Both area and edge effects have a strong influence on ecological processes in fragmented landscapes, but there is little understanding of how these two factors might interact to exacerbate local species declines. To test for synergistic interactions between area and edge effects, we sampled a diverse beetle community in a heavily fragmented landscape in New Zealand. More than 35,000 beetles of approximately 900 species were sampled over large gradients in habitat area (10(-2) 10(6) ha) and distance from patch edge (2(0)-2(10) m from the forest edge into both the forest and adjacent matrix). Using a new approach to partition variance following an ordination analysis, we found that a synergistic interaction between habitat area and distance to edge was a more important determinant of patterns in beetle community composition than direct edge or area effects alone. The strength of edge effects in beetle-species composition increased nonlinearly with increasing fragment area. One important consequence of the synergy is that the slopes of species area (SA) curves constructed from habitat islands depend sensitively on the distance from edge at which sampling is conducted. Surprisingly, we found negative SA curves for communities sampled at intermediate distances from habitat edges, caused by differential edge responses of matrix- vs. forest-specialist species in fragments of increasing area. Our data indicate that distance to habitat edge has a consistently greater impact on beetle community composition than habitat area and that variation in the strength of edge effects may underlie many patterns that are superficially related to habitat area.

Human African trypanosomiasis is caused by the Trypanosoma brucei parasite. The tsetse fly vector is of interest for its potential to prevent disease spread, as it is essential for T. brucei life cycle progression and transmission. The tsetse’s mutualistic endosymbiont Sodalis glossinidius has a link to trypanosome establishment, providing a disease control target. Here, we describe a new, experimentally verified model of S. glossinidius metabolism. This model has enabled the development of a defined growth medium that was used successfully to test aspects of S. glossinidius metabolism. We present S. glossinidius as uniquely adapted to life in the tsetse, through its reliance on the blood diet and host-derived sugars. Additionally, S. glossinidius has adapted to the tsetse’s obligate symbiont Wigglesworthia glossinidia by scavenging a vitamin it produces for the insect. This work highlights the use of metabolic modeling to design defined growth media for symbiotic bacteria and may provide novel inhibitory targets to block trypanosome transmission.

Context dependence in the effects of landscape matrix structure on habitat patch dynamics is rapidly becoming the modern paradigm for landscape ecology and the study of habitat fragmentation. Most of these studies have focused on the influence of matrix structure on between‐patch processes, or the influence of matrix structure on patch‐level dynamics, whereas matrix effects on within‐patch processes (such as edge effects) have been largely ignored. Here, we tested whether matrix contrast (the difference in vegetation structure and environmental conditions between the habitat patch and the adjacent matrix) alters ”two‐sided” patch‐to‐matrix edge response functions in invertebrate diversity and community composition across native forest boundaries. In a severely fragmented landscape in southeastern New Zealand, we selected paired native forest‐vs.‐pasture and native forest‐vs.‐plantation edge gradients within four catchments. We sampled invertebrates with flight intercept traps at nine distances across each of the patch‐to‐matrix gradients (giving a total of 72 sampling sites). We show unequivocally that, in historically forested landscapes such as these, conversion from a high‐contrast pasture matrix to a low‐contrast plantation matrix can mitigate, nullify, or even reverse edge response functions across whole invertebrate orders and across multiple species within diverse beetle assemblages. Variation in adjacent production land use altered the edge response functions for over 80% of all beetle species tested, predominantly through the provision of supplementary habitat in the adjacent forestry matrix, but also through the buffering effect of the plantation matrix compared to the pasture matrix on the relative abundances of some species within native remnants. These findings raise real prospects for active management intervention at the landscape scale, not only to mitigate edge effects on remnant communities, but to simultaneously address both production goals and biodiversity goals in modified landscapes.

We present a single-bacteria hydrodynamic trapping platform to detect antibiotic susceptibility and resistance by simultaneously monitoring motility and morphology of individual E. coli.

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