible contribution of nesfatin 1 to the energy homeostasis.

Application of the ELOHA Framework to Regulated Rivers in the Upper Tennessee River Basin: A Case Study

In order for habitat restoration in regulated rivers to be effective at large scales, broadly applicable frameworks are needed that provide measurable objectives and contexts for management. The Ecological Limits of Hydrologic Alteration (ELOHA) framework was created as a template to assess hydrologic alterations, develop relationships between altered streamflow and ecology, and establish environmental flow standards. We tested the utility of ELOHA in informing flow restoration applications for fish and riparian communities in regulated rivers in the Upper Tennessee River Basin (UTRB). We followed the steps of ELOHA to generate univariate relationships between altered flows and ecology within the UTRB. By comparison, we constructed multivariate models to determine improvements in predictive capacity with the addition of non-flow variables. We then determined whether those relationships could predict fish and riparian responses to flow restoration in the Cheoah River, a regulated system within the UTRB. Although ELOHA provided a robust template to construct hydrologic information and predict hydrology for ungaged locations, our results do not suggest that univariate relationships between flow and ecology (step 4, ELOHA process) can produce results sufficient to guide flow restoration in regulated rivers. After constructing multivariate models, we successfully developed predictive relationships between flow alterations and fish/riparian responses. In accordance with model predictions, riparian encroachment displayed consistent decreases with increases in flow magnitude in the Cheoah River; however, fish richness did not increase as predicted 4 years after restoration. Our results suggest that altered temperature and substrate and the current disturbance regime may have reduced opportunities for fish species colonization. Our case study highlights the need for interdisciplinary science in defining environmental flows for regulated rivers and the need for adaptive management approaches once flows are restored.

The Nocardia cyriacigeorgica GUH-2 genome shows ongoing adaptation of an environmental Actinobacteria to a pathogen’s lifestyle

BackgroundNocardia cyriacigeorgica is recognized as one of the most prevalent etiological agents of human nocardiosis. Human exposure to these Actinobacteria stems from direct contact with contaminated environmental matrices. The full genome sequence of N. cyriacigeorgica strain GUH-2 was studied to infer major trends in its evolution, including the acquisition of novel genetic elements that could explain its ability to thrive in multiple habitats.ResultsN. cyriacigeorgica strain GUH-2 genome size is 6.19 Mb-long, 82.7% of its CDS have homologs in at least another actinobacterial genome, and 74.5% of these are found in N. farcinica. Among N. cyriacigeorgica specific CDS, some are likely implicated in niche specialization such as those involved in denitrification and RuBisCO production, and are found in regions of genomic plasticity (RGP). Overall, 22 RGP were identified in this genome, representing 11.4% of its content. Some of these RGP encode a recombinase and IS elements which are indicative of genomic instability. CDS playing part in virulence were identified in this genome such as those involved in mammalian cell entry or encoding a superoxide dismutase. CDS encoding non ribosomal peptide synthetases (NRPS) and polyketide synthases (PKS) were identified, with some being likely involved in the synthesis of siderophores and toxins. COG analyses showed this genome to have an organization similar to environmental Actinobacteria.ConclusionN. cyriacigeorgica GUH-2 genome shows features suggesting a diversification from an ancestral saprophytic state. GUH-2 ability at acquiring foreign DNA was found significant and to have led to functional changes likely beneficial for its environmental cycle and opportunistic colonization of a human host.

Contrasting patterns of seed dispersal between alien mammals and native lizards in a declining plant species

The introduction of carnivorous mammals has led many native island species to extinction. In the Balearic Islands, the introduction of carnivorous mammals in the main islands has contributed to the extinction of the endemic lizard Podarcis lilfordi, which is an important seed disperser of many plant species. One of the introduced mammals, Martes martes (pine marten), is also known to disperse seeds and may replace the native lizard in this role in islands. However, little is known on the patterns of seed dispersal by these two different species and their possible implications for plant regeneration ability and population structure. We have compared the quality of seed deposition provided by both to the vulnerable Mediterranean shrub Cneorum tricoccon, by studying the pattern of seed distribution among sites generated by both dispersers as well as the suitability of those sites for seedling emergence and establishment. The study was carried out in two types of habitats (coastal shrublands and pine forests) and two islands (Mallorca and Dragonera). Lizards and mammals showed contrasting patterns of seed deposition and, where lizards were absent, mammals played their role as seed dispersers in pine forests but not in coastal shrublands. The lack of seed dispersal in the coastal shrubland seriously limits recruitment, by concentrating seeds under conspecifics and hindering colonisation opportunities, marking a long-term trend towards decline. The introduced predator replaces the native seed disperser in its service where it has gone extinct, although with important differences in the dispersal service provided.

