Peanut (Arachis hypogaea L.) and maize (Zea mays L.) are essential crops for Ghana’s economy and food security, but weed infestation poses a significant threat to their cultivation. Crop rotations influence weed communities, but little is known about these processes in peanut-cropping systems in West Africa. This study investigated the impact of different crop rotations and input levels on weed communities in Ghana over 3 yr. Results showed that low inputs (absence of herbicide and fertilization) favored species richness, while higher input levels (weed control with herbicides and fertilizer use) reduced it. Diversity and evenness were also affected by inputs, with varying patterns across locations and seasons. Weed population growth rates (λ) varied significantly by location and treatment; all management programs resulted in increasing weed populations. Principal component analysis revealed distinct associations between weed species and crop management. The majority of weed species exhibited a generalist behavior and did not associate with a particular management. However, billygoat weed (Ageratum conyzoides L.) and Benghal dayflower (Commelina benghalensis L.) were positively associated with high-input systems, while purple nutsedge (Cyperus rotundus L.) exhibited strong associations with low and medium inputs. The weed–crop rotation dynamics described here demonstrate how management drives the selection of weed species that are more pervasive and interfere with important food crops in Ghanaian agriculture.

A comparative analysis of taxonomic diversity on shrew cestodes among four islands in the Sea of Japan and the Sea of Okhotsk (Sakhalin, Kunashir, Hokkaido, and Moneron) was performed. Cestode species shared among the islands were identified and their host specificity was investigated. On Sakhalin Island, 33 species of the families Hymenolepididae, Dilepididae and Mesocestoididae were recorded in four shrew species (Sorex caecutiens, S. gracillimus, S. minutissimus and S. unguiculatus). In S. caecutiens, S. gracillimus, and S. unguiculatus on Kunashir Island, 22 species of the same families were found and, on Hokkaido Island, 23 species of the families Hymenolepididae and Dilepididae were recorded. On Moneron Island, three species of cestodes were registered in S. tundrensis. The Sakhalin–Hokkaido–Kunashir complex of shrew cestodes includes eastern-Palearctic, trans-Palearctic and endemic species. High endemism (~22%) of shrew tapeworms in the Sakhalin–Kunashir–Hokkaido Islands was noted as compared to continental territories. The different numbers of cestode species in S. unguiculatus (31), S. caecutiens (29), S. gracillimus (19) and S. minutissimus (1) were found. It was concluded that the cestodes species diversity of shrews of Sakhalin–Kunashir–Hokkaido depended primarily on the history of island formation, their modern physical and geographical features, the abundance of definitive and intermediate cestodes hosts and, to a lesser extent, on the size and remoteness of the islands from the mainland and the diversity of host species.

The Caatinga is the largest seasonal tropical dry forest with extreme environmental and meteorological conditions. It harbours many phytophysiognomies and vegetational units, but bat fauna is poorly known in many regions. We analysed the structure of bat assemblages by mist-netting during 99 nights in seven habitats throughout six sites in the northeasternmost region of the Caatinga in Rio Grande do Norte State, in the Brazilian northeast. With a sampling effort of 239 665 m2h, we captured 1575 individuals of 31 species of bats. Bat assemblages’ structure and species distribution changed according to the habitat type, and differences in richness, abundance, species composition, and trophic guild representation were found. The frugivore A. planirostris was widespread, and its superabundance hold for all habitats. The distinct array of the most abundant species with several exclusive species in each habitat suggests species- and trophic guild-specific preferences to particular habitats. Differences in the structure of bat assemblages may be driven by each habitat’s vegetational structure and plant composition (e.g., semi-open habitats vs. tall forest stands) that offers distinct exploitable resources (e.g., food and roosts). Finally, we discuss the importance of foraging habitats for the conservation of these unique bat assemblages in the northeasternmost region of the Caatinga dry forest.

Across many countries, increases in inequality driven by rising top incomes and wealth have not been accompanied by growing popular concern. In fact, citizens in unequal societies are less concerned than those in more egalitarian societies. Understanding how the general public perceive richness is an essential step towards resolving this paradox. We discuss findings from focus group research in London, UK, a profoundly and visibly unequal city, which sought to explore public perceptions of richness and the rich. Participants from diverse socio-economic backgrounds discussed their views of the ‘wealthy’ and the ‘super rich’ with reference to both vast economic resources and more intangible aspects, including, crucially, security. High levels of wealth and income were perceived to be necessary for achieving security for oneself and one’s family. The security of the rich was discussed in contrast to participants’ own and others’ insecurity in the context of a (neo)liberal welfare regime – specifically, insecurity about housing, personal finances, social security, health care and the future of the welfare state. In unequal countries, where insecurity is widespread, lack of confidence in collective welfare state provision may serve in the public imagination to legitimate private wealth accumulation and richness as a form of self-protection.

