Future Reproduction Research Articles

The role of the mating system and intraspecific brood parasitism in the costs of reproduction in a passerine bird.

Limited resources trigger trade-offs in resource allocation. Reproduction is one of the most demanding activities in terms of energy, and costs related to reproduction can be apparent either as reduced future reproduction or as survival. However, costs are not always detected, because individual heterogeneity in quality and resource acquisition may explain variation in costs among individuals. We conducted a comprehensive study in spotless starlings (Sturnus unicolor) nesting in Central Spain to determine whether costs of reproduction could be detectable in the short and/or long term and whether prenatal or postnatal investment were driving these costs. We took into account the lifehistory of the species, where egg volume is highly repeatable, males are facultatively polygynous, and intraspecific brood parasitism occurs. Females with a high reproductive effort in a breeding event also had a high reproductive effort in the second event of the season. The mating system and maternal age were reliable predictors of breeding success within a breeding event: monogamous and primary females, as well as older mothers, raised more nestlings than secondary females and 1-year-old females, respectively. However, when high-investing females suffered intra-brood parasitism in 1 year, we found a negative correlation between current and futurereproduction. These results suggest that, under some circumstances, females are able to skip the short-term costs of reproduction, but when extra effort is added, trade-offs arise. While most studies have focused on different aspects of individual quality on costs, the ecological context seems to represent an important component that should be taken into account.

Egg density and salinity influence filial cannibalism in common gobies

Filial cannibalism, i.e. the consumption of own offspring, has fascinated animal ecologists for many decades but is still not fully understood. Often assumed to happen primarily due to energetic needs of the cannibalizing parents, we here address a more recent notion that suggests an interplay between egg density, salinity, egg infections and filial cannibalism in fish. Previous evidence indicates that (a) filial cannibalism may be related to egg density that (b) egg pathogens such as water moulds spread more easily on high density clutches and are (c) generally suppressed in high salinity conditions and that (d) parents selectively cannibalize infected eggs, suggesting cannibalism to maximise in high density clutches in low salinity as a response to egg infections. We thus tested if egg density, salinity and their interaction directly affect filial cannibalism using the common goby (Pomatoschistus microps) as a model system. We additionally recorded male brood care behaviour and weight to account for other potentially salinity-related effects. While males unexpectedly cannibalized more eggs in low density instead of high density clutches, we found that egg consumption was higher in low salinity conditions in agreement with our prediction. Neither male behaviour nor metabolism did adequately explain this finding, indicating that variation in filial cannibalism under different environmental conditions such as salinity may indeed be driven by a differential prevalence of egg infections. During parental care, parents may forgo taking care of their offspring but rather invest in future reproduction. Filial cannibalism, the consumption of one’s own offspring, has often been considered to occur for energetic reasons or as a strategy to reduce investment in less valuable offspring. In this study we specifically test how male brood care behaviour, i.e. egg fanning and filial cannibalism is affected by salinity and egg density (how tightly females decide to place their eggs) in a small marine fish. Our experimental approach is to assess environmental influences and to show their relevance for the evolution and persistence of such a seemingly maladaptive behavioural trait with drastic consequences for fish reproduction. We conclude that variation in filial cannibalism under different environmental conditions such as salinity may indeed be driven by a differential prevalence of egg infections.

Corrigendum: Empirical analysis of the relationship between CC and SLOC in a large corpus of Java methods and C functions published on 9 December 2015

