Frazer Sinclair

Reconstructing Community Assembly in Time and Space Reveals Enemy Escape in a Western Palearctic Insect Community

How geographically widespread biological communities assemble remains a major question in ecology. Do parallel population histories allow sustained interactions (such as host-parasite or plant-pollinator) among species, or do discordant histories necessarily interrupt them? Though few empirical data exist, these issues are central to our understanding of multispecies evolutionary dynamics. Here we use hierarchical approximate Bayesian analysis of DNA sequence data for 12 herbivores and 19 parasitoids to reconstruct the assembly of an insect community spanning the Western Palearctic and assess the support for alternative host tracking and ecological sorting hypotheses. We show that assembly occurred primarily by delayed host tracking from a shared eastern origin. Herbivores escaped their enemies for millennia before parasitoid pursuit restored initial associations, with generalist parasitoids no better able to track their hosts than specialists. In contrast, ecological sorting played only a minor role. Substantial turnover in host-parasitoid associations means that coevolution must have been diffuse, probably contributing to the parasitoid generalism seen in this and similar systems. Reintegration of parasitoids after host escape shows these communities to have been unsaturated throughout their history, arguing against major roles for parasitoid niche evolution or competition during community assembly.

Food for Pollinators: Quantifying the Nectar and Pollen Resources of Urban Flower Meadows

Planted meadows are increasingly used to improve the biodiversity and aesthetic amenity value of urban areas. Although many ‘pollinator-friendly’ seed mixes are available, the floral resources these provide to flower-visiting insects, and how these change through time, are largely unknown. Such data are necessary to compare the resources provided by alternative meadow seed mixes to each other and to other flowering habitats. We used quantitative surveys of over 2 million flowers to estimate the nectar and pollen resources offered by two exemplar commercial seed mixes (one annual, one perennial) and associated weeds grown as 300m2 meadows across four UK cities, sampled at six time points between May and September 2013. Nectar sugar and pollen rewards per flower varied widely across 65 species surveyed, with native British weed species (including dandelion, Taraxacum agg.) contributing the top five nectar producers and two of the top ten pollen producers. Seed mix species yielding the highest rewards per flower included Leontodon hispidus, Centaurea cyanus and C. nigra for nectar, and Papaver rhoeas, Eschscholzia californica and Malva moschata for pollen. Perennial meadows produced up to 20x more nectar and up to 6x more pollen than annual meadows, which in turn produced far more than amenity grassland controls. Perennial meadows produced resources earlier in the year than annual meadows, but both seed mixes delivered very low resource levels early in the year and these were provided almost entirely by native weeds. Pollen volume per flower is well predicted statistically by floral morphology, and nectar sugar mass and pollen volume per unit area are correlated with flower counts, raising the possibility that resource levels can be estimated for species or habitats where they cannot be measured directly. Our approach does not incorporate resource quality information (for example, pollen protein or essential amino acid content), but can easily do so when suitable data exist. Our approach should inform the design of new seed mixes to ensure continuity in floral resource availability throughout the year, and to identify suitable species to fill resource gaps in established mixes.

Impacts of local adaptation of forest trees on associations with herbivorous insects: implications for adaptive forest management.

Disruption of species interactions is a key issue in climate change biology. Interactions involving forest trees may be particularly vulnerable due to evolutionary rate limitations imposed by long generation times. One mitigation strategy for such impacts is Climate matching – the augmentation of local native tree populations by input from nonlocal populations currently experiencing predicted future climates. This strategy is controversial because of potential cascading impacts on locally adapted animal communities. We explored these impacts using abundance data for local native gallwasp herbivores sampled from 20 provenances of sessile oak (Quercus petraea) planted in a common garden trial. We hypothesized that non‐native provenances would show (i) declining growth performance with increasing distance between provenance origin and trial site, and (ii) phenological differences to local oaks that increased with latitudinal differences between origin and trial site. Under a local adaptation hypothesis, we predicted declining gallwasp abundance with increasing phenological mismatch between native and climate‐matched trees. Both hypotheses for oaks were supported. Provenance explained significant variation in gallwasp abundance, but no gall type showed the relationship between abundance and phenological mismatch predicted by a local adaptation hypothesis. Our results show that climate matching would have complex and variable impacts on oak gall communities.

Eight new species of Cycloneuroterus Melika & Tang gallwasps from Taiwan and mainland China (Hymenoptera: Cynipidae: Cynipini)

Eight new species of cynipid gallwasps, Cycloneuroterus abei Melika & Tang, C. ergei Tang & Melika, C. gilvus Melika & Tang, C. globosus Melika & Tang, C. jianwui Tang & Melika, C. lohsei Melika & Tang, C. tumiclavus Tang & Melika, C. uraianus Tang & Melika, from Taiwan and mainland China are described. Descriptions, diagnoses, biology, and host associations for the new species and a key to all Cycloneuroterus species are given. All taxa are supported by morphological and molecular data. Seven newly described species induce galls on Quercus subgenus Cyclobalanopsis, while one, C. uraianus, induces galls on Castanopsis. This is the first Cycloneuroterus species known to associate with Castanopsis.

New species of cynipid inquilines of the genus Saphonecrus (Hymenoptera: Cynipidae: Synergini) from the Eastern Palaearctic, with a re-appraisal of known species world-wide.

Fifteen new species of cynipid inquilines, Saphonecrus chinensis Tang & Schwéger, S. gilvus Melika & Schwéger, S. globosus Schwéger & Tang, S. leleyi Melika & Schwéger, S. lithocarpii Schwéger & Melika, S. longinuxi Schwéger & Melika, S. morii Schwéger & Tang, S. nantoui Tang, Schwéger & Melika, S. nichollsi Schwéger & Melika, S. pachylomai Schwéger, Tang & Melika, S. robustus Schwéger & Melika, S. saliciniai Melika, Tang & Schwéger, S. shanzhukui Melika & Tang, S. symbioticus Melika & Schwéger, and S. taitungi Schwéger, Tang & Melika, from the Eastern Palaearctic are described. Descriptions, diagnoses, biology, and host associations for the new species, and a key to Palaearctic Saphonecrus species are given. All new taxa form distinct units as demonstrated by the molecular phylogenetic analyses of Palaearctic Saphonecrus species. The status of some earlier described Saphonecrus species is discussed also. The Synergini genus Lithonecrus Nieves-Aldrey & Butterill, 2014 is synonymized with Lithosaphonecrus Tang, Melika & Bozsó, 2013. Three Saphonecrus species are transferred to Synergus: Synergus brevis (Weld) comb. nova, Synergus hupingshanensis (Liu, Yang & Zhu) comb. nova, and Synergus yukawai (Wachi, Ide & Abe) comb. nova. Synophrus vietnamensis Abe, Ide, Konishi & Ueno is transferred to Lithosaphonecrus: Lithosaphonecrus vietnamensis Abe, Ide, Konishi & Ueno), comb. nova. The current number of valid Saphonecrus species worldwide is 36.