Variation in founder groups promotes establishment success in the wild

Environmental changes currently pose severe threats to biodiversity, and reintroductions and translocations are increasingly used to protect declining populations and species from extinction. Theory predicts that establishment success should be higher for more variable groups of dissimilar individuals. To test this ‘diversity promotes establishment’ hypothesis, we introduced colour polymorphic pygmy grasshoppers ( Tetrix subulata ) to different sites in the wild. The number of descendants found at the release sites the subsequent year increased with increasing number of colour morphs in the founder group, and variation in founder groups also positively affected colour morph diversity in the established populations. Since colour morphs differ in morphology, physiology, behaviour, reproductive life history and types of niche used, these findings demonstrate that variation among individuals in functionally important traits promotes establishment success under natural conditions, and further indicate that founder diversity may contribute to evolutionary rescue and increased population persistence.

Cardiac Telemetry, Natality, and Food Habits of Bighorn Sheep at Bighorn Canyon National Recreation Area

Data were collected from May 1988 to May 1989 to aid in the development of a management program for Rocky Mountain bighorn sheep (Ovis canadensis canadensis) at Bighorn Canyon National Recreation Area (BICA). A principle goal of the management program at BICA is to promote the continued expansion of a reintroduced population of bighorn sheep throughout its ancestral habitat (BICA 1984). In previous research at BICA (Coates and Schemnitz 1988) we identified 3 factors as potentially limiting to herd expansion: visitor and/or vehicular disturbance of bighorns (especially reproductive ewes), competition with horses for a limited supply of grasses, and possible genetic constraints on recruitment (i.e., inbreeding depression) resulting from small founder group size.

Cardiac Telemetry, Natality and Genetics of a Recolonized Population of Bighorn Sheep at a Wild Horse Range

Data were collected from 05-88 to 12-88 in continued research to aid in the development of a management program for Rocky Mountain bighorn Sheep (Ovid c. canadensis) at Bighorn Canyon National Recreation Area (BICA). A principle goal of the management program at BICA is to promote the continued expansion of a recolonized population throughout ancestral habitat in the area (BICA 1984). In previous research at BICA (Coates and Schemnitz, 1988), we identified 3 factors as potentially limiting to herd expansion: visitor and (or) vehicular disturbance of bighorns (esp. reproductive ewes), competition with horses for grasses, and possible genetic constraints on recruitment resulting from small founder-group size.