Characters of F 1 Hybrid Tadpoles between Six Species of Hyla

Abstract

Pigment patterns, tooth row ratios, and oral papillae were studied in 13 hybrid crosses of six species of Hyla. Pigment patterns that appeared to be controlled by dominant genes include the interorbital iridophore pattern of Hyla avivoca tadpoles, the copper-red tail saddles of H. avivoca, the yellow crossband on the body of H. cinerea tadpoles, the preorbital stripe of H. cinerea and H. avivoca, the striped tail pattern of H. femoralis and the unique melanophore distribution on the tail fin of H. gratiosa. On the anterior third of the tail in H. gratiosa, the melanophores are fibrillar and on the posterior portion they are punctate. These characteristics appeared in every hybrid tadpole involving at least one parent with the trait. The length of the third lower tooth row was somewhat intermediate between the parents but favored the parent with the longer row; this was particularly evident in crosses involving short and long-rowed parents. Lateral submarginal papillae tended to be intermediate in the hybrids, indicating a polygenic mode of inheritance, whereas a double row of marginal papillae on the ventral midline of the oral disc appeared to be dominant over a single row. Reciprocal crosses showed no detectable differences in hybrid characters. Natural hybrids between H. cinerea and H. gratiosa were morphologically similar to laboratory hybrids involving these two parents.