Figure 1

Average positions (error bars denote two standard errors) of Z. abyssinicus (parapatric and allopatric - open circles, sympatric - open square) and Z. poliogaster populations (parapatric and allopatric - black circles, sympatric - black square) within two dimensional acoustic PCA space (strongly driven by a variation of starting and lowest frequencies and of frequency range in the highland species Z. poliogaster , for summary of loadings see Table  1 ), convex hulls for both species exclude the respective sympatric populations.