Does cadmium pollution affect reproduction in the clam Ruditapes decussatus? A one-year case study

The effect of cadmium (Cd) on the reproduction of Ruditapes decussatus was monitored over a period of 12 months, from June 2001 to June 2002. Two sites "Bordj d'Ungha" and "El Hofra" differing by their degree of cadmium contamination were chosen in the Gulf of Gabès area (Tunisia). Annual mean concentrations of Cd in the whole soft tissues of clams from the site El Hofra were more than 4 times higher than those from the site Bordj d'Ungha (reference site). The gametogenic cycle of the clam R. decussatus was also investigated by histological examination and monthly observations of gonadal sections in a population of clams from both sites. The results show that gametogenesis occurred from March to December in clams from both sites. Nevertheless, spawning and emission of gametes were synchronized in both sexes from only the clams of the reference site. Although this species is considered as gonochoristic, 6.6% of hermaphroditic cases were observed in clams from both sites in which gametes of both males and females were in ripe stage. Moreover, the period of ripening of sexual products led to an increase of condition index and to a decrease of Cd concentrations in the whole soft tissues of clams from both sites, hence reflecting the phenomenon of "biological dilution".     

A Mössbauer spectroscopic study of the form of iron in iron overload

There are major differences in the temperature dependence of the Mössbauer spectra of ferritin and haemosiderin extracted from the organs of humans suffering from transfusional iron overload. Iron overload can also occur in animal systems as a result of artificial treatments or dietary factors. None of the animal systems which were investigated in the present study showed evidence in their Mössbauer spectra for the presence of the haemosiderin found in transfusional iron overload in humans. This suggests that the haemosiderin which occurs in the case of human transfusional iron overload may be specific to that situation.     

Does lake age affect zooplankton diversity in Mediterranean lakes and reservoirs? A case study from southern Italy

Zooplankton assemblages of 51 lacustrine environments located in the middle of the Mediterranean Region were analysed to evaluate the existence of an ‘age effect’ in determining their structure. The analysed datasets refer to two different geographic areas, one comprising 30 natural and artificial lakes in Sicily and the other an arrangement of 21 analogous aquatic ecosystems located at the bottom of the Italian Peninsula, a more pristine area called Southern Apennine region. Most of the natural lakes are of post-glacial origin. The artificial lakes in both datasets were built in the last century and offer the opportunity to evaluate the possible short-term effects of ageing on the structure of their zooplankton. A comparison of assemblages in the two regions by PERMANOVA and nMDS revealed that they are quite different; therefore they were analysed separately. An explorative analysis on the possible relationship between biological data and environmental data (including lake age) was performed on both datasets using DISTLM. The presence of an ‘age effect’ emerged only in the subset of artificial lakes of the Southern Apennine region; accordingly it was tested more in detail with an a posteriori PERMANOVA analysis in the subset of reservoirs that resulted positive in the first test. SIMPER allowed us to single out the main species responsible of changes in the zooplankton along the selected age groups. No age effect was evident in the Sicilian water bodies, where other variables, such as conductivity, trophic state, urbanisation and water level fluctuations proved to have a major role in shaping zooplankton assemblages. The results showed that the age effect is: (i) detectable only at a time scale of decades; (ii) masked by the human impact in the watershed.     

Does thermal history affect metabolic plasticity?: a study in three Phyllotis species along an altitudinal gradient

(1) The aim of this study was to understand the effects of thermal history in metabolic features such as maximum (MMR) and basal (BMR) metabolic rates, as well as in metabolic plasticity, considered as the total variation of MMR and BMR during the acclimation period. (2) We studied three species of the genus Phyllotis, from different thermal environments, in an altitudinal gradient from sea level to 3800m.a.s.l. Animals were acclimated to contrasting temperatures of 5 and 30 degrees C. To determine the metabolic flexibility, MMR was measured at intervals of 6 days during the acclimation period, while BMR values were obtained at the end of acclimations. Aerobic scope and the rates of change of MMR were estimated in all populations. (3) High- and low-altitude rodents did not show differences in BMR. However, both upper and lower limits of MMR, as well as aerobic scope, were significantly different between high- and low-altitude species, indicating similar ranges of metabolic plasticity. On the other hand, the rates of change of MMR were similar in all populations. (4) Our results indicate that thermal history has a profound effect on the individuals' thermogenic capacity, probably in both phylogenetic and ontogenetic levels. Low-altitude species could not increase MMR to the same levels as high-altitude species, while the later were unable to decrease MMR to achieve the values of the low-altitude species.     

