Trimerotropis pallidipennis (Burmeister, 1838)

Colombo, Pablo César & Remis, María Isabel, 2015, Morphometric variation in chromosomally polymorphic grasshoppers (Orthoptera: Acrididae) from South America: Bergmann and converse Bergmann patterns, Florida Entomologist 98 (2), pp. 570-570 : 570-

Trimerotropis pallidipennis

According to the data shown in Table 1 and Figure 1 , body size was strongly and negatively correlated with altitude (r = 0.9782, P = 0.0001). This result suggests that chromosome inversions may be associated with adaptation to different environments not only at population levels ( Colombo 2002) but also in a broader geographical scope. We think that in this case, body size–related variables may point in the direction of season length limitation due to a slower rate of growth caused by lower temperatures, along with the shortening of the time available for development ( Berner et al. 2004; Blanckenhorn & Demont 2004; Berner & Blanckenhorn 2006). An altitudinal cline related with body size, temperature, and development rate was studied in the European grasshopper Omocestus viridulus (L.) ( Berner et al. 2004; Berner & Blanckenhorn 2006); however, this species was revealed to be univoltine all along the gradient. Trimerotropis pallidipennis was shown to be bivoltine instead, at least in the high-mountain population of Uspallata (C. Lange, personal communication). We do not know whether there are variations in voltinism along the gradient.

One of the chromosome inversions affects a morphometric variable; in fact, inversion 6M in the population of Uspallata significantly increases tegmen length ( Table 2, from Colombo 2002). We think that the effect on a morphometric variable at a location may be related to the pattern of distribution on a broader geographical scope.

Colombo & Confalonieri (1996) found that inversion frequencies were negatively correlated with minimum temperature; we think now that this correlation may be masking several other variables, which in time are covariate with it. Chromosome inversions may be related with the adaptation to such variables.

Figures

Fig. 1. A) Trimerotropis pallidipennis: Tegmen length (in mm) against altitude; B) Leptysma argentina: Total body length in mm against latitude; C) Cornops aquati- cum: Tegmen length in mm against latitude in males; and D) Cornops aquaticum: Tegmen length in mm against latitude in females.