Cleaner wrasse influence habitat selection of young damselfish

The presence of bluestreak cleaner wrasse, Labroides dimidiatus, on coral reefs increases total abundance and biodiversity of reef fishes. The mechanism(s) that cause such shifts in population structure are unclear, but it is possible that young fish preferentially settle into microhabitats where cleaner wrasse are present. As a first step to investigate this possibility, we conducted aquarium experiments to examine whether settlement-stage and young juveniles of ambon damselfish, Pomacentrus amboinensis, selected a microhabitat near a cleaner wrasse (adult or juvenile). Both settlement-stage (0 d post-settlement) and juvenile (~5 weeks post-settlement) fish spent a greater proportion of time in a microhabitat adjacent to L. dimidiatus than in one next to a control fish (a non-cleaner wrasse, Halichoeres melanurus) or one where no fish was present. This suggests that cleaner wrasse may serve as a positive cue during microhabitat selection. We also conducted focal observations of cleaner wrasse and counts of nearby damselfishes (1 m radius) to examine whether newly settled fish obtained direct benefits, in the form of cleaning services, from being near a cleaner wrasse. Although abundant, newly settled recruits (<20 mm total length) were rarely (2 %) observed being cleaned in 20 min observations compared with larger damselfishes (58 %). Individual damselfish that were cleaned were significantly larger than the median size of the surrounding nearby non-cleaned conspecifics; this was consistent across four species. The selection by settlement-stage fish of a microhabitat adjacent to cleaner wrasse in the laboratory, despite only being rarely cleaned in the natural environment, suggests that even rare cleaning events and/or indirect benefits may drive their settlement choices. This behaviour may also explain the decreased abundance of young fishes on reefs from which cleaner wrasse had been experimentally removed. This study reinforces the potentially important role of mutualism during the processes of settlement and recruitment of young reef fishes.     

Patterns of resource-use and competition for mutualistic partners between two species of obligate cleaner fish

Cleaner mutualisms on coral reefs, where specialized fish remove parasites from many species of client fishes, have greatly increased our understanding of mutualism, yet we know little about important interspecific interactions between cleaners. Here, we explore the potential for competition between the cleaners Labroides dimidiatus and Labroides bicolor during two distinct life stages. Previous work has demonstrated that in contrast to L. dimidiatus, which establish cleaning stations, adult L. bicolor rove over large areas, searching for clients. We show that site-attached juvenile L. bicolor associate with different microhabitat than juvenile L. dimidiatus and that L. bicolor specialize on a narrower range of species than L. dimidiatus as both juveniles and adults. Further, we present evidence suggesting that differences in resource-use are influenced by competitive interactions between the two species. Finally, we discuss the implications of these results for understanding the ecology and evolution of the mutualism.     

Potential effects of fishing on cleaning interactions in a tropical reef

We investigated the effect of fishing on the behavior and abundance of the cleaner fish Labroides dimidiatus on the Great Barrier Reef, Australia, by comparing cleaner fish density (underwater visual census) and behavior (focal animal observations) at a fished and a no-take site. Cleaner fish density, as well as the number of individuals and species cleaned, did not differ significantly between sites; however, L. dimidiatus spent more time interacting (physical contact involving feeding bites) with individual clients at the no-take site, indicating that fishing can indirectly affect mutualistic interactions on tropical reefs.     

Effect of the removal of cleaner fish on the abundance and species composition of reef fish

The ecological significance of cleaner fish on coral reefs was investigated. I removed all cleaner fish, Labroides dimidiatus, from eight small reefs, measured the subsequent effect on the abundance and species composition of all reef fish after 3 and 6 months, and compared it with eight control reefs with cleaner fish. The removal of cleaner fish had no detectable effect on the total abundance of fish on reefs and the total number of fish species at both times. Multivariate analysis by non-metric multidimensional scaling and ANOSIM pairwise tests based on 191 fish species revealed no effect of cleaners on the community structure of fish. Similar results were obtained using principal components analysis on subsets of the data using the 33 most common fish species and the 15 most abundant species (≥5 individuals per reef ) with both log10 (x + 1) transformed data and with fish numbers standardized for abundance. This study demonstrates that the removal of cleaner fish for 6 months did not result in fish suffering increased mortality nor in fish leaving reefs to seek cleaning elsewhere. Received: 28 October 1996 / Accepted: 7 February 1997     

