The influence of maternal thermal environments on reproductive traits and hatchling traits in a Lacertid lizard,Takydromus septentrionalis

The thermal environment can induce substantial variation in important life-history traits. Experimental manipulation of the thermal environment can help researchers determine the contribution of this factor to phenotypic variation in life-history traits. During the reproductive season, we kept female northern grass lizards, Takydromus septentrionalis (Lacertidae), in three temperature-controlled rooms (25, 28 and 32 °C) to measure the effect of the maternal thermal environment on reproductive traits. Maternal thermal environment remarkably affected reproductive frequency and thereby seasonal reproductive output, but had little effect on reproductive traits per clutch or hatchling traits. Females kept at 32 °C produced more clutches and thus had shorter clutch intervals than females from 28 to 25 °C. Clutch size, clutch mass, relative clutch mass, egg size and hatchling traits did not vary among the three treatments. The eggs produced by the females were incubated at 27 °C and the traits of hatchlings were measured. The result that egg (offspring) size was independent of maternal thermal environments is consistent with the prediction of the optimal egg size (offspring) theory. The eggs produced by low temperature females (28 and 25 °C) took longer time to complete their post-oviposition development than did eggs produced by high temperature females (32 °C). This suggests that the eggs from low temperatures might have been laid when the embryos were at relatively early stages. Therefore, maternal thermal environment prior to oviposition could affect post-oviposition development in T. septentrionalis.     

A maze-lover's dream: Burrow architecture,natural history and habitat characteristics of Ansell's mole-rat (Fukomys anselli)

The Ansell's mole-rat (Fukomys anselli, Bathyergidae) is a small-sized social subterranean rodent whose distribution is confined to the Lusaka area in Zambia. It is an established model species for various laboratory studies, but until now the knowledge of its biology under natural conditions has been limited. Here, we provide the first comprehensive natural history and ecological data on a free living population from Miombo woodland. The Ansell's mole-rat lives in groups of up to 13 individuals (mean 9.7 ± 2.5; N = 9 complete, fully established family groups) with a single breeding pair per group. The family groups occupy very large and complex burrow systems consisting of 0.5–2.8 km of tunnels (mean = 1.2 ± 0.6 km, N = 15), which are densely branched and reticulated especially around nests. Burrow systems of neighbouring family groups were often interconnected by a freely passable tunnel, which has never before been documented in any African mole-rats. Mole-rat food density in the study area was relatively low (10.0 ± 8.4 m^?2) but its biomass was large (457 ± 889 g m^?2). This, together with a relatively workable soil (cone resistance = 529 ± 26 N cm^?2 at the end of June, with 10% soil humidity), indicates moderate ecological conditions, which disagrees with the aridity food-distribution hypothesis (AFDH) considering small body size and sociality in bathyergids adaptations to harsh environments.     

Conservation assessment of an extremely restricted bromeliad highlights the need for population-based conservation on granitic inselbergs of the Brazilian Atlantic Forest

Inselbergs support highly specialized vegetation with many endemic species. Here we studied by an integrated approach a rare and threatened species from Brazilian inselbergs. Pitcairnia encholirioides (Bromeliaceae) is included in the Red Book of Brazilian Flora, in the ‘Endangered’ category. Only one single population on unprotected private property was known at the beginning of our study. We studied several life-history traits including clonal growth, reproductive biology, seed germination and cryopreservation, and genetic diversity. Pitcairnia encholirioides has the phalanx type of clonal growth strategy. Its self-incompatible flowers are successfully pollinated by hummingbirds. However, less than 5% of clonal fragments produced flowers. Seeds can be wind-dispersed, but most of them are dispersed by gravity and fall close to the mother plant. The percentage and speed of germination were significantly affected by different temperatures, water potential, and red:far-red light ratios, although more than 80% of seeds germinated under optimal physiological conditions. The genetic diversity was very low (H_sp = 0.09) and the population was highly structured (Φ_ST = 0.51). The combination of dispersal mode and environmental conditions seems to be the main factor leading to the rarity of P. encholiroides. Low genetic diversity combined with small population size and low reproductive capacity suggest that the species is highly susceptible to environmental disturbance. Similarly to P. encholiroides, many species from Brazilian inselbergs are restricted to only a few localities. For more widely distributed species, a higher genetic diversity among populations has been consistently detected. The pattern of low gene flow of many species with small distributions highlight the importance of population-based conservation strategies for such taxa the areas of occurrence of which being naturally fragmented at inselberg sites. We discuss some strategies that may help in conservation of such species.     

