Contrasting Responses to Harvesting and Environmental Drivers of Fast and Slow Life History Species

According to their main life history traits, organisms can be arranged in a continuum from fast (species with small body size, short lifespan and high fecundity) to slow (species with opposite characteristics). Life history determines the responses of organisms to natural and anthropogenic factors, as slow species are expected to be more sensitive than fast species to perturbations. Owing to their contrasting traits, cephalopods and elasmobranchs are typical examples of fast and slow strategies, respectively. We investigated the responses of these two contrasting strategies to fishing exploitation and environmental conditions (temperature, productivity and depth) using generalized additive models. Our results confirmed the foreseen contrasting responses of cephalopods and elasmobranchs to natural (environment) and anthropogenic (harvesting) influences. Even though a priori foreseen, we did expect neither the clear-cut differential responses between groups nor the homogeneous sensitivity to the same factors within the two taxonomic groups. Apart from depth, which affected both groups equally, cephalopods and elasmobranchs were exclusively affected by environmental conditions and fishing exploitation, respectively. Owing to its short, annual cycle, cephalopods do not have overlapping generations and consequently lack the buffering effects conferred by different age classes observed in multi-aged species such as elasmobranchs. We suggest that cephalopods are sensitive to short-term perturbations, such as seasonal environmental changes, because they lack this buffering effect but they are in turn not influenced by continuous, long-term moderate disturbances such as fishing because of its high population growth and turnover. The contrary would apply to elasmobranchs, whose multi-aged population structure would buffer the seasonal environmental effects, but they would display strong responses to uninterrupted harvesting due to its low population resilience. Besides providing empirical evidence to the theoretically predicted contrasting responses of cephalopods and elasmobranchs to disturbances, our results are useful for the sustainable exploitation of these resources.     

Contrasting Responses of Soil Microbial and Nematode Communities to Warming and Plant Functional Group Removal Across a Post-fire Boreal Forest Successional Gradient

Global warming is causing increases in surface temperatures and has the potential to influence the structure of soil microbial and faunal communities. However, little is known about how warming interacts with other ecosystem drivers, such as plant functional groups or changes associated with succession, to affect the soil community and thereby alter ecosystem functioning. We investigated how experimental warming and the removal of plant functional groups along a post-fire boreal forest successional gradient impacted soil microbial and nematode communities. Our results showed that warming altered soil microbial communities and favored bacterial-based microbial communities, but these effects were mediated by mosses and shrubs, and often varied with successional stage. Meanwhile, the nematode community was generally unaffected by warming and was positively affected by the presence of mosses and shrubs, with these effects mostly independent of successional stage. These results highlight that different groups of soil organisms may respond dissimilarly to interactions between warming and changes to plant functional groups, with likely consequences for ecosystem functioning that may vary with successional stage. Due to the ubiquitous presence of shrubs and mosses in boreal forests, the effects observed in this study are likely to be significant over a large proportion of the terrestrial land surface. Our results demonstrate that it is crucial to consider interactive effects between warming, plant functional groups, and successional stage when predicting soil community responses to global climate change in forested ecosystems.     

Contrasting Phylogenetic and Diversity Patterns in Octodontoid Rodents and a New Definition of the Family Abrocomidae

Octodontoidea is the most species-rich clade among hystricomorph rodents. Based on a combined parsimony analysis of morphological and molecular data of extinct and extant species, we analyze the history of South American octodontoids and propose ages of divergence older than interpreted so far. Early Abrocomidae are recognized for the first time, and a new definition of the family is provided. Traditionally accepted fossil-based times of origin for the southern clades are reinterpreted as later stages of differentiation markedly uncoupled from the origin, differentiation implying specializations for open environments as shown in a morphospace of skull variation. Origin of crown groups is also strongly uncoupled from origin of clades as a consequence of extinction of deep lineages. In the resulting diversity pattern of modern southern clades of octodontoids, the combination of greater disparity, less content of evolutionary history, and lower taxonomic diversity, compared to their northern counterparts, appears at first counterintuitive. We propose that primary components of diversity derived from evolutionary transformation or anagenesis, on the one hand, and from cladogenesis and extinction, on the other, should not be considered associated, or at least not necessarily. Certain patterns of relationships between these distinct components could be driven by environmental dynamics. Like environments, octodontoid diversity would have been more stable in northern South America, whereas in the south, both strong adaptive change and extinction would have been triggered by emerging derived environments.     