Experimental confirmation of aggressive mimicry by a coral reef fish

A number of potential mimetic relationships between coral reef fishes have been described, but the underlying mechanisms are poorly understood. Similarities in colour between species have often been attributed to aggressive mimicry (where predators resemble models in order to deceive prey), however this has not been tested. The fang blenny, Plagiotremus rhinorhynchos is a specialized predator that feeds on tissues of other fishes. Some individuals appear to mimic the harmless cleaner wrasse Labroides dimidiatus in order to deceive fish visiting cleaning stations, thereby increasing access to food. In this study, the ecological relationship between the mimic and model was examined at Kimbe Bay (Papua New Guinea) and the hypothesis that colour similarities represent facultative aggressive mimicry was experimentally evaluated. Some juveniles exhibited a striking resemblance to the juvenile colouration of the cleaner wrasse, but only when in close proximity to the wrasse and only when similar in size. As predicted for mimics, P. rhinorhynchos co-occurred with L. dimidiatus, but was rare relative to the model. Among site comparisons showed that the abundance of mimetic type blennies was positively correlated with the abundance of juvenile cleaner wrasses. Approximately 50% of all P. rhinorhynchos were found 1 m from the nearest L. dimidiatus, a distance significantly shorter than expected if they were not associated. A cleaner wrasse removal experiment was carried out to test whether the colour displayed by the blenny and its foraging success were contingent upon the presence of a model. In all cases, removal of the model prompted a rapid colour change to a general non-mimetic colouration in P. rhinorhynchos. Removal of L. dimidiatus also resulted in a ~20% reduction in the average foraging success of the blenny compared to controls, supporting the hypothesis that the blenny is a facultative aggressive mimic of the cleaner wrasse.     

Cleaning up the biogeography of Labroides dimidiatus using phylogenetics and morphometrics

Cleaner fishes are some of the most conspicuous organisms on coral reefs due to their behaviour and prominent body pattern, consisting of a lateral stripe and blue/yellow colouration. All obligate cleaner fishes share this body stripe pattern, which is an important signal for attracting client fishes. However, variability in the cleaning signal of the cleaner fish Labroides dimidiatus has been documented across its range. Here, we investigate the geographic distribution of cleaner signal polymorphisms in L. dimidiatus and contrast this to phylogeographic variation in mitochondrial (mt) DNA. We used samples from 12 sites for genetic analyses, encompassing much of L. dimidiatus’ range from the Red Sea to Fiji. We obtained morphometric measures of the cleaner signal body stripe width from individuals among six of the sites and qualitatively grouped tail stripe shape. mtDNA control region sequences were used for phylogenetic and population genetic analyses. We found that body stripe width was significantly correlated with tail stripe shape and geographical location, with Indian Ocean populations differing in morphology from western Pacific populations. L. dimidiatus haplotypes formed two reciprocally monophyletic clades, although in contrast to morphology, Japanese cleaner fish fell within the same clade as Indian Ocean cleaner fish and both clade types were sympatric in Papua New Guinea. An additional novel finding of our research was that the inclusion of two closely related cleaner fish species, Labroides pectoralis and Labroides bicolor, in the phylogenetic analysis rendered L. dimidiatus polyphyletic. Overall, the findings suggest the diversity within L. dimidiatus is underestimated.     

