Journal Article
Evolution of the acoustic startle response of Mexican cavefish
Paz, A., McDole, B., Kowalko, J.E., Duboue, E.R. and Keene, A.C.
Record Number:
5121
Year:
2020
Journal:
Journal of Experimental Zoology. Part B Molecular and Developmental Evolution
Pages:
474-485
Volume:
334
Alternate Journal:
JEZB.MDE
Abstract:
The ability to detect threatening stimuli and initiate an escape response is essential
for survival and under stringent evolutionary pressure. In diverse fish species,
acoustic stimuli activate Mauthner neurons, which initiate a C‐start escape response.
This reflexive behavior is highly conserved across aquatic species and
provides a model for investigating the neural mechanism underlying the evolution of
escape behavior. Here, we characterize evolved differences in the C‐start response
between populations of the Mexican cavefish, Astyanax mexicanus. Cave populations
of A. mexicanus inhabit an environment devoid of light and macroscopic predators,
resulting in evolved differences in various morphological and behavioral traits. We
find that the C‐start is present in river‐dwelling surface fish and multiple populations
of cavefish, but that response kinematics and probability differ between populations.
The Pachón population of cavefish exhibits an increased response
probability, a slower response latency and speed, and reduction of the maximum
bend angle, revealing evolved differences between surface and cave populations.
Analysis of the responses of two other independently evolved populations of cavefish,
revealed the repeated evolution of reduced angular speed. Investigation of
surface‐cave hybrids reveals a correlation between angular speed and peak angle,
suggesting these two kinematic characteristics are related at the genetic or functional
levels. Together, these findings provide support for the use of A. mexicanus as
a model to investigate the evolution of escape behavior.
KEYWORDS
cavefish, convergent evolution, Mauthner, startle reflex
Times Cited:
1
Relevent Species: