Variation In Reproductive Investment Research Articles

Why are larger fish farther upstream? Testing multiple hypotheses using Silver Chub in two Midwestern United States riverscapes

AbstractObjectiveThree competing hypotheses might explain the widely documented intrapopulation larger‐fish‐upstream phenomenon. The age‐phased recruitment hypothesis posits that fish spawn downstream and move upstream as they age and grow, the static population with growth and mortality gradients hypothesis posits that fish spawn throughout a riverscape and growth is greater upstream while recruitment is greater downstream, and the colonization cycle hypothesis posits that fish spawn upstream, larvae drift downstream, and individuals move upstream as they age and grow.MethodsWe tested for the larger‐fish‐upstream pattern using populations of Silver Chub Macrhybopsis storeriana in the Arkansas and Ohio rivers, as well as investigated longitudinal variation in reproductive investment (Arkansas River), age structure for adult fish (Arkansas River), and number and occurrence of age‐0 fish (Ohio River).ResultThe larger‐fish‐upstream pattern was temporally persistent in both riverscapes. In the Arkansas River, reproductive investment was greatest upstream, where initiation of spawning likely occurred based on gonadosomatic indices. Adult fish were most numerous in the Arkansas River 125–175 km upstream from Kaw Reservoir, with age‐2 fish numbers peaking farther upstream compared with age‐1 fish. In the Ohio River, age‐0 fish counts increased downstream and were rare among the shortest river fragments (<100 km) between lock‐and‐dam structures. These findings are inconsistent with the age‐phased recruitment hypothesis based on upstream spawning in the Arkansas River and inconsistent with the static population with growth and mortality gradients hypothesis based on virtual absence of age‐2 fish downstream (Arkansas River) and age‐0 fish upstream (Ohio River). The most likely explanation for longitudinal variation in Silver Chub size distribution is downstream drift of ichthyoplankton followed by net upstream movement (i.e., colonization cycle hypothesis), but formal assessments of movement and ova characteristics require more research.ConclusionManaging multidimensional riverscapes requires insight into the mechanisms that regulate upstream‐to‐downstream patterns in fish populations, and our work underscores a potential size‐related benefit to maintaining broadscale longitudinal connectivity.

Breeding biology of the African Pygmy Falcon: long-term variation and seasonal decline in breeding performance of an arid zone raptor

Birds of prey are apex predators and understanding their life history can serve as a valuable baseline for investigating their ecological role. Pygmy Falcons (Polihieraxsemitorquatus), Africa’s smallest diurnal raptor, have evolved to be obligate associates of Sociable Weaver (Philetairussocius) colonies throughout their southern African range. As a predator, Pygmy Falcons likely impact prey communities in this system including their host and other colony associates. However, no study has explored their breeding biology in detail using long-term data. We provide results from 10 years of data collected between 2011 and 2020. We followed 66 unique Pygmy Falcon territories and 323 breeding attempts in the Kalahari, South Africa. We explored annual variation in the population density of Pygmy Falcons and investigated between- and within-season variation in reproductive investment and output. The highest average density was recorded in 2015 and the lowest in 2019 and 2020. Our results show that the breeding occurs between early austral spring (August) and late summer (February), with a peak from September to December. The maximum and most frequent clutch size was three eggs and falcons usually initiated only one breeding attempt (but up to three) in a season. The incubation and nestling periods lasted on average 33 (±SD 4) and 37 (± 5) days, respectively. A three-egg clutch size and number of fledglings produced varied between seasons, and breeding success showed a seasonal decline across the breeding season. Falcons were 7 times less likely to lay a 3-egg clutch in 2019 than in 2011 and 2012, and breeding attempts initiated in September were 3.4 times more likely to be successful than those initiated in November. Predation accounted for 49.5% of breeding failures. Our results show significant variation in the breeding parameters of these falcons, but further studies are needed to understand what drives these variations.