Does it always pay to defend one's nest? A case study in African penguin

Throughout the animal kingdom, individual variation in reproductive success is commonly observed, even under similar environmental conditions. However, the mechanisms behind such differences remain unclear. The notion of behavioural consistency in animals has developed rapidly since the early 21st century partly as an approach to understand among‐individual differences. In this context, a number of studies have highlighted the influence of pair assortment in personality on breeding success. In this study, we related breeding success to individual behaviour, specifically a risk‐taking behaviour, and pair assortment per behaviour in African penguins (Spheniscus demersus) over two breeding seasons of contrasting food availability. On Bird Island, Algoa Bay, South Africa, we used indices of boldness and overall mobility in penguins’ nest defence behaviour as a response to a standard pedestrian approach during chick‐rearing. These behaviours were consistent over the trials and indicated these traits may be related to personality in African penguins. Individuals were categorized as risk‐prone (“bold,” “mobile”) or risk‐averse (“shy,” “non‐mobile”). We then assessed their breeding success through chick growth and survival over 4 weeks in 2015 and 2016. There was weak positive assortment of pairs in relation to nest defence behaviour. However, pair assortment did not significantly influence birds’ breeding success. Shy penguins were generally the most successful (had the highest chick growth rates), which was especially apparent during a food shortage in 2016, possibly reflecting a higher energy investment when foraging. In contrast, chicks from bold parents grew significantly slower, especially in 2016. Bold parents may defend their nest successfully against predation or intra‐specific aggression when food is abundant, but when predation risks are limited and food availability is low, this strategy may not be beneficial. In the context of climate change, where food shortage events may become more frequent, risk‐averse individuals may be favoured and genetic diversity may be reduced in African penguins.     

Does diversity beget diversity? A case study of crops and weeds

Abstract. The ecological literature is ambiguous as to whether the initial diversity of a plant community facilitates or deters the diversity of colonizing species. We experimentally planted annual crop species in monoculture and polyculture, and examined the resulting weed communities. The species composition of weeds was similar among treatments, but the species richness of weeds was significantly higher in the polycultures than in the monocultures. This supports the ‘diversity begets diversity’ hypothesis. Environmental microheterogeneity, diversity promoters, and ecological equivalency do not seem able to explain the observed patterns.     

Can climate change jeopardize predator control of invasive herbivore species? A case study in avocado agro-ecosystems in Spain

Climate change is one of the most important factors affecting the phenology, distribution, composition and diversity of organisms. In agricultural systems many pests and natural enemies are arthropods. As poikilotherm organisms, their body temperature is highly dependent on environmental conditions. Because higher trophic levels typically have lower tolerance to high temperatures than lower trophic levels, trends towards increasing local or regional temperatures may affect the strength of predator/prey interactions and disrupt pest control. Furthermore, increasing temperatures may create climate corridors that could facilitate the invasion and establishment of invasive species originating from warmer areas. In this study we examined the effect of environmental conditions on the dynamics of an agro-ecosystem community located in southern Spain, using field data on predator/prey dynamics and climate gathered during four consecutive years. The study system was composed of an ever-green tree species (avocado), an exotic tetranychid mite, and two native species of phytoseiid mites found in association with this new pest. We also present a climatological analysis of the temperature trend in the area of study during the last 28 years, as evidence of temperature warming occurring in the area. We found that the range of temperatures with positive per capita growth rates was much wider in prey than in predators, and that relative humidity contributed to explain the growth rate variation in predators, but not in prey. Predator and prey differences in thermal performance curves could explain why natural enemies did not respond numerically to the pest when environmental conditions were harsh.     

Mitochondrial genome variations in advanced stage breast cancer: A case–control study

Entire mitochondrial DNA (mtDNA) sequencing was carried out in 101 primary breast cancer patients and 90 controls of south Indian origin. We identified 69 novel mutations in breast cancer patients and 637 reported polymorphisms in patients and/or controls. PolyPhen-2 analysis predicted 5 out of 14 novel missense mutations as ‘probably damaging variants’. Haplogrouping analysis identified a significant association between haplogroup M5 and breast cancer risk. Microsatellite instability and tumor specific large scale mtDNA deletions were not observed in tumor tissues from the patients. In conclusion, mtDNA mutations and haplogroups may constitute an inheritable risk factor for pathogenesis of breast cancer.     

HTERT MNS16A polymorphism in breast cancer: a case–control study

This case–control study aims to investigate the role of HTERT MNS16A polymorphism as a potential risk factors and/or a prognostic marker for breast cancer. 113 consecutive incident cases of histologically confirmed ductal breast cancer and 124 healthy controls were recruited. HTERT MNS16A polymorphism was genotyped (L: long allele, S: short allele); multivariate logistic regression was performed. No significant association was noted either at the overall analysis (OR?=?1.57, 95?% CI 0.84–2.93 for heterozygous LS carriers; OR?=?1.02, 95?% CI 0.54–1.95 for homozygous SS carriers) or at the subanalyses in premenopausal and postmenopausal women. With respect to survival analysis, HTERT MNS16A polymorphism was not associated with either disease-free survival or overall survival. HTERT MNS16A polymorphism does not seem to be a risk factor for breast cancer in the Caucasian Greek population. Further, larger studies from other countries and subjects seem to be needed as this novel polymorphism is being examined in depth.     