Marine protected areas (MPAs) have been demonstrated to positively affect various aspects of their ecosystems and communities. In the present study, the effectiveness of varying protection levels on the coastal fish populations within a multiple-use marine park in Greece was assessed through community-level metrics using a non-destructive underwater recording method (underwater drone/mini remotely operated vehicle). Two factors were examined, i.e. protection level (fully, partially and least protected area) and time period (early and late summer: beginning and towards the end of the fishing and touristic season). Our study demonstrated some first results that protection benefited both the commercial species and the entire fish community as a whole, in terms of diversity, abundance and richness, while non-commercial species did not differ among the studied protection levels. This finding, along with the fact that the prevailing conditions (water temperature, depth, habitat type) were similar in all three studied areas, that corresponded to different protection levels, and in both sampling periods, indicated that the observed results may be attributed to the varying protection levels. The studied fish communities did not seem to be affected by the more intense fishing and touristic period over the summer. In conclusion, protection from fishing seems to positively affect the studied coastal fish community as a whole and particularly the commercially important species that find a refuge within core areas of the Alonissos marine park.

Although it is generally known that a combination of abiotic and biotic drivers shapes the distribution and abundance of parasites, our understanding of the interplay of these factors remains to be assessed for most marine host species. The present field survey investigated spatial patterns of richness, prevalence and abundance of parasites in Mytilus galloprovincialis along the coast of the northern Adriatic Sea. Herein, the relationships between biotic (host size, density and local parasite richness of mussel population) and abiotic (eutrophication and salinity) drivers and parasite richness of mussel individuals, prevalence and abundance were analysed. Local parasite richness was the most relevant factor driving parasite species richness in mussel individuals. Prevalence was mainly driven by eutrophication levels in three out of four parasite species analysed. Similarly, abundance was driven mainly by eutrophication in two parasite species. Mussel size, density and salinity had only minor contributions to the best fitting models. This study highlights that the influence of abiotic and biotic drivers on parasite infections in mussels can be differentially conveyed, depending on the infection measure applied, i.e. parasite richness, prevalence or abundance. Furthermore, it stresses the importance of eutrophication as a major factor influencing parasite prevalence and abundance in mussels in the Adriatic Sea.

The Upper Gunnison Basin (UGB), Colorado, is a montane region characterized by unusual physiography and topographic isolation. Excavations of three caves in the UGB provide one of the most diverse records of high-elevation late Quaternary vertebrates in North America. The localities, Haystack Cave (2450 m above sea level [m asl]), Cement Creek Cave (2860 m asl), and Signature Cave (3055 m asl), together provide a near-continuous record of vertebrate communities that extends from before the last glacial maximum to the present. These communities largely represent a sagebrush (Artemisia spp.) steppe-tundra environment that prevailed throughout the UGB in the late Pleistocene. At least five taxa of extinct large mammals disappear from the UGB by the Early Holocene; one small mammal (the short-faced skunk Brachyprotoma cf. B. brevimala) also became extinct. The fossil record further indicates that only four small extant mammals (Sorex preblei, Dicrostonyx sp., Lemmiscus curtatus, and Urocitellus elegans) were extirpated from the UGB by the Early Holocene, in part because of community restructuring and loss of open habitats with expansion of forests to higher elevations. An analysis of taxonomic richness and evenness at Cement Creek Cave indicates high resilience in the small mammal community despite major climate shifts over the past 40,000+ yr.

Seasonality is an important aspect associated with population dynamic and structure of tropical insect assemblages. This study evaluated the effects of seasonality on abundance, richness, diversity and composition of an insect group, drosophilids, including species native to the Neotropical region and exotic ones. Three preserved fragments of the northern Atlantic Forest were surveyed, where temperatures are above 20 °C throughout the year and rainfall regimes define two seasons (dry and rainy). As opposed to other studies about arthropods in tropical regions, we observed that abundance of drosophilids was significantly higher in the dry season, possibly due to biological aspects and the colonization strategy adopted by the exotic species in these environments. Contrarily to abundance, we did not observe a seasonal pattern for richness. As for other parts of the Atlantic Forest, the most representative Neotropical species (Drosophila willistoni, D. sturtevanti, D. paulistorum and D. prosaltans) were significantly more abundant in the rainy season. Among the most abundant exotic species, D. malerkotliana, Zaprionus indianus and Scaptodrosophila latifasciaeformis were more importantly represented the dry season, while D. simulans was more abundant in the rainy period. The seasonality patterns exhibited by the most abundant species were compared to findings published in other studies. Our results indicate that exotic species were significantly more abundant in the dry season, while native ones exhibited an opposite pattern.