Crime and punishment in a roaming cleanerfish

Cheating is common in cooperative interactions, but its occurrence can be controlled by various means ranging from rewarding cooperators to active punishment of cheaters. Punishment occurs in the mutualism involving the cleanerfish Labroides dimidiatus and its reef fish clients. When L. dimidiatus cheats, by taking scales and mucus rather than ectoparasites, wronged clients either chase or withhold further visits to the dishonest cleaner, which leads to more cooperative future interactions. Punishment of cheating L. dimidiatus may be effective largely because these cleaners are strictly site-attached, increasing the potential for repeated interactions between individual cleaners and clients. Here, we contrast the patterns of cheating and punishment in L. dimidiatus with its close relative, the less site-attached Labroides bicolor. Overall, L. bicolor had larger home ranges, cheated more often and, contrary to our prediction, were punished by cheated clients as frequently as, and not less often than, L. dimidiatus. However, adult L. bicolor, which had the largest home ranges, did not cheat more than younger conspecifics, suggesting that roaming, and hence the frequency of repeated interactions, has little influence on cheating and retaliation in cleaner–client relationships. We suggest that roaming cleaners offer the only option available to many site-attached reef fish seeking a cleaning service. This asymmetry in scope for partner choice encourages dishonesty by the partner with more options (i.e. L. bicolor), but to be cleaned by a cleaner that sometimes cheats may be a better option than not to be cleaned at all.     

The Mangrove Nursery Paradigm Revisited: Otolith Stable Isotopes Support Nursery-to-Reef Movements by Indo-Pacific Fishes

Mangroves and seagrass beds have long been perceived as important nurseries for many fish species. While there is growing evidence from the Western Atlantic that mangrove habitats are intricately connected to coral reefs through ontogenetic fish migrations, there is an ongoing debate of the value of these coastal ecosystems in the Indo-Pacific. The present study used natural tags, viz. otolith stable carbon and oxygen isotopes, to investigate for the first time the degree to which multiple tropical juvenile habitats subsidize coral reef fish populations in the Indo Pacific (Tanzania). Otoliths of three reef fish species (Lethrinus harak, L. lentjan and Lutjanus fulviflamma) were collected in mangrove, seagrass and coral reef habitats and analyzed for stable isotope ratios in the juvenile and adult otolith zones. δ¹³C signatures were significantly depleted in the juvenile compared to the adult zones, indicative of different habitat use through ontogeny. Maximum likelihood analysis identified that 82% of adult reef L. harak had resided in either mangrove (29%) or seagrass (53%) or reef (18%) habitats as juveniles. Of adult L. fulviflamma caught from offshore reefs, 99% had passed through mangroves habitats as juveniles. In contrast, L. lentjan adults originated predominantly from coral reefs (65–72%) as opposed to inshore vegetated habitats (28–35%). This study presents conclusive evidence for a nursery role of Indo-Pacific mangrove habitats for reef fish populations. It shows that intertidal habitats that are only temporarily available can form an important juvenile habitat for some species, and that reef fish populations are often replenished by multiple coastal habitats. Maintaining connectivity between inshore vegetated habitats and coral reefs, and conserving habitat mosaics rather than single nursery habitats, is a major priority for the sustainability of various Indo Pacific fish populations.     

Presence of cleaner wrasse increases the recruitment of damselfishes to coral reefs

Mutualisms affect the biodiversity, distribution and abundance of biological communities. However, ecological processes that drive mutualism-related shifts in population structure are often unclear and must be examined to elucidate how complex, multi-species mutualistic networks are formed and structured. In this study, we investigated how the presence of key marine mutualistic partners can drive the organisation of local communities on coral reefs. The cleaner wrasse, Labroides dimidiatus, removes ectoparasites and reduces stress hormones for multiple reef fish species, and their presence on coral reefs increases fish abundance and diversity. Such changes in population structure could be driven by increased recruitment of larval fish at settlement, or by post-settlement processes such as modified levels of migration or predation. We conducted a controlled field experiment to examine the effect of cleaners on recruitment processes of a common group of reef fishes, and showed that small patch reefs (61–285 m²) with cleaner wrasse had higher abundances of damselfish recruits than reefs from which cleaner wrasse had been removed over a 12-year period. However, the presence of cleaner wrasse did not affect species diversity of damselfish recruits. Our study provides evidence of the ecological processes that underpin changes in local population structure in the presence of a key mutualistic partner.     

