Hearing dimorphism, trait variation and conflicts over space in the thoraxof the bushcricket Requena verticalis (Listroscelidinae : Tettigoniidae : Orthoptera)
Wj. Bailey et D. Kamien, Hearing dimorphism, trait variation and conflicts over space in the thoraxof the bushcricket Requena verticalis (Listroscelidinae : Tettigoniidae : Orthoptera), J COMP PH A, 187(8), 2001, pp. 647-652
Citations number
32
Categorie Soggetti
Physiology
Journal title
JOURNAL OF COMPARATIVE PHYSIOLOGY A-SENSORY NEURAL AND BEHAVIORAL PHYSIOLOGY
The hearing system of Requena verticalis is sexually dimorphic. Previous wo
rk has shown size of the auditory spiracle determines absolute threshold an
d as female spiracles are, on average, larger than mates, females are more
sensitive to the main energy of the male call. In all measured traits in mo
rphology and physiology, females showed lower coefficient of variation than
males. This difference was significant for bulla volume and hearing thresh
old. In addition, female ear size covaries with thorax dimensions but this
is not so in males. Such a finding suggests stabilising selection on ear si
ze in females, perhaps explained by the requirement of females to recognise
and locate the male. As the auditory bulla is larger in females than males
. so occupying thoracic space, we suggest a possible trade-off in this brac
hypterous species between hearing sensitivity and sound production. Finally
, we examine relative growth of body structures not associated with hearing
and those that influence hearing sensitivity. Scaling, where traits are un
der strong selection, may result in allometry. Female hearing traits show p
ositive allometry with absolute size and while the relationship between bul
la volume and spiracle area was positively allometric in females this was n
ot the case for males.