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Fulltext Ants are the major agents of resource removal from tropical rainforests

Griffiths HM, Ashton LA, Walker AE, Hasan F, Evans TA, Eggleton P, et al.

J Anim Ecol, 2018 Jan;87(1):293-300.
PMID: 28791685 DOI: 10.1111/1365-2656.12728

Ants are diverse and abundant, especially in tropical ecosystems. They are often cited as the agents of key ecological processes, but their precise contributions compared with other organisms have rarely been quantified. Through the removal of food resources from the forest floor and subsequent transport to nests, ants play an important role in the redistribution of nutrients in rainforests. This is an essential ecosystem process and a key energetic link between higher trophic levels, decomposers and primary producers. We used the removal of carbohydrate, protein and seed baits as a proxy to quantify the contribution that ants, other invertebrates and vertebrates make to the redistribution of nutrients around the forest floor, and determined to what extent there is functional redundancy across ants, other invertebrate and vertebrate groups. Using a large-scale, field-based manipulation experiment, we suppressed ants from c. 1 ha plots in a lowland tropical rainforest in Sabah, Malaysia. Using a combination of treatment and control plots, and cages to exclude vertebrates, we made food resources available to: (i) the whole foraging community, (ii) only invertebrates and (iii) only non-ant invertebrates. This allowed us to partition bait removal into that taken by vertebrates, non-ant invertebrates and ants. Additionally, we examined how the non-ant invertebrate community responded to ant exclusion. When the whole foraging community had access to food resources, we found that ants were responsible for 52% of total bait removal whilst vertebrates and non-ant invertebrates removed the remaining 48%. Where vertebrates were excluded, ants carried out 61% of invertebrate-mediated bait removal, with all other invertebrates removing the remaining 39%. Vertebrates were responsible for just 24% of bait removal and invertebrates (including ants) collectively removed the remaining 76%. There was no compensation in bait removal rate when ants and vertebrates were excluded, indicating low functional redundancy between these groups. This study is the first to quantify the contribution of ants to the removal of food resources from rainforest floors and thus nutrient redistribution. We demonstrate that ants are functionally unique in this role because no other organisms compensated to maintain bait removal rate in their absence. As such, we strengthen a growing body of evidence establishing ants as ecosystem engineers, and provide new insights into the role of ants in maintaining key ecosystem processes. In this way, we further our basic understanding of the functioning of tropical rainforest ecosystems.
Fulltext Termites can decompose more than half of deadwood in tropical rainforest

Griffiths HM, Ashton LA, Evans TA, Parr CL, Eggleton P

Curr Biol, 2019 02 18;29(4):R118-R119.
PMID: 30779897 DOI: 10.1016/j.cub.2019.01.012

Termite-mediated decomposition is an important, but often overlooked, component of the carbon cycle. Using a large-scale suppression experiment in Borneo, Griffiths et al. found that termites contribute between 58 and 64% of mass loss from dead wood.
Termites mitigate the effects of drought in tropical rainforest

Ashton LA, Griffiths HM, Parr CL, Evans TA, Didham RK, Hasan F, et al.

Science, 2019 01 11;363(6423):174-177.
PMID: 30630931 DOI: 10.1126/science.aau9565

Termites perform key ecological functions in tropical ecosystems, are strongly affected by variation in rainfall, and respond negatively to habitat disturbance. However, it is not known how the projected increase in frequency and severity of droughts in tropical rainforests will alter termite communities and the maintenance of ecosystem processes. Using a large-scale termite suppression experiment, we found that termite activity and abundance increased during drought in a Bornean forest. This increase resulted in accelerated litter decomposition, elevated soil moisture, greater soil nutrient heterogeneity, and higher seedling survival rates during the extreme El Niño drought of 2015-2016. Our work shows how an invertebrate group enhances ecosystem resistance to drought, providing evidence that the dual stressors of climate change and anthropogenic shifts in biotic communities will have various negative consequences for the maintenance of rainforest ecosystems.
Fulltext Sweet-beverage consumption and risk of pancreatic cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC)

Navarrete-Muñoz EM, Wark PA, Romaguera D, Bhoo-Pathy N, Michaud D, Molina-Montes E, et al.