Amphibian Species Contribute Similarly to Taxonomic,but not Functional and Phylogenetic Diversity: Inferences from Amphibian Biodiversity on Emei Mountain

Understanding the relationships between species,communities,and biodiversity are important challenges in conservation ecology.Current biodiversity conservation activities usually focus on species that are rare,endemic,distinctive,or at risk of extinction.However,empirical studies of whether such species contribute more to aspects of biodiversity than common species are still relatively rare.The aim of the present study was to assess the contribution of individual amphibian species to different facets of biodiversity,and to test whether species of conservation interest contribute more to taxonomic,functional,and phylogenetic diversity than do species without special conservation status.To answer these questions,19 000 simulated random communities with a gradient of species richness were created by shuffling the regional pool of species inhabiting Emei Mountain.Differences of diversity values were then computed before and after removing individual species in these random communities.Our results indicated that although individual species contributed similarly to taxonomic diversity,their contribution to functional and phylogenetic diversity was more idiosyncratic.This was primarily driven by the diverse functional attributes of species and the differences in phylogenetic relationships among species.Additionally,species of conservation interest did not show a significantly higher contribution to any facet of biodiversity.Our results support the claims that the usefulness of metrics based only on species richness is limited.Instead,assemblages that include species with functional and phylogenetic diversity should be protected to maintain biodiversity.     

On the Diversity of the Laccase Gene: A Phylogenetic Perspective from Botryosphaeria rhodina (Ascomycota: Fungi) and Other Related Taxa

The present study is the first describing the sequencing of a fragment of the copper-oxidase domain of a laccase gene in the family Botryosphaeriaceae. The aim of this work was to assess the degree of genetic and evolutionary relationships of a laccase gene from Botryosphaeria rhodina MAMB-05 with other ascomycete and basidiomycete laccase genes. The 193-amino acid sequences of the copper-oxidase domain from several different fungi, insects, a plant, and a bacterial species were retrieved from GenBank and aligned. Phylogenetic analyses were performed using neighbor-joining, maximum parsimony, and Bayesian inference methods. The organisms studied clustered into five gene clades: fungi (ascomycetes and basidiomycetes), insects, plants, and bacteria. Also, the topologies showed that fungal laccases of the ascomycetes and basidiomycetes are clearly separated into two distinct clusters. This evidence indicated that B. rhodina MAMB-05 and other closely related ascomycetes are a new biological resource given the biotechnological potential of their laccase genes.     

High Plant Diversity of Grasslands in a Landscape Context: A Comparison of Contrasting Regions in Central Europe

Some regions and habitats harbour high numbers of plant species at a fine scale. A remarkable example is the grasslands of the White Carpathian Mountains (Czech Republic), which holds world records in local species richness; however, the causes are still poorly understood. To explore the landscape context of this phenomenon and its relationships to diversity patterns at larger scales, we compared diversity patterns in grasslands and other vegetation types in the White Carpathians with those in nearby regions lacking extremely species-rich grasslands, using data from vegetation plots and flora grid mapping of entire landscapes. Although small-scale species richness of grasslands and ruderal/weed vegetation of the White Carpathians was higher than in the nearby regions, the number of grassland and ruderal/weed species in the regional flora of the White Carpathians was not. Diversity of forests was not higher in this region at any scale. Thus the remarkably high local species richness of the White Carpathian grasslands does not result from a larger grassland species pool in the region, but from the fine-scale co-occurrence of many grassland species in this landscape, which results in the formation of grassland communities that are locally rich but with similar species composition when comparing different sites (i.e. high alpha but low beta diversity). This pattern can be partly attributed to the large total area of these grasslands, which reduces random extinctions of rare species, low geological diversity, which enables many species to occur at many sites across the landscape, and high land-cover diversity, which supports mixing of species from different vegetation types.     

