Abstract
Previous work indicates that the O2, conductance of the jelly capsule (Go2) and O2 consumption (V̇o2) of Pseudophryne bibronii eggs increase in parallel during development such that perivitelline Po2 remains high and constant throughout incubation at 12° C (Seymour and Bradford 1987). To determine whether the pattern of capsular change is adaptively regulated, the eggs were incubated at selected Ta (7°, 12°, 17°, and 22° C), ambient Po2 (10, 15, 21, 30, and 40 kPa), and substrate water potential (0 and −25 kPa), and we measured V̇o2 Go2, incubation time, and differentiation rate. The Go2 is not directly affected by Ta, ambient Po2, or water potential, but it depends strongly on developmental stage. The embryo is apparently programmed to secrete specific substances that modify capsule morphology at specific stages of development, and it does not respond to environmental conditions by altering the time course of secretion. Consequently, Po2 in the perivitelline space is not regulated but declines at higher temperatures. At 17° C and 22° C, V̇o2 becomes limited by capsule Go2 in late stages of development. However, winter breeding at field temperatures averaging about 12° C reduces the possibility of O2 limitation and retardation of embryonic development.
Paper version not known (
Free)
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call