Brood Mass Research Articles

Breeding zebra finches prioritize reproductive bout over self-maintenance under food restriction.

Reproduction requires high amounts of energy, and challenging environments during breeding can force parents to prioritize their current reproductive bout over self-maintenance or vice versa. However, little is known about how common stressors, such as food restriction, can influence these trade-offs during breeding, and the physiological mechanisms for these trade-off decisions. In this study, adult zebra finches (Taeniopygia castanotis) were subjected to a control diet (ad libitum) or a 40% food restriction while raising nestlings and fledglings, and we measured body mass, furculum fat, plasma corticosterone (CORT) and blood glucose levels of the parents at the time of pairing, when their offspring fledged, and when their offspring reached nutritional independence. Offspring were also measured in body mass and growth rate from hatching until the end of the treatment period. Food-restricted parents had lower body mass when their offspring fledged and reached nutritional independence and higher baseline CORT at fledging compared to controls. Offspring did not differ in body mass or growth rate between treatment groups. However, there was no effect of food restriction on parents' furculum fat, baseline glucose, the adrenocortical response, or the glucose response. Furthermore, path analysis results suggest that alterations in baseline glucose is the primary driver of changes in body mass in parents and offspring brood mass. Taken together, these results suggest that food restriction during chick rearing in a short-lived passerine drives parents to prioritize their current reproductive bout over self-maintenance, and glucose could potentially be a mechanism for diverting energy toward parental effort.

Carcass size, not source or taxon, dictates breeding performance and carcass use in a burying beetle.

Small vertebrate carcasses represent critical resources for many terrestrial organisms, including burying beetles, which rely on carcasses for survival and breeding. Carcass attributes can influence the reproduction of burying beetles, yet most studies on their breeding ecology have used laboratory-reared carcasses of limited sizes. We conducted breeding and feeding experiments using a wide size range of lab (laboratory mice) and wild carcasses (wild mammals, birds and reptiles) to investigate how carcass size, source and taxon affect various breeding outcomes (e.g. clutch size, brood size and brood mass) of the burying beetle Nicrophorus nepalensis. Our results reveal a hump-shaped relationship between carcass size and breeding performance, with optimal breeding outcomes occurring on medium-sized carcasses. Furthermore, despite the variation in carcass tissue nutritional composition, breeding outcomes and larval growth did not differ between the two carcass sources or among the three wild carcass taxa. Finally, we found a larval quality-quantity trade-off across the range of carcasses examined, with carcass size shaping the larval life-history traits. Overall, these results elucidate how carcass resources may influence the breeding performance of burying beetles. Importantly, our study provides solid evidence validating decades of research using lab carcasses to study the reproductive ecology of burying beetles.

The effect of the egg-predator Carcinonemertes conanobrieni on the reproductive performance of the Caribbean spiny lobster Panulirus argus

BackgroundThe Caribbean spiny lobster Panulirus argus is heavily fished throughout its Greater Caribbean and Gulf of Mexico distribution, suggesting a heightened susceptibility to a fisheries collapse. In 2017, a nemertean worm, Carcinonemertes conanobrieni was described from ovigerous females of P. argus in Florida, USA. A year later, the presence of the same egg predator was recorded along the southern Caribbean coast (Colombia). The effect of this egg predator on the reproductive performance, including fecundity, embryo mortality, and reproductive output, of its host is unknown. This study tested whether C. conanobrieni affects embryo mortality, fecundity, and reproductive output in brooding females of P. argus.ResultsArtisan fishers caught 90 ovigerous lobsters near Pueblo Viejo, Magdalena, Colombia. Each ovigerous female was examined for the presence/absence of the egg predator. Lobster egg mortality (%), fecundity (nº eggs female−1), and reproductive output (%) were estimated. Prevalence of C. conanobrieni in the studied population was 87.78%. The mean intensity of C. conanobrieni (all life stages) in the population was 11.68 (± 1.98) egg predators per brood mass sample. Infected females brooding late-stage embryos exhibited lower fecundity, lower reproductive performance values, and higher embryo mortality compared to infected females brooding early-stage embryos. Embryo stage and worm infection level negatively impacted fecundity and reproductive output. Worm infection level and the number of adult nemertean worms also negatively affected embryo mortality.ConclusionsThese results demonstrate an adverse effect of C. conanobrieni on the reproductive performance of P. argus. The interactive impact of this egg predator, natural stressors, and anthropogenic stressors on individual P. argus reproductive performance could facilitate losses at large-scale fisheries levels.