INTRODUCTION During the preparation of the corresponding chapter in Davy Landman's PhD thesis, some minor graphical and statistical discrepancies were found in the paper “Empirical analysis of the relationship between CC and SLOC in a large corpus of Java methods and C functions.” To support future reproduction and use of this work, we prepared the current erratum, containing several updated figures, a diagnosis of the cause of the errors, and an explanation of the effect on the original paper. None of the issues reported in this erratum influence the conclusions of the original paper. ISSUES DISCOVERED The hexagonal scatter plots in Figure lack a more prominent line at CC = 0. This was caused by a bug *reported and confirmed: https://github.com/tidyverse/ggplot2/issues/2061in ggplot, which would filter out data around the limits. The R 2 values in the Tables B and B of the C corpus were off by a maximum of 0.01 from the actual result. The cause was that this table was not re-calculated after fixing a bug in the “remove out-of-scope code” phase. Note that the impact of this error is scattered throughout the paper, as the correlations of Tables and are often repeated for clarity in the remaining sections (for example, the R 2 of the linear model for all the C functions is 0.43 instead of 0.44). Our R code calculating the log-transformed linear fit contained an error. The dashed lines in Figures, and are impacted and the shape of the residual plot in 11. The biggest impact is in Figure, where the original fit seemed to miss the data almost entirely. We misinterpreted this phenomenon in the last sentence of the second paragraph of section 4.4.2; it is not caused by the skewness of the distributions of the two metrics, but rather by the current bug. The custom implementation of the log-scaled y-axis of the residual plots in Figure contained two errors: ∘ The labels on the y-axis were off by a factor 10 ∘For the negative side of the residual plot, we took the absolute, calculated the log10 value, and made it negative again. However, values between 0 and 1 (the values close to the linear fit) turn into a negative value (as log10(1) equals 0). This caused strange outliers in the original plots that were not scrutinized. The fixed residual plots do not have this outliers and look much more like the data in Figure. We republished the data sets related to the current paper on Zenodo to increase their availability: ∘ Landman, Davy. (2015). A Curated Corpus of Java Source Code based on Sourcerer (2015) [Data set]. Zenodo. http://doi.org/10.5281/zenodo.208213 ∘Landman, Davy. (2015). A Large Corpus of C Source Code based on Gentoo packages [Data set]. Zenodo. http://doi.org/10.5281/zenodo.208215 ∘Davy Landman. (2015, February 26). cwi-swat/jsep-sloc-versus-cc. Zenodo. http://doi.org/10.5281/zenodo.293795 NEW IMAGES The remaining part of this erratum contains updated tables and figures as replacements for the original paper. 8 (Figure presented.) Scatter plots of SLOC vs CC zoomed in on the bottom left quadrant. The solid and dashed lines are the linear regression before and after the log transform. The grayscale gradient of the hexagons is logarithmic 4 Correlations for part of the tail of the independent variable SLOC. All correlations have a high significance level p≤1×10 −16.(b) C functions (Table presented.) 5 Correlations for part of the tail of the independent variable SLOC removed. All correlations have a high significance level p≤1×10 −16.(b) C functions (Table presented.) 9 (Figure presented.) Scatter plots of SLOC vs CC on a log-log scale. The solid and dashed lines are the linear regression before and after the log transform. The grayscale gradient of the hexagons is logarithmic 11 (Figure presented.) Residual plot of the linear regressions after the log transform, both axis are on a log scale. The grayscale gradient of the hexagons is logarithmic 12 (Figure presented.) Scatter plots of SLOC vs CC for Java and C files. The solid and dashed lines are the linear regression before and after the log transform. The grayscale gradient of the hexagons is logarithmic.

Zebra finch nestlings, rather than parents, suffer from raising broods under low nutritional conditions

