Genetic Relationships and Reproductive Isolation in Southeastern Frogs of the Genera Pseudacris and Hyla

Interstitial hybridization sites of the (TTAGGG)_n telomeric sequence on the chromosomes of some North American hylid frogs

“…Given the homogeneity among hylid karyotypes, the interstitial sites prob ably did not arise through such mechanisms as chromosomal fusions, fissions, or inversions, since one would also expect to see differences in chromosomal morphology. Most of the simi larities and differences between the species examined in this study seemed to agree with our understanding of the systematics of this group of animals (Mecham, 1965: Fortman and Altig. 1974: Maxson and Wilson.…”

Analysis of a Hybrid Zone between Chorus Frogs of the Pseudacris nigrita Complex in the Southern United States

“…Artificial hybridization experiments have shown that P. nigrita from Florida and P. t. feriarum from eastern Alabama have a high level of genetic compatibility (Mecham, 1965). Also, the protein data are consistent with a high proportion of hybrid individuals being backcross progeny or later than F1 generation hybrids.…”

Reproductive Character Displacement in the Acoustic Communication System of Green Tree Frogs (Hyla Cinerea)

“…Males of H. cinerea usually call from elevated perches in or around ponds, whereas H. gratiosa males typically call while floating in the water (Mecham 1960). Calling males and satellites of H. cinerea attempt to mate with other frogs that they detect in their vicinity (Perrill et al 1978).…”

“…Hyla cinerea and H. gratiosa are more genetically compatible than most other combinations of North American hylids: several combinations of mixed parental, hybrid ϫ parental, and hybrid ϫ hybrid crosses yielded similarly high fertilization rates, and the development of the cleaved eggs was normal (Mecham 1965). Only some hybrid crosses (F 1 female ϩ H. cinerea male) resulted in about 10% reduction in egg cleavage (Mecham 1960). However, lower than expected percentages of hybrids and backcrosses in an introgressing population in Alabama suggest low-level genetic incompatibility (Lamb and Avise 1986;Schlefer et al 1986).…”

“…They also have all the necessary features of a suitable system to study reproductive character displacement as laid out by Howard (1993): (1) the traits under consideration (advertisement call, female call preferences) serve as reproductive barriers (Oldham and Gerhardt 1975); (2) the members of the species pair occur in sympatry and one (H. cinerea) or both also occur in allopatry (Fig. 1); (3) heterospecific matings, interspecific hybrids, and backcrosses occur frequently in mixed-species choruses, especially in human-disturbed breeding sites (Gerhardt 1974a;Gerhardt et al 1980;Mecham 1960;Lamb and Avise 1986;Schlefer et al 1986); and (4) there is evidence of selection against hybrids (Gerhardt 1974a;Schlefer et al 1986). …”