Perinatal effects of exposure to PCBs on social preferences in young adult and middle-aged offspring mice

In social species, social interactions between conspecifics constitute a fundamental component to establish relations, provide best chances to reproduce, and even improve survival rates. In this study, a three-chambered social approach test was used to estimate the level of sociability and level of preference for social novelty in both male and female young adult (postnatal day (PND) 50) and middle-aged (PND 330) offspring mice (n = 10 per group) that were perinatally exposed to a mixture of six polychlorinated biphenyls (PCBs), 28, 52, 101, 138, 153, and 180, at environmentally low doses (10 and 1000 ng/kg b.w. for dams during gestation and lactation), a profile that closely mimics human exposure to contaminated fish. Our results showed that PCBs bidirectionally modulated social preferences in offspring mice, and the effects were sex and age dependent. However, increased levels of social interactions were rather frequently detected in both assays of the three-chambered test. Reduced social interaction was only induced in 1000 ng/kg PCB-exposed middle-aged males, which exhibited similar preferences to social and non-social stimuli when compared to middle-aged controls. Furthermore, results showed that plasma levels of both corticosterone and acetylcholinesterase activity were higher in all PCB-exposed middle-aged males and females than in their control counterparts. In summary, although the effects of PCBs were only of moderate magnitude, our results suggest that a PCB mixture can act as an endocrine disruptor in offspring mice, disturbing the formation of normal social habits.     

Inferred kinship patterns reveal low levels of extra-pair paternity in the endangered Neotropical Jabiru Stork (Jabiru mycteria, Aves: Ciconiiformes)

The present study inferred the genetic mating system in a natural breeding population of the Jabiru Stork (Jabiru mycteria), a Neotropical wading bird considered endangered in part of its distribution range. Based on data from eight microsatellite loci, maximum-likelihood kinship reconstruction techniques, parentage assignment analyses and effective population size (Ne) estimates were applied to samples collected in the Brazilian Pantanal wetland (N = 45 nestlings from 20 nests; N = 17 shed adult feathers from 11 nests). The relationship diagnosis was determined for most of the complete clutches (86.66 %): 92.31 % were full siblings and 7.69 % were half siblings. Shed feathers collected from the nests matched the genetic parents of the offspring in 80 % of cases. Feathers collected from the ground below the nests were compatible with the putative parents in 41.67 % of cases. A mean Ne of 35 reproductive individuals was inferred, corresponding to an Ne/Nc ratio of 0.09, which is similar to the ratio found in populations of a number of different wild animals. The higher proportion of full siblings identified in the broods suggests that genetic monogamy is the prevalent mating system in the Jabiru Stork, while the detection of half siblings suggests some degree of extra-pair paternity. The present findings are in agreement with previous ecological observations of social monogamy in this species, despite the isolated evidence of extra-pair copulation events. This study also demonstrates the usefulness of a noninvasive approach to sampling adults and performing parentage and relatedness analyses in an elusive, threatened species.     

The risk of cancer in the offspring and parental length of life

BackgroundWe investigated if cancer onset in offspring is related to having short-lived parents for different cancer types and to see if there was a difference in smoking- and non-smoking related cancers.MethodsOur study included 524,391 individuals born in Norway 1940–1950. All children were followed up for cancer from the age of 20 until they were between 59 and 69 years. Parental longevity was examined by grouping parental age of death into parents dying before 75 years of age and parents dying at 75 years of age or older.ResultsAn increased risk of 1.14 (95%CI = 1.10–1.19) among male offspring and 1.08 (95%CI = 1.04–1.12) among female offspring was observed for total cancer when both parents died before the age of 75 compared to offspring with two long-lived parents. The highest increase was found for cancer in the lungs and trachea for both male (HR = 1.67, 95%CI = 1.50–1.86) and female offspring (HR = 1.53, 95%CI = 1.33–1.76). For other smoking-related cancers, the risk was lower. No increased risk was observed for non-smoking-related cancers.ConclusionOffspring of long-lived parents have lower risk of developing cancer compared with offspring of short-lived parents. Intergenerational transmission of risk factors from parents to offspring may play an important role, especially for tobacco-related cancers. However, genetic factors cannot be ruled out, since consistent evidence has implicated genetic factors in smoking behaviour.     