Long-term effects of the cleaner fish Labroides dimidiatus on coral reef fish communities

Cleaning behaviour is deemed a mutualism, however the benefit of cleaning interactions to client individuals is unknown. Furthermore, mechanisms that may shift fish community structure in the presence of cleaning organisms are unclear. Here we show that on patch reefs (61–285 m²) which had all cleaner wrasse Labroides dimidiatus (Labridae) experimentally removed (1–5 adults reef⁻¹) and which were then maintained cleaner-fish free over 8.5 years, individuals of two site-attached (resident) client damselfishes (Pomacentridae) were smaller compared to those on control reefs. Furthermore, resident fishes were 37% less abundant and 23% less species rich per reef, compared to control reefs. Such changes in site-attached fish may reflect lower fish growth rates and/or survivorship. Additionally, juveniles of visitors (fish likely to move between reefs) were 65% less abundant on removal reefs suggesting cleaners may also affect recruitment. This may, in part, explain the 23% lower abundance and 33% lower species richness of visitor fishes, and 66% lower abundance of visitor herbivores (Acanthuridae) on removal reefs that we also observed. This is the first study to demonstrate a benefit of cleaning behaviour to client individuals, in the form of increased size, and to elucidate potential mechanisms leading to community-wide effects on the fish population. Many of the fish groups affected may also indirectly affect other reef organisms, thus further impacting the reef community. The large-scale effect of the presence of the relatively small and uncommon fish, Labroides dimidiadus, on other fishes is unparalleled on coral reefs.     

Patterns of Local Distribution of Labroides Dimidiatus in French Polynesian Atolls

Cleaning behaviour by fishes has been described to be either facultative or specialised. If being specialised in cleaning is more advantageous than to be a facultative cleaner, cleaner fishes would prefer to settle on reefs were ecological conditions promote specialisation. To test this hypothesis, we looked at the influence of physical and ecological factors on cleaner wrasse abundance, studying variations in L. dimidiatus density between 10 atolls of French Polynesia. We used a multiple regression method based on permutations of distance matrices. Our study reveals that L. dimidiatus are significantly more numerous at sites where ecological factors, such as the species richness of the fish community, may promote their cleaning activity. Moreover, they were significantly more abundant in atolls presenting a large number of sedentary fish species, few predators and few fishes living in large groups. Finally, physical factors, such as the distance between atolls, the lagoon surface, the mean percentage of hard substrate, the mean current index, and the mean depth, play a minor role in the occurrence of L. dimidiatus.     

Association of CDKN1B gene polymorphisms with susceptibility to breast cancer: a meta-analysis

A number of case–control studies have been conducted to investigate the association of CDKN1B gene polymorphisms with breast cancer. However, these studies reported conflicting results. The aim of our study was to quantitatively summarize the association of CDKN1B gene polymorphisms with breast cancer. Systemic searches of the PubMed, Excerpta Medica Database, and Chinese Biomedical Literature Database databases were performed, with the last report up to Oct 2012. Odds ratios (ORs) with 95 % confidence intervals (CIs) were used to assess the strength of the association. Seven studies including 6,822 cases and 7,186 controls were involved in this meta-analysis, which was performed for two CDKN1B gene polymorphisms (rs2066827 and rs34330). Significant association was found for rs34330 polymorphism (T versus C: OR = 1.10, 95 % CI = 1.03–1.18, P = 0.003; CT + TT versus CC: OR = 1.38, 95 % CI = 0.98–1.93, P = 0.07; TT versus CC + CT: OR = 1.06, 95 % CI = 0.93–1.21, P = 0.38; TT versus CC: OR = 1.23, 95 % CI = 1.04–1.45, P = 0.02; CT versus CC: OR = 1.42, 95 % CI = 0.97–2.09, P = 0.07), but not for rs2066827 polymorphism (G versus T: OR = 0.99, 95 % CI = 0.91–1.08, P = 0.84; TG + GG versus TT: OR = 0.98, 95 % CI = 0.89–1.08, P = 0.69; GG versus TT + TG: OR = 1.04, 95 % CI = 0.83–1.30, P = 0.75; GG versus TT: OR = 1.03, 95 % CI = 0.82–1.30, P = 0.77; TG versus TT: OR = 0.97, 95 % CI = 0.88–1.08, P = 0.58). This meta-analysis suggests that breast cancer may be associated with CDKN1B gene rs34330 polymorphism, but not rs2066827 polymorphism.     

