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Christensen TK, Balsby TJS. Condition dependent strategies of egg size variation in the Common Eider Somateria mollissima. PLoS One 2020; 15:e0226532. [PMID: 32716933 PMCID: PMC7384649 DOI: 10.1371/journal.pone.0226532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 07/07/2020] [Indexed: 11/18/2022] Open
Abstract
We analysed intraclutch egg-size variation over the laying sequence in relation to clutch size, and the relation between clutch size and female body condition, in the Common Eider Somateria mollissima during an 8-year period. The aim was to assess if eiders adjusted egg size within the laying sequence depending on clutch sizes in response to body condition, as such an adjustment could have adaptive implications on reproductive success through a size advantage for the hatchlings. The analyses were performed on a population level; and then at the individual level using data from recaptured females that changed clutch size between years. Based on 1,099 clutches from 812 individual females, population clutch size averaged 4.13 eggs (range: 1–6), with 4- and 5-egg clutchesconstituting c.70% of all clutches, taking turns in being the most represented clutch size. Clutch size was positively related to female pre-laying body condition at both the population and individual levels. Egg size varied significantly within and between clutch sizes and changes were significantly related to the laying sequence. First eggs were significantly larger in 4-egg clutches and second eggs marginally smaller than in 5-egg clutches, a pattern also found among individual females changing clutch size between years. The relationship between female pre-laying body condition and clutch size, and the intraclutch egg-size pattern indicate that both clutch size and egg size are actively adapted to the pre-breeding body condition of the female. As egg size potentially optimise reproductive success through a size advantage in hatchlings, the observed pattern of intraclutch egg-size variation suggests that female eiders possesses a finely tuned conditional dependent mechanism that may optimize reproductive output in years were females are in suboptimal body condition for breeding.
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2
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Braasch A, Becker PH. Maternal investment in last-laid eggs does not compensate for hatching asynchrony in a seabird. Oecologia 2019; 190:47-58. [DOI: 10.1007/s00442-019-04399-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 04/02/2019] [Indexed: 11/28/2022]
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3
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Bowers EK, Jenkins JB, Mueller AJ, Miller KD, Thompson CF, Sakaluk SK. Condition-Dependent Begging Elicits Increased Parental Investment in a Wild Bird Population. Am Nat 2019; 193:725-737. [PMID: 31002567 DOI: 10.1086/702848] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The coevolution of parental supply and offspring demand has long been thought to involve offspring need driving begging and parental care, leaving other hypotheses underexplored. In a population of wild birds, we experimentally tested whether begging serves as a negatively condition-dependent signal of need or a positively condition-dependent signal of quality. Across multiple years, we supplemented nestling house wrens with food shortly after hatching and simultaneously manipulated corticosterone levels to simulate the hunger-induced increase in glucocorticoids thought to mediate begging. This allowed us to also test whether begging is simply a proximate signal of hunger. Days after supplementation ended, food-supplemented nestlings were in better condition than nonsupplemented nestlings and begged for food at an increased rate; their parents, in turn, increased provisioning to a greater extent than parents of nonsupplemented young, as begging positively predicted provisioning. Food-supplemented nestlings therefore attained above-average condition, which predicted their recruitment as breeding adults in the local population. Glucocorticoids increased begging in the short term, but this transient effect depended on satiety. Thus, glucocorticoids promoted begging as a proximate response to hunger, whereas the longer-term changes in nestling condition, begging, and food provisioning suggest that begging ultimately signals offspring quality to elicit increased investment, thereby enhancing offspring survival.
