Lack of Genic Diversity Within and Among Populations of an Endangered Plant, <i>Howellia aquatilis</i>

Abstract

Abstract: Howellia aquatilis (Campanulaceae) is a rare aquatic plant considered endangered throughout its range in the Pacific Northwest. Howellia appears to have a narrow ecological amplitude, occurring only in temporary ponds suwounded by trees. Anatomical observations of developing flowers indicate a restrictive breeding system approaching obligate self‐fertilization. We used protein electrophoresis to examine the genetic structure of four populations from throughout the range of species. Eight enzymes encoded by 18 putative loci showed no variation, either within or among populations. Howellia's small ecological amplitude and lack of genetic variability lead us to believe that the species is prone to extinction A conservation strategy for this species should include protection of ponds that are currently inhabited by Howellia as well as ponds that will become appropriate habitat in the future. To insure against large‐scale environmental perturbations, multiple pond clusters throughout the range of the species should be protected.