Allozyme Variation in Hellianthus Praecox Ssp. Hirtus, A Rare Sunflower from Southern Texas

Abstract

Allozyme data were used to evaluate the genetic status of a rare endemic sunflower from Texas, Helianthus praecox ssp. hirtus. Comprising approximately 200 plants, the taxon is presently known from a single population in the Carrizo Springs region of Southern Texas. Electrophoretic examination of I 7 enzyme loci revealed that ssp. hirtus is genetically similar to, but distinct from, the two more widespread subspecies of H. praecox: ssp. praecox and ssp. runyonii. Levels of genetic variation in the single population of ssp. hirtus (P = 0.4 7, A = 1.88, and H = 0.17) are similar to those observed for other populations in the H. praecox complex (P = 0.44, A = 1.68, and H = 0.15). Thus, if isozyme loci are used as the one indicator of genetic variation in ssp. hirtus, it cannot be concluded that this taxon is endangered due to a loss of genetic variation. Nevertheless, due to the highly endemic status of ssp. hirtus serious conservation efforts must be made to ensure the long-term preservation of this taxon. Several management recommendations are given herein.

Fragmentation and genetic differentiation among subpopulations of the endangered Hawaiian mintHaplostachys haplostachya(Lamiaceae)

“…Many studies have demonstrated that small populations are genetically depauperate (Jennersten 1988; Lesica et al 1988; Hickey et al 1991; Soltis et al 1992; Pavlik et al 1993; Hartl & Pucek 1994; Kress et al 1994; however, also see Rieseberg & Doyle (1989), Dinerstein & McCracken (1990) and Sherwin et al (1991)). It is generally accepted that small populations will have a lower capacity to grow and adapt.…”

“…This increase in homozygosity and the potential fixation of alleles with deleterious effects may lead to inbreeding depression within the local population (Willis 1993) and ultimately to local extinctions (Fahrig & Merriam 1994). Numerous studies have demonstrated that small populations of rare plant species tend to have lower levels of genetic variation than those of related species with more extensive populations (Jennersten 1988; Lesica et al 1988; Hickey et al 1991; Soltis et al 1992; Pavlik et al 1993; Hartl & Pucek 1994; Kress et al 1994), although this is not always so (Rieseberg & Doyle 1989).…”

Skim-Sequencing Reveals the Likely Origin of the Enigmatic Endangered Sunflower Helianthus schweinitzii

“…Since the implementation of screens for allozyme variation [1,2] and through recent developments in next generation sequencing [3], molecular data have provided conservation managers and evolutionary biologists with key information for conservation planning. This information has been used, for example, to designate evolutionarily significant units for conservation action by augmenting knowledge on the morphology and ecology of populations [4,5].…”

Efficacité comparée de la pollinisation d'espèces sauvages d'Helianthus par plusieurs genres d'insectes

“…Ce type de protection n'est pas forcément une garantie pour le maintien des formes sauvages. En effet de nombreux écotypes appartenant aux espèces Helianthus californicus (Rogers et al, 1982) et Helianthus proecox ssp hirtus (Rieseberg et Doyle, 1989) (Clements, 1982 (Crossa, 1989 (Dozet et al, 1993 (1988,1990) (Taséi, 1976 ;Pouvreau, 1984 (Serieys, 1992 …”