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4
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Song Z, Zou Y, Hu C, Ye Y, Wang C, Qing B, Komdeur J, Ding C. Silver spoon effects of hatching order in an asynchronous hatching bird. Behav Ecol 2018. [DOI: 10.1093/beheco/ary191] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Zitan Song
- School of Nature Conservation, Beijing Forestry University, Beijing, China
| | - Yuqi Zou
- School of Nature Conservation, Beijing Forestry University, Beijing, China
| | - Canshi Hu
- School of Nature Conservation, Beijing Forestry University, Beijing, China
- College of Life Science, Guizhou University, Guiyang, Guizhou, China
| | - Yuanxing Ye
- School of Nature Conservation, Beijing Forestry University, Beijing, China
| | - Chao Wang
- Shaanxi Hanzhong Crested Ibis National Nature Reserve, Yangxian, Shaanxi, China
| | - Baoping Qing
- Shaanxi Hanzhong Crested Ibis National Nature Reserve, Yangxian, Shaanxi, China
| | - Jan Komdeur
- Behavioural Physiology and Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Changqing Ding
- School of Nature Conservation, Beijing Forestry University, Beijing, China
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5
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Koykka C, Wild G. The influence of environmental variance on the evolution of signaling behavior. Behav Ecol 2018. [DOI: 10.1093/beheco/ary072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Cody Koykka
- Department of Applied Mathematics, The University of Western Ontario, London, ON, Canada
| | - Geoff Wild
- Department of Applied Mathematics, The University of Western Ontario, London, ON, Canada
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Muller D, Giron D, Desouhant E, Rey B, Casas J, Lefrique N, Visser B. Maternal age affects offspring nutrient dynamics. JOURNAL OF INSECT PHYSIOLOGY 2017; 101:123-131. [PMID: 28735010 DOI: 10.1016/j.jinsphys.2017.07.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 06/14/2017] [Accepted: 07/17/2017] [Indexed: 06/07/2023]
Abstract
The internal physiological state of a mother can have major effects on her fitness and that of her offspring. We show that maternal effects in the parasitic wasp Eupelmus vuilleti become apparent when old mothers provision their eggs with less protein, sugar and lipid. Feeding from a host after hatching allows the offspring of old mothers to overcome initial shortages in sugars and lipids, but adult offspring of old mothers still emerged with lower protein and glycogen quantities. Reduced egg provisioning by old mothers had adverse consequences for the nutrient composition of adult female offspring, despite larval feeding from a high-quality host. Lower resource availability in adult offspring of old mothers can affect behavioural decisions, life histories and performance. Maternal effects on egg nutrient provisioning may thus affect nutrient availability and fitness of future generations in oviparous animals.
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Affiliation(s)
- Doriane Muller
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261 CNRS/Université François-Rabelais de Tours, Avenue Monge, 37200 Tours, France
| | - David Giron
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261 CNRS/Université François-Rabelais de Tours, Avenue Monge, 37200 Tours, France
| | - Emmanuel Desouhant
- Université Lyon 1, Laboratoire de Biométrie et Biologie Evolutive, F-69000 Lyon, UMR CNRS 5558, F-69622 Villeurbanne, France
| | - Benjamin Rey
- Université Lyon 1, Laboratoire de Biométrie et Biologie Evolutive, F-69000 Lyon, UMR CNRS 5558, F-69622 Villeurbanne, France
| | - Jérôme Casas
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261 CNRS/Université François-Rabelais de Tours, Avenue Monge, 37200 Tours, France
| | - Nicolas Lefrique
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261 CNRS/Université François-Rabelais de Tours, Avenue Monge, 37200 Tours, France
| | - Bertanne Visser
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261 CNRS/Université François-Rabelais de Tours, Avenue Monge, 37200 Tours, France.