Plant invasions in arid areas: special problems and solutions: a South African perspective

Management of invasive alien plants in arid areas is complicated by the cryptic and stochastic nature of the invasion process, the low density of researchers, extension officers and farmers in these areas, the complex, delayed and sometimes, indirect, effects of alien invasive plants on these ecosystems, and by high and shifting values placed on goods and services derived from invasive alien plant species. Fluctuating vegetation cover together with convergent adaptations for dispersal and facilitation enables some desert aliens to invade intact vegetation. Invasive plants in arid areas are not all arid-adapted: the most problematic species globally are phreatic, wetland or oasis specialists that can colonise remote wetlands and springs through a combination of wind-dispersed seeds and vegetative reproduction. Their success is often linked to disturbance and facilitated by agricultural activities including water extraction, cropping and livestock management. Invasive alien plants in arid region wetlands have an impact on forage, water resources and biodiversity in these key resource areas, that is disproportionately great relative to the area they occupy. Management of arid region aliens could include pre-introduction biocontrol planning that makes it possible to use aliens while reducing invasion risks. An alternative is to replace the aliens with extralimital indigenous plants that can supply the rangeland services perceived to be absent from arid environments—but such interventions may carry even greater risks.     

Forest Management and Plant Species Diversity in Chestnut Stands of Three Mediterranean Areas

Over many centuries, chestnut fruits had an important role as food, while chestnut wood was used for local purposes. Today sweet chestnut stands are very common around the western Mediterranean Basin, and it is necessary to analyze the dynamic of plant species diversity in different chestnut stand types (groves and coppices) to guide management strategies that will allow the conservation of biodiversity. Our objective was to analyze consequences on plant species diversity of various management strategies in chestnut stands of three Mediterranean areas, Salamanca (Spain), the Cévennes (France), and Etna volcano (Italy). We found that plant species diversity is different according to management types; it is higher in groves than in coppice stands. We also demonstrated that Castanea sativa cultivated groves were characterized by small heliophillous therophytes. C. sativa abandoned groves, mixed C. sativa–Quercus pyrenaica coppice stands, Q. pyrenaica coppice stands, and young C. sativa coppice stands were characterized by hemicryptophytes with anemochorous dispersal mode and chamaephytes. Medium and old C. sativa coppice stands (that differ by the shoot age) were characterized by phanerophytes with zoochorous dispersal mode. Human perturbations maintain a quite high level of species diversity. In contrast, the abandonment of chestnut stands leads to homogeneous vegetation with decreasing diversity. One solution could be to maintain a landscape mosaic constituted of diverse chestnut stands modified by human activities (groves, cultivated or abandoned, and coppice stands). This could enhance regional plant diversity.     

Ecological Diversity in South American Mammals: Their Geographical Distribution Shows Variable Associations with Phylogenetic Diversity and Does Not Follow the Latitudinal Richness Gradient

The extent to which the latitudinal gradient in species richness may be paralleled by a similar gradient of increasing functional or phylogenetic diversity is a matter of controversy. We evaluated whether taxonomic richness (TR) is informative in terms of ecological diversity (ED, an approximation to functional diversity) and phylogenetic diversity (AvPD) using data on 531 mammal species representing South American old autochthonous (marsupials, xenarthrans), mid-Cenozoic immigrants (hystricognaths, primates) and newcomers (carnivorans, artiodactyls). If closely related species are ecologically more similar than distantly related species, AvPD will be a strong predictor of ED; however, lower ED than predicted from AvPD may be due to species retaining most of their ancestral characters, suggesting niche conservatism. This pattern could occur in tropical rainforests for taxa of tropical affinity (old autochthonous and mid-Cenozoic immigrants) and in open and arid habitats for newcomers. In contrast, higher ED than expected from AvPD could occur, possibly in association with niche evolution, in arid and open habitats for taxa of tropical affinity and in forested habitats for newcomers. We found that TR was a poor predictor of ED and AvPD. After controlling for TR, there was considerable variability in the extent to which AvPD accounted for ED. Taxa of tropical affinity did not support the prediction of ED deficit within tropical rainforests, rather, they showed a mosaic of regions with an excess of ED interspersed with zones of ED deficit within the tropics; newcomers showed ED deficit in arid and open regions. Some taxa of tropical affinity showed excess of ED in tropical desert areas (hystricognaths) or temperate semideserts (xenarthrans); newcomers showed excess of ED at cold-temperate latitudes in the Northern Hemisphere. This result suggests that extreme climatic conditions at both temperate and tropical latitudes may have promoted niche evolution in mammals.     

