Variability in Eggshell Pore Area in Relation to Brood Hatching Patterns in House Wrens (Troglodytes Aedon)
Submission Type
Event
Expected Graduation Date
2013
Location
Atrium, Center for Natural Sciences, Illinois Wesleyan University
Start Date
4-20-2013 9:00 AM
End Date
4-20-2013 10:00 AM
Disciplines
Biology
Abstract
The House Wren (Troglodytes aedon) is a songbird that exhibits both synchronous and asynchronous hatching. Asynchronous hatching, which occurs when eggs within a clutch hatch two or more days apart, often results in a competitive advantage to the first-hatched nestlings. Two mechanisms by which asynchronous hatching occurs include the onset of incubation and variability in eggshell pore area. Larger eggshell pores would allow for increased gas exchange, which would result in faster development and earlier hatching. We tested the hypothesis that eggshell characteristics contribute to brood hatching patterns by counting and measuring pores from House Wren eggshells. If this hypothesis is correct, we predict that there should be differences in pore area between the first and last-laid eggs within clutches. Only one of twelve clutches (8.3%, N = 48 eggs, 1,502 fragments) showed significant differences in pore area between the first two and last two laid eggs. Given that approximately half of broods in this House Wren population hatch asynchronously, we did not support our hypothesis that eggshell pore area influences brood hatching patterns.
Variability in Eggshell Pore Area in Relation to Brood Hatching Patterns in House Wrens (Troglodytes Aedon)
Atrium, Center for Natural Sciences, Illinois Wesleyan University
The House Wren (Troglodytes aedon) is a songbird that exhibits both synchronous and asynchronous hatching. Asynchronous hatching, which occurs when eggs within a clutch hatch two or more days apart, often results in a competitive advantage to the first-hatched nestlings. Two mechanisms by which asynchronous hatching occurs include the onset of incubation and variability in eggshell pore area. Larger eggshell pores would allow for increased gas exchange, which would result in faster development and earlier hatching. We tested the hypothesis that eggshell characteristics contribute to brood hatching patterns by counting and measuring pores from House Wren eggshells. If this hypothesis is correct, we predict that there should be differences in pore area between the first and last-laid eggs within clutches. Only one of twelve clutches (8.3%, N = 48 eggs, 1,502 fragments) showed significant differences in pore area between the first two and last two laid eggs. Given that approximately half of broods in this House Wren population hatch asynchronously, we did not support our hypothesis that eggshell pore area influences brood hatching patterns.