Evaluating the strength of western honey bee (Apis mellifera L.) colonies fed pollen substitutes over winter

AbstractWestern honey bees (Apis mellifera L.) need good nutrition to combat multiple stressors. Beekeepers often feed artificial protein diets (i.e. pollen substitutes) when their colonies lack natural pollen resources. However, it is unclear whether pollen substitutes improve honey bee colony strength and health during pollen dearths and when no pollen stores are available, as can occur during late fall and winter. We fed 56 managed honey bee colonies one of two commercially available pollen substitutes (AP23® and MegaBee®) or no diet (control) over the late fall and winter in north‐central Florida under a simulated pollen dearth and when the colonies lacked pollen stores. We determined the change in adult bee mass and the final brood mass of each colony throughout the feeding period. On average, colonies in each of the three treatment groups experienced a loss in total adult bee mass during the feeding period, which is typical of colonies during winter. Nevertheless, colonies that received AP23 lost significantly less adult bee mass than did control colonies, with colonies that received MegaBee having a loss in adult bee mass intermediate to those of the other two groups. The AP23 and MegaBee colonies had significantly greater brood mass than did control colonies. When accounting for total change in colony biomass (adult bee mass + brood mass), the AP23 group lost significantly less mass than did control colonies, with the MegaBee colonies having a mass loss intermediate to those of the other two groups. Colonies consumed significantly more AP23 than they consumed MegaBee. Collectively, our data suggest that it may be beneficial for beekeepers in warm climates to feed pollen substitutes to stressed honey bee colonies over winter to lessen the loss in total colony biomass.

The effect of avian brood parasitism on physiological responses of host nestlings.

Avian obligate brood parasites lay their eggs in the nests of other species that may provide care for the foreign offspring. Brood parasitism often imparts substantial fitness losses upon host nestlings when they are raised alongside the typically more competitive, larger, and older parasitic chick(s). Whereas fitness costs due to reduced host offspring survival in parasitized broods have been studied in detail, the physiological changes in host nestlings caused by parasitic nestmate(s) are less well known. We compared prothonotary warbler (Protonotaria citrea) nestlings, a host of the nest-sharing brown-headed cowbird (Molothrus ater), in experimentally parasitized vs. non-parasitized broods. Our aim was to determine whether cohabitation with brood parasitic young impacted host nestling baseline corticosterone plasma concentrations, immune responses, body condition, and mortality. Corticosterone levels and body condition of host nestlings were similar between nests with or without a cowbird nestmate, whereas host immune responses were lower and nestling mortality was greater in parasitized broods, irrespective of variation in brood size or total brood mass. We detected no trade-offs of baseline corticosterone levels with either immune responses or with body condition. These results suggest that this host species' nestlings experience some adverse fitness-relevant physiological effects in parasitized broods, but are also resilient in other aspects when coping with brood parasitism.

Life cycle of the dung beetle Onthophagus cervus (Fabricius, 1798) (Coleoptera: Scarabaeidae: Scarabaeinae) in moist belts of south India

Biology, nesting behaviour, and the factors favouring the high abundance of prominent dung beetle species, Onthophagus cervus (Fabricius, 1798) in an open agricultural field in North Kerala were studied. Short life cycle with high fecundity, low egg mortality, shorter larval duration, shorter developmental period, short generation time, female-biased sex ratio, and longer survivability of females were recorded. Female-biased sex ratio in O. cervus indicates that mating competition takes place between male offsprings and the high cost of producing males led to their reduction. Broad categorization of Onthophagus species is provided based on the comparison of data of brood mass production, fecundity, duration of egg, larval, pupal, adult stages, adult mortality and life span of various Onthophagus species. Higher abundance of O. cervus in the region is attributed to traits that are characterize of r-selection such as high fecundity, small body size, low egg mortality, shorter larval duration, early onset of maturity, and shorter developmental period. Short generation time which enables attaining maturity earlier together with female biased sex ratio, longer duration of females favouring high egg production and shallow tunnels which enable easy and fast tunnelling process and development in thin soil top soil layer are the other factors that contributed to the higher abundance of O. cervus. Present study showed that geographic region wise knowledge on the life history traits of prominent dung beetles are necessary for interpretation of the exact mechanism behind their seasonality and abundance in specific regions and the generated data will be useful for the conservation of species in natural habitats.