In sexually reproducing species, parents and offspring have different optima in terms of the amount of parental investment. For offspring, higher investment than the parental optimum generally increases their fitness. However, such higher investment will, in theory, result in net parental fitness loss because increased benefits from current offspring will be more than offset by a potential decrease in parental survival or future reproduction. Whether and how parents respond to a shortfall in resources might therefore have important fitness consequences. Here, we manipulate the nutritional condition of captive zebra finch families to investigate how variation in environmental conditions influences parental resource allocation between themselves and their offspring. By allowing the same zebra finch pairs to raise one brood under high and another brood under low nutritional conditions, we found that parents lost more body mass and their offspring grew at slower rates under low nutritional conditions. Therefore, both parents and their offspring were affected by the nutritional treatments. Offspring incurred greater costs, because slower growth rates under low nutritional conditions resulted in an overall lower body mass of nestlings after reaching independence. Nutritional treatments had sex-specific effects on parental body mass, because, in contrast to fathers, only mothers recouped their losses under high nutritional conditions. Furthermore, both parents spent less time brooding their nestlings under low nutritional conditions. Parental strategies hence vary with the nutritional quality of their food, even in captivity, supporting the idea that parental resource allocation may be driven by the expected costs and benefits from current offspring. Parental care is among the most influential traits affecting fitness in many sexually reproducing animals. The more care offspring receive, the higher their chances of survival and reproduction. However, caring for their young does not only provide benefits for parents: all costs of parental care are paid by them. Parental resource allocation is therefore expected to be optimised. But how should parents respond to changing environmental conditions when they are already breeding? By manipulating nutritional conditions in a captive population of zebra finches Taeniopygia guttata, we show that both parents and their offspring lose body mass under low nutritional conditions. The effect on offspring was more pronounced and long lasting, and parents also decreased their parental effort. Our results show plasticity in parental investment of zebra finches in response to nutritional conditions and reproductive value of their offspring.

Simulated moult reduces flight performance but overlap with breeding does not affect breeding success in a long‐distance migrant

Abstract Long‐distance migrants are time‐constrained as they need to incorporate many annual cycle stages within a year. Migratory passerines moult in the short interval between breeding and migration. To widen this interval, moult may start while still breeding, but this results in flying with moulting wings when food provisioning. We experimentally simulated wing gaps in breeding male pied flycatchers by plucking two primary feathers from both wings. We quantified the nest visitations of both parents, proportion of high‐quality food brought to the nestlings and adults and nestlings condition. Differences in oxidative damage caused by a possible reduction in flight efficiency were measured in amounts of ROMs and OXY in the blood. We also measured how flight performance was affected with recordings of the male`s escape flight using high‐speed cameras. Finally, we collected data on adult survival, clutch size and laying date in the following year. “Plucked” males travelled a 5% shorter distance per wingbeat, showing that our treatment reduced flight performance. In line with this, “plucked” males visited their nests less often. Females of “plucked” males, however, visited the nest more often than controls, and fully compensated their partner's reduced visitation rate. As a result, there were no differences between treatments in food quality brought to the nest, adult or chick mass or number of successfully fledged chicks. Males did not differ in their oxidative damage or local survival to the following year. In contrast, females paired with plucked males tended to return less often to breed in the next year in comparison to controls, but this difference was not significant. For the birds that did return, there were no effects on breeding. Our results reveal that wing gaps in male pied flycatchers reduce their flight performance, but when it occurs during breeding they prioritise their future reproduction by reducing parental care. As a result, there is no apparent detriment to their condition during breeding. Because non‐moulting females are able to compensate their partner's reduced care, there is also no immediate cost to the offspring, but females may pay the cost suffering from a reduced survival. A plain language summary is available for this article.

A quadratic correlation between long-term mean group size and group density in a cooperatively breeding passerine.

Both mean group size (MGS) and mean group density (MGD) are critical indices to characterize a population of cooperatively breeding birds. When a population reaches its carrying capacity, both long‐term MGS and long‐term MGD will remain relatively stable. However, there has been little study of how these two variables relate. The Masked laughingthrush Garrulax perspicillatus is a cooperatively breeding bird living in fragmented habitats. During 2010 and 2012‐2016, we used song playback to observe and confirm the group sizes and territory ranges of the birds and the data of bird presence to determine habitat suitability. By grouping the nearest territories according to their geographical coordinates, we divided the whole study area into 12 subareas and the whole population into 12 subpopulations. Then, we calculated both MGS and MGD for different time durations for each subpopulation. Finally, using MGD as independent variable and MGS as the dependent variable, we explored the correlations between MGS and MGD by fitting quadratic functions and modeling quadratic regression. Both MGS and MGD were averaged for different time durations and were cross‐related. Our results show that the MGS for more than 2 years significantly correlated with MGD for more than 3 years in a reverse parabolic shape, differing from that of short‐term effects. Our findings suggest that long‐term MGD is a better predictor of long‐term habitat quality and that long‐term MGS is determined by long‐term habitat quality in Masked Laughingthrushes. Based on above findings, we can infer that: (1) Long‐term habitat quality determines the long‐term MGS, but it sets no prerequisite for the status and source of group members; (2) Long‐term MGS in certain populations is adapted to the corresponding level of long‐term habitat quality, it facilitates us to predict the helper effects on current or future survival or reproduction in different situations. These findings and inferences are both helpful for us to understand the evolution of cooperative breeding.