Characterizing the long-term effect of agricultural management systems on weed communities will aid in developing sustainable weed management practices. Weed seedbanks and aboveground biomass were measured within a corn–soybean–wheat crop sequence from 1990 through 2002 at Hickory Corners, MI. Four management systems were compared: conventional (CONV; full rates of N fertilizer and herbicides, moldboard tillage), no till (NT; same as CONV with no primary tillage), reduced input (RI; reduced rates of N fertilizer and herbicides, moldboard tillage, mechanical weed control, wheat underseeded with red clover), and organic (ORG; same as RI but no synthetic inputs). Multivariate ordinations of weed seedbanks showed a divergence of the CONV and NT systems from the RI and ORG systems. The CONV and NT seedbanks were dominated by grass species (mainly fall panicum and large crabgrass), whereas the RI and ORG systems were dominated by common lambsquarters and common chickweed. Within a single growing season, weed seedbanks in the RI and ORG systems were positively correlated with weed biomass whereas seedbanks in the CONV and NT system had little predictive value. Weed biomass from 1990 through 2002 showed a strong association of grass weed species with the corn phase of the CONV and NT system and common lambsquarters and redroot pigweed with the corn and soybean phases of the RI and ORG systems. Weed biomass diversity measures were negatively correlated with soybean yields in RI and ORG and wheat yields in NT, RI, and ORG. It is not clear whether crops were less competitive in the NT, RI, and ORG treatments, allowing new weed species to enter the plots, or whether less effective weed management in the NT, RI, and ORG treatments resulted in increased species richness, causing reduced crop yields. Mechanistic studies are needed to elucidate the relationship between weed community diversity and crop performance.

The expansion of populations of invasive species continues to compromise the ecological and economic integrity of our natural resources. The negative effects of invasive species on native biota are widely reported. However, less is known about how the duration (i.e., age of oldest invaders) and intensity (i.e., density and percent cover) of an invasion influences native plant diversity and abundance at the microsite scale. We examined the influence of density, percent cover, and age of Amur honeysuckle (a nonnative invasive shrub), and several environmental factors on native plant taxa at 12 mixed hardwood forests in Indiana, USA. Overall, study sites with the greatest taxonomic diversity (Shannon's Diversity; H′), richness (S), percent cover, and density of native vegetation also had the lowest percent cover of Amur honeysuckle in the upper vertical stratum (1.01 to 5 m). Based on linear mixed model analyses, percent cover of Amur honeysuckle in the upper vertical stratum was consistently and negatively correlated with H′, S, total percent cover, and woody seedling density of native taxa at the microsite scale (P < 0.05). Duration of Amur honeysuckle at the microsite scale was not significant when percent cover of Amur honeysuckle in the upper vertical stratum was included in models. However, duration of Amur honeysuckle invasion was significantly correlated with dependent variables and with upper-stratum honeysuckle cover, suggesting that older Amur honeysuckle in a microsite resulted in greater light competition from above for native understory plant species. Beyond increased cover and shading, our results do not provide evidence of duration-related effects from long-term dominance of honeysuckle in our sampled mixed hardwood forest sites.

Dominant woody species can determine the structure and composition of a plant community by affecting environmental conditions experienced by other species. We explored how dominant tree species affect the tree species richness, diversity, evenness and vertical structural heterogeneity of non-dominant species in wet and dry miombo woodlands of Tanzania. We sampled 146 plots from eight districts with miombo woodlands, covering a wide range of topographic and climatic conditions. We recorded 217 woody plant species belonging to 48 families and 122 genera. Regression analysis showed significant negative linear associations between tree species richness, relative species profile index of the non-dominant and the relative abundance of the dominant tree species (Brachystegia spiciformis and Brachystegia microphylla in wet, and Brachystegia spiciformis and Julbernardia globiflora in dry miombo woodlands). Shannon diversity and evenness had strong non-linear negative relationships with relative abundance of dominant tree species. A large number of small individual stems from dominant and non-dominant tree species suggesting good regeneration conditions, and intensive competition affecting survival. We suggest that dominant miombo tree species are suppressing the non-dominant miombo tree species, especially in areas with high recruitments, perhaps because of their important adaptive features (extensive root systems and ectomycorrhizal associations), which enhance their ability to access limited nutrients.

