12 research outputs found
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Rethinking megafauna
Concern for megafauna is increasing among scientists and non-scientists. Many studies have emphasized that megafauna play prominent ecological roles and provide important ecosystem services to humanity. But, what precisely are “megafauna”? Here we critically assess the concept of megafauna and propose a goal-oriented framework for megafaunal research. First, we review definitions of megafauna and analyze associated terminology in the scientific literature. Second, we conduct a survey among ecologists and paleontologists to assess the species traits used to identify and define megafauna. Our review indicates that definitions are highly dependent on the study ecosystem and research question, and primarily rely on ad hoc size-related criteria. Our survey suggests that body size is crucial, but not necessarily sufficient, for addressing the different applications of the term megafauna. Thus, after discussing the pros and cons of existing definitions, we propose an additional approach by defining two function-oriented megafaunal concepts: “keystone megafauna” and “functional megafauna”, with its variant “apex megafauna”. Assessing megafauna from a functional perspective could challenge the perception that there may not be a unifying definition of megafauna that can be applied to all eco-evolutionary narratives. In addition, using functional definitions of megafauna could be especially conducive to cross-disciplinary understanding and cooperation, improvement of conservation policy and practice, and strengthening of public perception. As megafaunal research advances, we encourage
scientists to unambiguously define how they use the term “megafauna” and to present the logic underpinning their definition
Simulating rewetting events in intermittent rivers and ephemeral streams: a global analysis of leached nutrients and organic matter
Climate change and human pressures are changing the global distribution and extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56‐98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached organic matter. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events
Data from: Carnivore carcasses are avoided by carnivores
1. Ecologists have traditionally focused on herbivore carcasses as study models in scavenging research. However, some observations of scavengers avoiding feeding on carnivore carrion suggest that different types of carrion may lead to differential pressures. Untested assumptions about carrion produced at different trophic levels could therefore lead ecologists to overlook important evolutionary processes and their ecological consequences. 2. Our general goal was to investigate the use of mammalian carnivore carrion by vertebrate scavengers. In particular, we aimed to test the hypothesis that carnivore carcasses are avoided by other carnivores, especially at the intra-specific level, most likely to reduce exposure to parasitism. 3. We take a three-pronged approach to study this principle by: i) providing data from field experiments, ii) carrying out evolutionary simulations of carnivore scavenging strategies under risks of parasitic infection, and iii) conducting a literature-review to test two hypotheses regarding parasite life-history strategies. 4. First, our field experiments showed that the mean number of species observed feeding at carcasses and the percentage of consumed carrion biomass were substantially higher at herbivore carcasses than at carnivore carcasses. This occurred even though the number of scavenger species visiting carcasses and the time needed by scavengers to detect carcasses were similar between both types of carcasses. In addition, we did not observe cannibalism. Second, our evolutionary simulations demonstrated that a risk of parasite transmission leads to the evolution of scavengers with generally low cannibalistic tendencies, and that the emergence of cannibalism-avoidance behavior depends strongly on assumptions about parasite-based mortality rates. Third, our literature review indicated that parasite species potentially able to follow a carnivore–carnivore indirect cycle, as well as those transmitted via meat consumption, are rare in our study system. 5. Our findings support the existence of a novel coevolutionary relation between carnivores and their parasites, and suggest that carnivore and herbivore carcasses play very different roles in food webs and ecosystems
Fruit and vegetable intake and vitamin C transporter gene (SLC23A2) polymorphisms in chronic lymphocytic leukaemia
Purpose There is currently no convincing epidemiological evidence that
fruit and vegetable consumption, the primary source of vitamin C, plays
a role in chronic lymphocytic leukaemia (CLL) aetiology. We hypothesized
that variations in vitamin C dietary intake as well as in genetic
variability in vitamin C transporter gene SLC23A2 could explain some
inconsistencies in the literature.
Methods Fruit/vegetable/vitamin C consumption from food frequency
questionnaires and six low-penetrance genetic susceptibility
polymorphisms in vitamin C transporter gene SLC23A2 (rs1715364,
rs6133175, rs1776948, rs6139587, rs369270 and rs6052937) were examined
in 434 CLL cases and 1257 randomly selected controls from primary care
centres with genetic data of whom 275 cases and 1094 controls having
both diet and genetic information. Logistic regression models were used
to estimate odds ratio (OR) and 95 % confidence intervals (CI). Purpose
There is currently no convincing epidemiological evidence that fruit and
vegetable consumption, the primary source of vitamin C, plays a role in
chronic lymphocytic leukaemia (CLL) aetiology. We hypothesized that
variations in vitamin C dietary intake as well as in genetic
Results CLL patients were more likely to have a higher fruit consumption
than controls (highest versus lowest quartile in g/day OR: 1.48; 95 %
CI: 1.00 to 2.18; P = 0.03), whereas no associations were found with
vegetable or total vitamin C intake. Based on log-additive models,
rs6133175_A > G (OR: 1.19, 95 % CI: 1.00 to 1.41; P = 0.05) and
rs1776948_T > A (OR: 1.20; 95 % CI: 1.01 to 1.41; P = 0.04) were
associated with CLL. The haplogenotype analysis (rs1715364, rs6133175)
supported the genotype results. No gene-diet interactions in CLL
remained statistically significant after correction for multiple
testing.