Maternal allocation of carotenoids increases tolerance to bacterial infection in brown trout.

Life-history theory predicts that iteroparous females allocate their resources differently among different breeding seasons depending on their residual reproductive value. In iteroparous salmonids there is typically much variation in egg size, egg number, and in the compounds that females allocate to their clutch. These compounds include various carotenoids whose functions are not sufficiently understood yet. We sampled 37 female and 35 male brown trout from natural streams, collected their gametes for in vitro fertilizations, experimentally produced 185 families in 7 full-factorial breeding blocks, raised the developing embryos singly (n=2960), and either sham-treated or infected them with Pseudomonas fluorescens. We used female redness (as a measure of carotenoids stored in the skin) and their allocation of carotenoids to clutches to infer maternal strategies. Astaxanthin contents largely determined egg colour. Neither egg weight nor female size was correlated with the content of this carotenoid. However, astaxanthin content was positively correlated with larval growth and with tolerance against P. fluorescens. There was a negative correlation between female skin redness and the carotenoid content of their eggs. Although higher astaxanthin contents in the eggs were associated with an improvement of early fitness-related traits, some females appeared not to maximally support their current offspring as revealed by the negative correlation between female red skin colouration and egg carotenoid content. This correlation was not explained by female size and supports the prediction of a maternal trade-off between current and future reproduction.

Paternal investment with an uncertain future: effects of predator exposure on filial cannibalism and nesting behaviour

Owing to trade-offs between investment in current and future reproduction, factors that diminish a parent's survival prospects, such as predation threat, are expected to increase investment in existing young. Nevertheless, effects of predation risk on parental investment have only rarely been examined, and not at all within the context of filial cannibalism (parental consumption of their own offspring). We examined filial cannibalism and nest characteristics in a small fish with paternal egg care, the sand goby, Pomatoschistus minutus, both when exposed to a common piscivore, the perch, Perca fluviatilis, and in the absence of predators. We found that when males consumed only some of their eggs (partial filial cannibalism), the number of eaten eggs did not depend on predation threat, possibly indicating that partial clutch consumption is largely motivated by benefits to existing young. Total filial cannibalism (whole clutch consumption) was marginally less common under predator exposure, while its strongest predictor was small clutch size. This suggests that the return on parental investment has a greater influence on total filial cannibalism than the likelihood of future breeding. Regarding nest architecture, males that consumed their entire brood after exposure to a predator built larger nest entrances, possibly to facilitate predator evasion. Males that cared for at least part of their brood, however, maintained small nest entrances regardless of predation threat. Furthermore, more elaborate nests were not associated with greater egg consumption, suggesting that filial cannibalism is not employed to sustain nest building.