Cross-species infection among humans, chimpanzees (Pan troglodytes) and baboons (Papio spp.) is potentially a significant public health issue in Africa, and of concern in the conservation of P. troglodytes. However, to date, no statistical comparisons have been made between the prevalence, richness and composition of parasite communities in sympatric populations of baboons and P. troglodytes. We compared parasite communities in sympatric P. troglodytes and Papio papio living in a wilderness site, in the Republic of Senegal, West Africa. We asked whether, in the absence of humans, there are significant differences between these hosts in their interactions with gastrointestinal parasites. We tested whether host, location, or time of collection accounted for variation in prevalence, richness and community composition, and compared prevalence across six studies. We concluded that, despite being closely related, there are significant differences between these two hosts with respect to their parasite communities. At our study site, prevalence of Balantidium, Trichuris and Watsonius was higher in P. papio. Papio papio harboured more parasites per host, and we found evidence of a positive association between Trichuris and Balantidium in P. troglodytes but not P. papio.

This study aimed at describing the quantitative variations of epiphytic diatoms in Rhodophyta Galaxaura rugosa, collected in the Fernando de Noronha archipelago (north-eastern Brazil), during two annual periods (June 2006 and June 2007). The distribution of epiphytic diatoms in G. rugosa confirmed the occurrence of a quantitative variation/zoning along the thallus of the analysed host, with an increase in density (cells per gram wet weight of seaweed) of apical portions towards the basal parts of the seaweed, regardless of the collection points and the annual periods. The abundance was characterized by individuals with pennate symmetry with raphe, belonging to the Bacillariophyceae class. This fact is the result of the host being collected in an insular environment with great water movement under the direct action of trade winds and ocean currents for most of the year. The study confirmed that in marine ecosystems with strong hydrodynamics, epiphytic flora tends to comprise species with the largest adhesive strength.

The influence of the sediment grain size and the trophic status of the reservoirs on the composition, richness and biomass of Oligochaeta community was tested. Samples were taken from the littoral and profundal zones of 30 neotropical reservoirs from six different watersheds during two hydrological periods (dry and rainy seasons). The sample units were ordinated, with principal component analyses, according to differences in the sediment grain size, sample depth and dissolved oxygen. The results of a multiple response permutation procedure (MRPP) analysis revealed significant differences in species composition between littoral and profundal zones, trophic status (oligotrophic, mesotrophic and eutrophic) and different watersheds. The environment–species relationship was tested using redundancy analyses. In order to test which environmental variables, either granulometric or limnological, influenced the Oligochaeta community variability we used a partitioning procedure of inertia. Local variations, including reservoir zone and trophic status, were primarily influenced by differences in sediment type and depth. Significant differences in the total biomass between zones, trophic status, watershed and hydrological period were also demonstrated by a Kruskal–Wallis or Mann–Whitney test. The most prevalent taxa were the cosmopolitan tubificids Bothrioneurum sp. and Branchiura sowerbyi, and the naidids Dero (Dero) digitata and Pristina breviseta, which are dependent on periphyton for food. Higher biomass values were recorded in mesotrophic reservoirs, due to increased nutrient availability and adequate dissolved oxygen supply. Our results indicate that the Oligochaete community structure is directly influenced by local environmental variation in neotropical reservoirs; and that the sediment grain size is the most important factor in determining the Oligochaete community structure.

Fish assemblages inhabiting the mountain streams of the Guiana shield have scarcely been studied. Here we investigated fish assemblages in eight headwater mountain streams of the Mount Itoupé (French Guiana), and tested how local freshwater fish assemblages are shaped by environmental characteristics. We show that Mount Itoupé streams host uneven species assemblages, characterized by low species richness (less than ten species per site) and a high proportion of small Siluriform species. Differences in fish assemblage composition between the sites were mainly due to basin identity, but regional climate and position of the site in the river gradient also had a significant effect, although of lower magnitude. In contrast, local habitat hardly affected fish richness, abundances or assemblage composition. Species richness increased along the upstream–downstream gradient, whereas fish abundance depended mainly on the slope orientation of Mount Itoupé. Although these results need confirmation on a larger amount of sampling sites, located on other Guianese mountains, this preliminary study shows that the mountain streams of the Guiana Shield, although rarely investigated, host not only uneven species assemblages, but also present an original combination of environmental determinants shaping fish assemblage structure. Those rare and original ecosystems hence deserve more attention and should be preserved from human disturbances.