Juveniles stick to adults: recruitment of the tube-dwelling polychaete Lanice conchilega (Pallas, 1766)

Juveniles of the tube-dwelling polychaete L. conchilega were found attached to adult tubes at an exposed beach in South Wales (U.K.). They attached to the upper part of tubes protruding above the sediment. The aim of this study was to determine the timing of juvenile settlement on to adult tubes, their abundance and size distribution, and the time of detachment and densities in the sediment after re-settlement. Furthermore, to establish whether the sediment composition of juvenile tubes differed from those of adults and the surrounding sediment. In 1998, 1999 and 2000, tubes of adult L. conchilegawere sampled and numbers of attached juveniles were quantified and their sizes measured. Densities of solitary L. conchilega in the sediment were estimated, as well as the size distribution of solitary tubes. On average, 5–13 juveniles were attached to single adult tubes in spring, but numbers varied greatly with up to 72 juveniles on a single tube in April 1998. Availability of a hard substratum and chemical cues are discussed as potential factors triggering the attachment of juveniles to adult tubes. Juveniles started to detach and re-settle in the sediment 1 month after attachment. Once settled in the sediment, juvenile numbers decreased steeply, but the size distribution of solitary L. conchilega suggested that some juveniles survived in the population. However, the extent to which numbers of juvenile recruits contribute to the density of adults remained unclear. Juveniles used a smaller mean particle size for tube building than adults, but both actively selected particles.     

Associations between interferon regulatory factor 5 polymorphisms and rheumatoid arthritis: a meta-analysis

The aim of this study was to determine whether interferon regulatory factor 5 (IRF5) polymorphisms confers susceptibility to rheumatoid arthritis (RA) in populations with different ethnicities. We searched the literature using the Pubmed and Embase databases and conducted meta-analyses on associations between the four IRF5 polymorphisms (rs2004640, rs729302, rs752637, and rs2280714) and RA susceptibility, using fixed and random effects models. A total of 12 comparison studies were considered in this meta-analysis, which in total involved 7,916 RA patients and 6,452 controls, and eight European, three Asian, and one Argentinean population. Meta-analysis showed an association between the minor allele of rs2004640 and RA in all subjects (odds ratio [OR] = 0.928, 95 % confidence interval [CI] = 0.865–0.996, P = 0.037). After stratification by ethnicity, analysis indicated that the minor allele was significantly associated with RA in Europeans (OR = 0.889, 95 % CI = 0.839–0.941, P = 5.03 × 10^?6), but not in Asians (OR = 1.057, 95 % CI = 0.978–1.144, P = 0.164). A direct comparison between anti-citrullinated peptide antibody-positive and -negative patients revealed no difference of the frequency of the rs2004640 minor allele (OR = 1.047, 95 % CI = 0.813–1.348, P = 0.724). Meta-analysis identified a significant association between RA and the minor allele of the rs729302 polymorphism in the overall population (OR = 0.896, 95 % CI = 0.826–0.972, P = 0.009) and in Asians (OR = 0.862, 95 % CI = 0.795–0.935, P = 3.50 × 10^?5), but not in Europeans (OR = 0.951, 95 % CI = 0.877–1.031, P = 0.225). Meta-analysis showed an association between the minor allele of rs752637 and RA in Europeans (OR = 0.858, 95 % CI = 0.789–0.932, P = 3.03 × 10^?5), but not in Asians (OR = 1.035, 95 % CI = 0.918–1.168, P = 0.572). No association was found between the rs2280714 polymorphism and RA susceptibility. This meta-analysis confirms that the IRF5 rs2004640, rs729302 and rs752637 polymorphisms are associated with RA susceptibility in different ethnic groups, especially in Europeans and Asians, but further study of this association is required in other ethnic groups.     