The impact of pollen quality on the sensitivity of bumblebees to pesticides

With 2000 species currently recorded in Europe, bees are a highly diversified and efficient group of pollinating insects. Their decline could therefore lead to a risk for ecosystems functioning and crop yields. The drivers of this decline have been well documented in Europe and involve multiple factors such as pesticides, pathogens, poor nutrition, climate change, and their respective interactions. For pesticides, there is a lack of information concerning the impacts of exposure when the bees have access to pollen diet of different nutritional quality (e.g. variation in sterol and protein content). We performed bioassays on nine groups consisting of 10 Bombus terrestris microcolonies (i.e. queen less colonies) each in a fully crossed experiment including controls without pesticide, two different doses of neonicotinoid imidacloprid (2 and 20 μg/L) and three pollen diets (i.e. Salix mix, cellulose-diluted Salix mix and cellulose-diluted Salix mix enriched with soy protein). All colonies were fed ad libitum with syrup and pollen. We measured the collection of pollen and syrup, the brood mass and the pollen efficacy (ratio of brood mass/pollen) at the end of the experiment. All these variables were affected by the imidacloprid doses, especially pollen efficacy, which was two and 10 times lower than the control for the 2 and 20 μg/L treatments, respectively. As expected, pollen efficacy was also affected by the pollen diet. However, when exposed to imidacloprid, the three different pollen diets did not affect micro-colonies performances. Overall, we show that diet quality does not affect sensitivity to imidacloprid exposure. It seems therefore that the negative effects of imidacloprid exposure cannot be compensated for by a pollen diet of high quality.

The effect of parasite density on host colonisation success by a mobile avian ectoparasite

1. Full understanding of the dynamics of host–parasite interactions requires elucidation of the principles governing host colonisation. With respect to mobile parasites, little is known about their dispersal behaviour and the factors affecting host colonisation success.2. Here, the effect of parasite density manipulations on the colonisation success of the carnid fly Carnus hemapterus, an avian ectoparasite, was experimentally explored.3. Most host nests were colonised within the same breeding season, but the abundance of flies colonising the nests varied broadly both within and between years.4. Experimental increase in the density of carnid flies in the vicinity of host nests did not result in higher parasite abundance in these nests. Host colonisation success in terms of parasite abundance was not related to indices of parasite density around host nests.5. Parasite abundance in colonised host nests was positively related to host density and brood mass and negatively related to date. Host nests in trees held fewer carnid flies than those on cliffs and farmhouses.6. The dispersal ability of C. hemapterus is apt for rapid colonisation of new host nests, but it is unable to explain the broad heterogeneity in parasite abundance between host nests.

Are older parents less flexible? Testing age-dependent plasticity in Nicrophorus vespilloides burying beetles

Phenotypic plasticity is an important mechanism facilitating adaptation to environmental change that often varies among individuals. One reason for this individual variation is that plasticity may depend on state variables, such as size, condition or age, which affect the costs and benefits of plasticity. Recent theoretical work predicts that plasticity will decrease as an organism ages because costs of plasticity mean that flexible phenotypic adjustments by individuals to environmental change will be less beneficial as age-related survival prospects decrease. Here we used Nicrophorus vespilloides burying beetles to test this prediction in the context of parental care. Burying beetles use the carcasses of small vertebrates as resources for breeding and have complex, extended, flexible parental care. Our experiment manipulated female age and (the order of presentation of) carcass size in a repeated-measures design to test the prediction that older beetles are less plastic than younger beetles in parental care. We found evidence in support of our central prediction: young females showed greater mean levels of plasticity than older beetles for all traits (parental care, number of offspring, brood mass) except mean larval mass (i.e. size of offspring), with the response to changes in carcass size dependent on the order of carcass presentation for young females but not for older females. Between-trait correlation analysis revealed age-related trade-offs between the size and number of offspring for older, but not young, mothers. The three age-dependent traits, which were intercorrelated, were also repeatable, indicating potential for coevolutionary responses to selection.