Temporal changes in the breeding bird community caused by post-fire treatments after the Samcheok forest fire in Korea

The Samcheok forest fire of April 2000 was the biggest stand-replacing fire recorded in Korea, and led to the largest-scale salvage logging operation (performed until 2005) ever implemented. We investigated the effects of the treatments performed after the fire on the breeding bird community in 2002–2005 (the management period) and 2006–2008 (the post-management period). A total of 75 line transect surveys resulted in 660 detections of 54 species in undisturbed stands (CO), in burned and naturally restored stands (NI), and in burned and logged stands (IT). Four species (Parus major, Aegithalos caudatus, Dendrocopos kizuki, and Parus ater) were identified as indicator species in CO which showed no temporal changes in bird communities and habitat structure. Among the various stand treatments, the standardized species richness was highest in CO (11.6 ± 4.6 species/transect in 2002–2005, 12.1 ± 3.5 in 2006–2008), and this richness did not change over time. On the other hand, low richness was observed in NI (6.8 ± 2.6 in 2002–2005, 9.6 ± 2.3 in 2006–2008), and the lowest richness was seen in IT (5.0 ± 2.4 in 2002–2005, 6.1 ± 1.8 in 2006–2008), but both of these increased over time. Although the bird abundances in NI and IT were lower than those in CO (38.0 ± 27.7 birds/transect in 2002–2005, 31.3 ± 10.9 in 2006–2008), the abundances in NI (15.1 ± 8.6 in 2002–2005, 17.6 ± 11.4 in 2006–2008) and IT (11.7 ± 8.3 in 2002–2005, 10.0 ± 4.6 in 2006–2008) were not significantly different. There was no significant difference in abundance between time periods for any of the stand treatments. These results imply that NI (i.e., no salvage logging) allows greater bird richness but not abundance to be recovered compared to IT. No indicator species was consistently present in NI throughout the two time periods covered due to the rapid regrowth of vegetation, but four open-habitat dwellers (Falco tinnunculus, Phoenicurus auroreus, Emberiza cioides, and Sturnus cineraceus) colonized IT during the post-management period. The bird assemblage in IT, as assessed by canonical correspondence analysis, shifted to open habitats, while the avifauna in NI became similar to that in CO over time. While post-fire treatment can provide new colonization opportunities for open-habitat dwellers, the slow colonization process, the low species richness, and the low bird abundance observed in large areas of IT indicate that post-fire treatment using salvage logging inhibits the restoration of forest bird communities by producing a poorer breeding bird community that is very different from the original one. Based on these lessons from the response to the Samcheok forest fire, we suggest that preserving as much of the disturbed forest as possible is essential, and that the current approach to post-fire treatment—intensive salvage logging—needs to be revised to ensure the effective restoration of breeding bird communities in disturbed temperate pine forests.

Вплив мультипробіотика “Апібакт®” на продукцію інтерферону й активність 2',5'-олігоаденілат-синтетази в лімфоцитах тимусу щурів за умов гіпоацидності, викликаної омепразолом

The interferon (IFN) production by rat thymus lymphocytes and the activity of IFN-induced 2′,5′-oligoadenylate synthetase (2′,5′-OA-synthetase) in these cells were stu­died at hypoacidity of gastric juice evoked by omeprazole injection and also at combined omeprazol and multiprobiotic “Apibact®” treatment. The IFN production by thymocytes of rats with hypoacidity of gastric juice was shown to increase by 2.5±1.2 times in comparison to control (intact animals), the 2′,5′-OAS activity decreased by 28±1.34%. Both the IFN production and enzyme activity were increased comparative to unstimulated cells in response to IFN inducers – phytohemagglutinin A (PHA) (20 µg/ml) and cycloferon (50 µg/ml) treatment in vitro. Administration of “Apibact®” in parallel with omeprazole administration, led to amplification of the PHA action on IFN production and 2′,5′-OAS activity in thymocytes. Probably, the IFN synthesis by thymocytes is stimulated under hypoacidity of gastric juice. It may be a result of activation of immune response to opportunistic microflora colonization of stomach. “Apibact®” exhibit immunomodulatory properties, amplifying the ability of thymocytes to synthesize IFN in response to exoge­nous stimulation in rats with hypoacidity of gastric juice. Keywords: hypoacidity, omeprazol, multiprobiotics, “Apibact®”, thymocytes, 2′,5′-oli­goadenylate synthetase, interferon inducers.