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7
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LaBarbera K, Cramer ERA, Veronese D, Lovette IJ. Growth benefit to house wren nestlings of having an asynchronously late-hatching nestmate is greater for extra-pair offspring. Behav Ecol Sociobiol 2017. [DOI: 10.1007/s00265-017-2283-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Bowers EK, Thompson CF, Sakaluk SK. Within-female plasticity in sex allocation is associated with a behavioural polyphenism in house wrens. J Evol Biol 2016; 29:602-16. [PMID: 26687708 DOI: 10.1111/jeb.12810] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 12/07/2015] [Accepted: 12/14/2015] [Indexed: 01/14/2023]
Abstract
Sex allocation theory assumes individual plasticity in maternal strategies, but few studies have investigated within-individual changes across environments. In house wrens, differences between nests in the degree of hatching synchrony of eggs represent a behavioural polyphenism in females, and its expression varies with seasonal changes in the environment. Between-nest differences in hatching asynchrony also create different environments for offspring, and sons are more strongly affected than daughters by sibling competition when hatching occurs asynchronously over several days. Here, we examined variation in hatching asynchrony and sex allocation, and its consequences for offspring fitness. The number and condition of fledglings declined seasonally, and the frequency of asynchronous hatching increased. In broods hatched asynchronously, sons, which are over-represented in the earlier-laid eggs, were in better condition than daughters, which are over-represented in the later-laid eggs. Nonetheless, asynchronous broods were more productive later within seasons. The proportion of sons in asynchronous broods increased seasonally, whereas there was a seasonal increase in the production of daughters by mothers hatching their eggs synchronously, which was characterized by within-female changes in offspring sex and not by sex-biased mortality. As adults, sons from asynchronous broods were in better condition and produced more broods of their own than males from synchronous broods, and both males and females from asynchronous broods had higher lifetime reproductive success than those from synchronous broods. In conclusion, hatching patterns are under maternal control, representing distinct strategies for allocating offspring within broods, and are associated with offspring sex ratios and differences in offspring reproductive success.
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Affiliation(s)
- E K Bowers
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - C F Thompson
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - S K Sakaluk
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA
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9
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Bowers EK, White A, Lang A, Podgorski L, Thompson CF, Sakaluk SK, Jaeckle WB, Harper RG. Eggshell porosity covaries with egg size among female House Wrens ( Troglodytes aedon) but is unrelated to incubation onset and egg-laying order within clutches. CAN J ZOOL 2015; 93:421-425. [PMID: 26146408 DOI: 10.1139/cjz-2014-0279] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In birds, the duration of egg incubation (the time from incubation onset to hatching) can affect multiple components of nest success, but what affects incubation duration? Previous studies suggest that incubation duration is affected by both parental behavior and components of the egg, which have yet to be determined. One egg component that may be related to incubation behavior and the time until hatching is eggshell porosity, which affects the exchange of metabolic gasses and water vapor across the shell and, thus, the speed of embryonic development and incubation duration. We tested whether eggshell porosity was associated with the timing of incubation onset by female House Wrens (Troglodytes aedon Vieillot, 1809), and whether porosity varied within clutches in a manner that might be associated with incubation periods and hatching patterns (i.e., synchronous vs. asynchronous hatching). Eggshell porosity was unrelated to the onset of maternal incubation and did not differ between early and later-laid eggs within clutches, but differed significantly among females and covaried with egg size. We conclude that producing all eggshells of similar porosity within clutches, while adjusting incubation onset once most or all eggs are laid, provide facultative maternal control over variation in hatching patterns.
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Affiliation(s)
- E K Bowers
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - A White
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - A Lang
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - L Podgorski
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - C F Thompson
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - S K Sakaluk
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - W B Jaeckle
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - R G Harper
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
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10
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Sun Z, Hamel JF, Parrish CC, Mercier A. Complex offspring size effects: variations across life stages and between species. Ecol Evol 2015; 5:1117-29. [PMID: 25798228 PMCID: PMC4364825 DOI: 10.1002/ece3.1320] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 11/04/2014] [Indexed: 11/09/2022] Open
Abstract
Classical optimality models of offspring size and number assume a monotonically increasing relationship between offspring size and performance. In aquatic organisms with complex life cycles, the size-performance function is particularly hard to grasp because measures of performance are varied and their relationships with size may not be consistent throughout early ontogeny. Here, we examine size effects in premetamorphic (larval) and postmetamorphic (juvenile) stages of brooding marine animals and show that they vary contextually in strength and direction during ontogeny and among species. Larger offspring of the sea anemone Urticina felina generally outperformed small siblings at the larval stage (i.e., greater settlement and survival rates under suboptimal conditions). However, results differed when analyses were conducted at the intrabrood versus across-brood levels, suggesting that the relationship between larval size and performance is mediated by parentage. At the juvenile stage (15 months), small offspring were less susceptible than large ones to predation by subadult nudibranchs and both sizes performed similarly when facing adult nudibranchs. In a sympatric species with a different life history (Aulactinia stella), all juveniles suffered similar predation rates by subadult nudibranchs, but smaller juveniles performed better (lower mortalities) when facing adult nudibranchs. Size differences in premetamorphic performance of U. felina were linked to total lipid contents of larvae, whereas size-specific predation of juvenile stages followed the general predictions of the optimal foraging strategy. These findings emphasize the challenge in gathering empirical support for a positive monotonic size-performance function in taxa that exhibit complex life cycles, which are dominant in the sea.