Geographic variation in reproductive investment of seven populations of male Brown frog (Rana kukunoris), endemic to the eastern Tibetan Plateau

Abstract Life-history theory suggests that male anurans living in harsh and unpredictable environmental conditions (e.g., low temperature and/or high seasonality) should decrease reproductive investment because of short periods of activity and poor productivity. Although geographic variations in female life-history traits have been investigated intensively across a wide range of taxa, similar studies in males have been scarce. Here, we examined geographic variation in male testis mass of the brown frog (Rana kukunoris) across seven different altitudes on the eastern Tibetan plateau, and tested the hypothesis that relative size of testis mass should increase with increasing temperature and/or decreasing seasonality. In this study, we found male body condition, age and testis mass did not increase with temperature and temperature seasonality, which do not conform to our previous hypothesis, revealing that differences in temperature and temperature seasonality across populations could not drive the evolution of testis size. However, we found a positive correlation between testis mass and body condition or age when controlling for population and the effect of temperature and temperature seasonality, indicative of a condition-dependent expression of testis size. In addition, a correlation between testis mass and operational sex ratio was not significant, suggesting that male–male competition did not lead to increasing levels of sperm competition.

Genetic Variation in Reproductive Investment Across an Ephemerality Gradient in Daphnia pulex.

Species across the tree of life can switch between asexual and sexual reproduction. In facultatively sexual species, the ability to switch between reproductive modes is often environmentally dependent and subject to local adaptation. However, the ecological and evolutionary factors that influence the maintenance and turnover of polymorphism associated with facultative sex remain unclear. We studied the ecological and evolutionary dynamics of reproductive investment in the facultatively sexual model species, Daphnia pulex. We found that patterns of clonal diversity, but not genetic diversity varied among ponds consistent with the predicted relationship between ephemerality and clonal structure. Reconstruction of a multi-year pedigree demonstrated the coexistence of clones that differ in their investment into male production. Mapping of quantitative variation in male production using lab-generated and field-collected individuals identified multiple putative quantitative trait loci (QTL) underlying this trait, and we identified a plausible candidate gene. The evolutionary history of these QTL suggests that they are relatively young, and male limitation in this system is a rapidly evolving trait. Our work highlights the dynamic nature of the genetic structure and composition of facultative sex across space and time and suggests that quantitative genetic variation in reproductive strategy can undergo rapid evolutionary turnover.

Effect of body size, age and timing of breeding on clutch and egg size of female Eastern Gray Treefrogs, Hyla versicolor

Abstract Information on how organisms allocate resources to reproduction is critical for understanding population dynamics. We collected clutch size (fecundity) and egg size data of female Eastern Gray Treefrogs, Hyla versicolor, and examined whether observed patterns of resource allocation are best explained by expectations arising from life history theory or by expected survival and growth benefits of breeding earlier. Female Hyla versicolor showed high between-individual variation in clutch and egg size. We did not observe maternal allocation trade-offs (size vs number; growth vs reproduction) predicted from life history theory, which we attribute to the large between-female variation in resource availability, and the low survival and post-maturity growth rate observed in the study population. Rather, clutches are larger at the beginning of the breeding season, and this variation in reproductive investment aligns with seasonal variation in ecological factors affecting offspring growth and survival.

Individual heterogeneity in fitness in a long-lived herbivore.

Heterogeneity in the intrinsic quality and nutritional condition of individuals affects reproductive success and consequently fitness. Black brant (Branta bernicla nigricans) are long‐lived, migratory, specialist herbivores. Long migratory pathways and short summer breeding seasons constrain the time and energy available for reproduction, thus magnifying life‐history trade‐offs. These constraints, combined with long lifespans and trade‐offs between current and future reproductive value, provide a model system to examine the role of individual heterogeneity in driving life‐history strategies and individual heterogeneity in fitness. We used hierarchical Bayesian models to examine reproductive trade‐offs, modeling the relationships between within‐year measures of reproductive energy allocation and among‐year demographic rates of individual females breeding on the Yukon‐Kuskokwim Delta, Alaska, using capture–recapture and reproductive data from 1988 to 2014. We generally found that annual survival tended to be buffered against variation in reproductive investment, while breeding probability varied considerably over the range of clutch size‐laying date combinations. We provide evidence for relationships between breeding probability and clutch size, breeding probability and nest initiation date, and an interaction between clutch size and initiation date. Average lifetime clutch size also had a weak positive relationship with apparent survival probability. Our results support the use of demographic buffering strategies for black brant. These results also indirectly suggest associations among environmental conditions during growth, fitness, and energy allocation, highlighting the effects of early growth conditions on individual heterogeneity, and subsequently, lifetime reproductive investment.