预处理方式对香蒲和芦苇种子萌发的影响

Global changes and human activities have negative effects on the wetland habitats,which decrease the area of wetland,reduce species diversity,and hinder the ecological functions. Wetland restoration,especially dominant plants restoration is critical and urgent to improve wetland conditions and areas worldwide. As the largest tributary of the Heilong River,Songhua River drains nearly 70% of the Northeast China's land area. The riparian wetland along the downstream of Songhua River is suffering from ecological degradation of native vegetation. Typha domingensis(T. domingensis) and Phragmites australis(P. australis) are two dominant species in this basin,and play an important role in sustaining regional environmental functions. Seeds are produced annually,which would allow ample opportunities for colonization by sexual propagation. Seed propagation is considered to be an effective and feasible technique for vegetation restoration. In order to explore the optimal seed-soaking reagents to accelerate seed germination of T. domingensis and P. australis,the pure live seeds of both species were collected from a riparian wetland along the downstream of Songhua River(47°16'39.4.″ N,132°02'44. 2″ E),and the seeds germination experiment was conducted in incubator(LRH-250-GS II,China) with an alternating diurnal regime of 12 h of daylight at 25 ℃ and 12 h of darkness at 15 ℃ in laboratory. Effects of 8 different pretreatments(untreated,soaking with distilled water,soaking with 0.1% H2O2,soaking with 0.1% H2O2and then rinsing with distilled water,soaking with 0.1% KNO3,soaking with 0.1% KNO3and then rinsing with distilled water,soaking with0.1% KMnO4,soaking with 0.1% KMnO4and then rinsing with distilled water,respectively) on germination percentage(GP) and germination speed(GS) of T. domingensis and P. australis seeds are observed for 10 days. For each treatment,100 seeds(four replicates) were placed on a layer of Whatman grade No.1 filter paper(pH 7) in 90 mm Petri dishes with distilled water to keep moist during the whole experiment. Results showed as follows:(1) Differences between untreated seeds and pretreated ones with reagent soaking on GP and GS of T. domingensis and P. australis were significant;(2) GP and GS of T. domingensis under the pretreatment of soaking with 0.1% KMnO4and then rinsing with distilled water were significantly greater than that of the rest pretreatments,and the average GP of T. domingensis was about 3.1 times greater than the untreated and the GS was up to 16. 17 ± 0. 80;(3) Seed germination of P. australis performed best under the treatment of soaking with 0.1% concentration KNO3and rinsing with distilled water,and its GP and GS were up to 96%—99% and 28.43±0.71,respectively. The results indicate that seed pretreatment(seed-soaking reagent) is one of the most indispensable and efficient methods of accelerating the seed germination and seedling growth of T. domingensis and P.australis. Rapid and effective restoration of the two dominant plants in the riverine wetlands along the downstream of Songhua River,therefore,could be expected through collecting their pure live seeds and pretreating the seeds with 0.1%KMnO4and 0.1% KNO3and then rinsing with distilled water respectively before dispersal.

Deciphering the upper Famennian Hangenberg Black Shale depositional environments based on multi-proxy record