Plant community response to loss of large herbivores: comparing consequences in a South African and a North American grassland

Loss of biodiversity poses one of the greatest threats to natural ecosystems throughout the world. However, a comprehensive understanding of the impacts of species losses from upper trophic levels is still emerging. Here we compare the impacts of large mammalian herbivore species loss on grassland plant community structure and composition in a South African and North American grassland. Herbaceous plant communities were surveyed at sites without large mammalian herbivores present and at sites with a single species of herbivore present in both locations, and additionally at one site in South Africa with multiple herbivore species. At both the North American and South African locations, plant communities on sites with a single herbivore species were more diverse and species rich than on sites with no herbivores. At the multi-herbivore site in South Africa, plant diversity and richness were comparable to that of the single herbivore site early in the growing season and to the no herbivore site late in the growing season. Analyses of plant community composition, however, indicated strong differences between the multi-herbivore site and the single and no herbivore sites, which were more similar to each other. In moderate to high-productivity ecosystems with one or a few species of large herbivores, loss of herbivores can cause a significant decrease in plant diversity and richness, and can have pronounced impacts on grassland plant community composition. In ecosystems with higher herbivore richness, species loss may also significantly alter plant community structure and composition, although standard metrics of community structure may obscure these differences.     

Amphibian Beta Diversity in the Brazilian Atlantic Forest: Contrasting the Roles of Historical Events and Contemporary Conditions at Different Spatial Scales

Current patterns of biodiversity distribution result from a combination of historical and contemporary processes. Here, we compiled checklists of amphibian species to assess the roles of long-term climate stability (Quaternary oscillations), contemporary environmental gradients and geographical distance as determinants of change in amphibian taxonomic and phylogenetic composition in the Brazilian Atlantic Forest. We calculated beta diversity as both variation in species composition (CBD) and phylogenetic differentiation (PBD) among the assemblages. In both cases, overall beta diversity was partitioned into two basic components: species replacement and difference in species richness. Our results suggest that the CBD and PBD of amphibians are determined by spatial turnover. Geographical distance, current environmental gradients and long-term climatic conditions were complementary predictors of the variation in CBD and PBD of amphibian species. Furthermore, the turnover components between sites from different regions and between sites within the stable region were greater than between sites within the unstable region. On the other hand, the proportion of beta-diversity due to species richness difference for both CBD and PBD was higher between sites in the unstable region than between sites in the stable region. The high turnover components from CBD and PBD between sites in unstable vs stable regions suggest that these distinct regions have different biogeographic histories. Sites in the stable region shared distinct clades that might have led to greater diversity, whereas sites in the unstable region shared close relatives. Taken together, these results indicate that speciation, environmental filtering and limited dispersal are complementary drivers of beta-diversity of amphibian assemblages in the Brazilian Atlantic Forest.     

