Browsing by Author "van Noort, Simon"

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    Afrotropical Ophioninae (Hymenoptera, Ichneumonidae): an update of Gauld and Mitchell’s revision, including two new species and an interactive matrix identification key
    (Pensoft Publishers, 2014) Rousse, Pascal; van Noort, Simon
    The revision of the Afrotropical Ophioninae is updated, based on the examination of about 800–900 individuals in the South African and European museum collections. A robust interactive matrix key was built to provide quick and reliable identifications. The key is available online at http://www.waspweb.org. Two new species are described: Dicamptus maxipol sp. n. and Enicospilus gauldetmitchellorum sp. n. Numerous new distribution and biological records are provided, and noticeable morphological intra-specific variations are detailed. Enicospilus batus Gauld & Mitchell, syn. n. is considered as a junior synonym of E. luebberti (Enderlein).
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    Bee diversity in Angola and community change along an altitudinal gradient at Serra da Chela (Bruco)
    (2020) Figueira Fernandes Elizalde, Sara Raquel; Picker, Mike; van Noort, Simon
    Insects, including wild bees (Hymenoptera: Anthophila) are exceptional model organisms to assess the effect of climate variation on species richness along altitudinal gradients. Climate variables and weather conditions are of extreme importance for insects particularly since their capacity of body temperature regulation is determined by the ambient temperature. Additionally, bee diversity has proven to be strongly related to the availability of host plants, determinant factors for their presence or absence and both of which are limited at higher altitudes. Therefore, the study of wild bee diversity at various altitudes in the tropics could provide information on possible responses of bee species and communities to climate variations, important to estimate effects of climate change on an important ecosystem service such as pollination. Bees being ecologically important insects with close links to plants, high richness and abundance are well-suited as terrestrial habitat bioindicators. The group is sensitive to environmental disturbances relies upon local plant communities and comprises an assemblage of species with varying social structure, nesting guilds and other life history traits. Additionally, bees are likely more susceptible to negative effects of small effective population size. The life history traits determine the individual and community response to environmental changes. Records from the literature revealed a collector and seasonal bias, with greater effort applied around big cities or specific collecting locations and mainly in the wet season. A preliminary checklist of bees of Angola was created and comprises 209 bee species from 47 genera and five families, but a major proportion of the country's area remains to be surveyed. A national inventory of Angolan bees is proposed, making use of standardized methods and sampling either one quarter degree cell or half degree cells, ideally in both dry and rainy seasons. Wild bee communities were sampled along an altitudinal gradient (760-1651 m.a.s.l) in the biodiversity rich and critically endangered Angolan escarpment. Pan traps, malaise traps and sweep netting were used at twelve sampling points, with an average of 70 m difference in altitude between points. Sweep netting proved to be the most efficient technique. Overall, 845 individuals were collected, representing 51 identified species, 34 genera and five bee families. Contrary to the trends observed in other studies in the tropics, a consistent increase in bee diversity (carried out at genera level) with increasing altitude, from the lower altitude (H'=2,14) to the higher altitude of the gradient (H'=2,26) was found. In addition, community structure differed along the gradient, with distinctive communities in low elevation sites being dominated by Braunsapis, Ceratina, Hypotrigona and Anthidiellum, and high elevation sites the distinctive communities were dominated by Amegilla, Macrogalea, Patellapis and Xylocopa. This result might be consistent with findings from studies of other taxa that attribute to the Angolan escarpment an importance as a centre of endemism and speciation. The results from this study are possibly explained by a combination of factors where the exceptional geomorphology and landscape shape the (direct) influence of environmental variables such as temperature and precipitation on the vegetation communities along the gradient therefore (indirectly) affecting bee community assemblages, particularly for the more specialized bee genera and species. Limited research has been done on the variation of bee body size along altitudinal gradients, but the few studies that have been carried out indicate that future changes (warming) in climatic conditions will most probably alter bees body size (by reduction), consequently affecting their thermoregulatory capacity and, at a larger scale, the overall patterns of community assembly. Along the tropical altitudinal gradient of this study, bee body size was found to increase with altitude by 58% (mean length at lower altitude = 5.06mm against mean = 7.99mm at higher altitude elevation sites) at the community level but also at the intra-specific level, with Macrogalea candida increasing 4% in size between the lower altitude and summit of the transect (mean length at lower altitude = 8.76mm against mean = 9.12mm at higher altitude elevation sites), suggesting that the fairly small temperature gradient along the transect was sufficient to select for body size – either directly, but more likely through multiple avenues, including indirect effects such as changes in rainfall, plant community composition and plant phenology. This result constitutes, to my best knowledge, the first demonstration of Bergmann's rule applicability at different levels of biotic organization of bee communities in the tropical region. Effective conservation planning is highly dependent on robust, spatially explicit biodiversity data. The generation of comprehensive insect profiles through long term monitoring studies at the national level can identify areas with high species turnover and endemism – patterns that could be missed if only vertebrate data were considered. In under-developed countries like Angola, where a poorly documented but highly rich biodiversity is severely threatened by unregulated land use, and research is hampered by financial constraints and lack of human resources, the combined use of indicator taxa for both terrestrial (bees) and freshwater (Odonata) environments might be a reasonable surrogate for total biodiversity status assessments. The results from this study highlight the need for long term monitoring to efficiently assess bee diversity, especially in critically endangered landscapes where anthropogenic pressures are high.