Association between the CYP1A2-164 A/C polymorphism and colorectal cancer susceptibility: a meta-analysis

To date, epidemiological studies have assessed the association between CYP1A2-164 A/C polymorphism and colorectal cancer susceptibility. However, the results of these studies remained controversial. We aimed to examine the associations by conducting a meta-analysis of case–control studies. A total of 11 studies including 5,093 cases and 5,941 controls evaluated the association between the CYP1A2-164 A/C polymorphism and colorectal cancer susceptibility. No significantly associations were found in all genetic models (CC vs. AA: OR = 1.14, 95 % CI = 0.93–1.40; AC vs. AA: OR = 1.05, 95 % CI = 0.91–1.20; dominant model: OR = 1.08, 95 % CI = 0.95–1.24; recessive model: OR = 1.10, 95 % CI = 0.95–1.28). In the subgroup analysis by ethnicity or source of controls, there were still no significant associations detected in all genetic models. This meta-analysis suggested the CYP1A2-164 A/C polymorphism was not a risk factor for increasing colorectal cancer, further large and well-designed studies are needed to confirm these conclusions.     

The novel human MRC1 gene polymorphisms are associated with susceptibility to pulmonary tuberculosis in Chinese Uygur and Kazak populations

The MRC1 gene, encoding the human mannose receptor (MR), is a member of the C-type lectin receptors family. MR can recognize and bind to Mycobacterium tuberculosis by the extracellular structure, and play a role in antigen-presenting and maintaining a stable internal environment. This study aimed to investigate potential associations of SNPs in exon 7 of the MRC1 gene with pulmonary tuberculosis (TB). G1186A, G1195A, T1212C, C1221G, C1303T and C1323T were genotyped using PCR and DNA sequencing in 595 Chinese Uygur and 513 Kazak subjects. In the Uygur, the frequency of allele G (P = 0.031, OR = 1.29, 95 % CI = 1.02–1.62) and AA genotype (P = 0.033, OR = 1.64, 95 % CI = 1.04–2.60) for G1186A was lower in the pulmonary TB than healthy control and were significantly correlated with pulmonary TB. After adjustment for age and gender, G1186A was found to be additive models in association with pulmonary TB (P = 0.04, OR = 1.27, 95 % CI = 1.01–1.60). By calculating linkage disequilibrium, the frequency of haplotype GGTCCT (P = 0.032, OR = 0.75, 95 % CI = 0.57–0.97) and GGTCCC (P = 0.044, OR = 0.57, 95 % CI = 0.33–0.99) was significantly associated with pulmonary TB. No association was found between other SNPs and pulmonary TB. In the Kazak, all SNPs were not associated with pulmonary TB. Our results suggest that genetic factors play an important role in susceptibility to pulmonary TB at the individual level, and provide an experimental basis to clarify the pathogenesis of pulmonary TB.     

Roving and Service Quality in the Cleaner Wrasse Labroides bicolor

The cleaner wrasse Labroides dimidiatus occupies fixed ‘cleaning stations’ on coral reefs, which ‘client’ reef fish visit repeatedly to have parasites removed. Conflict arises because cleaners prefer to cheat by feeding on client mucus instead of parasites. Clients can prevent L. dimidiatus from always cheating using control mechanisms such as chasing and partner switching, which depend on repeated interactions. These control mechanisms would be undermined in the absence of frequent repeated interactions, if cleaners roved over large areas. Roving behaviour has been anecdotally described for the closely related cleaner wrasse Labroides bicolor. Here we report field data comparing these two species in Moorea, French Polynesia. Our results confirmed that L. bicolor home ranges are much larger than L. dimidiatus home ranges, and showed that cleaning interactions occurred all over the L. bicolor home range: home range of cleaning interactions increased with total home range size. Moreover, we found that cleaner initiation of interactions increased with home range size in L. bicolor, which would give L. bicolor with large home ranges additional leverage to increase cheating. In line with these results, we found that client jolt rate (used as a measure of cheating) was higher among clients of cleaners with large home ranges. Our results emphasise the importance of game structure and control over initiating interactions as parameters in determining the nature of interactions in mutualisms.     