A friend in need: Time-dependent effects of stress on social discounting in men

Stress is often associated with a tend-and-befriend response, a putative coping mechanism where people behave generously towards others in order to invest in social relationships to seek comfort and mutual protection. However, this increase in generosity is expected to be directed only towards a delimited number of socially close, but not distant individuals, because it would be maladaptive to befriend everyone alike. In addition, the endocrinological stress response follows a distinct temporal pattern, and it is believed that tend-and-befriend tendencies can be observed mainly under acute stress. By contrast, the aftermath (> 1 h after) of stress is associated with endocrinological regulatory processes that are proposed to cause increased executive control and reduced emotional reactivity, possibly eliminating the need to tend-and-befriend. In the present experiment, we set out to investigate how these changes immediately and > 1 h after a stressful experience affect social-distance-dependent generosity levels, a phenomenon called social discounting. We hypothesized that stress has a time-dependent effect on social discounting, with decisions made shortly after (20 min), but not 90 min after stress showing increased generosity particularly to close others. We found that men tested 20 min after stressor onset indeed showed increased generosity towards close but not distant others compared to non-stressed men or men tested 90 min after stressor onset. These findings contribute to our understanding on how stress affects prosocial behavior by highlighting the importance of social closeness and the timing of stress relative to the decision as modulating factors in this type of decision making in men.     

Effect of water temperature on reproductive performance and offspring quality of rare minnow,Gobiocypris rarus

Water temperature plays a significant role in the reproductive processes of temperate fishes. In the present study, the effects of water temperature on the reproductive performance and offspring quality of rare minnow (Gobiocypris rarus) were evaluated by cultured parent fish at different temperature (18～30 ℃) in a 2-month trial. The results revealed that rare minnows could spawn continuously within the range from 18 ℃ to 30 ℃, and these at 24 ℃ and 27 ℃ spawned every 3–4 days. Batch size of rare minnow increased with increasing water temperature, while egg production increased with increasing water temperature and then decreased at 30 ℃. High water temperature (30 ℃) had significantly adverse effects on fertilization rate and hatching rate (P<0.05). It was found that the oocyte growth at 18 ℃, 21 ℃, and 30 ℃ were slower than those at 24 ℃ and 27 ℃. Histologic analysis further showed that low temperature (18 ℃ and 21 ℃) slowed down vitellogenesis and oocyte maturation, while high temperature (30 ℃) had suppressive effects on oocyte maturation and ovulation. Based on present results, it was concluded that 24–27 ℃ was optimal breeding temperature for rare minnows and water temperature higher than 30 ℃ resulting from climate change would pose a threat to its wild populations.     

Brown bear reintroduction in the Southern Alps: To what extent are expectations being met?

Large carnivores, such as brown bears (Ursus arctos), are flagship species for the conservation of biodiversity and their reintroduction represents a strong challenge. However, the results of reintroductions have only recently been documented in the literature. Given the global decline of large carnivores, documenting the results of such attempts is crucial for future conservation management. Here we examined the reintroduction of brown bears into the Italian Alps. The majority of bears released (10 individuals) adapted well to the release area and this resulted in the increase of the brown bear population. At the end of 2012, the area with a stable presence of females was around 1250 km² (minimum density = 3 bear/100 km²). Between 2002 and 2012, 34 reproductive events occurred and a total of 74 cubs were born, thus reaching a minimum population size of 47 individuals. No less than 21 young males dispersed into adjacent Italian regions or into other countries, such as Switzerland, Austria, and Germany. However, despite a high mortality rate and at least two cases of illegal killing reported in the last 2 years (2013 and 2014), a remarkable population growth rate (current level of 15.6%) has been observed.The damages correlated with bear population size (F = 17.922, p < 0.01) were primarily inflicted on beehives (39%) and livestock (26%), with an economic relevance of € 41,374 per year for compensation and € 23,527 per year for prevention. The only case of injury to humans ever since the beginning of the project was recorded in 2014, when a female defending her two cubs inflicted minor physical injuries to a man. And yet, public opinion changed radically, from a widespread acceptance of bears at the beginning of the project to an opposition to their presence, the increase of their population, and the new translocations aiming at replacing problem bears that had previously been removed. According to the present trend, the population may reach a range of 60–94 individuals in 2017. Therefore, a proper management of problem bears should be considered a key factor for the restoration and improvement of the social acceptance of this species.     