Sexual size dimorphism, allometry and fecundity in a lineage of South American viviparous lizards (Liolaemidae: Phymaturus)

In living organisms with sexual reproduction, the presence of sexual size dimorphism (SSD) is common. The main explanations for this phenomenon are based on sexual selection or the fecundity advantage hypothesis (natural selection). Here, we tested Rensch's rule in species of the viviparous lizard genus Phymaturus; additionally, we tested if there is a pattern of sexual size dimorphism or if it depends upon other morphological traits. We found no evidence for Rensch's rule in these lizards. After testing for multiple or single regime evolutionary models, we found that body size most likely evolved under multi-regime Ornstein-Uhlenbeck evolutionary model; the same was observed for abdomen width in females, a fecundity advantage hypothesis trait. For species with female biased SSD there is a positive relationship between snout-vent length and width of the belly, supporting the fecundity advantage hypothesis. Additionally, the relationship between brood size and brood mass with body size and body mass (respectively) were positive giving strength to the fecundity advantage hypothesis. Finally, our results show males did not show a clear pattern in relation to the sexual selection hypothesis, probably because sexual selection is a complex aspect that involves behavior and color. On the other hand, female body size and reproductive output are related to mean seasonal air temperature and its combination with mean annual air temperature in an evolutionary fashion framework, such as fecundity advantage hypothesis in these lizards.

Reproductive strategies of the crinoid-associated shrimps <i>Cristimenes commensalis</i> (Borradaile, 1915) and <i>Pontoniopsis comanthi</i> Borradaile, 1915 (Crustacea: Palaemonidae)

Tropical shallow-water crinoids offer shelter to a diversity of marine life, including various symbiotic palaemonid shrimp species. In this study, the reproductive features of the shrimps Cristimenes commensalis and Pontoniopsis comanthi inhabiting comatulid crinoids are studied and compared. Ovigerous females were collected from the crinoids Anneissia bennetti and Comaster nobilis from Iriomote-jima, Japan. All specimens were examined for the following traits: carapace length, fecundity, embryo volume, brood mass volume and dry weight of the females and the eggs. Cristimenes commensalis produced 15–117 eggs with a volume of 0.04 mm3 ±0.00, whereas the smaller-sized species P. comanthi produced 12–57 eggs with a volume of 0.02 mm3 ±0.01. The reproductive output (RO) of C. commensalis was 0.16±0.03, considerably lower than that of P. comanthi at 0.31±0.05. Data is beginning to emerge on the fecundity and reproductive output of symbiotic palaemonid shrimps, although comparisons remain hampered by the general lack of knowledge on their biology in general. Pontoniopsis comanthi has the highest recorded reproductive output so far, despite being the smallest species studied. Our results confirm that inhabiting a sheltered habitat allows symbiotic shrimps to allocate more energy to embryo production than free-living species. Different reproductive strategies are, however, apparent for these species inhabiting the same host species, implying the existence of differential selective forces.

Interspecific Variation in Reproductive Effort in Two Assemblages of Dusky Salamanders

Abstract Body-size variation in desmognathan salamanders in the southern Appalachian Mountains is coupled with trade-offs among life-history traits that affect growth, survival, and reproduction. Reproductive effort is an important trait that is often measured as the gonadosomatic index (GSI), defined as clutch mass relative to total body mass. I measured GSI as brood mass relative to maternal body mass in two assemblages of Desmognathus in the Cowee and Nantahala mountains of southwestern North Carolina. I also re-evaluated the size–fecundity relationship in the Nantahala Mountain assemblage on the basis of newer data. In addition, I examined the potential trade-off between number and size of offspring in several species in both assemblages. Among species, GSI decreased slightly with increasing body size; the trend is considered a probable effect of decreasing metabolic rate with body size rather than a trade-off with one or another life-history trait. Although both propagule size and number increased 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.