Extreme allomaternal care and unequal task participation by unmated females in a cooperatively breeding spider

Division of reproductive behaviour and alloparental care are key aspects of many animal societies. In cooperatively breeding species, variation in helping effort and unequal task participation are frequently observed. However, the extent to which the reproductive state of an individual affects the tasks performed during offspring care remains poorly understood. In the social spider Stegodyphus dumicola, approximately 40% of females reproduce, and mothers show extended maternal care including eggsac tending, regurgitation feeding and matriphagy, in which they are consumed by the offspring. We asked whether and to what extent virgin females participate in extreme maternal care and whether they differ from reproducing females in foraging activity. We show that virgin females contributed to all aspects of extended brood care, including regurgitation feeding and matriphagy. This suggests a physiological adaptation in virgin females to cooperative breeding, since in the subsocial Stegodyphus lineatus only mated females provide extended maternal care. Although virgin females and mothers are behaviourally totipotent, we found evidence for task differentiation as virgins engaged less in brood care and more in prey attack than mothers. High relatedness among nestmates and low probability of future reproduction in virgin helpers suggest alignment of reproductive interests between mothers and allomothers. Therefore, extreme allomaternal care by virgin helpers can be considered an adaptation to cooperative breeding in social spiders.

Differential Allocation Revisited: When Should Mate Quality Affect Parental Investment?

Differential allocation (DA) is the adaptive adjustment of reproductive investment (up or down) according to partner quality. A lack of theoretical treatments has led to some confusion in the interpretation of DA in the empirical literature. We present a formal framework for DA that highlights the nature of reproductive benefits versus costs for females mated to males of different quality. Contrary to popular belief, analytical and stochastic dynamic models both show that additive benefits of male quality on offspring fitness have no effect on optimal levels of female investment and thus cannot produce DA. Instead, if offspring fitness is affected multiplicatively by male quality, or male quality affects the female cost function, DA is expected because of changes in the marginal benefits or costs of extra investment. Additive male quality effects on the female cost function can cause a novel form of weak DA, because reduced costs can slightly favor current over future reproduction. Combinations of these distinct effects in more realistic model scenarios can explain various patterns of positive and negative DA reported for different species and mating systems. Our model therefore sheds new light on the diversity of empirical results by providing a strong conceptual framework for the DA hypothesis.

Sociodemographic variation in foraging behavior and the adaptive significance of worker production in the facultatively social small carpenter bee, Ceratina calcarata

Provisioning for young offspring is an archetypical form of parental investment. Ceratina calcarata bees provide extended maternal care to their young and demonstrate an unusual strategy of dual-phase pollen provisioning. Most bees first gather provisions as they establish nests in spring. However, C. calcarata mothers will also feed their newly eclosed young a second time, perhaps ensuring their survival during a long winter diapause. Some mothers rear a small, worker-like daughter to assist them during this second provisioning phase. We studied provisioning behavior in C. calcarata to examine patterns of maternal investment and foraging dynamics throughout the breeding season. Mothers typically made a high number of short-duration foraging trips each day, whereas late-season females tended to make fewer and longer trips. This difference in foraging duration may indicate a lower risk of brood loss in those nests where mature offspring are present. Nest demographic data revealed that an offspring laid in the first brood cell position is typically female and usually smaller than her siblings. In 29% of the nests, this small daughter was observed to adopt a forager role at maturity and provisioned for her siblings. Dwarf daughters had a higher number of active days and foraging trips per day in orphaned nests than in nests where a mother was present. The foraging behaviors of worker-like daughters were similar in length of foraging trip and handling time to mothers during this second provisioning period. We hypothesize that incipiently social foraging by this smallest daughter may act as a form of insurance against brood loss during occasions when a mother is unable to sufficiently provision for her eclosed offspring during the second phase. Parental investment in the size and sex of offspring is under strong selection for assured fitness returns. For example, many social insect mothers make an initial investment in small offspring to take on risky foraging behavior while they specialize on future reproduction. Solitary and facultatively social species provide an important baseline to understand the evolution of social complexity from natural variation in maternal care and foraging behavior. Here, we characterize the parental investment strategies of a subsocial small carpenter bee and reveal the potential adaptive significance of prolonged maternal care and worker production in this species. Mothers provide an initial investment that is extended by workers providing alloparental care to siblings. Maternal manipulation of dwarf eldest daughters may serve as an insurance mechanism in the event of maternal mortality to assure the survival of siblings.