Sampling of Bemisia tabaci adults using a pre-programmed autonomous pest control robot

An autonomous robot (Cabbot) was built to control insect pests in a plastic greenhouse and utilized to sample adult whiteflies (Bemisia tabaci) on paprika plants (Capsicum annum var. angulosum). To accomplish this, a sampling device consisting of an air compressor for pest agitation, a sticky trap (100 mm × 150 mm) and an image processing system for pest identification were installed on the Cabbot. The sampling precision of the Cabbot (D = 0.16) was higher than that of the sticky trap (D = 0.19) when sampling of adult white flies was conducted in caged pots. The Cabbot could also collect a substantial number of individuals within a short duration (3 minutes). The collection efficiency (i.e., percent of samples collected at least n (1 in this case) individuals to the total sample number) of insects by the Cabbot was markedly high at low population size, showing approximately 30% when the population size was ≤ 16 individuals per plant. The sampling precision and collection efficiency suggested that the Cabbot is effective in local, short-term sampling and could be used for early warning of pest occurrences.     

Bionomics of Orasema simplex (Hymenoptera: Eucharitidae), a parasitoid of Solenopsis fire ants (Hymenoptera: Formicidae) in Argentina

Biological characteristics of the parasitoid Orasema simplex Heraty (Hymenoptera: Eucharitidae), a potential candidate for the biological control of fire ants in the United States were investigated. Female survivorship, fertility and oviposition preferences were studied in the laboratory. Naturally parasitized colonies were examined to determine offspring sex ratio, development success and time, and to artificially parasitize healthy ant colonies. In addition, field studies were carried out to establish natural oviposition substrates and adult activity patterns. Orasema simplex female survivorship was 3.6 ± 1.5 days. Newly emerged females contained 613.5 ± 114.0 mature eggs. The adult development success in natural parasitized colonies was 22.2% with a female-biased sex ratio (4:1). The time required from planidia to adult was 29.5 ± 5.4 days. In the field, adults were mostly found around the ant nests at midday. A broad range of plant species was observed as oviposition substrates. The transfer of planidia to healthy ant colonies was achieved but the development success was very low. Orasema simplex appears to have a limited potential as a fire ant biocontrol agent because of cosmetic damage to a wide variety of plants used for oviposition. However, further studies are necessary to evaluate the real damage exerted by oviposition punctures.     

Why Wasp Foundresses Change Nests: Relatedness,Dominance, and Nest Quality

The costs and benefits of different social options are best understood when individuals can be followed as they make different choices, something that can be difficult in social insects. In this detailed study, we follow overwintered females of the social wasp Polistes carolina through different nesting strategies in a stratified habitat where nest site quality varies with proximity to a foraging area, and genetic relatedness among females is known. Females may initiate nests, join nests temporarily or permanently, or abandon nests. Females can become helpers or egglayers, effectively workers or queens. What they actually do can be predicted by a combination of ecological and relatedness factors. Advantages through increased lifetime success of individuals and nests drives foundresses of the social wasp Polistes from solitary to social nest founding. We studied reproductive options of spring foundresses of P. carolina by monitoring individually-marked wasps and assessing reproductive success of each foundress by using DNA microsatellites. We examined what behavioral decisions foundresses make after relaxing a strong ecological constraint, shortage of nesting sites. We also look at the reproductive consequences of different behaviors. As in other Polistes, the most successful strategy for a foundress was to initiate a nest as early as possible and then accept others as subordinates. A common feature for many P. carolina foundresses was, however, that they reassessed their reproductive options by actively monitoring other nests at the field site and sometimes moving permanently to new nests should that offer better (inclusive) fitness prospects compared to their original nests. A clear motivation for moving to new nests was high genetic relatedness; by the end of the foundress period all females were on nests with full sisters.     

Social and genetic structure in colonies of the social wasp <Emphasis Type="Italic">Microstigmus nigrophthalmus</Emphasis>

Microstigmus (Hymenoptera: Crabronidae) is a genus of social apoid wasps which represents an origin of sociality independent from vespoids, but which has so far received little attention. Though group-nesting is widespread in Microstigmus, genetic relatedness has so far been studied in only one species, M. comes. We report on the social biology of M. nigrophthalmus, drawing from behavioural observations and molecular genetic analyses of relatedness and kinship. There was no evidence of distinctive behavioural suites that distinguished reproductive and non-reproductive individuals. Females could mate more than once, but mating frequency was low. Mean relatedness within nests was high, particularly between females (close to 0.5), but pairwise relatedness values were very variable, as nestmates displayed a wide range of relationships. Such high levels of relatedness should be a factor promoting social nesting and cooperative brood care in this species, as females gain only a slight genetic advantage through rearing their own offspring rather than those of nestmates. This study provides the finest analysis of genetic structure so far in an apoid wasp, and indicates that the form of sociality varies greatly between species of Microstigmus.     