Fecundity and reproductive output of the caridean shrimp Periclimenes paivai associated with scyphozoan jellyfish

Periclimenes paivai is notable for its symbiotic lifestyle with jellyfish. The objective of this study was to investigate the fecundity and reproductive output of females, and specifically to determine whether females protected in their host have a greater reproductive success than other shrimp species. All anatomical parts of the medusae were analyzed and the P. paivai individuals were separated. Among 83 females analyzed, 65 presented embryos in the first developmental stage, and 18 were in the final stage of development. The mean fecundity was 229.08 ± 120.04 in initial-stage embryos and 191 ± 114.76 in final-stage embryos. We observed a positive relationship between the embryo number and the female size; however, the embryo number was not related to the embryonic stage, which indicates that females did not lose their embryos during the incubation period. The weight of brood mass during production is closely related to the female weight according to the results of linear regression, as fecundity increased with female size. In its symbiosis, P. paivai can increase the amount of energy used to produce embryos (mean reproductive output = 10.38%) and can elevate the reproductive success.

Nesting biology and life history of the dung beetle Onthophagus lecontei (Coleoptera: Scarabaeinae)

Obtaining knowledge about a species’ life history and reproductive behaviour is fundamental for understanding its biology, ecology, and potential role in ecosystem services. Here, we focused on the dung beetle speciesOnthophagus lecontei. Adults were collected in the field and then confined to terrariums, where they were supplied with semi-fresh domestic goat dung (Capra aegagrusErxleben, 1777). After being paired (26 pairs), the nesting behavior of beetles was observed under laboratory conditions and the preimaginal development of individuals obtained from mating (from the deposition of the egg until the emergence of the adult) was described. Their nesting behavior was found to be characteristic of what is known as pattern I, which comprises building of brood masses, oviposition of a single egg in each brood mass, development of three larval instars, construction of a pupation chamber, pupal stage and adult emergence. Both sexes were involved in the handling of dung, tunnel construction, and mass nest elaboration. Pairs built from one to seven brood masses. The pre-nesting period (feeding) lasted 16 days; the egg stage two days, the larval period 22 days; the pupal period 11 days and the imagoes four days, after which the adults emerged. Our results are discussed and compared with other species in the genus. However, our knowledge of this dung beetle is still limited, and further studies are required in all areas of its biology.

Active parental care, reproductive performance, and a novel egg predator affecting reproductive investment in the Caribbean spiny lobster Panulirus argus

We used the Caribbean spiny lobster Panulirus argus, one of the largest brooding invertebrates in the Western Atlantic, to test for the presence/absence of active parental care and to explore reproductive performance in large brooding marine organisms. Given [i] the compact and large embryo masses produced by P. argus, [ii] the expected disproportional increase in brooding costs with increasing embryo mass size, and [iii] the theoretical allometry of egg production with increasing body size, we predicted that parental females in this large species will engage in active brood care. We also predicted that larger broods from larger lobsters should suffer higher mortality and brood loss than smaller broods from smaller lobsters if parental care was minimal or absent. Lastly, we expected smaller females to allocate disproportionably more resources to egg production than larger females in the case of minimal parental care. Females brooding early and late embryos were collected from different reefs in the Florida Keys Reef tract, transported to the laboratory, and maintained in separate aquaria to describe and quantify active parental care during day and night. A second set of females was retrieved from the field and their carapace length, fecundity, egg size, reproductive output and presence/absence of brood-dwelling pathogens was recorded. Laboratory experiments demonstrated that brooding females of P. argus engaged in active brood care. Females likely use some of the observed behaviors (e.g., abdominal flapping, pleopod beating) to provide oxygen to their brood mass. In Panulirus argus, females did not suffer brood loss during embryo development. Also, reproductive output increased more than proportionally with a unit increase in lobster body weight. Our results agree with the view that large brooding marine invertebrates can produce large embryo masses if they engage in active parental care and that the latter behavior greatly diminishes reproductive performance costs associated with producing large embryo masses. Lastly, we report on a nemertean worm that, we show, negatively impacts female reproductive performance.

