title: Incubation temperature influences trade-off between structural size and energy reserves in mallard hatchlings.
abstract: The reproductive success of precocial birds depends on investments in clutch formation and incubation. Egg quality strongly affects the phenotypic traits correlated with survival of the hatchling, but parental ability to maintain incubation temperature can also influence hatchling outcomes. The effect of incubation temperature on hatchling phenotype has been widely studied in reptiles but not in birds. The aim of this study was to explore the effects of egg mass and incubation temperature on the incubation period, hatchability, and hatchling phenotype of the mallard (Anas platyrhynchos). Mallard eggs were incubated under six constant incubation temperatures (ranging from 35.0° to 39.0°C). Hatchlings were weighed, and their structural size was measured. Some hatchlings were used for an examination of residual yolk sac mass and basic chemical composition of the yolk-free body. All investigated phenotypic traits except for chemical composition were positively correlated with egg mass. Incubation temperature did not affect hatchling body mass, but increased temperatures led to a decreased yolk-free body mass and structural size of hatchlings and to increased yolk sac mass. Our results suggest that there is a trade-off between the yolk-free body size and energetic reserves in the form of the yolk sac and that this trade-off is modulated by incubation temperature.
authors.affiliation: Department of Ecology, Faculty of Science, Charles University in Prague, Viničná 7, CZ-128 44 Praha 2, Czech Republic; 2Department of Quality of Agricultural Products, Faculty of Agrobiology, Food, and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, CZ-160 00, Praha 6, Czech Republic; 3Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, CZ-128 44 Praha 2, Czech Republic; 4Institute of Vertebrate Biology, v.v.i., Academy of Sciences of the Czech Republic, Květná 8, CZ-603 65, Brno, Czech Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Koláčková
authors.forename: Ludmila
authors.initials: L
authors.lastname: Prokůpková
authors.forename: Tomáš
authors.initials: T
authors.lastname: Albrecht
authors.forename: David
authors.initials: D
authors.lastname: Hořák
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D049628:Body Size; D004372:Ducks / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000196:embryology*; D047108:Embryonic Development / Q000502:physiology; D010063:Ovum / Q000737:chemistry; D010641:Phenotype; D013696:Temperature; D015017:Yolk Sac / Q000737:chemistry*