Comparative analyses of life-history strategies in Asiatic and African wild asses using a demographical approach

Abstract. Trade-offs such as the ones between reproduction and longevity or present and future reproduction are believed to shape reproductive patterns. We here used zoo data to investigate trade-offs and life histories in four taxa of Asiatic (Equus hemionus ssp.) and African wild asses (Equus africanus ssp.). All taxa showed even in captivity peak birth rates during the periods of highest food availability in their natural environments. Sex-specific survival rates with females living longer than males were evident in kulan and onager but not in kiang and Somali wild ass, pointing towards different life-history strategies even among closely related taxa. Females achieved their highest reproductive output earlier in life than males, which is typical for polygynous mating systems. Offspring number and longevity were positively rather than negatively correlated. Taken together evidence for reproductive trade-offs was weak, though the length of the reproductive period was negatively related to birth rates wi...

Feeding upon and preserving a carcass: the function of prehatch parental care in a burying beetle

Parental care must respond to variation in environmental challenges and some of these challenges result from the altered niche during the evolution of care. One important variable is the quality of the resources for young. Burying beetles prepare small, vertebrate carcasses in varying states of decay as food for their young by removing hair, rounding and applying antimicrobial secretions. The present study examined carcass preparation (prehatch care), an elaborate behaviour whose benefits have been surprisingly difficult to demonstrate. Benefits were assessed by comparing brood success when a parent completed care using a fully prepared carcass or when using a substitute, same-age carcass that had not been prepared by a parent. The outcome was very different depending on whether the substitute carcass was intact (no holes) or had simulated feeding holes that a parent would normally make during the prehatch period. When Nicrophorus orbicollis utilized a prepared carcass, the brood mass was no greater than when using an intact, nonprepared carcass. When the substituted nonprepared carcass had simulated feeding holes, however, a prepared carcass resulted in a greater brood mass and heavier larvae on both fresh and aged carcasses. The importance of attending to holes opened in the carcass was clear from the rapid repair of experimentally introduced holes. While offspring fared worse when developing on an aged carcass, the parent's future reproduction and longevity were not compromised, suggesting that parents protect their future reproduction in a challenging environment. It is hypothesized that a primary benefit of resource handling in burying beetles is to minimize microbial activity at holes the parent must make in the carcass, a need that was amplified as carrion beetles evolved to breed on small, preempted carcasses without fly larvae as a nutritional resource.

Flexibility in the duration of parental care: Female leopards prioritise cub survival over reproductive output.

Deciding when to terminate care of offspring is a key consideration for parents. Prolonging care may increase fitness of current offspring, but it can also reduce opportunities for future reproduction. Despite its evolutionary importance, few studies have explored the optimal duration of parental care, particularly among large carnivores. We used a 40-year dataset to assess the trade-offs associated with the length of maternal care in leopards in the Sabi Sand Game Reserve, South Africa. We compared the costs imposed by care on the survival and residual reproductive value of leopard mothers against the benefits derived from maternal care in terms of increased offspring survival, recruitment and reproduction. We also examined the demographic and ecological factors affecting the duration of care in the light of five explanatory hypotheses: litter size, sex allocation, resource limitation, timing of independence and terminal investment. Duration of care exhibited by female leopards varied markedly, from 9 to 35months. Mothers did not appear to suffer any short- or long-term survival costs from caring for cubs, but extending care reduced the number of litters that mothers could produce during their lifetimes. Interestingly, the duration of care did not appear to affect the post-independence survival or reproductive success of offspring (although it may have indirectly affected offspring survival by influencing dispersal distance). However, results from generalised linear mixed models showed that mothers prolonged care during periods of prey scarcity, supporting the resource limitation hypothesis. Female leopards also cared for sons longer than daughters, in line with the sex-allocation hypothesis. Cub survival is an important determinant of the lifetime reproductive success in leopards. By buffering offspring against environmental perturbation without jeopardising their own survivorship, female leopards apparently "hedge their bets" with current offspring rather than gamble on future offspring which have a small probability of surviving. In many species, parents put their own needs before that of their offspring. Leopard mothers appear sensitive to their offspring's demands, and adjust levels of care accordingly.