Does human-induced habitat transformation modify pollinator-mediated selection? A case study in Viola portalesia (Violaceae)

Pollinator-mediated selection is one of the most important factors driving adaptation in flowering plants. However, as ecological conditions change through habitat loss and fragmentation, the interactions among species may evolve in new and unexpected directions. Human-induced environmental variation is likely to affect selection regimes, but as yet no empirical examples have been reported. In the study reported here, we examined the influence of human-induced habitat transformation on the composition of pollinator assemblages and, hence, pollinator-mediated selection on the flower phenotype of Viola portalesia (Violaceae). Our results indicate that pollinator assemblages differed substantially in terms of species composition and visitation rate between nearby native and transformed habitats. Similarly, the insect species that contributed most to visitation rates differed between plant populations. While the magnitude and sign of pollinator-mediated selection on flower length and width did not differ between sites, selection for flower number lost significance in the transformed habitat, and a significant pattern of disruptive selection for flower shape, undetected in the native habitat, was present in the transformed one. Overall, the results of this study suggest that human-induced habitat change may not only modify the species composition of pollinator assemblages, relaxing the selection process on some flower characters, but they may also create new opportunities for fitness-trait covariation not present in pristine conditions.     

Why are Dormice rare? A case study in conservation biology

In the last 100 years, the Dormouse Muscardinus avellcmarius has disappeared from about half its geographical range in Britain. Evidence is presented which indicates that declining range and numbers are due to a complex interplay of factors which include fragmentation, deterioration and loss of specialized habitat. The Dormouse is unusual in being a relatively A-selected small mammal, with exacting ecological requirements which render it very vulnerable, particularly to habitat fragmentation. The Dormouse is also sensitive to climate, both directly and probably indirectly through the effects of weather on the timing and abundance of food (insects, flowers and fruits). Combined with low population density and low intrinsic rate of population increase, this makes the Dormouse highly vulnerable, not just to absolute climatic measures (e.g. temperature, rainfall), but especially to climatic stochasticity, particularly at the edge of its range. There are strong associations between the distribution and changing status of the Dormouse and various climatic parameters, and clear parallels with other climate-sensitive taxa, notably bats and butterflies.
The Dormouse is a very specialized species, highly sensitive to environmental change, resulting in its piecemeal, progressive extinction, particularly in northern counties. It is likely to be a very sensitive indicator species for monitoring future changing environments and an excellent model for studying the effects of habitat fragmentation, climatic shifts and climatic stochasticity.     

Does the number of sons born affect long-term mortality of parents? A cohort study in rural Bangladesh

It has been suggested that bearing sons increases long-term mortality in women, because sons may be more physiologically demanding to produce than daughters. In this historical cohort study in rural Bangladesh, no association between the number of sons born and mortality was seen in women in the unadjusted analyses. However, a significant reduction in mortality with the number of surviving sons was seen. In addition, after adjusting for the number of surviving sons, there was evidence of increasing mortality with the number of sons born, in women. In men, mortality also depended strongly on the number of surviving sons, but not on the number born. These data provide support for negative long-term costs of bearing sons in mothers in rural Bangladesh, and suggest that there are context-specific factors that mask the true effects of sons in some populations.     

Do species converge during adaptation? A case study in Drosophila

Adaptation to novel environments is a crucial theme in evolutionary biology, particularly because ex situ conservation forces populations to adapt to captivity. Here we analyze the evolution of life-history traits in two closely related species, Drosophila subobscura Collin and Drosophila madeirensis Monclus, during adaptation to the laboratory. Drosophila madeirensis, an endemic species from Madeira, is here shown to have less ability to adapt to the laboratory. Early fecundity was the only trait where this species showed a significant improvement with time. By comparison, D. subobscura improved in most traits, and its early fecundity increased faster than that of D. madeirensis. Our findings suggest that different species, even closely related ones, may adapt at different rates to the same environment.     