Presented for the first time in this paper are the results of a detailed multi-proxy investigation conducted on the Hangenberg Black Shale (HBS) from the Polish part of the Laurussian Shelf, which provide details about the environmental conditions in existence during deposition of the shale and the role played by anoxic conditions in the mass extinction events that occurred at the end of the Devonian times. Inorganic and organic redox indicators indicate that bottom water redox conditions changed periodically from being mainly anoxic/euxinic to oxic or being partially depleted in oxygen. U/Th values above 1.25, Ni/Co values above 7 and V/(V+Ni) values above 0.8 recorded from the lower part of the HBS all point to anoxic/euxinic conditions being present, as do high total organic carbon contents (TOC) above 10% and degree of pyritisation (DOP) values around 0.75%. However, the presence of benthic fauna over the lower part of the HBS attests to opportunistic colonisation of the seafloor during oxic episodes. Evidence for similar episodes has also been recognised over the middle part of the HBS, e.g., U/Th values below 1.25, Ni/Co values below 4, V/(V+Ni) values below 0.8, TOC values of 3% to 5.5% and DOP values of 0.4% to 0.75%, plus the common occurrence of benthic fauna. Anoxic conditions returned during the deposition of the upper part of the HSB, though they were not as well developed as when the lower part of the shale was laid down.Of interest is the presence of small pyrite framboids and isorenieratene biomarkers in all the analysed samples, which suggest that euxinic conditions persisted in the photic zone of the water column. A twenty centimetre thick layer of volcanogenic deposits (tuffites) is present in the middle part of the HBS, the geochemical characteristics of which are typical of ocean floor basalts. The occurrence of volcanogenic material below and within the HBS, together with an absence of calcium carbonate over its upper part, the presence of abundant tetrads just above the black shale and a drastic decrease in faunal frequency in the upper part of the HBS imply that volcanism may have caused oceanic acidification (or hypercapnia) that in turn potentially may have influenced the Hangenberg mass extinction event.

Ichnology and sedimentology of the Triassic carbonates of North‐west Sardinia, Italy

AbstractThe classical Middle to Upper Triassic carbonate sections at Monte Santa Giusta and Punta del Lavatoio, North‐west Sardinia (Italy), referred to the Muschelkalk and Keuper lithofacies group, are revisited and their trace fossil content is investigated for the first time. A combined ichnological and sedimentological study reveals insights into the depositional environments, regional context, palaeogeography and sequence stratigraphy. The results indicate deposition on a homoclinal carbonate ramp with broad facies belts. All recognized trace fossils are also known from time‐equivalent deposits of Germany and thus indicate a close affinity between the North‐west Sardinian Triassic and the Germanic Basin. Only a few trace fossils are particularly abundant and these indicate opportunistic colonization by their producers, which is probably related to restricted endobenthic conditions due to reduced oxygen and/or increased salinity. The trace fossil association can be grouped into a softground suite belonging to the Cruziana ichnofacies, and a firmground suite of the Glossifungites ichnofacies. This discrimination enables an interpretation of the northern Monte Santa Giusta section as a carbonate ramp with extensive tidal flats and abundant carbonate accumulation in a relatively proximal position, whereas the southern Punta del Lavatoio section exhibits broad lagoonal environments with reduced sedimentation in a deeper and more Tethys‐influenced area. The Sardinian sections are ichnologically similar to the Anisian–Ladinian succession known from the Tatra Mountains, but differ from it by having a slightly higher ichnodiversity, which again can be attributed to a less restricted lagoonal environment. This study demonstrates the importance of integrating trace fossil analysis in sedimentological and palaeontological investigations of carbonate systems.

The intermediate disturbance hypothesis and plant invasions: Implications for species richness and management

The intermediate disturbance hypothesis (IDH) predicts a hump-shaped pattern between community diversity and disturbance, and is central to understanding patterns of species diversity. Here, we examine IDH in the context of alien plant invasions. IDH can offer insight into the role of disturbance in facilitating plant invasions and the effect of these invasions on floristic diversity. Early stages of succession are most susceptible to invasion because resources and colonisation opportunities are elevated after disturbance. This trend is accentuated by human-mediated dispersal, a bias towards early successional species in the alien species pool, the tendency for fast-growing species to profit most from enemy release, and increased disturbance levels in human-modified habitats. Human disturbance, coupled with plant introductions, extends the diversity–disturbance curve and shifts peak diversity towards higher disturbance levels. However, invasive aliens can reduce native diversity at the community scale, especially in mid succession where competitive interactions structure communities. Certain invasive plants may have higher impacts because they overcome some life history tradeoffs as a result of their association with humans or novel evolutionary histories, e.g. enemy release. This may directly or indirectly (e.g. through plastic reallocation of resources from defence into growth) enable invasive plants to colonise earlier or persist into later stages of succession. By modifying disturbance regimes, invaders that transform the environment may also interfere with succession and precipitate low diversity communities. Low introduction rates of late successional species may currently limit impacts of aliens under infrequent disturbance. IDH is a useful framework for understanding ecological communities. However, because of the novel evolutionary histories of alien species and the anthropogenic context in which they invade, disturbance levels that maximise total diversity in invaded communities can differ from those that maximise native diversity. Joint consideration of IDH and alien invasion patterns suggests a range of strategies can be used to manage diversity.

