The Population Biology of the White-lipped Land Snail, Triodopsis albolabris
McCracken GF. 1976. The Population Biology of the White-lipped Land Snail, Triodopsis albolabris. Cornell University
ABSTRACT: The population structure of the white-lipped land snail, Triodopsis albolabris was investigated from two approaches: (l) intensive capture-recapture studies and field observations were conducted in two natural populations to obtain estimates of population size, individual survivorship, and the amount of gene flow between populations; (2) allozyme variation was examined at eight genetic loci in 17 populations ranging from Quebec to central Alabama to determine the genetic relationships among populations and to survey variability throughout the species' range. In addition, a laboratory colony was maintained to determine the genetic bases of the allozyme polymorphisms, and to investigate the breeding system of this hermaphroditic snail.... There was much genetic heterogeneity among populations. Adjacent populations in the same forest had different alleles at the same loci. Undoubtedly, this was due to founder effects or drift. Standardized genetic variances (Fst ' s) among populations were very large. Apportionment of diversity analyses also demonstrated great interpopulation genetic heterogeneity. The patterns of this heterogeneity suggest that the stochastic effects of genetic drift, bottlenecks, and founder effects are very important in determining the genetic composition of T. albolabris populations. Most likely, these forces have been important in the evolutionary diversification of this sedentary animal. Genetic analyses showed that the northern "subspecies", T. a. albolabris is actually a different species from the southern "subspecies", T. a_. major. In Virginia and Tennessee these "subspecies" were found existing in syrapatric but reproductively isolated populations. This confirms their status as distinct species. Morphological measurements support this conclusion. Genetic evidence suggests that T. a. major may actually be a complex of species, consisting, perhaps, of three species....
- Type
- Academic
- Authors
- McCracken, Gary
- Date of Issue
- 1976-05
- Publisher
- Cornell University
- Units
- BLRI , GRSM
- Keywords
- APHN, Appalachian Highlands Network, Big Locust, BLRI, Blue Ridge Parkway, Great Smoky Mountains National Park, GRSM, GRSM-01689, Henwallow, land snail, Peaks of Otter, SER, Southeast Region, taxonomy, thesis