Am J Clin Nutr, 2016 Sep;104(3):760-8.
PMID: 27510540 DOI: 10.3945/ajcn.116.130963

BACKGROUND: The consumption of sweet beverages has been associated with greater risk of type 2 diabetes and obesity, which may be involved in the development of pancreatic cancer. Therefore, it has been hypothesized that sweet beverages may increase pancreatic cancer risk as well.
OBJECTIVE: We examined the association between sweet-beverage consumption (including total, sugar-sweetened, and artificially sweetened soft drink and juice and nectar consumption) and pancreatic cancer risk.
DESIGN: The study was conducted within the European Prospective Investigation into Cancer and Nutrition cohort. A total of 477,199 participants (70.2% women) with a mean age of 51 y at baseline were included, and 865 exocrine pancreatic cancers were diagnosed after a median follow-up of 11.60 y (IQR: 10.10-12.60 y). Sweet-beverage consumption was assessed with the use of validated dietary questionnaires at baseline. HRs and 95% CIs were obtained with the use of multivariable Cox regression models that were stratified by age, sex, and center and adjusted for educational level, physical activity, smoking status, and alcohol consumption. Associations with total soft-drink consumption were adjusted for juice and nectar consumption and vice versa.
RESULTS: Total soft-drink consumption (HR per 100 g/d: 1.03; 95% CI: 0.99, 1.07), sugar-sweetened soft-drink consumption (HR per 100 g/d: 1.02; 95% CI: 0.97, 1.08), and artificially sweetened soft-drink consumption (HR per 100 g/d: 1.04; 95% CI: 0.98, 1.10) were not associated with pancreatic cancer risk. Juice and nectar consumption was inversely associated with pancreatic cancer risk (HR per 100 g/d: 0.91; 95% CI: 0.84, 0.99); this association remained statistically significant after adjustment for body size, type 2 diabetes, and energy intake.
CONCLUSIONS: Soft-drink consumption does not seem to be associated with pancreatic cancer risk. Juice and nectar consumption might be associated with a modest decreased pancreatic cancer risk. Additional studies with specific information on juice and nectar subtypes are warranted to clarify these results.
Fulltext Association Between Soft Drink Consumption and Mortality in 10 European Countries

Mullee A, Romaguera D, Pearson-Stuttard J, Viallon V, Stepien M, Freisling H, et al.

JAMA Intern Med, 2019 Nov 01;179(11):1479-1490.
PMID: 31479109 DOI: 10.1001/jamainternmed.2019.2478

IMPORTANCE: Soft drinks are frequently consumed, but whether this consumption is associated with mortality risk is unknown and has been understudied in European populations to date.
OBJECTIVE: To examine the association between total, sugar-sweetened, and artificially sweetened soft drink consumption and subsequent total and cause-specific mortality.
DESIGN, SETTING, AND PARTICIPANTS: This population-based cohort study involved participants (n = 451 743 of the full cohort) in the European Prospective Investigation into Cancer and Nutrition (EPIC), an ongoing, large multinational cohort of people from 10 European countries (Denmark, France, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden, and the United Kingdom), with participants recruited between January 1, 1992, and December 31, 2000. Excluded participants were those who reported cancer, heart disease, stroke, or diabetes at baseline; those with implausible dietary intake data; and those with missing soft drink consumption or follow-up information. Data analyses were performed from February 1, 2018, to October 1, 2018.
EXPOSURE: Consumption of total, sugar-sweetened, and artificially sweetened soft drinks.
MAIN OUTCOMES AND MEASURES: Total mortality and cause-specific mortality. Hazard ratios (HRs) and 95% CIs were estimated using multivariable Cox proportional hazards regression models adjusted for other mortality risk factors.
RESULTS: In total, 521 330 individuals were enrolled. Of this total, 451 743 (86.7%) were included in the study, with a mean (SD) age of 50.8 (9.8) years and with 321 081 women (71.1%). During a mean (range) follow-up of 16.4 (11.1 in Greece to 19.2 in France) years, 41 693 deaths occurred. Higher all-cause mortality was found among participants who consumed 2 or more glasses per day (vs consumers of <1 glass per month) of total soft drinks (hazard ratio [HR], 1.17; 95% CI, 1.11-1.22; P