| the effect of drought stress on inbreeding depression in four populations of the mediterranean outcrossing plant crepis sancta (asteraceae). | the effect of physiological stress on the magnitude of inbreeding depression in plants has been the subject of few studies and is currently controversial because of contradictory results. we measured the inbreeding depression at three drought stress levels, precisely defined by a preliminary physiological experiment. we also tested the hypothesis that more highly self-compatible populations exhibit reduced inbreeding depression due to purging of deleterious mutations. the study was conducted on ... | 2000 | 11012734 |
| capitulum characters in a seed heteromorphic plant, crepis sancta (asteraceae): variance partitioning and inference for the evolution of dispersal rate. | in crepis sancta (asteraceae), achenes produced in the periphery of the flower head have reduced dispersal ability and are larger than achenes produced in the centre of the head, which disperse farther. the proportion of central achenes produced by a single individual represents the potential dispersal rate of its progeny. seed variation in dispersal ability may be important where there is spatio-temporal variability of habitats, but its evolutionary significance mainly depends on the heritabili ... | 2001 | 11298818 |
| rapid evolution of seed dispersal in an urban environment in the weed crepis sancta. | dispersal is a ubiquitous trait in living organisms. evolutionary theory postulates that the loss or death of propagules during dispersal episodes (cost of dispersal) should select against dispersal. the cost of dispersal is expected to be a strong selective force in fragmented habitats. we analyzed patchy populations of the weed crepis sancta occupying small patches on sidewalks, around trees planted within the city of montpellier (south of france), to investigate the recent evolutionary conseq ... | 2008 | 18316722 |
| Determinants of extinction in fragmented plant populations: Crepis sancta (asteraceae) in urban environments. | Local populations are subject to recurrent extinctions, and small populations are particularly prone to extinction. Both demographic (stochasticity and the Allee effect) and genetic factors (drift load and inbreeding depression) potentially affect extinction. In fragmented populations, regular dispersal may boost population sizes (demographic rescue effect) or/and reduce the local inbreeding level and genetic drift (genetic rescue effect), which can affect extinction risks. We studied extinction ... | 2011 | 22200853 |
| inbreeding depression under intraspecific competition in a highly outcrossing population of crepis sancta (asteraceae): evidence for frequency-dependent variation. | inbreeding depression is a major selective factor acting to maintain outcrossing in hermaphroditic plants. recently it has been shown that environmental conditions may greatly affect the levels of inbreeding depression. in this study, the effects of intraspecific competition, from either crossed or inbred progeny, and plant density on the expression of inbreeding depression were estimated for the allogamous colonizing plant crepis sancta (asteraceae). the population used in this experiment showe ... | 2001 | 21669674 |
| pollination processes and the allee effect in highly fragmented populations: consequences for the mating system in urban environments. | the urban environment was used to study the plant reproductive system in small fragmented populations as well as the potential adaptations of plants to urban conditions. we examined the effect of density on the pollination process and on reproduction in urban populations of the allogamous species crepis sancta. the habitat is composed of small uncultivated square patches (c. 2 m2) regularly spaced along the pavement in streets of the city of montpellier, france. pollinator behaviour (the presenc ... | 2006 | 17096802 |