Variation in reproductive investment increases body temperature amplitude in a temperate passerine

Many birds and mammals show substantial circadian variation in body temperature, which has been attributed to fluctuations in ambient temperature and energy reserves. However, to fully understand the variation in body temperature over the course of the day, we also need to consider effects of variation in work rate. We made use of a dataset on body temperature during the resting and active periods in female marsh tits (Poecile palustris) that bred in a temperate area and were subjected to experimental changes in reproductive investment through brood size manipulations. Furthermore, the amplitude increased with daytime, but were unaffected by nighttime, ambient temperature. Amplitudes in females with manipulated broods were 44% above predictions based on inter-specific allometric relationships. In extreme cases, amplitudes were > 100% above predicted values. However, no individual female realised the maximum potential amplitude (8.5 °C, i.e. the difference between the highest and lowest body temperature within the population) but seemed to prioritise either a reduction in body temperature at night or an increase in body temperature in the day. This suggests that body temperature amplitude might be constrained by costs that preclude extensive use of both low nighttime and high daytime body temperatures within the same individual. Amplitudes in the range found here (0.5–6.7 °C) have previously mostly been reported from sub-tropical and/or arid habitats. We show that comparable values can also be found amongst birds in relatively cool, temperate regions, partly due to a pronounced increase in body temperature during periods with high work rate.

Variation in Reproductive Investment among Ohio Reservoir Largemouth Bass Populations

AbstractReproductive investment, expressed in terms of fecundity and egg quality produced by individual female fish, varies among populations for many species, reflecting plasticity in life history strategies related to intraspecific density dependence or environmental variability. Fisheries scientists and managers have long sought to understand differences in Largemouth Bass Micropterus salmoides population dynamics, yet basic life history traits, such as variation in reproductive investment, remain largely unknown. We determined the fecundity–weight and ovary energy density–weight relationships (where fecundity indexes egg quantity and ovary energy density indexes egg quality) for Largemouth Bass populations from 19 Ohio reservoirs and examined factors that were correlated with population‐specific differences. We found that both relationships varied among reservoir populations, with some interannual variation in reservoirs sampled in multiple years. We then related fecundity and ovary energy density to (1) population characteristics, including population density (as indexed by standard shoreline boat electrofishing CPUE, fish/h) and growth (as indexed by the growth coefficient k from the von Bertalanffy growth function); and (2) reservoir characteristics, including reservoir size (as surface area) and productivity (as Secchi transparency depth). We found that populations with greater fecundity also exhibited greater ovary energy density, indicating that the quantity and quality of reproductive output were greater in some populations than in others. Populations with high reproductive investment were associated with low Largemouth Bass density, fast growth, large reservoir size, and high productivity (i.e., low Secchi transparency). The among‐population variation in reproductive investment provides evidence of density‐dependent control of fecundity and egg quality.

Winter corticosterone and body condition predict breeding investment in a nonmigratory bird