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Affiliation(s)
- Zhao Sun
- Department of Ocean Sciences, Memorial University St. John's, Newfoundland and Labrador, A1C 5S7, Canada
| | - Jean-François Hamel
- Society for the Exploration and Valuing of the Environment (SEVE) 21 Phils Hill Road, Portugal Cove-St. Philips, Newfoundland and Labrador, A1M 2B7, Canada
| | - Christopher C Parrish
- Department of Ocean Sciences, Memorial University St. John's, Newfoundland and Labrador, A1C 5S7, Canada
| | - Annie Mercier
- Department of Ocean Sciences, Memorial University St. John's, Newfoundland and Labrador, A1C 5S7, Canada
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11
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Brien ML, Webb GJ, McGuinness K, Christian KA. The relationship between early growth and survival of hatchling saltwater crocodiles (Crocodylus porosus) in captivity. PLoS One 2014; 9:e100276. [PMID: 24960026 PMCID: PMC4069027 DOI: 10.1371/journal.pone.0100276] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Accepted: 05/26/2014] [Indexed: 11/19/2022] Open
Abstract
Hatchling fitness in crocodilians is affected by "runtism" or failure to thrive syndrome (FTT) in captivity. In this study, 300 hatchling C. porosus, artificially incubated at 32°C for most of their embryonic development, were raised in semi-controlled conditions, with growth criteria derived for the early detection of FTT (within 24 days). Body mass, four days after hatching (BM4d), was correlated with egg size and was highly clutch specific, while snout-vent length (SVL4d) was much more variable within and between clutches. For the majority of hatchlings growth trajectories within the first 24 days continued to 90 days and could be used to predict FTT affliction up to 300 days, highlighting the importance of early growth. Growth and survival of hatchling C. porosus in captivity was not influenced by initial size (BM4d), with a slight tendency for smaller hatchlings to grow faster in the immediate post-hatching period. Strong clutch effects (12 clutches) on affliction with FTT were apparent, but could not be explained by measured clutch variables or other factors. Among individuals not afflicted by FTT (N = 245), mean growth was highly clutch specific, and the variation could be explained by an interaction between clutch and season. FTT affliction was 2.5 times higher among clutches (N = 7) that hatched later in the year when mean minimum air temperatures were lower, compared with those clutches (N = 5) that hatched early in the year. The results of this study highlight the importance of early growth in hatchling C. porosus, which has implications for the captive management of this species.
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Affiliation(s)
- Matthew L. Brien
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, Australia
- Wildlife Management International Pty. Limited, Karama, NT, Australia
| | - Grahame J. Webb
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, Australia
- Wildlife Management International Pty. Limited, Karama, NT, Australia
| | - Keith McGuinness
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, Australia
| | - Keith A. Christian
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, Australia
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12
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Parejo D, Avilés JM, Rodríguez J. Supplemental food affects egg size but not hatching asynchrony in rollers. Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1360-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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13
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Krist M, Munclinger P. Superiority of extra-pair offspring: maternal but not genetic effects as revealed by a mixed cross-fostering design. Mol Ecol 2011; 20:5074-91. [PMID: 22061105 DOI: 10.1111/j.1365-294x.2011.05337.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Extra-pair copulations (EPC) are the rule rather than an exception in socially monogamous birds, but despite widespread occurrences, the benefits of female infidelity remain elusive. Most attention has been paid to the possibility that females gain genetic benefits from EPC, and fitness comparisons between maternal half-siblings are considered to be a defining test of this hypothesis. Recently, it was shown that these comparisons may be confounded by within-brood maternal effects where one such effect may be the distribution of half-siblings in the laying order. However, this possibility is difficult to study as it would be necessary to detect the egg from which each chick hatched. In this study, we used a new approach for egg-chick assignment and cross-fostered eggs on an individual basis among a set of nests of the collared flycatcher Ficedula albicollis. After hatching, chicks were ascribed to mothers and therefore to individual eggs by molecular genetic methods. Extra-pair young predominated early in the laying order. Under natural conditions, this should give them a competitive advantage over their half-siblings, mediated by hatching asynchrony. However, we experimentally synchronized hatching, and after this treatment, extra-pair young did not outperform within-pair young in any studied trait including survival up to recruitment and several indicators of reproductive success and attractiveness. We obtained only modest sample sizes for the last two traits and did not test for extra-pair success of male offspring. Thus, we cannot exclude the possibility of advantages of extra-pair young during the adult phase of life. However, our data tentatively suggest that the more likely reason for females' EPCs is the insurance against the infertility of a social mate.