Cropping systems that rely on renewable energy and resources and are based on ecological principles could be more stable and productive into the future than current monoculture systems with serious unintended environmental consequences such as soil erosion and water pollution. In nonagricultural systems, communities with higher species diversity have higher productivity and provide other ecosystem services. However, communities of well-adapted crop species selected for biomass production may respond differently to increasing diversity. Diversity effects may be due to complementarity among species (complementary resource use and facilitative interactions) or positive selection effects (e.g., species with higher productivity dominate the mixture), and these effects may change over time or across environments. Our goal was to identify the ecological mechanisms causing diversity effects in a biodiversity experiment using agriculturally relevant species, and evaluate the implications for the design of sustainable cropping systems. We seeded seven perennial forage species in a replicated field experiment at two locations in Iowa, USA, and evaluated biomass productivity of monocultures and two- to six-species mixtures over 3 years after the establishment year under management systems of contrasting intensity: one or three harvests per year. Productivity increased with seeded species richness in all environments, and the positive relationship did not change over time. Polyculture overyielding was due to complementarity among species in the community rather than to selection effects of individual species. Complementarity increased as a log-linear function of species richness in all environments, and this trend was consistent across years. Legume–grass facilitation may explain much of this complementarity effect. Although individual species with high biomass production had a major effect on productivity of mixtures, the species producing the highest biomass in monoculture changed over the years in most environments. Furthermore, transgressive overyielding was observed and was more prevalent in later years, in some environments. We conclude that choosing a single well-adapted species for maximizing productivity may not be the best alternative over the long term and that high levels of species diversity should be included in the design of productive and ecologically sound agricultural systems.

The extent to which host biology, ecology and phylogeny determine the diversity of macroparasite assemblages has been investigated in recent years in several taxa, including fish. However, consensus has not been reached probably as a result of data being collected from different sources, different temporal scales or host and parasite biogeography and phylogeny having greater influence than expected. The present study evaluates the relative importance of 27 biological, ecological and phylogenetic characteristics of 14 flatfish species on the diversity of their ecto- and endoparasite assemblages, comprising a total of 53 taxa. Redundancy analyses were applied to the mean abundance of each parasite taxa infecting each host and to the richness, taxonomic distinctness and variance in taxonomic distinctness calculated for each assemblage within each host. Only a few host characteristics contributed significantly to the observed patterns: host distribution was more important in determining the type and mean abundance of ectoparasites present in an assemblage, whereas diversity of these assemblages were mainly related to the host's maximum size. Endoparasite mean abundance and diversity were mostly influenced by the number of food items ingested and by the presence of Crustacea and Polychaeta in the diet. However, the sympatric occurrence of related hosts also played an important role in the diversity values found in macroparasite assemblages. Results showed that a host characteristic has different importance according to the host-parasite relationship being examined, suggesting an important role for host-parasite co-evolution on the diversity of extant macroparasite assemblages.

Complete inventories of the fauna at a given place, for a specific community or geographical area are often exceedingly hard to get. In recent years a number of estimation techniques have emerged that can be used to extrapolate from these samples to the true number of species in an area. These estimation models are based on different mathematical approaches and can be classified as either species accumulation curves or nonparametric estimators (Brose et al., 2003, Ecology, 84, 2364–2377). In this paper, we have tested the performance of some of the richness estimators on nineteen mountain ponds in Castilla y León (Spain) in order to provide guidance on their potential use in future researches. We collected benthic macroinvertebrate of these ponds from the littoral zone with a pond net by kicking and sweeping. Ten-second samples were collected in each pond up to a total time of 3 to 5 minutes per pond, depending on the pond size. In addition, two of the ponds, were sampled in 2004, 2006 and 2007 providing a three-year time series. The results of this study showed that Jackknife 2 was the best of the evaluated methods based on all chosen criteria and also performed well across all studied ponds. Jackknife 1, Chao 1 and Chao 2 also presented good results and they were inferior to Jackknife 2 mainly because of the requirement for larger sub-sample sizes.

The abundance of epiphytes has been assumed to be important in explaining the high diversity of tropical canopy arthropods. In this study we assessed the possible role that the presence of epiphytes may have on the diversity and abundance of canopy insects in an experimental study conducted in a coffee plantation in Coatepec, Veracruz, Mexico. Epiphytes were removed from trees in one of two plots in two sites of the coffee plantation. In each plot we collected insects from three Inga jinicuil trees by knockdown insecticide fogging. Insects were sorted to morphospecies, counted and measured. Trees with epiphytes had significantly higher numbers of species and individuals and insects larger than 5 mm were also more species-rich and abundant in trees with epiphytes. The magnitude of the enhancement was surprisingly large with the epiphyte plot samples having on average 90% more individuals and 22% more species than plots without epiphytes. These differences were even greater for large (>5 mm) insects (184% and 113% respectively). Our results support the tenet that epiphytes provide valuable resources to arthropods, which we have illustrated for canopy insects in shade trees of coffee plantations.