When earwig mothers do not care to share: Parent–offspring competition and the evolution of family life

AbstractKin competition often reduces – and sometimes entirely negates – the benefits of cooperation among family members. Surprisingly, the impact of kin competition on the fitness effects of family life only received close scrutiny in studies on sibling rivalry, whereas the possibility of parent–offspring competition has attracted much less attention. As a consequence, it remains unclear whether and how parent–offspring competition could have affected the early evolution of parental care and family life.Here, we examined the occurrence and consequences of parent–offspring competition over food access in the European earwigForficula auricularia, an insect with facultative family life reminiscent of an ancestral state. Specifically, we (1) raised earwig offspring under food limitation either together with or without their mother, and (2) tested whether and how the — potentially competitive — weight gains of mothers and offspring during family life affected the offsprings' survival rate and morphology, and the future reproductive investment of their mother.In line with the occurrence of parent–offspring competition, we showed that high maternal weight gains during family life reduced the survival prospects of maternally tended offspring, while they increased the mothers' investment into the production of a second clutch (but not the body size of the surviving offspring). Conversely, high offspring weight gains generally increased the offsprings' survival, but did so to a larger extent when they were together with their mother. Intriguingly, mothers that had exhibited a low initial weight showed especially high weight gains.Overall, our results demonstrate that maternal presence under food restriction triggered a local competition between mothers and their offspring. This competition limited offspring survival, but allowed mothers to increase their investment into future reproduction and/or to maintain their current body condition. On a general level, our findings reveal that parent–offspring competition can counteract the benefits of (facultative) parental care, and may thus impede the evolution of family life in resource‐poor environments.Aplain language summaryis available for this article.

High reproductive effort is associated with decreasing mortality late in life in captive ruffed lemurs.

Evolutionary theories of senescence predict that a high allocation to reproduction during early life should have long-term deleterious consequences on future reproduction or survival because individuals have to face an energy allocation trade-off between reproductive effort and the maintenance of body condition. Using a high-quality dataset from 1,721 red ruffed lemurs (RRL, Varecia rubra) and 3,637 black and white ruffed lemurs (BWRM, V. variegata) living in captivity, we tested the existence of a trade-off between reproductive effort and late-life survival after accounting for possible confounding effects of natal environmental conditions. We report clear evidence of actuarial senescence (i.e., the decline of annual survival with increasing age) in both sexes and for both species of ruffed lemurs. RRL had a lower baseline mortality and senesced faster than BWRL, resulting in similar distributions of longevities for both species. No between-sex difference was observed in any species. Lastly, a higher reproductive effort was positively associated with an increase of survival late in life, and thereby an increased longevity. These findings indicate that individual quality rather than trade-off drives the association between reproductive success and survival pattern among individual lemurs of both species in the protected environment provided by zoos. Lemurs are among the world's highest conservation priorities and better understanding factors influencing their longevity and actuarial senescence patterns should improve their conservation.

Parental Risk-Taking at Natural Northern Bobwhite Nests

Parental risk-taking at the nest is critical to examining the trade-offs between current and future reproduction. Using Northern Bobwhites ( Colinus virginianus) at camera-monitored nests in the natural environment, we examined how parental and offspring characteristics, predator community, and predator type affected flush distance of incubating birds to approaching predators. During 1999–2006, we monitored 118 predation interactions at nests at two pairs of study sites in southern Georgia and northern Florida, USA where mesomammalian predators were experimentally reduced or not reduced. The results showed that incubating parent birds allowed closer approaches by predators that typically only consumed eggs ( e.g. Nine-banded Armadillos Dasypus novemcinctus, Virginia Opossums Didelphis virginiana, and snakes) than by predators that could harm the adults (including Bobcats Lynx rufus and Raccoons Procyon lotor) prior to flushing from the nest. Our data did not support the hypotheses that parent-offspring characteristics and predator community affect parental risk-taking at the nest. Our findings suggest that parent birds incorporate information about predator identity over parental and offspring characteristics or predator community into anti-predator decisions at the nest in systems with high predation risk.