Childhood environmental harshness predicts coordinated health and reproductive strategies: A cross-sectional study of a nationally representative sample from France

There is considerable variation in health and reproductive behaviours within and across human populations. Drawing on principles from Life History Theory, psychosocial acceleration theory predicts that individuals developing in harsh environments decrease their level of somatic investment and accelerate their reproductive schedule. Although there is consistent empirical support for this general prediction, most studies have focused on a few isolated life history traits and few have investigated the way in which individuals apply life strategies across reproductive and somatic domains to produce coordinated behavioural responses to their environment. In our study, we thus investigate the impact of childhood environmental harshness on both reproductive strategies and somatic investment by applying structural equation modeling (SEM) to cross-sectional survey data obtained in a representative sample of the French population (n = 1015, age: 19–87 years old, both genders). This data allowed us to demonstrate that (i) inter-individual variation in somatic investment (e.g. effort in looking after health) and reproductive timing (e.g. age at first birth) can be captured by a latent fast-slow continuum, and (ii) faster strategies along this continuum are predicted by higher childhood harshness. Overall, our results support the existence of a fast-slow continuum and highlight the relevance of the life history approach for understanding variations in reproductive and health related behaviours.     

Analysis of a stochastic SIR epidemic on a random network incorporating household structure

This paper is concerned with a stochastic SIR (susceptible → infective → removed) model for the spread of an epidemic amongst a population of individuals, with a random network of social contacts, that is also partitioned into households. The behaviour of the model as the population size tends to infinity in an appropriate fashion is investigated. A threshold parameter which determines whether or not an epidemic with few initial infectives can become established and lead to a major outbreak is obtained, as are the probability that a major outbreak occurs and the expected proportion of the population that are ultimately infected by such an outbreak, together with methods for calculating these quantities. Monte Carlo simulations demonstrate that these asymptotic quantities accurately reflect the behaviour of finite populations, even for only moderately sized finite populations. The model is compared and contrasted with related models previously studied in the literature. The effects of the amount of clustering present in the overall population structure and the infectious period distribution on the outcomes of the model are also explored.     

Effects of short- and long-term changes in spatial density on the social behavior of captive chimpanzees (Pan troglodytes)

The constraints of captivity may often require non-human primates to experience restrictions in space for both long- and short-term periods of time. The tension-reduction model predicts that great apes should increase affiliative behaviors and decrease aggressive behaviors as a coping strategy. The conflict avoidance model, however, predicts that great apes should decrease all social interactions (affiliative and aggressive) as a coping strategy. The purpose of this study was to test the conflict-avoidance and tension-reduction models by examining the effects of both short-term (1–2 days) and long-term (6 months) changes in spatial density on social behavior in 23 adult captive chimpanzees (6 males, 17 females) housed at the Primate Foundation of Arizona. Affiliative (i.e., social groom, social play) and agonistic (i.e., charging display, attack) were assessed using scan-sampling techniques while subjects were rotated from high-density to low-density conditions for varying lengths of time. Results of short-term increases in spatial density (crowding) supported the conflict-avoidance strategy for females, through reduced levels of aggressive (F_1,16 = 17.11, p = 0.001) and affiliative (F_1,16 = 21.13, p < 0.001) behaviors. Males, however, supported the tension-reduction model during short-term high-density by decreasing aggression (F_1,5 = 10.53, p = 0.02) while increasing affiliation (F_1,5 = 9.10, p = 0.03). Females partially supported the tension-reduction model during long-term high-density by increasing affiliative behaviors (F_1,16 = 14.19, p = 0.002) compared to short-term high-density levels, while rates of aggression remained low. Finally, males supported the tension-reduction by reducing aggression (F_1,5 = 7.668, p = 0.04) and increasing affiliation (F_1,5 = 6.08, p = 0.05) during long-term high-density. Results confirm that chimpanzees use different strategies during short-term versus long-term increases in spatial density and that these strategies may be influenced by individual sex. However, sample sizes are small and additional research on male chimpanzees is needed.     