Seascape-scale trophic links for fish on inshore coral reefs

It is increasingly accepted that coastal habitats such as inshore coral reefs do not function in isolation but rather as part of a larger habitat network. In the Caribbean, trophic subsidies from habitats adjacent to coral reefs support the diet of reef fishes, but it is not known whether similar trophic links occur on reefs in the Indo-Pacific. Here, we test whether reef fishes in inshore coral, mangrove, and seagrass habitats are supported by trophic links. We used carbon stable isotopes and mathematical mixing models to determine the minimum proportion of resources from mangrove or seagrass habitats in the diet of five fish species from coral reefs at varying distances (0–2,200 m) from these habitats in Moreton Bay, Queensland, eastern Australia. Of the fish species that are more abundant on reefs near to mangroves, Lutjanus russelli and Acanthopagrus australis showed no minimum use of diet sources from mangrove habitat. Siganus fuscescens utilized a minimum of 25–44 % mangrove sources and this contribution increased with the proximity of reefs to mangroves (R ² = 0.91). Seagrass or reef flat sources contributed a minimum of 14–78 % to the diet of Diagramma labiosum, a species found in higher abundance on reefs near seagrass beds, but variation in diet among reefs was unrelated to seascape structure. Seagrass or reef flat sources also contributed a minimum of 8–55 % to a fish species found only on reefs (Pseudolabrus guentheri), indicating that detrital subsidies from these habitats may subsidize fish diet on reefs. These results suggest that carbon sources from multiple habitats contribute to the functioning of inshore coral reef ecosystems and that trophic connectivity between reefs and mangroves may enhance production of a functionally important herbivore.     

Strong distance-dependent effects for a spatially aggregated tropical species

A fundamental aspect of the Janzen–Connell Hypothesis (JCH) is that distance- and density-dependent mortality reduce the local dominance of species and cause regular rather than random or aggregated spatial patterns. Despite this explicit linkage between process and pattern, very few studies have explored how JCH processes translate into the spatial distributions of adult populations. In field experiments, we assessed germination, mortality and growth of conspecific and heterospecific seedlings beneath and away from Esenbeckia leiocarpa, a highly aggregated tropical tree species. We also investigated the effects of vertebrates using exclosures in the field, and the effects of pathogens in a soil sterilization shadehouse experiment. Germination of conspecifics underneath Esenbeckia was reduced by 64 % and mortality increased 28–123 % when compared to seedlings growing under other tree species; 99–100 % of Esenbeckia seedlings died under conspecifics. Heterospecifics were much less affected by Esenbeckia canopies. However, we found no evidence that either vertebrate herbivores or soil pathogens affected seed germination and seedling performance. Although many tropical tree species are aggregated, our results are the first to demonstrate strong negative distance-dependence for an aggregated species and one of the few to explore germination in the context of the JCH and show differences between conspecifics and heterospecifics, thus suggesting a broader role for Janzen–Connell processes as determinants of the distribution and abundance of tree species in tropical forests.     

Polymorphism of DNA repair gene XRCC1 and hepatitis-related hepatocellular carcinoma risk in Indian population

Background Hepatocellular carcinoma (HCC) is one of the life-threatening malignancies worldwide with hepatitis B and C virus infection as the major risk factor. The risk of HCC might also increase because of the hereditary genetic defects in DNA repair genes. In this regard, X-ray cross-complementing group 1 gene (XRCC1) is a major DNA repair gene involved in base excision repair (BER). Aim The present study was designed with an aim to find out any possible association between XRCC1 (codons 194, 280, and 399) polymorphisms and the risk of developing hepatitis virus-related HCC in Indian population. Methods A total of 407 subjects comprising (170 controls, 174 chronic viral hepatitis, and 63 HCC subjects) were included in the study. PCR–RFLP was used for the genotyping of the three codons of XRCC1. Results The study revealed that two genotypes Arg194Trp and Arg280His increased the risk of HCC by 2.27- (95% CI = 1.01–5.08; P < 0.001) and 4.95-folds (95% CI = 2.48–9.89; P < 0.001), respectively. Interestingly, the risk for HCC was further enhanced by 35.96 (95% CI = 11.64–110.91; P < 0.001) and 5.28 times (95% CI = 2.81–9.09; P < 0.001) when the genotype Arg280His was found in association with Arg194Trp and Arg399Gln, respectively. Conclusion These preliminary results suggest a positive association of XRCC1 genotypes and risk of hepatitis virus-related HCC in India.