Abstract Reproduction is an energetically demanding life history stage that requires costly physiological and behavioral changes, yet some individuals will invest more into reproduction and breed more successfully than others. To understand variation in reproductive investment, previous studies have evaluated factors during breeding, but conditions outside of this life history stage may also play a role. Using a free-ranging population of black-capped chickadees (Poecile atricapillus), we assessed the repeatability of plastic traits relating to energetic condition (circulating initial corticosterone concentrations and body condition) during the nonbreeding season and evaluated whether these traits predicted reproductive investment in the subsequent breeding season. We found that initial corticosterone concentrations and an index of body condition, but not fat score, were moderately repeatable over a 1-week period in winter. This trait repeatability supports the interpretation that among-individual variation in these phenotypic traits could reflect an intrinsic strategy to cope with challenging conditions across life history stages. We found that females with larger fat reserves during winter laid eggs sooner and tended to spend more time incubating their eggs and feeding their offspring. In contrast, we found that females with higher residual body mass delayed breeding, after controlling for the relationship between fat score and timing of breeding. Additionally, females with higher initial corticosterone in winter laid lighter eggs. Our findings suggest that conditions experienced outside of the breeding season may be important factors explaining variation in reproductive investment.

Age-Specific Reproductive Investment and Offspring Performance in an Orb-web Spider, Argiope radon

Temporal variation in reproductive investment, e.g. maternal egg provisioning, has a substantial effect on offspring fitness therefore has received great attention by evolutionary biologists. Maternal allocation into egg size and egg content directly influences performance of offspring in many taxa, but spiders have rarely been investigated in this regard. In this study, we investigate the temporal changes in maternal reproductive investment and offspring performance in an orb-web, Argiope radon. A group of male and female spiders were mated randomly in the laboratory. Female spiders were kept under standard condition until they laid egg sacs. For each egg sac, egg sac mass, egg size and egg protein content were measured across all egg sacs. Once the spiderlings emerged, emerging time and toleration to starvation of the spiderlings were recorded. Egg sacs laid early in life were heavier, have larger eggs and offspring emerge sooner than the egg sacs laid by the old females. The spiderlings from the early egg sacs were more likely to emerge, however, these offspring had less toleration to starvation than the egg sacs laid by old females. There was no significant correlation between egg size and egg protein content with offspring performance. The results showed how the female spiders strategically allocate resources to egg sacs and its consequences on the offspring emerging time and toleration to starvation. This study suggests an adaptive maternal reproductive investment strategy which allows the female spiders to gain maximum fitness in each reproductive bout.

Higher rates of prebreeding condition gain positively impacts clutch size: A mechanistic test of the condition‐dependent individual optimization model

Abstract A combination of timing of and body condition (i.e., mass) at arrival on the breeding grounds interact to influence the optimal combination of the timing of reproduction and clutch size in migratory species. This relationship has been formalized by Rowe et al. in a condition‐dependent individual optimization model (American Naturalist, 1994, 143, 689‐722), which has been empirically tested and validated in avian species with a capital‐based breeding strategy. This model makes a key, but currently untested prediction; that variation in the rate of body condition gain will shift the optimal combination of laying date and clutch size. This prediction is essential because it implies that individuals can compensate for the challenges associated with late timing of arrival or poor body condition at arrival on the breeding grounds through adjustment of their life history investment decisions, in an attempt to maximize fitness. Using an 11‐year data set in arctic‐nesting common eiders (Somateria mollissima), quantification of fattening rates using plasma triglycerides (an energetic metabolite), and a path analysis approach, we test this prediction of this optimization model; controlling for arrival date and body condition, females that fatten more quickly will adjust the optimal combination of lay date and clutch size, in favour of a larger clutch size. As predicted, females fattening at higher rates initiated clutches earlier and produced larger clutch sizes, indicating that fattening rate is an important factor in addition to arrival date and body condition in predicting individual variation in reproductive investment. However, there was no direct effect of fattening rate on clutch size (i.e., birds laying on the same date had similar clutch sizes, independent of their fattening rate). Instead, fattening rate indirectly affected clutch size via earlier lay dates, thus not supporting the original predictions of the optimization model. Our results demonstrate that variation in the rate of condition gain allows individuals to shift flexibly along the seasonal decline in clutch size to presumably optimize the combination of laying date and clutch size. A plain language summary is available for this article.

Reproductive Investment and Health Costs in Roma Women.

