PT  - JOURNAL ARTICLE
AU  - Littlejohn, M. J.
AU  - Oldham, R. S.
TI  - Rana pipiens Complex: Mating Call Structure and Taxonomy
AID  - 10.1126/science.162.3857.1003
DP  - 1968 Nov 29
TA  - Science
PG  - 1003--1005
VI  - 162
IP  - 3857
4099  - http://science.sciencemag.org/content/162/3857/1003.short
4100  - http://science.sciencemag.org/content/162/3857/1003.full
SO  - Science1968 Nov 29; 162
AB  - Geographic variability in call structure indicates that four largely allopatric populations of leopard frogs are present in the central United States. These forms appear to maintain their distinctness in narrow zones of sympatry, and most adult males can be separated morphologically. It is suggested that the four forms represent distinct species and that the idea of gradual clinal variability in one wide-ranging species is wrong.