Young females pay higher costs of reproduction in a short-lived bird

Theory predicts a trade-off between current reproduction and future reproduction or survival. Nevertheless, costs of reproduction are often not found owing to heterogeneity in environment or individuals, or to studies not evaluating multiple costs or reproductive metrics that could influence costs. Detecting costs of reproduction is further complicated by the fact that they may increase with age if physiological condition declines in older individuals, or decrease with age if younger individuals are less efficient at acquiring resources than older individuals. We used a 37-year study to evaluate costs of reproduction in song sparrows (Melospiza melodia). Our results support theoretical expectations for short-lived species by demonstrating costs of reproduction on future survival, but not on future reproduction. We examined two metrics of reproductive allocation—reproductive effort and termination of breeding—and found that only higher reproductive effort increased costs. Thus, testing of multiple allocation metrics may be necessary because results may not be coincident between metrics. Lastly, we observed that younger females paid higher costs of reproduction than older females. Although older female sparrows senesced, they had lower costs of reproduction than younger females who may be less able to acquire food or high-quality mates. By taking into account variation among individuals and examining multiple metrics, our study provides strong support for costs of reproduction and a decrease in costs with age. One premise of life history theory is that reproduction is costly, but evidence of such costs remains mixed. Mixed results may arise because resources are not always limiting for all individuals or in all environments, leading to temporal, spatial, and individual heterogeneity in trade-offs between current reproduction and future reproduction or survival that can be hard to detect. Costs may also vary with age, depending on how resource acquisition and allocation vary with age. We used a 37-year study of female song sparrows (Melospiza melodia) to control statistically for individual and environmental heterogeneity and test multiple cost metrics. We demonstrate marked costs of reproduction on future survival, particularly in young females.

Does specific demographic education change young people’s opinions about reproduction? The case of Serbia

Population education is one of the strategic measures to encourage giving birth in low-fertility Serbia. The expected result is that such education may have an effect on reproductive intentions and overall people behavior. This study explores the thoughts about reproduction of three different student groups from the University of Belgrade, whereas their specific knowledge about demography ranges from basic to very good. The intention was to clarify whether awareness and knowledge about demographic problems change attitudes on reproduction of future highly educated people. The study was performed via a survey that was conducted among: Demography students, who have studied demographic phenomena for at least 3 years, students who have taken only one course in demography during their studies and students who have not acquainted themselves with demographics throughout their studies. It is based on the students’ views of ideal, desired and expected family size, on an evaluation of factors that affect reproduction, on identifying other beliefs relevant for future reproduction, as well as on a discussion with Demography students. Demographic education did not show to be an essential factor of differentiating reproductive norms of students. “Collective rationality” and a reflection of the economic crisis on reproductive intentions are dominant student responses.

Advanced auricular prosthesis development by 3D modelling and multi-material printing

We investigate the use of medical imaging, digital design and 3D printing technologies as a viable means of reproducing a person’s anatomy, with the intension of producing a working, patient specific prosthesis. This approach offers several advantages over traditional techniques, as data capture is non-intrusive, models can be made using quantitative methodologies, design iterations can be digitally stored for future reproduction, and additive manufacturing ensures no loss of quality when converting the digital model into a physical part. We also present a combined model segmentation with multi-material printing approach to increase the colour complexity of the final model. When combined with multi-material printing using elastic materials, our approach provides a comprehensive strategy to accurately realising mimic of both skin pigmentation and the tactile feel of human tissues. Ultimately, we believe our approach provides an innovative strategy for prosthesis production which could have considerable potential for implementation in a clinical setting.