Carcass Age and Reproductive Costs forNicrophorus orbicollis(Coleoptera: Silphidae)

The life history costs of living in microbially dense environments can be high. To assess the importance of these costs for natural selection, it is necessary to know how costs vary with environmental conditions. Adult burying beetles prepare vertebrate carcasses of varying age and states of deterioration as a resource for their young. In the present study, Nicrophorus orbicollis Say females were presented with either fresh or aged (80 h) large carcasses (30-39 g) to examine effects on their lifetime reproductive success (four reproductive attempts) and survival. Reproductive success and survival were also measured for female offspring that developed on fresh and aged carcasses. Carcass age had no measurable effect on lifetime reproductive output or life span of either parents or their adult offspring. In a separate experiment using medium-sized carcasses (22-24 g), the reproductive performance of females in a single reproductive attempt was negatively affected by carcass age (13.9% less brood mass). The results suggest that the costs of using a single older carcass are relatively minor when measured over a lifetime. Alternative costs of using older carcasses and explanations for the complex antimicrobial traits of burying beetles are discussed.

Short‐ and long‐term effects of tracking devices on the European Roller Coracias garrulus

Tracking devices have contributed enormously to our knowledge of avian migration, although their effects on birds are controversial. Here, we study the short‐ and long‐term effects of deploying geolocators on European Rollers Coracias garrulus and assess the optimal weight of tracking devices to use. In nests in which both parents had geolocators, brood mass was lighter than in nests where only one or neither parent had a geolocator. The year‐to‐year recapture rate for Rollers tagged with geolocators was lower than that for control birds and the recapture rate in different populations was negatively related to the device‐to‐bird weight ratio, decreasing greatly when the weight ratio exceeded 2.5%.

Lethal and Sublethal Effects of Ivermectin on Onthophagus landolti (Coleoptera: Scarabaeidae).

Previous work has documented toxic effects of ivermectin (IVM) on dung beetles from the Old World, but very little is known about this drug's effect on Neotropical dung beetles. Accordingly, we conducted a bioassay with dung spiked with IVM to assess its lethal and sublethal effects on the Neotropical dung beetle Onthophagus landolti Harold. The experimental design consisted of five treated groups G1, G2, G3, G4, and G5 receiving 0.001, 0.01, 0.1, 1.0, and 10 mg IVM/kg dung fresh weight, respectively, and two control groups (solvent control [CGA] and untreated control [CGU]). Adult survival and fecundity were measured throughout a 10-d period, and subsequent egg development and survival were monitored. Adult survival was only affected for treatment groups G4 and G5 groups (70 and 30%, respectively); groups G1, G2, G3 and both controls exhibited 100% survival. Fecundity was completely suppressed under treatment groups G4 and G5. Group G3 only had 1.7 and 2.1% brood mass production relative to CGA and CGU, respectively. Additionally, for groups G1 and G2 the proportion of adults emerging from brood masses was lower relative to CGA. Furthermore, development time for the second generation in groups G1 and G2 was 12.5% slower relative to control groups. Finally, dung removal by beetles from groups G3, G4, and G5 was significantly lower relative to control groups. In conclusion, toxic effects of IVM on O. landolti are associated mainly with reduced fecundity and lower dung-removal by adult beetles as well as reduced survival and slower development of offspring.

Reproductive Investment in a Phyletic Giant, the Caribbean King CrabDamithrax spinosissimus: Exploring Egg Production Costs in Large Brooding Marine Inertebrates

ABSTRACT The Caribbean king crab Damithrax spinosissimus, a phyletie giant and the largest crab in the western Atlantic, was used to explore the costs of brooding, in terms of reproductive investment, in marine invertebrates. Given (i) the theoretical allometry between gamete production and brooding surfaces and (ii) increased physiological costs with increased brood mass, it was expected that larger broods from larger crabs should suffer higher mortality and brood loss than smaller broods from smaller crabs. It was also expected that smaller females should allocate disproportionably more resources to egg production than larger females. In D. spinosissimus, fecundity in females carrying early and late embryos varied, respectively, between 5.170 and 26.024 eggs/crab (mean ± SD = 16.569 ± 4.899) and between 1.966 and 26.906 eggs/crab (15.147 ± 7.003). In disagreement with expectation, females did not experience brood loss during embryo development. Egg mortality in females carrying early and late eggs varie...