Variation in eggshell characteristics and gas exchange of montane and lowland coot eggs

Carey, Cynthia; León‐Velarde, Fabiola; Dunin-Borkowski, Olga; Bucher, Theresa L.; Torre, Grimaneza de la; Espinoza, Daniel Alonso; Monge, Carlos

doi:10.1007/bf00692411

Cited by 27 publications

(21 citation statements)

References 33 publications

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“…Third, increased egg size at high elevations could be adaptive for reasons of water and heat retention. Selection may favour bigger eggs because lower absolute air pressure at high elevations leads to higher water loss (Rahn & Ar, ; Carey et al , , ). Rahn et al () demonstrated that water loss is reduced at higher elevation by a reduction of pore area in the shell.…”

Section: Life Histories Along Elevational Gradientsmentioning

confidence: 99%

Elevational trends in life histories: revising the pace‐of‐life framework

2014

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Life-history traits in birds, such as lifespan, age at maturity, and rate of reproduction, vary across environments and in combinations imposed by trade-offs and limitations of physiological mechanisms. A plethora of studies have described the diversity of traits and hypothesized selection pressures shaping components of the survival-reproduction trade-off. Life-history variation appears to fall along a slow-fast continuum, with slow pace characterized by higher investment in survival over reproduction and fast pace characterized by higher investment in reproduction over survival. The Pace-of-Life Syndrome (POLS) is a framework to describe the slow-fast axis of variation in life-history traits and physiological traits. The POLS corresponds to latitudinal gradients, with tropical birds exhibiting a slow pace of life. We examined four possible ways that the traits of high-elevation birds might correspond to the POLS continuum: (i) rapid pace, (ii) tropical slow pace, (iii) novel elevational pace, or (iv) constrained pace. Recent studies reveal that birds breeding at high elevations in temperate zones exhibit a combination of traits creating a unique elevational pace of life with a central trade-off similar to a slow pace but physiological trade-offs more similar to a fast pace. A paucity of studies prevents consideration of the possibility of a constrained pace of life. We propose extending the POLS framework to include trait variation of elevational clines to help to investigate complexity in global geographic patterns.

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Section: Life Histories Along Elevational Gradientsmentioning

confidence: 99%

Elevational trends in life histories: revising the pace‐of‐life framework

2014

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“…As birds breed in almost all terrestrial environments, including habitats with extreme levels of humidity, altitude and temperature ( Lomholt, 1976 ; Sotherland et al, 1980 ; Davis et al, 1984 ; Davis and Ackerman, 1985 ; Arad et al, 1988 ; Carey et al, 1989 ; Carey et al, 1990 ; Walsberg and Schmidt, 1992 ; Carey, 1994 ), the structure of the eggshell is likely to play an important role in allowing bird species to successfully expand into and inhabit a wide variety of habitats. To fully understand the diversity of avian eggshell structure requires an analysis of the evolutionary basis of the structural adaptations for eggshells' gas exchange in different environments and nesting conditions, and across species with varying life histories (e.g.…”

Section: Introductionmentioning

confidence: 99%

Nesting behaviour influences species-specific gas exchange across avian eggshells

Portugal

Maurer

Thomas

et al. 2014

Journal of Experimental Biology

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Carefully controlled gas exchange across the eggshell is essential for the development of the avian embryo. Water vapour conductance (GH2O) across the shell, typically measured as mass loss during incubation, has been demonstrated to optimally ensure the healthy development of the embryo while avoiding desiccation. Accordingly, eggs exposed to sub-optimal gas exchange have reduced hatching success. We tested the association between eggshell GH2O and putative life-history correlates of adult birds, ecological nest parameters and physical characteristics of the egg itself to investigate how variation in GH2O has evolved to maintain optimal water loss across a diverse set of nest environments. We measured gas exchange through eggshell fragments in 151 British breeding bird species and fitted phylogenetically controlled, general linear models to test the relationship between GH2O and potential predictor parameters of each species. Of our 17 life-history traits, only two were retained in the final model: wet-incubating parent and nest type. Eggs of species where the parent habitually returned to the nest with wet plumage had significantly higher GH2O than those of parents that returned to the nest with dry plumage. Eggs of species nesting in ground burrows, cliffs and arboreal cups had significantly higher GH2O than those of species nesting on the ground in open nests or cups, in tree cavities and in shallow arboreal nests. Phylogenetic signal (measured as Pagel's λ) was intermediate in magnitude, suggesting that differences observed in the GH2O are dependent upon a combination of shared ancestry and species-specific life history and ecological traits. Although these data are correlational by nature, they are consistent with the hypothesis that parents constrained to return to the nest with wet plumage will increase the humidity of the nest environment, and the eggs of these species have evolved a higher GH2O to overcome this constraint and still achieve optimal water loss during incubation. We also suggest that eggs laid in cup nests and burrows may require a higher GH2O to overcome the increased humidity as a result from the confined nest microclimate lacking air movements through the nest. Taken together, these comparative data imply that species-specific levels of gas exchange across avian eggshells are variable and evolve in response to ecological and physical variation resulting from parental and nesting behaviours.

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“…A study on red-winged blackbirds (Agelaius phoeniceus ) over 2900 m altitudinal gradient found no differences in embryonic metabolism, incubation period, and hatchling mass (Carey et al 1982). In contrast, eggs of montane coots ( Fulica americanal laid at 4150 m have depressed metabolic rate and prolonged incubation period, but hatch with the same mass as that of lowland coots (Carey et al 1989).…”

Section: Oxygen Consumption and Growthmentioning

confidence: 98%

“…Similar findings have been reported for eggs of the green sea turtle, the loggerhead, and the snapping turtle (Ackerman 1981a;Kam 1988). In avian eggs, depression of metabolism and growth by hypoxia has been interpreted as either an inability of embryos to take up enough oxygen from surroundings (Carey et al 1982;Snyder et al 1982;Carey et al 1989), or an adaptive adjustment to maintain air-cell P 02 adequate for tissue oxygenation (Wangensteen et al 1974; Beattie and Smith 1975).…”

Section: Oxygen Consumption and Growthmentioning

confidence: 99%

“…Severe hypoxia (P 02 = 95 mmHg or lower) retards development and growth and prolongs the incubation period in chicken and montane coot (Fulica americanal embryos (Wangesteen et al 1974;Carey et al 1989). In most cases, the development and growth of high altitude species are not affected by hypoxia encountered in natural habitats, as found in bar-headed geese (Anser indicusl .…”

Section: Introductionmentioning

confidence: 99%

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