Evolution, radiation and chemotaxonomy of Lamellodysidea, a demosponge genus with anti-plasmodial metabolites

Sponges of the family Dysideidae (Dictyoceratida) are renowned for their diversity of secondary metabolites, and its genus Lamellodysidea, particularly Lamellodysidea herbacea, is the most studied taxon biochemically. Despite its importance, the taxonomic status of L. herbacea—whether it is a distinct species or a species complex—has never been assessed. Recent biochemical profiling revealed anti-plasmodial activity of brominated compounds in Lamellodysidea of the Pacific. Here, we present a comparative chemotaxonomic and molecular analysis of selected Dysideidae from the Pacific and the Indian Ocean (New Caledonia, Great Barrier Reef, Fiji, Mayotte, Guam, Palau). We investigated the phylogenetic relationships between the populations and assessed their bioactive (PBDE) compounds in order to unravel the taxonomic status of this commercially important group of sponges and assessed patterns of dispersal and biochemical variation. The molecular phylogeny was based on the internal transcribed ribosomal spacer and compared against a PBDE phylogeny for several specimens. Molecular data revealed a diversity of Indo-Pacific L. herbacea populations, also reflected by different PBDE compound profiles. Molecular and biochemical data also revealed a Lamellodysidea species new to science. Several specimens misidentified as Lamellodysidea were detected based on their position on different clades in the molecular phylogeny and their production of different halogenated compounds (brominated vs. chlorinated). The direct comparison of molecular and biochemical data also provided evidence for the occurrence of a host switch event and support for the theory that abiotic factors, such as sedimentation, affect the chemical constituents produced in L. herbacea.     

Molecular phylogeny and DNA barcoding of tropical eastern Pacific shallow-water gorgonian octocorals

The octocoral fauna inhabiting the shallow waters (<50 m) of the eastern Pacific has been the subject of renewed interest, and the taxonomy of the most important genera in the region has been reviewed and clarified. Many new species have been described, significantly increasing the known biological diversity of the region. Despite their importance as potential sister-groups of Caribbean octocorals, the phylogenetic relationships of eastern Pacific octocorals remain poorly studied. Here, using partial mitochondrial MutS and igr1-COI sequences, we provide a phylogenetic assessment of a broad sample of eastern Pacific shallow-water octocorals and investigate their phylogenetic relationships with Caribbean gorgonians. We corroborate the monophyly of Pacifigorgia, Leptogorgia and Eugorgia and provide evidence of a close relationship between Swiftia and Psammogorgia, currently placed in Plexauridae. In addition, the phylogenies obtained here provide insights into the historical biogeography and phylogenetic diversity of the eastern Pacific octocoral assemblages and on character evolution among this diverse faunal assemblage. Finally, we evaluate the classification power of DNA barcoding for identifying species of shallow-water eastern Pacific octocorals and assess the use of a nuclear intron (SRP54) to supplement traditional mitochondrial barcodes in this group of organisms.     

Desert pastoralists’ negative and positive effects on rare wildlife in the Gobi

In arid regions of the developing world, pastoralists and livestock commonly inhabit protected areas, resulting in human–wildlife conflict. Conflict is inextricably linked to the ecological processes shaping relationships between pastoralists and native herbivores and carnivores. To elucidate relationships underpinning human–wildlife conflict, we synthesized 15 years of ecological and ethnographic data from Ikh Nart Nature Reserve in Mongolia's Gobi steppe. The density of argali (Ovis ammon), the world's largest wild sheep, at Ikh Nart was among the highest in Mongolia, yet livestock were >90% of ungulate biomass and dogs >90% of large‐carnivore biomass. For argali, pastoral activities decreased food availability, increased mortality from dog predation, and potentially increased disease risk. Isotope analyses indicated that livestock accounted for >50% of the diet of the majority of gray wolves (Canis lupus) and up to 90% of diet in 25% of sampled wolves (n = 8). Livestock composed at least 96% of ungulate prey in the single wolf pack for which we collected species‐specific prey data. Interviews with pastoralists indicated that wolves annually killed 1–4% of Ikh Nart's livestock, and pastoralists killed wolves in retribution. Pastoralists reduced wolf survival by killing them, but their livestock were an abundant food source for wolves. Consequently, wolf density appeared to be largely decoupled from argali density, and pastoralists had indirect effects on argali that could be negative if pastoralists increased wolf density (apparent competition) or positive if pastoralists decreased wolf predation (apparent facilitation). Ikh Nart's argali population was stable despite these threats, but livestock are increasingly dominant numerically and functionally relative to argali. To support both native wildlife and pastoral livelihoods, we suggest training dogs to not kill argali, community insurance against livestock losses to wolves, reintroducing key native prey species to hotspots of human–wolf conflict, and developing incentives for pastoralists to reduce livestock density.     

