Journal article

Publication year: 2017

Pages: 104-116

Journal: Brain, Behavior and Evolution

Volume number: 89

Issue number: 2

DOI Link: https://doi.org/10.1159/000462957

Publisher: Karger Publishers

Abstract: 

Animals' adaptations to cave habitats generally include elaboration of
extraoptic senses, and in insects the receptor structures located on the
legs are supposed to become more prominent in response to constant
darkness. The receptors for detecting substrate vibrations are often
highly sensitive scolopidial sensilla localized within the legs or the
body. For troglobitic insects the evolutionary changes in vibroreceptor
organs have not been studied. Since rock is an extremely unfavorable
medium for vibration transmission, selection on vibration receptors may
be weakened in caves, and these sensory organs may undergo regressive
evolution. We investigated the anatomy of the most elaborate internal
vibration detection system in orthopteroid insects, the scolopidial
subgenual organ complex in the cave cricket Dolichopoda araneiformis
(Orthoptera: Ensifera: Rhaphidophoridae). This is a suitable model
species which shows high levels of adaptation to cave life in terms of
both phenotypic and life cycle characteristics. We compared our data
with data on the anatomy and physiology of the subgenual organ complex
from the related troglophilic species Troglophilus neglectus. In D. araneiformis,
the subgenual organ complex contains three scolopidial organs: the
subgenual organ, the intermediate organ, and the accessory organ. The
presence of individual organs and their innervation pattern are
identical to those found in T. neglectus, while the subgenual organ and the accessory organ of D. araneiformis contain about 50% fewer scolopidial sensilla than in T. neglectus. This suggests neuronal regression of these organs in D. araneiformis,
which may reflect a relaxed selection pressure for vibration detection
in caves. At the same time, a high level of overall neuroanatomical
conservation of the intermediate organ in this species suggests
persistence of the selection pressure maintaining this particular organ.
While regressive evolution of chordotonal organs has been documented
for insect auditory organs, this study shows for the first time that
internal vibroreceptors can also be affected.

Harvard Citation style: Strauß, J. and Stritih, N. (2017) Neuronal Regression of Internal Leg Vibroreceptor Organs in a Cave-Dwelling Insect (Orthoptera: Rhaphidophoridae: Dolichopoda araneiformis), Brain, Behavior and Evolution, 89(2), pp. 104-116. https://doi.org/10.1159/000462957

APA Citation style: Strauß, J., & Stritih, N. (2017). Neuronal Regression of Internal Leg Vibroreceptor Organs in a Cave-Dwelling Insect (Orthoptera: Rhaphidophoridae: Dolichopoda araneiformis). Brain, Behavior and Evolution. 89(2), 104-116. https://doi.org/10.1159/000462957