In this paper, we examine whether variation in reproductive investment affects the health of Roma women using a dataset collected through original anthropological fieldwork among Roma women in Serbia. Data were collected in 2014–2016 in several Roma semi-urban settlements in central Serbia. The sample consisted of 468 Roma women, averaging 44 years of age. We collected demographic data (age, school levels, socioeconomic status), risk behaviors (smoking and alcohol consumption), marital status, and reproductive history variables (the timing of reproduction, the intensity of reproduction, reproductive effort and investment after birth), in addition to self-reported health, height, and weight. Data analyses showed that somatic, short-term costs of reproduction were revealed in this population, while evolutionary, long-term costs were unobservable—contrariwise, Roma women in poor health contributed more to the gene pool of the next generation than their healthy counterparts. Our findings appear to be consistent with simple trade-off models that suggest inverse relationships between reproductive effort and health. Thus, personal sacrifice—poor health as an outcome—seems crucial for greater reproductive success.

Drivers of tree fecundity in pedunculate oak (Quercus robur) refugial populations at the species' southwestern range margin.

The current low latitudinal range margins of many extra-tropical plant species consist of small and scattered populations that persist locally in microrefugia. It remains poorly understood how their refugial distribution affects mating patterns and reproductive success. Here we examine flower and acorn production and their determinants in refugial populations of the widespread European forest tree pedunculate oak (Quercus robur). We monitored male flower, female flower and acorn production in 159 adult trees from 12 oak stands over 2years. We related these and derived parameters to a series of ecological and genetic predictor variables extrinsic (stand size, density and isolation as well as elevation, topography and forest cover) or intrinsic (size, phenology and several genotypic measures) to the target tree. Tree fertility was unrelated to extrinsic factors but determined by tree size, although we detected size-independent variation in reproductive investment. Female flower number accurately predicted acorn crop size. Fruit set differed between years, evidencing the existence of pollen limitation at the landscape but not at the local scale. Fruit setalso tended to increase with the number of mates of the target tree. We detected no other evidence for genetic constraints on mating. Reproduction was triggered by a combination of small-scale and landscape-scale drivers. Although short-distance mating prevailed, limited pollen flow did not appear to significantly constrain reproductive success. The high intrinsic ability of populations to maintain their reproductive capacity may help explain their successful long-term persistence in an adverse broader environment.

Geographical variation in reproductive investment across avian assemblages in Europe: effects of environmental drivers differ between altricial and precocial species

Reproductive traits provide information about the ways by which available resources are allocated during breeding. We tested for environmental drivers of large scale geographical patterns in assemblage mean clutch size, number of broods and overall reproductive investment per breeding season in European birds. We combined data about geographical distribution with published information about reproductive traits, and calculated mean trait values for avian assemblages occurring in 50 × 50 km grid cells. In total, we employed data from 499 species and 2059 assemblages. As the time available for breeding and the amount of food limit the reproductive effort, we related the geographical variation in reproductive traits to the length of breeding season, normalized difference vegetation index (NDVI) as a surrogate of resource availability, and its seasonality. Geographical patterns in traits may differ between reproductive modes, thus we performed the analyses separately for altricial Passerines (n = 203) and precocial non‐passerine species (n = 164) and controlled for the effect of taxonomy. Large clutches dominated in areas with high NDVI and, in precocial birds, also in areas with high annual seasonality and a long breeding season. High number of broods and high overall reproductive investment dominated in areas with a long breeding season, and high number of broods was found also in areas with low annual seasonality, but only in precocial species. High overall reproductive investment dominated in highly productive areas and also in areas with low annual seasonality in both groups. The increase in reproductive investment is caused mostly by an increase in the number of broods related to the length of season and partly by increase in clutch size related to NDVI. We found a negative correlation between clutch size and the number of broods in Passerines, which might suggest a trade‐off between these traits. Processes behind trait patterns differ between altricial and precocial species.

Reproductive investment and multiple spawning evidence in the redfinger rubble crab Eriphia gonagra (Brachyura, Eriphioidea)

Abstract The variation in reproductive investment (RI) and the hypothesis of multiple spawning were evaluated in the redfinger rubble crab Eriphia gonagra (Fabricius, 1781). The gonads and embryos showed synchronous development, and fecundity and RI varied widely among females of the same size class. The mean RI value recorded was 11.31%, with no significant differences among the means for different size classes. The allometric analysis of fecundity indicated RI decrease while body size increase, but we suggested that this occurs due to size overestimation where the largest width of carapace was used as body size reference in these analyzes. In addition, we found an isometric relationship for “female weight vs. egg number”, and also for “female weight vs. egg weight”, indicating that RI ​​increased proportionally with size of females. Relatively high frequencies both of smaller females with rudimentary gonads, and of larger females with developed gonads were observed. This indicates that larger females take place more frequently in the population reproductive output over time. This difference could not be observed by means of RI analyses of captured and fixed crabs, for which only one stage of gonad development and/or one spawning is usually recorded.

Weather Mediated Impacts on the Breeding Output of an Afro-Palearctic Migratory Waterbird

Understanding the consequences of changing environmental conditions on the demographic parameters of migratory species is key for addressing the widely reported declines for many of these species. We explore the variation in reproductive investment and output of Purple Herons ( Ardea purpurea) in two breeding seasons, with very different precipitation levels but similar temperatures. Despite similar investment in egg volume, reproductive output in the drier year was less than half of the wetter year (∼1.9 vs ∼4.1 chicks per pair) due to weather mediated higher predation. The current predictions of erratic precipitation and warming may threaten the breeding output of waterbirds, if water levels are unsuitable during the breeding season.

Altitudinal variation in male reproductive investment in a polyandrous frog species (Hyla gongshanensis jingdongensis)

Competition for fertilization in multi-male group spawning can drive variation in male reproductive investment (i.e., testis mass and sperm size). Inter-population comparisons of variation in energetic availability and allocation along geographical gradients allow insights into the mechanisms shaping the reproductive investments of animals. Although inter-population differences in female reproductive investment (i.e., clutch size and egg size) have been studied extensively across a wide range of taxa, little information on variation in reproductive investment in males is available. Here, we studied altitudinal variation in testis mass and sperm length among three populations in the Jingdong tree frog (Hyla gongshanensis jingdongensis), a polyandrous species, in Yunnan Province in China. The results showed that individuals exhibited smaller testes at higher altitudes while testes mass was positively correlated with body size, body condition and age. Longer sperm length was observed in the middle-altitude population. Moreover, we found that sperm number was positively correlated with testes mass and sperm length. Our correlational findings suggest that environmental constraints at high altitude select for less investment in testes and offspring number.

Elevation‐Related Differences in Parental Risk‐Taking Behavior are Associated with Cognitive Variation in Mountain Chickadees

AbstractBreeding animals must balance their current reproductive effort with potential costs to their own survival and consequently to future reproduction. Life‐history theory predicts that variation in reproductive investment should be based on fecundity and life expectancy with longer‐lived species favoring their own survival over parental investment. Recently, variation in parental risk taking was also linked with differences in cognition suggesting a potential trade‐off between cognitive ability and risk taking. Here, we tested whether mountain chickadees from two different elevations with known differences in cognitive ability differ in their parental risk taking by comparing the responses of nesting birds to a potential predator. Higher elevations are associated with shorter breeding season limiting renesting opportunities, but chickadees at high elevations also have better cognitive abilities, which might be potentially associated with better survival. Compared to lower elevations, high‐elevation chickadees laid larger clutches, showed longer latencies to return to the nest in the presence of a hawk, had lower fledging success, and exhibited higher rate of complete nest failures. Nestling development among successful nests, however, was similar between elevations. These data are not consistent with life‐history hypothesis because birds at high elevation invest more in the clutch, while at the same time take less risk when facing potential danger to themselves, which could jeopardize their current reproductive success. These data, however, are consistent with the hypothesis that better cognitive abilities might be associated with less parental risk taking.

Within-plant variation in reproductive investment: consequences for selection on flowering time.

Variation among the leaves, flowers or fruit produced by a plant is often regarded as a nuisance to the experimenter and an impediment to selection. Here, we suggest that within-plant variation can drive selection on other plant-level traits. We examine within-plant variation in floral sex allocation and in fruit set and predict that such variation generates variation in male success among plants, thereby driving selection on flowering time. We tested this prediction in a simulation model estimating selection on flowering time through male fitness when floral sex allocation and/or fruit set vary directionally among flowers on plants. We parameterized the model through a quantitative literature survey of within-plant change in sex allocation. As predicted, within-plant variation in floral sex allocation and in fruit set probability can generate selection on flowering time through male fitness. Declining fruit set from first to last flowers on plants, as occurs in many species, selected for early flowering onset through male fitness. This result was robust to self-incompatibility and to varying returns on male versus female investment. Selection caused by declining fruit set was strong enough to reverse the selection for late flowering that can be caused by intrafloral protandry. Our model provides testable predictions regarding selection on flowering time through male fitness. The model also establishes the intriguing possibility that within-plant variation may influence selection on other traits, regardless of whether that variation is under selection itself.

Temperature- and income resource availability-mediated variation in reproductive investment in a multiple-batch-spawning Japanese anchovy

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 516:251-262 (2014) - DOI: https://doi.org/10.3354/meps10969 Temperature- and income resource availability-mediated variation in reproductive investment in a multiple-batch-spawning Japanese anchovy Michio Yoneda1,*, Hajime Kitano2, Hiroshige Tanaka3, Kohei Kawamura4, Sethu Selvaraj4, Seiji Ohshimo5, Michiya Matsuyama4, Akio Shimizu6 1National Research Institute of Fisheries and Environment of Inland Sea, Hakatajima Station, Imabari 794-2305, Japan 2Fisheries Research Institute of Karatsu, Department of Joint Research, Faculty of Agriculture, Kyushu University, Karatsu 847-0132, Japan 3Hokkaido National Fisheries Research Institute, Kushiro 085-0802, Japan 4Laboratory of Marine Biology, Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan 5National Research Institute of Far Seas Fisheries, Shizuoka 424-8633, Japan 6National Research Institute of Fisheries Science, Fukuura, Yokohama 236-8648, Japan *Corresponding author: myoneda@fra.affrc.go.jp ABSTRACT: Multiple batch spawning over a season should have an advantage for maternal fitness in unpredictable environments, but the manner in which females allocate resources to reproduction is not well understood. We explored the effects of temperature and food availability on reproductive traits in Japanese anchovy Engraulis japonicus using several physiological analyses. Under ad libitum food availability, temperature had a significant effect on batch intervals by changing the growth rate and size of oocytes during vitellogenesis. The latter is likely to result in variations in the size and total nutritional content of eggs. Relative batch fecundity, however, was not significantly influenced by temperature regimes. Reproductive effort per spawning was significantly higher at lower temperature, caused by the production of eggs with higher nutritional content, while total reproductive effort in a given period of time increased in water at a higher temperature due to shortening of batch intervals. Short-term food manipulation also had a significant effect on reproductive output. Insufficient income resources could lead to prolonged batch intervals, but the relative batch fecundity remained constant independent of the temperature regime. Our findings suggest that female Japanese anchovy may maintain reproductive effort per spawning relative to the prevailing temperature at the expense of more spawning events in a nutritionally harsh environment. Thus, although the total reproductive effort of well-fed specimens increased in water with increasing temperature due to shortened batch intervals, this variation may be caused by a compensatory response to the level of income resources available. KEY WORDS: Engraulis japonicus · Phenotypic plasticity · Energy allocation · Reproductive effort · Batch interval · Egg size · Egg production Full text in pdf format Supplementary material PreviousNextCite this article as: Yoneda M, Kitano H, Tanaka H, Kawamura K and others (2014) Temperature- and income resource availability-mediated variation in reproductive investment in a multiple-batch-spawning Japanese anchovy. Mar Ecol Prog Ser 516:251-262. https://doi.org/10.3354/meps10969 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 516. Online publication date: December 03, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.