Master of Science (M.Sc.)
Prenatal acoustic communication affects embryonic development in ways that modify, and potentially optimize, the postnatal phenotype. In zebra finch (Taeniopygia guttata), prenatal exposure to a heat-induced parental call affects the behavior, growth, and ultimate fitness of individuals in hotter environments. However, observing the effects of heat calling on the postnatal phenotype does little to inform our understanding of how embryos are immediately perceiving and reacting to this signal. Here, we tested whether prenatal exposure to heat calls induces an immediate response from embryos that can be detected by changes in vibrations at the egg’s surface. More specifically, we used laser Doppler vibrometry (LDV) to measure the frequency and amplitude of egg vibrations to assess (i) whether unstimulated eggs exhibit a generalized vibration profile, and (ii) whether this profile changes in response to heat calls played back at four different amplitudes. We found variation in vibration intensity across many frequencies in unstimulated live eggs compared to dead eggs, suggesting randomness or idiosyncrasy in embryonic movements. However, a discernible peak in vibration amplitude between 40 to 45 Hz could be an important identifier for eggs at this stage of development. Importantly, exposure to heat calls affected a two-fold increase in the proportion of eggs exhibiting changes in the intensity of 10 to 15 Hz vibrations. Although the mechanism affecting this response remains unclear, this result provides evidence that developing altricial bird embryos are capable of both perceiving and responding to acoustic stimuli. Moreover, this immediate vibration responses to parental calls supports the potential for communication between parents and their embryos in the nest. Although we acknowledge that anthropogenic sources of noise and other substrate-borne vibrations may affect the transmission and subsequent benefit of this subtle form of communication, egg vibrations may nevertheless be an important tool for measuring embryonic perception.
© The Author
Ellott, Liz Rose, "Egg Vibrations In Response To Parental Calls: Scrambled Eggs Or Genuine Feedback?" (2023). Dissertations, Theses, and Masters Projects. William & Mary. Paper 1697552662.
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