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Affiliation(s)
- Miloš Krist
- Museum of Natural History, nám. Republiky 5, 771 73 Olomouc, Czech Republic.
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14
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Bowers EK, Sakaluk SK, Thompson CF. Adaptive sex allocation in relation to hatching synchrony and offspring quality in house wrens. Am Nat 2011; 177:617-29. [PMID: 21508608 DOI: 10.1086/659630] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Increased variance in the reproductive success of males relative to females favors mothers that optimally allocate sons and daughters to maximize their fitness return. In altricial songbirds, one influence on the fitness prospects of offspring arises through the order in which nestlings hatch from their eggs, which affects individual mass and size before nest leaving. In house wrens (Troglodytes aedon), the influence of hatching order depends on the degree of hatching synchrony, with greater variation in nestling mass and size within broods hatching asynchronously than in those hatching synchronously. Early-hatching nestlings in asynchronous broods were heavier and larger than their later-hatching siblings and nestlings in synchronous broods. The effect of hatching order was also sex specific, as the mass of males in asynchronous broods was more strongly influenced by hatching order than the mass of females, with increased variation in the mass of males relative to that of females. As predicted, mothers hatching their eggs asynchronously biased first-laid, first-hatching eggs toward sons and late-laid, late-hatching eggs toward daughters, whereas females hatching their eggs synchronously distributed the sexes randomly among the eggs of their clutch. We conclude that females allocate the sex of their offspring among the eggs of their clutch in a manner that maximizes their own fitness.
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Affiliation(s)
- E Keith Bowers
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, 61790, USA.
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15
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Affiliation(s)
- Miloš Krist
- Museum of Natural History, nám. Republiky 5, 771 73 Olomouc, Czech Republic.
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16
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Kozlowski CP, Ricklefs RE. Egg size and yolk steroids vary across the laying order in cockatiel clutches: a strategy for reinforcing brood hierarchies? Gen Comp Endocrinol 2010; 168:460-5. [PMID: 20600043 DOI: 10.1016/j.ygcen.2010.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 04/20/2010] [Accepted: 06/14/2010] [Indexed: 11/18/2022]
Abstract
When a female bird begins incubation before clutch completion, the nestlings hatch sequentially, and a size hierarchy forms within the brood. This size hierarchy may be minimized or exacerbated through differential allocation of resources to eggs across the laying order. In this study, we characterize intra-clutch variation in cockatiel clutches by measuring egg mass, yolk mass, and concentrations of yolk testosterone, androstenedione, and corticosterone. Cockatiels are a long-lived member of the Psittaciformes. Because asynchronous hatching may reduce sibling competition and allow for extended development periods in long-lived birds, we predicted that female cockatiels would allocate maternal resources in a way that would reinforce the brood size hierarchy. Significant within-clutch differences in egg size and steroid concentrations were observed. Eggs at the end of the laying sequence were smaller and had significantly smaller yolks than eggs early in the laying order. Fifth-laid eggs, as well as first-laid eggs, contained significantly lower concentrations of testosterone than eggs in other positions of the laying sequence. No differences in yolk androstenedione concentration were observed. Yolk corticosterone concentrations increased linearly with laying order. Together, these patterns might reinforce the brood size hierarchy created by asynchronous hatching.
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Affiliation(s)
- Corinne P Kozlowski
- Research Department, Saint Louis Zoo, 1 Government Drive, St Louis, MO 63110, USA.
