Reproduction and development of the endangered sedum integrifolium ssp. leedyi (Crassulaceae)

Abstract

Information on reproduction and life history is important for the conservation of endangered plants. We investigated rates of flowering, seed set, and germination in populations of the endangered perennial plant Sedum integrifolium ssp. leedyi. Germination and flowering rates differed significantly among populations, but seed set rate did not. We assayed 26 plant clusters (81 stems) from four of the five known populations for evidence of clonal reproduction using 28 randomly amplified polymorphic DNA (RAPD) markers. Of the 81 stems, 75 had unique genotypes and three pairs had identical genotypes, suggesting that clonal reproduction is infrequent. Flowering, seed set, and germination rates were correlated with our estimates of ratios of effective to actual population sizes (Ne/N), but not with Ne. The single formally protected population may be experiencing inbreeding depression. We grew plants from seed to maturity in a greenhouse, with a germination rate of 77% and survival of 98% of the germinants at 6 mo, suggesting that this will be a viable means of ex situ propagation. Plants flowered 4-6 mo after germination and produced mature fruits 1-2 mo later, suggesting that they have the potential to sexually reproduce in their first or second season of growth.

Effects of self-pollination and maternal resources on reproduction and offspring performance in the wild lupine, Lupinus perennis (Fabaceae)

“…First, understanding and evaluating inbreeding depression in endangered species requires consideration of the environmental variation experienced by both parents and offspring. The effects of inbreeding on endangered species have generally been studied in the greenhouse or other fairly benign conditions (Schemske et al 1994;Olfelt et al 1998). Estimates of inbreeding depression in such generous conditions may underestimate (or at least differ from) the effects of inbreeding in natural environments.…”

The relative importance of sexual reproduction versus clonal spread in an aridland bunchgrass

“…Allozymes (reviewed in Ellstrand and Roose 1987; see also Parks and Werth 1993;Montalvo et al 1997;Mayes et al 1998;Pappert et al 2000), anonymous DNA markers (Hsiao and Rieseberg 1994;Stewart and Porter 1995;Stiller and Denton 1995;Steinger et al 1996;Olfelt et al 1998;Suzuki et al 1999;Corradini et al 2002) and a combination of both methods (Waycott 1995;Ayres and Ryan 1997;Esselman et al 1999;Ge and Sun 1999) have been effectively used in studies of clonal plant populations. Molecular methods are also valuable tools for identifying levels of genetic variation within and among plant populations, providing information that can be used to infer their reproductive systems and demographic histories.…”

Impact of clonal growth on effective population size in Hymenoxys herbacea (Asteraceae)

“…In his literature survey, Frankham (1995) did not explore the demographic characters associated with variation in N e /N ratios. Although effective size estimates for clonal plants do not always incorporate measures of asexual reproduction, N e /N ratios from clonal organisms tend to be lower than those published for nonclonal organisms (Orive, 1993;Olfelt et al, 1998;Richman and Kohn, 1999). The generality of this trend is unclear given the small number of studies and the likely presence of confounding life history characters associated with clonality such as perenniality and outcrossing.…”