Captive Breeding of Delta Smelt: Overview of Genetic Issues

Phil Hedrick, Arizona State University, Tempe, AZ

It is important in conservation genetics and captive breeding to plan for managing the three major types of genetic variation: adaptive, neutral, and detrimental. An example of adaptive variation are genes determining disease resistance and data in winter run Chinook salmon will be presented. Neutral variation is used for identification and estimation and examples of identifying subspecies and species in jumping mice and topminnows and estimating effective population size in winter run Chinook salmon will be discussed. Detrimental variation can results in inbreeding depression and genetic load. Data demonstrating inbreeding depression in winter run Chinook salmon and reduction of genetic load, or genetic rescue, in Florida panthers and Mexican wolves will be presented.

Genetic changes in captive populations can be caused by small population size, inbreeding, and adaptation to captivity. To avoid these genetic changes, which are nearly always detrimental to fitness, the following recommendations are suggested. These are (1) keeping the population size as large as possible, (2) breeding that minimizes mean kinship (to keep inbreeding low, equalize founder contribution, and help minimize captive adaptation), (3) maintaining independent, replicate populations, (4) minimizing the number of generations in captivity, (5) periodically incorporating new wild-caught individuals into the captive population, and (6) making the captive environment should be as similar as possible to the natural environment.

Back to CABA-CALFED Seminars