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17
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Food supplementation affects egg albumen content and body size asymmetry among yellow-legged gull siblings. Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-0993-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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18
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Forbes S, Wiebe M. Egg size and asymmetric sibling rivalry in red-winged blackbirds. Oecologia 2010; 163:361-72. [DOI: 10.1007/s00442-010-1629-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Accepted: 03/29/2010] [Indexed: 10/19/2022]
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19
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Riehl C. Egg ejection risk and hatching asynchrony predict egg mass in a communally breeding cuckoo, the Greater Ani (Crotophaga major). Behav Ecol 2010. [DOI: 10.1093/beheco/arq038] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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20
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Mortola JP, Al Awam K. Growth of the chicken embryo: implications of egg size. Comp Biochem Physiol A Mol Integr Physiol 2010; 156:373-9. [PMID: 20307682 DOI: 10.1016/j.cbpa.2010.03.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 03/03/2010] [Accepted: 03/04/2010] [Indexed: 11/25/2022]
Abstract
Among avian species with large differences in egg size, changes in eggshell conductance and incubation time permit the water loss necessary for embryonic development. To what extent this happens for different-size eggs within a species is much less known. Chicken eggs with fresh egg weight (Wegg) either large (L, approximately 66 g) or small (S, approximately 51 g) were incubated at 38 degrees C and 60% humidity; their yolk and albumen scaled almost in proportion to Wegg. Eggshell gas conductance scaled to 0.77 of Wegg, as it occurs inter-specifically, while external pipping and hatching occurred at similar times in S and L. Hence, L lost less water during incubation than S, and embryos of L were over-hydrated and those of S were dehydrated. The absolute values of embryo's weight, growth rate, oxygen consumption and the weight of the chorioallantoic membrane were similar between S and L during the first half of incubation, and greater in L in the second half. Incubation in hypoxia reduced growth rate in both sets and maintained the difference in growth trajectories between S and L. The energetic cost of growth and tissue maintenance did not differ significantly. It is concluded that, among chicken eggs of different sizes, 1) the growth rate of the embryo relates to the size of its egg, probably genetically and because of differences in water content, 2) eggshell conductance contributes, but incubation time does not, to the requirements for water loss. Therefore, the egg water balance during incubation may be the physiological constraint that limits the maximal variability in egg size compatible with embryonic survival.
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Affiliation(s)
- Jacopo P Mortola
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec, Canada.
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Maddox JD, Weatherhead PJ. Seasonal sex allocation by Common Grackles? Revisiting a foundational study. Ecology 2009; 90:3190-6. [PMID: 19967874 DOI: 10.1890/08-2180.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Despite the general importance of replication in science, relatively few behavioral ecology studies are repeated. Here we repeat the seminal 1977 research of H. F. Howe, who found that the proportion of male nestlings at hatching in nests of Common Grackles (Quiscalus quiscula) increased as the breeding season progressed. Howe interpreted this pattern as an adaptive response to changing food conditions that favored greater production of daughters (the sex less expensive to rear) when food was scarce and sons when food was more abundant. Using DNA-based sexing and larger samples, we found no evidence of nonrandom seasonal sex allocation and no evidence that sons were more vulnerable to starvation than daughters. These patterns also prevailed among renesting efforts late in the season, when starvation was extreme. Although there is no way to exclude the possibility that grackles employed different sex allocation tactics in the two studies, similarities in weather, habitat, nesting phenology, and starvation rates make it seem unlikely that ecological differences between our study and Howe's explain the disparate results, whereas failure of assumptions that Howe was unable to test seems more plausible.
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Affiliation(s)
- J Dylan Maddox
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois, Shelford Vivarium, 606 E. Healey St., Champaign, Illinois 61820, USA.
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Reed W, Clark M, Vleck C. Maternal Effects Increase Within‐Family Variation in Offspring Survival. Am Nat 2009; 174:685-95. [DOI: 10.1086/605962] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Evolution of Adaptation and Mate Choice: Parental Relatedness Affects Expression of Phenotypic Variance in a Natural Population. Evol Biol 2008. [DOI: 10.1007/s11692-008-9017-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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