Long-term adaptations of a migratory bird (Little Tern Sternula albifrons) to quasi-natural flooding disturbance

Population size of migratory birds responds to various types of environmental factors, which affect different stages of bird population. In the current study, we analyzed a long-term avifauna monitoring database to investigate population changes in the migratory bird Little Tern, Sternula albifrons, with respect to a quasi-natural disturbance, flooding, induced by a regional characteristic climate pattern, the Korean Monsoon (KM), in the Nakdong River Estuary of South Korea. We scrutinized the time-delayed influence by means of wavelet transformation and year-to-year comparison. Little Tern individuals started to grow in April, and reached its maximum generally in May or June, and an abrupt decrease of individual number was observed after KM occurred. Sequential time-series analysis based on wavelet transformation revealed that the changing pattern of the population size of Little Tern in the estuary was linked to the previous year's flooding (a 9- to 10-month delay), which is regarded as the time difference between Little Tern breeding season and previous KM period. Stronger flooding waters during KM season expelled comparably more individuals of Little Tern from the estuary (r² = 0.595; p < 0.05; n = 9), and the more the individuals left, the smaller the bird arrived at the estuary in the next year. Further examination revealed that earlier initiation and longer duration of KM in year_t − 1 negatively affected the newly arriving Little Tern individuals in the current year (i.e., year_t; r² = 0.809 for impact of KM onset, r² = 0.909 for impact of KM duration; n = 10, respectively; p < 0.005). The Little Tern population gradually increased when summer flooding was not strong in the previous successive years, from which we concluded that the population of the migratory bird Little Tern tends to adapt to quasi-natural disturbance (flooding) to maintain their population size.     

Comparison of the life tables and predation rates of Harmonia dimidiata (F.) (Coleoptera: Coccinellidae) fed on Aphis gossypii Glover (Hemiptera: Aphididae) at different temperatures

The life histories and predation rates of the ladybird beetle Harmonia dimidiata (F.) were compared among beetles kept at 15, 20, and 25 °C. The beetles were fed on Aphis gossypii Glover and were maintained at 70 ± 10% RH and a 14:10 (L:D) h photoperiod. According to the age-stage, two-sex life table, the net reproductive rates (R₀) were 147.4, 98.7, and 62.5 offspring for beetles kept at 15, 20, and 25 °C, respectively. Additionally, we employed both the jackknife and bootstrap techniques for estimating the means, variances, and standard errors of the population parameters. The sample means of R₀ and the other population parameters obtained using the bootstrap technique fit a normal distribution, but the jackknife technique generated biologically meaningless zero values for R₀. The net predation rates were 10963, 13050, and 7492 aphids for beetles kept at 15, 20, and 25 °C, respectively. For a comprehensive comparison of predation potential, we incorporated both the finite rate and the predation rate into the finite predation rate. When both the growth rate and the predation rate were considered, our results showed that H. dimidiata is a more efficient biological control agent for A. gossypii at 20 and 25 °C than at 15 °C.     

Reproductive factors and breast cancer risk among BRCA1 or BRCA2 mutation carriers: Results from ten studies

Although reproductive factors are among the most well-established risk factors for breast cancer in the general population, it is still a matter for debate whether these factors act as risk modifiers among BRCA1 or BRCA2 mutation carriers. This meta-analysis is the first to be performed to determine the relationship between reproductive factors and breast cancer risk among BRCA1 and BRCA2 mutation carriers. We searched the PubMed database up to February 2013. A total of ten studies met the inclusion criteria. The results showed that the reproductive factors may be associated with breast cancer risk only among BRCA1 mutation carriers. No association was found between parity and breast cancer risk. Compared with women at the youngest age in the first-birth category, women in the oldest age category were at a 38% lower risk of breast cancer (RR = 0.62, 95%CI = 0.45–0.85). Breastfeeding for at least 1 or 2 years was associated with a 37% reduction in breast cancer risk (RR = 0.63, 95%CI = 0.46–0.86). Women at the oldest age in the menarche category were at a 34% lower risk of breast cancer (RR = 0.66, 95%CI = 0.53–0.81) than women in the youngest age category. However, none of the reproductive factors were associated with breast cancer risk among BRCA2 mutation carriers. In conclusion, late age at first birth, breastfeeding, and late age at menarche protect against breast cancer in BRCA1 mutation carriers only. Further studies are needed to explore the mechanisms.