Lack of association between LXRα and LXRβ gene polymorphisms and prevalence of metabolic syndrome: A case–control study of an Iranian population

The metabolic syndrome (MetS) is considered to be a major risk factor for type 2 diabetes mellitus and cardiovascular diseases. It is characterized by central adiposity, high blood pressure, glucose intolerance and abnormalities of lipoprotein metabolism. The cause of MetS is likely to be due to a complex interaction between genetic and environmental factors. Liver X receptors alpha (NR1H3) and beta (NR1H2) play a key role in lipid and carbohydrate metabolism. The aim of this study was to investigate the contribution of genetic polymorphisms in the LXRs to risk of MetS and related traits. Two common SNPs in NR1H3 (rs11039155 and rs2279238) and in NR1H2 (rs17373080 and rs2695121) were genotyped using TaqMan assays in MetS patients (n = 265) and controls (n = 219). Logistic regression analyses were performed to calculate the odds ratios (ORs) as a measure of association of genotypes with the presence of MetS and related phenotypes. Although The NR1H2 polymorphism rs2695121 was nominally associated with MetS but correction for multiple-testing and adjustment for age, sex and number of MetS criteria, failed to identify any significant interactions associated with prevalence of MetS. However in the haplotype analysis, a LXRα haplotype AC, was more common in controls and was associated with a significant protective effect for MetS (OR [95% CI] = 0.25 [0.07–0.88], p = 0.031). In conclusion, this study suggests that the above-named variants in LXRα and LXRβ genes are not potential contributors to the risk of MetS and related traits in an Iranian population.     

Does land-use change affect biodiversity dynamics at a macroecological scale? A case study of birds over the past 20 years in Japan

Because the effects of land-use change on biodiversity have primarily been examined at or below the regional scale, it remains unclear whether such effects scale up to the macroecological scale (i.e. nationwide or continental scale). In Japan, forests have become more mature since the cessation of most forestry efforts in the 1970s. At a nationwide scale, this forest maturation may lead to reductions in the abundance of species that depend on early successional forests (early successional species) and increases in the abundance of species that depend on mature forests (mature forest species). Japan has met its high demand for wood through imports from South-east Asia, resulting in deforestation there. Therefore, the abundance of mature forest species that migrate long distances to overwinter in South-east Asia may decrease. We examined changes in the range sizes of birds in Japan over the past 20 years using the living planet index (LPI). The LPI indicated that the range sizes of early successional species decreased. For mature forest species, the range sizes of long-distance migrants decreased, whereas those of short-distance migrants and residents increased. Our predictions were generally supported. Our results indicate that the effects of land-use change extend to the macroecological scale and that such changes in one country can affect the biodiversity dynamics in other countries. Forest maturation in Japan and concomitant deforestation in South-east Asia have been caused by internationally coupled socioeconomic processes. Therefore, biodiversity conservation at the macroecological scale must consider the role of land use, and such efforts will require both international and socioeconomic perspectives.     

Does hydrologic regime affect fish diversity? -A case study of the Yangtze Basin (China)

The Yangtze Basin is taken as a case study to investigate statistically whether the hydrologic regime affects fish diversity. Jaccard’s similarity index (I _JS) is used to characterize the fish species similarity of any pair of sample rivers. On the basis of the IHA (Indicators of Hydrologic Alteration) method, a series of hydrologic indicators, some of which are modified according to the practical hydrologic characters of the Yangtze Basin, are used to characterize the hydrologic regime. A new index, named the degree of the hydrologic regime difference (I _DHRD) is constructed to measure the difference between hydrologic regimes of any pair of sample rivers. An exponential model is used to estimate the correlation curve of I _JS and I _DHRD. We observed a negative relationship between I _JS and I _DHRD, which suggests that hydrologic regime affects fish diversity.     

A case–control study between interleukin-10 gene variants and periodontal disease in dogs

Periodontal disease (PD) refers to a group of inflammatory diseases that affect the periodontium, the organ which surrounds and supports the teeth. PD is a highly prevalent disease with a multifactorial etiology and, in humans the individual susceptibility is known to be strongly determined by genetic factors. Several candidate genes have been studied, namely genes related with molecules involved in the inflammatory response. Interleukin-10 (IL-10) is a cytokine with important anti-inflammatory and immunomodulatory roles, and several studies indicate an association between IL10 polymorphisms and PD. In dogs, an important animal model in periodontology, PD is also a highly prevalent naturally occurring disease, and only now are emerging the first studies evaluating the genetic predisposition. In this case–control study, a population of 90 dogs (40 dogs with PD and 50 healthy dogs) was used to study the IL10 gene, and seven new genetic variations in this gene were identified. No statistically significant differences were detected in genotype and allele frequencies of these variations between the PD cases and control groups. Nevertheless, one of the variations (IL10/2_g.285G > A) leads to an amino acid change (glycine to arginine) in the putative signal peptide, being predicted a potential influence on IL-10 protein functionality. Further investigations are important to clarify the biological importance of these new findings. The knowledge of these genetic determinants can help to understand properly the complex causal pathways of PD, with important clinical implications.