A Call for Urgent Monitoring of Food and Water Security Based on Relevant Indicators for the Arctic

This perspective paper argues for an urgent need to monitor a set of 12 concrete, measurable indicators of food and water security in the Arctic over time. Such a quantitative indicator approach may be viewed as representing a reductionist rather than a holistic perspective, but is nevertheless necessary for actually knowing what reality aspects to monitor in order to accurately understand, quantify, and be able to project critical changes to food and water security of both indigenous and non-indigenous people in the Arctic. More relevant indicators may be developed in the future, taking us further toward reconciliation between reductionist and holistic approaches to change assessment and understanding. However, the potential of such further development to improved holistic change assessment is not an argument not to urgently start to monitor and quantify the changes in food and water security indicators that are immediately available and adequate for the Arctic context.     

Temporal changes in the trophic ecology of the asymbiotic gorgonian Leptogorgia virgulata

Gorgonians are widespread sub-littoral benthic suspension feeders in the world oceans. However, data on their trophic ecology and role in benthic–pelagic coupling and biogeochemical cycles remain limited. This study assesses the trophic ecology of Leptogorgia virgulata in the Skidaway River estuary, USA (31.9896N, 81.0242W) by analysing carbon and nitrogen isotopic signatures of its soft tissue and different-sized fractions of particulate organic matter (POM) in its environment. Samples were taken in 5 April, 2 August, and 15 October 2012 and 11 January 2013. Results support a distinct temporal shift in the diet of L. virgulata from the POM fraction <10 µm (i.e. pico- and nanoplankton) to the 10–63-µm fraction (i.e. microplankton). This trophic regime is likely associated with the natural abundance of prey items within these size classes, thus suggesting that L. virgulata may be an opportunistic feeder, and seasonal shifts in food availability in the water column affect its diet. As such small prey items affect the bioenergetics of L. virgulata, it is important to understand the implications of changes in food availability associated with environmental drivers on the physiology and population dynamics of this dominant species in the western Atlantic Ocean.     

Proposing an information criterion for individual-based models developed in a pattern-oriented modelling framework

Individual-based models (IBMs) have been improved in quality and reliability in recent years with an approach called pattern-oriented modelling (POM). POM proposes guidelines to develop models reproducing multiple patterns observed on the field and to test systematically how well the IBMs reproduce them. POM studies used generally traditional methods of goodness of fit such as the sum of squares evaluation or ad hoc comparisons of fitting errors and variations. Model selection, however, can be a rigorous statistical approach based on information theory and information criteria such as the Akaike's information criterion (AIC) or the deviance information criterion (DIC). So far, it has not been tried to link POM to these rigorous techniques. The main problems to achieve that are: (a) the difficulty to have likelihood functions for IBMs’ parameters and (b) the possibility to obtain posterior distributions of IBMs’ parameters given the patterns to reproduce. In a first part, this paper answers problem (a) by proposing and explaining how to calculate a deviance measure (POMDEV) for models developed in a context of POM. And while answering the second problem, a second part of the paper proposes an information criterion for model selection in a POM context (the pattern-oriented modelling information criterion: POMIC). This criterion does not yet have the same theoretical foundation as, e.g., AIC, but uses formal analogies to the DIC. In a third part POMIC is tested with a modelling exercise. This exercise shows the potential of POMIC to use multiple patterns for selecting among multiple potential submodels and eventually select the most parsimonious and well fitting model version. We conclude that POMIC, although being a heuristically derived approach, can greatly improve the POM framework.