Ectomycorrhizal symbiosis of tropical African trees

The diversity, ecology and function of ectomycorrhizal (EM) fungi and ectomycorrhizas (ECMs) on tropical African tree species are reviewed here. While ECMs are the most frequent mycorrhizal type in temperate and boreal forests, they concern an economically and ecologically important minority of plants in African tropical forests. In these African tropical forests, ECMs are found mainly on caesalpionioid legumes, Sarcolaenaceae, Dipterocarpaceae, Asterpeiaceae, Phyllantaceae, Sapotaceae, Papilionoideae, Gnetaceae and Proteaceae, and distributed in open, gallery and rainforests of the Guineo-Congolian basin, Zambezian Miombo woodlands of East and South-Central Africa and Sudanian savannah woodlands of the sub-sahara. Overall, EM status was confirmed in 93 (26%) among 354 tree species belonging to EM genera. In addition, 195 fungal taxa were identified using morphological descriptions and sequencing of the ML5/ML6 fragment of sporocarps and ECMs from West Africa. Analyses of the belowground EM fungal communities mostly based on fungal internal transcribed spacer sequences of ECMs from Continental Africa, Madagascar and the Seychelles also revealed more than 350 putative species of EM fungi belonging mainly to 18 phylogenetic lineages. As in temperate forests, the /russula-lactarius and /tomentella-thelephora lineages dominated EM fungal flora in tropical Africa. A low level of host preference and dominance of multi-host fungal taxa on different African adult tree species and their seedlings were revealed, suggesting a potential for the formation of common ectomycorrhizal networks. Moreover, the EM inoculum potential in terms of types and density of propagules (spores, sclerotia, EM root fragments and fragments of mycelia strands) in the soil allowed opportunistic root colonisation as well as long-term survival in the soil during the dry season. These are important characteristics when choosing an EM fungus for field application. In this respect, Thelephoroid fungal sp. XM002, an efficient and competitive broad host range EM fungus, possessed these characteristics and appeared to be a good candidate for artificial inoculation of Caesalps and Phyllanthaceae seedlings in nurseries. However, further efforts should be made to assess the genetic and functional diversity of African EM fungi as well as the EM status of unstudied plant species and to strengthen the use of efficient and competitive EM fungi to improve production of ecologically and economically important African multipurpose trees in plantations.

ICHNOLOGICAL RECORD OF ENVIRONMENTAL CHANGES IN EARLY QUATERNARY (GELASIAN-CALABRIAN) MARINE DEPOSITS OF THE STIRONE SECTION, NORTHERN ITALY

Nineteen ichnotaxa occur in a 94-m-thick section of Gelasian–Calabrian siliciclastic deposits along the Stirone River. The most common trace fossils are grouped in 17 clusters based on a K-Means Cluster Analysis. This grouping is related to distal, archetypal and proximal Cruziana ichnofacies. Successions of ichnotaxa and clusters as represented in Detrended Correspondence Analyses determine environmental trends that helped establish a sequence stratigraphic scheme, which is not always obvious in the sedimentary record. The depositional sequences are separated by three sequence boundaries (A–C), which are well expressed in the ichnological record. Primary fabrics are less frequent in the archetypal and proximal Cruziana ichnofacies than in their idealized models. This is probably due to less intense storms in the small and protected paleo-Adriatic Sea and to intense bioturbation. Small-scale intervals with low ichnodiversity and ichnofabrics commonly dominated by one trace fossil are present. This suggests stressed conditions and opportunistic colonization related to small, but probably frequent, seafloor disturbances. The record of these disturbances— possibly caused by storm and bottom currents, deposition, or possibly erosion—has been obliterated by subsequent bioturbation. The disappearance of Schaubcylindrichnus, the smaller size of Scolicia and Ophiomorpha, and a slight decrease in trace fossil diversity in the Calabrian part of the section is interpreted to record climate cooling. This is also supported by the general decrease in ichnodiversity in Pleistocene versus Pliocene shallow-marine to slope siliciclastic facies.

