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Inheritance of song and stridulatory peg number divergence between Chorthippus brunneus and C. jacobsi , two naturally hybridizing grasshopper species (Orthoptera: Acrididae)
Author(s) -
SALDAMANDO C. I.,
MIYAGUCHI S.,
TATSUTA H.,
KISHINO H.,
BRIDLE J. R.,
BUTLIN R. K.
Publication year - 2005
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2004.00838.x
Subject(s) - biology , grasshopper , reproductive isolation , genetic divergence , acrididae , orthoptera , evolutionary biology , sexual selection , zoology , divergence (linguistics) , epistasis , allopatric speciation , genetics , genetic diversity , ecology , population , gene , linguistics , demography , philosophy , sociology
Knowledge of the genetic basis of divergence in mating signal characters that contribute to reproductive isolation is critical to understanding speciation. Here, we describe a semi‐automated system for characterizing grasshopper acoustic signals. We used this system to study the genetic basis of divergence in three male calling song components [echeme (EL), syllable (SL) and phrase (PL) lengths] between Chorthippus brunneus and C. jacobsi , two species of grasshoppers that hybridize in northern Spain. We also studied the number of pegs in the stridulatory file. For all characters, additive effects accounted for most of the genetic differentiation between species. However, the three song components also showed small but significant epistatic effects. No sex linkage was detected. Wright–Castle–Lande estimates of the minimum numbers of genetic factors underlying song and peg number divergence were low: peg number ( n e = 5.87 ± 5.84), SL ( n e = 2.37 ± 4.79) and PL ( n e = 0.87 ± 0.86). On the other hand, EL appeared to be controlled by many genes. These results suggest that divergence in SL and PL might be driven by sexual selection whereas EL might not be under selection. This is consistent with experimental results on female song preference in related species. However, the fact that few factors appear to underlie the differences in peg number is surprising. Peg number is not closely related to song characteristics. It often varies between closely related grasshopper species and it has been assumed to be a neutral character. The biometrical approaches used here tend to underestimate the number of factors influencing a trait but provide valuable background for subsequent quantitative trait loci analyses.