title: Pollinator-mediated gene flow fosters genetic variability in a narrow alpine endemic, Abronia alpina (Nyctaginaceae).
abstract: OBJECTIVE
  For rare and endemic plants that exist in small, isolated habitats, natural selection is expected to favor self-compatibility, which can result in low genetic diversity due to inbreeding and genetic drift. Using Abronia alpina, a rare alpine endemic of the California Floristic Province, we demonstrate that there are exceptions to these predictions.
  
  
  METHODS
  We present the results of both a pollination experiment and a genetic study using AFLPs (amplified fragment length polymorphisms). Using controlled hand-pollination and pollinator observations, we examined the breeding system, pollination ecology, and mechanism for self-incompatibility in A. alpina.
  
  
  RESULTS
  Abronia alpina exhibits an allogamous mating system with probable self-incompatibility resulting from limited growth of pollen tubes originating from self-pollination. Only xenogamous crosses and open-pollinated controls produced seed, and only xenogamous crosses produced pollen tubes that reached the ovary. The molecular study shows that A. alpina has substantial genetic diversity for a rare, endemic species, evidenced by the high percentage of polymorphic loci and average expected heterozygosity. Gene flow among subpopulations, as inferred from AFLP markers, appears to be substantial, although the Kern River is an important physical barrier.
  
  
  CONCLUSIONS
  Our results indicate that A. alpina is dependent on insects for both seed production and the maintenance of genetic diversity. This finding suggests that pollinators may be crucial to the long-term adaptive potential of rare, endemic plants and that conservation of rare endemics is, in part, dependent on community-level interactions such as plant-pollinator mutualisms.
authors: Environmental Genetics and Genomics Laboratory, Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011, USA. Meredith.jabis@gmail.com
authors: Meredith D
authors: MD
authors: Jabis
authors: Tina J
authors: TJ
authors: Ayers
authors: Gerard J
authors: GJ
authors: Allan
mesh_terms: D000818:Animals; D001947:Breeding; D002140:California; D017753:Ecosystem; D035264:Flowers / Q000502:physiology; D051456:Gene Flow / Q000235:genetics*; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D007313:Insecta / Q000502:physiology*; D039281:Nyctaginaceae / Q000235:genetics* / Q000502:physiology*; D010802:Phylogeny; D054817:Pollination / Q000502:physiology*; D012098:Reproduction / Q000502:physiology; D060436:Self-Incompatibility in Flowering Plants; D013045:Species Specificity