Random movement pattern of fed and unfed adult Colorado potato beetles in bare‐ground habitat

Although the successful management of the Colorado potato beetle Leptinotarsa decemlineata (Say) depends on the prevention of its dispersal, its walking pattern in the landscape remains poorly understood. In the present study, post‐diapause, early summer, late summer and colony adult beetles, both fed and unfed before release, were tracked with a harmonic radar to establish their walking movement pattern in a bare‐ground field. The random walk model successfully described the dispersal of all beetle types, whether fed or unfed. The diverse life history of this species was manifested by an increased distance travelled and deviations of individual paths from the random model. Starved post‐diapause beetles travelled furthest and individual paths deviating from random were both local and directed, probably aiming to maximize opportunities for host colonization. Starved early summer beetles also travelled further than fed beetles but relied more on random movement to disperse in the habitat. Starving had little impact on the distance travelled or the path deviations of late summer beetles that are searching for overwintering site rather than hosts. The increased displacement of starving beetles over fed beetles corresponded with an increased walking step and index of straightness. The impact of starvation on travel distance was greater than expected from laboratory tests. In conclusion, the results obtained in the present study suggest a random walking pattern to search arable land until host volatile or visual impulses trigger a more directed walk or flight.

The Role of Abandoned Channels as Refugia for Sustaining Pioneer Riparian Forest Ecosystems

In disturbance-prone ecosystems, organisms often persist in spatial refugia during stressful periods. A clear example is the colonization of abandoned river channels by pioneer riparian trees. Here, we examine the prominence of this establishment pathway for a foundation tree species (Fremont cottonwood, Populus fremontii) within the riparian corridor of a large river, the Sacramento River in central California. We quantified the total proportion of forest that initiated as a result of channel abandonment for a 160-km reach, analyzed concurrent patterns of tree establishment with floodplain accretion and sedimentation history, and developed a conceptual model of biogeomorphic evolution of abandoned channels. Historical air photo analysis indicated that stands associated with abandoned channels comprised more than 50% of the total extant cottonwood forest area. Tree-ring evidence showed that cottonwood stands commonly developed immediately following abandonment, and the recruitment window ranged from 4 to 40 years, but was less than 10 years at most sites. Rates of floodplain rise and fine sediment accumulation were high in young sites and decreased logarithmically over time. Together, these results suggest that abandoned channels are an important refuge for cottonwood recruitment, that the greatest opportunity for colonization occurs within a short period after the cutoff event, and that sedimentation processes influence the duration of the colonization window. On rivers where tree recruitment along the active channel is severely limited by hydrologic regulation and/or land management, abandoned channel refugia may play an even more important role in sustaining an ecologically functional riparian corridor. Preserving bank erosion, active meander corridors and forest regeneration zones created by cutoff events are therefore key conservation measures on shifting rivers.

MtDNA markers reveal the existence of allopatric evolutionary lineages in the threatened lampreys Lampetra fluviatilis (L.) and Lampetra planeri (Bloch) in the Iberian glacial refugium

The Iberian Peninsula has been identified as an important glacial refugium during the Pliocene and Pleistocene epochs for the genus Lampetra, providing intermittent refuge and postglacial opportunities for colonization and expansion. We used mitochondrial DNA markers to investigate the processes that have shaped present-day genetic constitution of the genus Lampetra within the Iberian Peninsula. We surveyed 1,173 bp of the cytochrome b gene and 829 bp of the genes ATPase subunits 6 and 8 in 233 individuals of Lampetra fluviatilis (L.) and Lampetra planeri (Bloch) from 21 localities along their distribution range in the Iberian Peninsula. We identified four highly divergent allopatric evolutionary lineages that evolved by fragmentation during the Pliocene and Pleistocene likely driven by environmental factors, namely regional geomorphic events. The high level of genetic divergence between the four lineages suggests that sufficient time has apparently passed by to originate a complex of incipient or cryptic resident species and allows the definition of four evolutionary significant units (ESUs) for L. planeri and one ESU for L. fluviatilis. These findings have important consequences for the interpretation of refugia biological diversity and have major implications on the conservation of these threatened species.