The biodiversity dose-response curve translates theory and practice from ecological restoration into research and clinical priorities for fecal microbiota transplantation.

Discoveries of the beneficial effects of gut microbiota have led to efforts to cultivate healthy gut flora to treat disease. The field of ecological restoration specializes on reestablishment of desired species in disturbed ecosystems, which suggests that it may be applicable to microbe restoration in the gut. Common language can lower barriers to interdisciplinary insights. Here I introduce the concept of a "biodiversity dose-response curve" to translate ideas from ecological restoration into research and clinical priorities for fecal microbiota transplantation (FMT). The curve is based on a relationship between ecosystem structure, measured as species diversity found in both nature and gut ecosystems, and ecosystem function, which are the measurable parameters that contribute to ecosystem and human health. I explain why the biodiversity dose-response curve may follow the ecological model of a "rivet-redundancy" relationship, in which the overlap of multiple organisms' functional contributions to a system mask the impact of initial losses of diversity, but, at a certain level of loss, function declines sharply. (Imagine an airplane that flies with a few rivets missing, until it loses enough to fail.) The biodiversity dose-response curve indicates that seemingly healthy individuals may be suboptimal donors; it highlights the importance of recipient diet in FMT success; and it introduces the concept of "passive restoration" into the field of gut medicine. These insights, which may help to explain low success rates of FMT in the treatment of non-Clostridium dificile conditions, are less apparent in the absence of interdisciplinary integration.

A restoration ecology perspective on the treatment of inflammatory bowel disease.

The human gut can be considered an ecosystem comprised of a community of microbes and nonliving components such as food metabolites and food additives. Chronic diseases are increasingly associated with disruption of this ecosystem. The science of restoration ecology was developed to restore degraded ecosystems, but its principles have not been applied widely to gut medicine, including the treatment of inflammatory bowel disease (IBD). One principle of ecological restoration is that 'passive' restoration, which involves removing an ecosystem disturbance, should occur before attempting additional 'active' interventions. We discuss evidence that poor diet is principle source of disturbance in IBD, and therefore requires better attention in its research and clinical care. Another restoration principle is that higher biodiversity may improve ecosystem behavior, but this idea has not been tested for its possible importance in donor stool during fecal microbiota transplants. Lay summary: In patients with chronic disease the gut microbiome behaves like a disturbed ecosystem. Principles borrowed from the science of restoration ecology identify a need to better understand the influence of diet on treatment of inflammatory bowel disease and the importance of donor diversity in fecal microbiota transplants.

Widespread Chemical Detoxification of Alkaloid Venom by Formicine Ants.

The ability to detoxify defensive compounds of competitors provides key ecological advantages that can influence community-level processes. Although common in plants and bacteria, this type of detoxification interaction is extremely rare in animals. Here, using laboratory behavioral assays and analyses of videotaped interactions in South America, we report widespread venom detoxification among ants in the subfamily Formicinae. Across both data sets, nine formicine species, representing all major clades, used a stereotyped grooming behavior to self-apply formic acid (acidopore grooming) in response to fire ant (Solenopsis invicta and S. saevissima) venom exposure. In laboratory assays, this behavior increased the survivorship of species following exposure to S. invicta venom. Species expressed the behavior when exposed to additional alkaloid venoms, including both compositionally similar piperidine venom of an additional fire ant species and the pyrrolidine/pyrroline alkaloid venom of a Monomorium species. In addition, species expressed the behavior following exposure to the uncharacterized venom of a Crematogaster species. However, species did not express acidopore grooming when confronted with protein-based ant venoms or when exposed to monoterpenoid-based venom. This pattern, combined with the specific chemistry of the reaction of formic acid with venom alkaloids, indicates that alkaloid venoms are targets of detoxification grooming. Solenopsis thief ants, and Monomorium species stand out as brood-predators of formicine ants that produce piperidine, pyrrolidine, and pyrroline venom, providing an important ecological context for the use of detoxification behavior. Detoxification behavior also represents a mechanism that can influence the order of assemblage dominance hierarchies surrounding food competition. Thus, this behavior likely influences ant-assemblages through a variety of ecological pathways.

An alternative scoring method for skin conductance responding in a differential fear conditioning paradigm with a long-duration conditioned stimulus.

Researchers examining skin conductance (SC) as a measure of aversive conditioning commonly separate the SC response into two components when the CS-UCS interval is sufficiently long. This convention drew from early theorists who described these components, the first- and second-interval responses, as measuring orienting and conditional responses, respectively. The present report critically examines this scoring method through a literature review and a secondary data analysis of a large-scale study of police and firefighter trainees that used a differential aversive conditioning procedure (n=287). The task included habituation, acquisition, and extinction phases, with colored circles as the CSs and shocks as the UCS. Results do not support the convention of separating the SC response into first- and second-interval responses. It is recommended that SC response scores be derived from data obtained across the entire CS-UCS interval.