Conclusions These data suggest that both fruit intake and genetic marker
in SLC23A2 may play an independent role in CLL biology
Hormonal contraception and postmenopausal hormone therapy in Spain: time trends and patterns of use
Objective: This study aims to describe time trends in and patterns of
use of hormonal contraception and postmenopausal hormone therapy and to
identify factors associated with their use among Spanish women.
Methods: We performed a cross-sectional analysis using data from 1,954
population controls (aged 24-85 y) in 12 provinces of Spain who were
enrolled in the Multi Case-Control Spain study (2007-2013). Data were
collected from a questionnaire conducted face-to-face by trained
personnel. We collected information on sociodemographic factors,
lifestyle, sleep patterns, reproductive history, and occupational
history.
Results: Overall, 48.5% of Spanish women reported ever use of hormonal
contraception, and 9.8% of women in the postmenopausal group reported
use of postmenopausal hormone therapy. Younger cohorts used hormonal
contraception for a longer period, whereas postmenopausal hormone
therapy use dramatically dropped in the 2000s. Women with higher
education levels (including education of partners) and smoking history
were the most probable users of hormonal contraception, whereas inverse
associations were observed among housewives, obese women, and
nulliparous women. Postmenopausal hormone therapy use was associated
with a surgical or therapeutic cause of menopause and with occupational
history of rotating shifts.
Conclusions: In this Spanish population, several demographic, lifestyle,
occupational, and reproductive factors are associated with use of
hormonal compounds. Characterizing hormonal users and monitoring trends
in the use of these hormonal compounds are essential from a public
health perspective
Rethinking megafauna
Concern for megafauna is increasing among scientists and non-scientists.
Many studies have emphasized that megafauna play prominent ecological
roles and provide important ecosystem services to humanity. But, what precisely
are ‘megafauna’? Here, we critically assess the concept of megafauna
and propose a goal-oriented framework for megafaunal research. First, we
review definitions of megafauna and analyse associated terminology in
the scientific literature. Second, we conduct a survey among ecologists and palaeontologists to assess the species traits used to identify
and define megafauna. Our reviewindicates that definitions
are highly dependent on the study ecosystem and research
question, and primarily rely on ad hoc size-related criteria.
Our survey suggests that body size is crucial, but not necessarily
sufficient, for addressing the different applications of
the term megafauna. Thus, after discussing the pros and
cons of existing definitions, we propose an additional
approach by defining two function-oriented megafaunal
concepts: ‘keystone megafauna’ and ‘functional megafauna’,
with its variant ‘apex megafauna’. Assessing megafauna
from a functional perspective could challenge the perception
that theremay not be a unifying definition ofmegafauna that
can be applied to all eco-evolutionary narratives. In addition,
using functional definitions of megafauna could be
especially conducive to cross-disciplinary understanding
and cooperation, improvement of conservation policy and
practice, and strengthening of public perception. As megafaunal
research advances, we encourage scientists to
unambiguously define how they use the term ‘megafauna’
and to present the logic underpinning their definition.http://royalsocietypublishing.org/journal/rspbam2021Centre for Wildlife Managemen
Alkylphenolic compounds and risk of breast and prostate cancer in the MCC-Spain study
Background: Alkylphenolic compounds are chemicals with endocrine
disrupting properties that have been widely used in industry with
important changes in their usage over time. Few epidemiologic studies
have evaluated the effect of alkylphenolic compounds on human health.
Objectives: We investigated whether occupational exposure to
alkylphenolic compounds is associated with breast and prostate cancer.
Methods: We carried out a population-based case-control study including
1513 incident cases of breast cancer, 1095 of prostate cancer, and 3055
controls, frequency matched by sex, age and region. Occupational
exposure to alkylphenolic compounds was estimated using a recently
developed job-exposure matrix, which considered different scenarios of
exposure and different subtypes of alkylphenolic compounds.
Results: History of occupational exposure to alkylphenolic compounds was
modestly associated with breast cancer (OR = 1.23; 95% CI = 1.01-1.48).
Within the different scenarios, the occupational use of domestic
tensioactives was positively associated with breast cancer (OR = 1.28;
95% CI = 1.02-1.60), while occupational exposure in other scenarios
showed mostly a suggestion of a similar positive associations. Exposure
to nonylphenol ethoxylates was positively associated with breast cancer
(OR = 1.21; 95% CI = 1.00-1.47), while exposure to other compounds was
uncommon. In general, we did not observe associations between
alkylphenolic compounds and prostate cancer, except for a positive
association among men occupationally exposed to cosmetic, hair and
personal hygiene products.
Conclusions: Our findings suggest a modest association between breast
cancer risk and occupational exposure to alkylphenolic compounds, and no
associations between these compounds and prostate cancer risk. These
findings warrant further corroboration in other studies