Functional studies of skeletal anatomy are predicated on the fundamental assumption that form will follow function. For instance, previous studies have shown that the femora of specialized leaping primates are more robust than those of more generalized primate quadrupeds. Are such differences solely a plastic response to differential loading patterns during postnatal life, or might they also reflect more canalized developmental mechanisms present at birth? Here, we show that perinatal
1. Burying beetles (
2. One little‐studied species,
3. We find that development is not only extremely slow in this species, but it is also delayed even in comparison to other burying beetles reared at similar temperatures. However, the presence of parents reduces the time that offspring take to leave the carcass. This decrease in development time does not appear to result in a trade‐off with mortality or body size.
4. From these results, we suggest that very slow development may be advantageous when living in a particularly cold environment. Additionally, one role of extended parental care may be to assist offspring in dealing with these harsh conditions, and to mitigate the potentially negative consequences of adopting such a slow life‐history strategy.
more » « less- NSF-PAR ID:
- 10072897
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Ecological Entomology
- Volume:
- 44
- Issue:
- 1
- ISSN:
- 0307-6946
- Page Range / eLocation ID:
- p. 11-16
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ABSTRACT Lemur catta Propithecus coquereli , a closely related species specialized for vertical clinging and leaping (a highly unusual locomotor mode in which the hindlimbs are used to launch the animal between vertical tree trunks). These results suggest that functional differences in long bone cross‐sectional dimensions are manifest at birth, belying simple interpretations of adult postcranial form as a direct record of loading patterns during postnatal life. Despite these significant differences in bone robusticity, we find that hindlimb bone mineralization, material properties, and measures of whole‐bone strength generally overlap in perinatalL. catta P. coquereli , indicating little differentiation in postcranial maturity at birth despite known differences in the pace of craniodental development between the species. In a broader perspective, our results likely reflect evolution acting during prenatal ontogeny. Even though primates are notable for relatively prolonged gestation and postnatal parental care, neonates are not buffered from selection, perhaps especially in the unpredictable and volatile environment of Madagascar. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 303:250–264, 2020. © 2018 American Association for Anatomy -
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Abstract Aim Understanding variation in offspring energy expenditure is important because energy is critical for growth and development. Weather may exert proximate effects on offspring energy expenditure, but in altricial species these might be masked by parental care and huddling with siblings. Such effects are particularly important to understand given changing global weather patterns, yet studies of wild offspring in the presence of parental care are lacking. Offspring energy expenditure may also vary among species due to evolved responses to environmental selection pressures, requiring studies at both proximate and ultimate levels.
Location USA, South Africa, Malaysia.
Time period 2016–2019.
Major taxa studied Songbirds.
Methods We used the doubly‐labelled water technique to estimate nestling daily energy expenditure of 54 songbird species across three continents. We used Bayesian phylogenetic mixed models to test proximate and evolutionary causes of variation in offspring energy expenditure while accounting for phylogeny and phylogenetic uncertainty.
Results Offspring energy expenditure increased with more rainfall and colder air temperatures, but decreased among offspring in broods with more siblings. Across species, nestling and adult mortality, but not growth rate, were positively associated with offspring energy use.
Main conclusions Weather had clear proximate effects on offspring energy expenditure and parents were either unable or unwilling to fully offset these effects. However, the decrease in offspring energy use when huddling with more siblings demonstrated a modulating effect of life history traits. For example, high nest predation rates favour reduced parental care and can force offspring to spend more energy coping with environmental conditions. Furthermore, reduced energy expenditure is thought to facilitate increased longevity, which is increasingly realized with lower extrinsic mortality rates, providing an explanation for the positive association between adult mortality and offspring energy expenditure. Ultimately, both proximate and evolutionary influences need to be considered to better understand causes of offspring energetics.
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When evaluating avian reproduction, life history theory examines the trade‐offs between parental effort, the number and size of offspring, and the rate of nestling development. The growth rates and body sizes of developing birds vary geographically and can diverge with both latitude and migratory strategy. In terms of offspring size, growth rate can deviate in nestlings of the same or similar species due to the correlated influences of weather events, predation pressure, food availability, number of nestmates and parental provisioning. Furthermore, a longer photoperiod for species nesting at higher latitudes increases the duration over which a nestling can be fed each day, and increased nestling provisioning has been positively correlated with growth rate. Whether the amount of time a bird is fed during development drives this variation in growth rate and morphology is unknown. By removing supplemental environmental stressors (e.g. weather, predation) and standardizing feeding rate and environment, we explored the influence of daily duration of nestling provisioning on dark‐eyed junco Junco hyemalis nestlings. We hand‐reared 65 chicks of a sedentary junco subspecies J. h. carolinensis under both their natural photoperiod and the longer photoperiod of a closely related migratory subspecies J. h. hyemalis and compared growth rate, mass, morphology and the amount of food consumed. Average growth rate, fasted mass, wing length and total daily food consumption were all greater in birds hand‐reared under the longer, more northern photoperiod treatment. These findings suggest that increased daily photoperiod at higher latitudes may allow for greater total food provisioning and thus may play a role in the ability of parents in compressed breeding seasons to produce high quality offspring. This points to a trade‐off between provisioning effort and nestling growth rate in lower latitude (shorter photoperiod) populations and points to an important role of developmental plasticity on growth rate and morphology.more » « less
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Abstract Parents faced with a predator must choose between their own safety versus taking care of their offspring. Each choice can have fitness costs. Life‐history theory predicts that longer‐lived species should be less willing than shorter‐lived species to return to care for their offspring after a predator disturbance because they have more opportunities to reproduce in the future. We increased adult predation risk during incubation for 40 bird species in north temperate, tropical, and south temperate latitudes. We found that species with higher adult survival probabilities were more cautious, waiting longer before returning to the nest to provide care. Contrary to other studies, we also found that parents were more risk averse and waited longer to return in smaller than larger species, likely reflecting greater vulnerability of smaller species. Ultimately, the relative risk a predator poses to a species and the probability of future reproduction predict parental risk taking across the world.
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Abstract Elucidating factors that limit the number of offspring produced is fundamental to understanding life‐history evolution. Here, we examine the hypothesis that parental ability to maintain an optimal physical developmental environment for all offspring constrains clutch size via effects on offspring quality.
Experimental laboratory studies of birds have shown that a <1°C difference in average incubation temperature has diverse effects on fitness‐related post‐hatching offspring phenotypes. Thus, the inability of parents to maintain optimal incubation temperatures could constrain clutch sizes.
A fundamental question that has not been sufficiently addressed is whether larger clutch sizes lead to
within nest variation in egg temperature that is large enough to produce offspring with different phenotypes within a brood. This could lead to differential survival among offspring, and could create a trade‐off between offspring number and quality.We manipulated clutch size in nests of free‐living wood ducks and measured incubation temperature among and within clutches using multiple temperature loggers.
As clutch size increased, average incubation temperatures were lower and more variable, and eggs took longer to hatch. Notably, the range in
average incubation temperature among eggswithin nests increased with clutch size and exceeded 1°C in large clutches. Clutch size did not affect hatch success.In conjunction with our companion laboratory studies that used artificial incubation to document the effects of temperature variation on fitness‐related traits in this species, our work suggests that suboptimal incubation temperatures could be a factor that limits clutch size through diminishing returns on post‐hatch offspring quality.
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