Time-Lag in Responses of Birds to Atlantic Forest Fragmentation: Restoration Opportunity and Urgency

There are few opportunities to evaluate the relative importance of landscape structure and dynamics upon biodiversity, especially in highly fragmented tropical landscapes. Conservation strategies and species risk evaluations often rely exclusively on current aspects of landscape structure, although such limited assumptions are known to be misleading when time-lag responses occur. By relating bird functional-group richness to forest patch size and isolation in ten-year intervals (1956, 1965, 1978, 1984, 1993 and 2003), we revealed that birds with different sensitivity to fragmentation display contrasting responses to landscape dynamics in the Brazilian Atlantic Forest. For non-sensitive groups, there was no time-lag in response: the recent degree of isolation best explains their variation in richness, which likely relates to these species’ flexibility to adapt to changes in landscape structure. However, for sensitive bird groups, the 1978 patch area was the best explanatory variable, providing evidence for a 25-year time-lag in response to habitat reduction. Time-lag was more likely in landscapes that encompass large patches, which can support temporarily the presence of some sensitive species, even when habitat cover is relatively low. These landscapes potentially support the most threatened populations and should be priorities for restoration efforts to avoid further species loss. Although time-lags provide an opportunity to counteract the negative consequences of fragmentation, it also reinforces the urgency of restoration actions. Fragmented landscapes will be depleted of biodiversity if landscape structure is only maintained, and not improved. The urgency of restoration action may be even higher in landscapes where habitat loss and fragmentation history is older and where no large fragment remained to act temporarily as a refuge.     

Contrasting Population and Life History Responses of a Young Morph-Pair of European Whitefish to the Invasion of a Specialised Coregonid Competitor,Vendace

Invasions of non-native species represent a global problem of great scientific interest. Here we study in detail the response in population and life history characteristics of closely related native species, with divergent habitat preferences, that are impacted by an invading species over a sufficient time period to allow a new stable state to become established. A time series of 20 years starting at the first occurrence of the invader (vendace Coregonus albula (L.)) allows exploration of the long term population and life history response of two ecologically, morphologically, and genetically different native sympatric morphs (DR- and SR-) of congeneric whitefish C. lavaretus (L.). The whitefish morphs are taxonomically equally related to the invading vendace, but only the planktivorous DR-whitefish share its pelagic niche. We would expect that the ecological differences between the whitefish morphs may be used as a predictor of competitive effects. Vendace exhibited an initial boom-and-bust development, and has continued to fluctuate in density. The responses of the pelagic DR-whitefish were: i) an immediate habitat shift, ii) a subsequent population decline caused by increased annual mortality, and iii) a new stable state at a lower density and apparently relaxed competition. The ecologically more distant benthivorous SR-whitefish also showed significant, but a much more limited response during this process, indicating damped indirect interactions through the food-web. This long-term case-study found that in two native eco-species equally related to the invader, only one of the eco-species was highly affected. Direct competition for resources is obviously important for species interactions, whereas the taxonomic relatedness per se seems to offer little predictive power for invasion effects.     

Diversity and dynamics of bacterial populations during spontaneous sorghum fermentations used to produce ting, a South African food

Ting is a spontaneously fermented sorghum food that is popular for its sour taste and unique flavour. Insight of the microbial diversity and population dynamics during sorghum fermentations is an essential component of the development of starter cultures for commercial production of ting. In this study, bacterial populations associated with spontaneous sorghum fermentations were examined using a culture-independent strategy based on denaturing gradient gel electrophoresis and sequence analysis of V3-16S rRNA gene amplicons, and a culture-dependent strategy using conventional isolation based on culturing followed by 16S rRNA and/or pheS gene sequence analysis. The entire fermentation process was monitored over a 54 h period and two phases were observed with respect to pH evolution and microbial succession. The first phase of the process (0-6 h) was characterized by relatively high pH conditions and the presence of Enterococcus mundtii, albeit that this species was only detected with the culture-dependent approach. The second phase of the fermentation process (12-54 h) was characterized by increased acidity and the predominance of a broader range of lactic acid bacteria, including Lactococcus lactis, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus rhamnosus, Weissella cibaria, Enterococcus faecalis, and a close relative of Lactobacillus curvatus, as well as some members of the Enterobacteriaceae family. The Lb. curvatus-like species was only detected with PCR-DGGE, while the majority of the other species was only detected using the culture-dependent approach. These findings highlighted the fact that a combination of both approaches was essential in revealing the microbial diversity and dynamics during spontaneous sorghum fermentations.