Figure 2.

A robust spiracle extension response (SER) was performed by repleta species

(A) Description of cold-evoked SER, with images (subject, D. arizonae).

(B) % SER following segmental cold stimulation via cold-probe assay ±standard error of the proportion. N = 30, n = 10, each referring to the number of larvae assayed.

(C) Ancestral state reconstruction by single-rate continuous-time Markov chain model indicates that the SER behavior most likely evolved in a common repleta ancestor after the group split from other drosophilids.