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    Codivergence and multiple host species use by fig wasp populations of the Ficus pollination mutualism
    (BioMed Central Ltd, 2012) McLeish, Michael; van Noort, Simon
    BACKGROUND:The interaction between insects and plants takes myriad forms in the generation of spectacular diversity. In this association a species host range is fundamental and often measured using an estimate of phylogenetic concordance between species. Pollinating fig wasps display extreme host species specificity, but the intraspecific variation in empirical accounts of host affiliation has previously been underestimated. In this investigation, lineage delimitation and codiversification tests are used to generate and discuss hypotheses elucidating on pollinating fig wasp associations with Ficus. RESULTS: Statistical parsimony and AMOVA revealed deep divergences at the COI locus within several pollinating fig wasp species that persist on the same host Ficus species. Changes in branching patterns estimated using the generalized mixed Yule coalescent test indicated lineage duplication on the same Ficus species. Conversely, Elisabethiella and Alfonsiella fig wasp species are able to reproduce on multiple, but closely related host fig species. Tree reconciliation tests indicate significant codiversification as well as significant incongruence between fig wasp and Ficus phylogenies. CONCLUSIONS: The findings demonstrate more relaxed pollinating fig wasp host specificity than previously appreciated. Evolutionarily conservative host associations have been tempered by horizontal transfer and lineage duplication among closely related Ficus species. Independent and asynchronistic diversification of pollinating fig wasps is best explained by a combination of both sympatric and allopatric models of speciation. Pollinator host preference constraints permit reproduction on closely related Ficus species, but uncertainty of the frequency and duration of these associations requires better resolution.
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    Host-plant species conservatism and ecology of a parasitoid fig wasp genus (Chalcidoidea; Sycoryctinae; Arachonia)
    (Public Library of Science, 2012) McLeish, Michael J; Beukman, Gary; van Noort, Simon; Wossler, Theresa C
    Parasitoid diversity in terrestrial ecosystems is enormous. However, ecological processes underpinning their evolutionary diversification in association with other trophic groups are still unclear. Specialisation and interdependencies among chalcid wasps that reproduce on Ficus presents an opportunity to investigate the ecology of a multi-trophic system that includes parasitoids. Here we estimate the host-plant species specificity of a parasitoid fig wasp genus that attacks the galls of non-pollinating pteromalid and pollinating agaonid fig wasps. We discuss the interactions between parasitoids and the Ficus species present in a forest patch of Uganda in context with populations in Southern Africa. Haplotype networks are inferred to examine intraspecific mitochondrial DNA divergences and phylogenetic approaches used to infer putative species relationships. Taxonomic appraisal and putative species delimitation by molecular and morphological techniques are compared. Results demonstrate that a parasitoid fig wasp population is able to reproduce on at least four Ficus species present in a patch. This suggests that parasitoid fig wasps have relatively broad host- Ficus species ranges compared to fig wasps that oviposit internally. Parasitoid fig wasps did not recruit on all available host plants present in the forest census area and suggests an important ecological consequence in mitigating fitness trade-offs between pollinator and Ficus reproduction. The extent to which parasitoid fig wasps exert influence on the pollination mutualism must consider the fitness consequences imposed by the ability to interact with phenotypes of multiple Ficus and fig wasps species, but not equally across space and time.
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    Intergrative taxonomy and biogegraphy of ants in the genus Anoplolepis (Hymenoptera: Formicidae) in Southern Africa
    (2022) Ndaba, Abusisiwe; Janion-Scheepers, Charlene; Mbanyana-Nhleko, okuthula; Munyai, Caswell; van Noort, Simon
    Taxonomy has played an important role in biodiversity assessments. It provides an understanding of biodiversity components, data that are essential for making decisions on conservation and sustainable use and is also a foundation for phylogenetic studies. Although this field of study has played an important role in identifying and describing biodiversity, the issue of cryptic species has posed many taxonomic challenges. In most taxonomic groups, species with subtle differences and high intraspecific variation are often misidentified when morphological data is not supported by other methods, for example, genetic data. The genus Anoplolepis is one of several polymorphic groups of ants. Although this genus is widely distributed in the Afrotropical region, it is understudied. This study aimed to: 1) resolve taxonomic challenges of the ant genus Anoplolepis in southern Africa, including the production of updated identification keys for the species and the description of new species; 2) resolve taxonomic challenges of the ant genus using molecular data; 3) to understand and update the geographical distribution of species within Anoplolepis; 4) verify the existing distributional records for the invasive species, A. gracilipes in South Africa and monitor the main introduction pathways; and 5) to assess the overall changes in ant assemblages of ants collected between harbours and provinces and test the effectiveness of the pitfall trapping and baiting method in sampling ants. Material from various institutions and organisations were used to conduct this study, as well as new material collected. By using a combination of traditional morphological taxonomy and DNA barcoding, a total of 16 species were identified. Of these, 11 species were determined using morphological features and phylogenetic analysis based on molecular data, with the five remaining species being identified using only morphological features. Based on morphological assessment, one species (Anoplolepis sp. nov. 12) was deemed to be new to science. This study showed that the DNA barcoding method (CO1) was not efficient to delimit some of the species in this genus, highlighting the need to prioritize more fine-scale molecular markers, especially when working with polymorphic or cryptic species. Overall, the distribution of species in this genus shows that this genus is widely distributed across southern Africa. The invasive species A. gracilipes was not detected across all the sampled harbours, nor from any of the material housed at the Iziko Museums of South Africa, loaned from other institutions and organisations in South Africa and other countries used for this study. This is a positive outcome for conservation authorities. This species is highly invasive elsewhere in the world, and if introduced outcompetes native fauna and may result in ecosystem collapse. Although A. gracilipes was not detected in the samples from this study, early detection and eradication of this species should be prioritized. This can be done through existing pest monitoring programs at harbours, and thorough biosecurity measures. This study contributed to developing scarce skills such as the taxonomic identification and the descriptions of new species, increasing the barcoding database of ants in South Africa, and the overall revision of this economically and ecologically important ant genus.
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    A multilocus phylogeny of the world Sycoecinae fig wasps (Chalcidoidea: Pteromalidae)
    (Public Library of Science, 2013) Cruaud, Astrid; Underhill, Jenny G; Huguin, Maïlis; Genson, Gwenaëlle; Jabbour-Zahab, Roula; Tolley, Krystal A; Rasplus, Jean-Yves; van Noort, Simon
    The Sycoecinae is one of five chalcid subfamilies of fig wasps that are mostly dependent on Ficus inflorescences for reproduction. Here, we analysed two mitochondrial ( COI , Cyt b ) and four nuclear genes (ITS2, EF-1α, RpL27a, mago nashi ) from a worldwide sample of 56 sycoecine species. Various alignment and partitioning strategies were used to test the stability of major clades. All topologies estimated using maximum likelihood and Bayesian methods were similar and well resolved but did not support the existing classification. A high degree of morphological convergence was highlighted and several species appeared best described as species complexes. We therefore proposed a new classification for the subfamily. Our analyses revealed several cases of probable speciation on the same host trees (up to 8 closely related species on one single tree of F. sumatrana ), which raises the question of how resource partitioning occurs to avoid competitive exclusion. Comparisons of our results with fig phylogenies showed that, despite sycoecines being internally ovipositing wasps host-switches are common incidents in their evolutionary history. Finally, by studying the evolutionary properties of the markers we used and profiling their phylogenetic informativeness, we predicted their utility for resolving phylogenetic relationships of Chalcidoidea at various taxonomic levels.