Global urban environmental change drives adaptation in white clover.

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

Indirect interactions in the High Arctic

Peer reviewe

Related herbivore species show similar temporal dynamics

1. Within natural communities, different taxa display different dynamics in time. Why this is the case we do not fully know. This thwarts our ability to predict changes in community structure, which is important for both the conservation of rare species in natural communities and for the prediction of pest outbreaks in agriculture 2. Species sharing phylogeny, natural enemies and/or life history traits have been hypothesized to share similar temporal dynamics. We operationalized these concepts into testing whether feeding guild, voltinism, similarity in parasitoid community, and/or phylogenetic relatedness explained similarities in temporal dynamics among herbivorous community members. 3. Focusing on two similar data sets from different geographical regions (Finland and Japan), we used asymmetric eigenvector maps as temporal variables to characterize species- and community-level dynamics of specialist insect herbivores on oak (Quercus). We then assessed whether feeding guild, voltinism, similarity in parasitoid community, and/or phylogenetic relatedness explained similarities in temporal dynamics among taxa. 4. Species-specific temporal dynamics varied widely, ranging from directional decline or increase to more complex patterns. Phylogeny was a clear predictor of similarity in temporal dynamics at the Finnish site, whereas for the Japanese site, the data were uninformative regarding a phylogenetic imprint. Voltinism, feeding guild and parasitoid overlap explained little variation at either location. Despite the rapid temporal dynamics observed at the level of individual species, these changes did not translate into any consistent temporal changes at the community level in either Finland or Japan. 5. Overall, our findings offer no direct support for the notion that species sharing natural enemies and/or life history traits would be characterised by similar temporal dynamics, but reveal a strong imprint of phylogenetic relatedness. As this phylogenetic signal cannot be attributed to guild, voltinism or parasitoids, it will likely derive from shared microhabitat, microclimate, anatomy, physiology or behaviour. This has important implications for predicting insect outbreaks and for informing insect conservation. We hope that future studies will assess the generality of our findings across plant-feeding insect communities and beyond, and establish the more precise mechanism(s) underlying the phylogenetic imprint.</p

Belowground–aboveground interactions between pathogens and herbivores

Plants are attacked by pathogens and herbivores with a wide range of lifestyles, both belowground and aboveground. These pathogens and herbivores often co-occur on the same host plant, even though one of them may be in the roots and the other in the shoots. It has long been known that pathogens and herbivores can affect each other when sharing the same part of the plant, but more recently it has been shown that these interactions can span the belowground–aboveground divide. Root pathogens, for instance, can affect foliar herbivores, and, vice versa, foliar herbivores can affect root pathogens. Likewise, root herbivores can affect foliar pathogens and, vice versa, foliar pathogens can affect root herbivores. Such cross-compartment interactions are indirect (i.e., plant-mediated) and may involve induction and priming of common plant defenses, or altered plant quality. This chapter will review the literature and present a framework for this novel type of aboveground–belowground interactions between pathogens and herbivores