Geographic variation in resource dominance-discovery in Brazilian ant communities.

A predictive framework for the ecology of species invasions requires that we learn what limits successful invaders in their native range. The red imported fire ant (Solenopsis invicta) is invasive in the United States, Puerto Rico, Australia, New Zealand, and China. Solenopsis invicta appears to be a superior competitor in its introduced range, where it can cause the local extirpation of native species, but little is known about its competitive ability in its native range in South America. Here we examine the competitive ability of S. invicta for food resources in three widely separated Brazilian ant communities. Each of these communities contains 20-40 ant species, 8-10 of which were common and frequently interacted with S. invicta. S. invicta at all three sites was attacked by several species-specific phorid parasitoids, and at one site, two other species were attacked by their own specialized parasitoids. We examined interactions in these local communities for evidence that trade-offs among ant species between resource dominance and resource discovery, and between resource dominance and parasitoid vulnerability facilitate local coexistence. The trade-off between resource dominance and resource discovery was strong and significant only at Santa Genebra, where parasitoids had no effect on the outcome of confrontations at resources. At Bonito, parasitoids significantly reduced the ability of S. invicta, which was the top-ranked behavioral dominant, from defending and usurping food resources from subordinate species. In the Pantanal, S. invicta ranked behind three other ant species in a linear hierarchy of behavioral dominance, and lost the majority of its interactions with a fourth more subordinate species, Paratrechina fulva, another invasive species. Parasitoids of S. invicta were uncommon in the Pantanal, and did not affect its low position in the hierarchy relative to the other two sites. Parasitoids, however, did affect the ability of Linepithema angulatum, the top-ranked behavioral dominant in this community, from defending and usurping resources from behavioral subordinates. These results indicate that both interspecific competition and trait-mediated indirect effects of phorid parasitoids affect the ecological success of the red imported fire ant in its native range, but that the relative importance of these factors varies geographically.

Parasitoids deter foraging by Argentine ants (Linepithema humile) in their native habitat in Brazil.

The Argentine ant, Linepithema humile, has invaded sites across Africa, Australia, Europe, and North America. In its introduced ranges it eliminates native ants and tends agricultural pests. Few studies have examined the ecology of Argentine ants in their native habitat. This study examined the effects of parasitoid flies, genus Pseudacteon, on the foraging behavior of Argentine ants in part of their native range in southern Brazil. Pseudacteon parasitoids commonly attacked Argentine ants, but not other ant species, in daylight at temperatures above 18°C. Argentine ants abandoned food resources and returned underground in the presence of parasitoids. Parasitoid attack rates diminished as Argentine ants retreated underground. Where parasitoids were present, Argentine ants were abundant at food resources only during times of day when parasitoids were inactive. Where parasitoids were absent, Argentine ants were abundant at food resources throughout the day. Overall, the presence of parasitoids explained observed variation in Argentine ant foraging far better than temperature, although temperature had some effect. The results suggest that Pseudacteon parasitoids inhibit the ability of Argentine ants to gather food resources in their native habitat in Brazil.

LIFE-HISTORY ADAPTATION AND REPRODUCTIVE ISOLATION IN A GRASSHOPPER HYBRID ZONE.

Patterns of life-history adaptation and reproductive isolation were investigated in the acridid grasshoppers Melanoplus sanguinipes and M. devastator, which hybridize along an altitudinal gradient in the Sierra Nevada of California. Melanoplus sanguinipes females crossed with M. devastator males produced eggs that were approximately half as viable as eggs from other crosses. Diminished viability was not attributable either to infection by Wolbachia pipientis or to failure of sperm transfer. When offered an opportunity to choose a mate, females from all populations discriminated against males of the other species, whereas in no-choice tests measuring copulation duration only females from the tails of the clines showed preferences. Melanoplus sanguinipes, found at high elevations where the growing season is short, exhibited faster egg hatch, faster larval development, smaller adult body sizes, and smaller clutch sizes than M. devastator. Melanoplus devastator, from California's Central Valley, endured a hot and dry summer in a reproductive diapause that was absent in M. sanguinipes. Clines in reproductive diapause and clutch size coincided with the region of reproductive incompatibility. Development time, body size, and hatch time also changed across the hybrid zone, but the regions of largest transitions in these traits were either difficult to locate using the limited populations studied here or were not coincident with the zone's center. A method is described for combining ecological and phylogenetic analyses to address the unknown issue of whether life-history divergence has conributed to reproductive isolation in this system.