The fine-scale pattern of correlated paternity was characterized within a population of the narrow-endemic model plant species, Centaurea corymbosa, using microsatellites and natural progeny arrays. We used classical approaches to assess correlated mating within sibships and developed a new method based on pairwise kinship coefficients to assess correlated paternity within and among sibships in a spatio-temporal perspective. We also performed numerical simulations to assess the relative significance of different mechanisms promoting correlated paternity and to compare the statistical properties of different estimators of correlated paternity. Our new approach proved very informative to assess which factors contributed most to correlated paternity and presented good statistical properties. Within progeny arrays, we found that about one-fifth of offspring pairs were full-sibs. This level of correlated mating did not result from correlated pollen dispersal events (i.e., pollen codispersion) but rather from limited mate availability, the latter being due to limited pollen dispersal distances, the heterogeneity of pollen production among plants, phenological heterogeneity and, according to simulations, the self-incompatibility system. We point out the close connection between correlated paternity and the "TwoGener" approach recently developed to infer pollen dispersal and discuss the conditions to be met when applying the latter.C ORRELATED paternity refers to the fact that dif-or embryo abortion, as well as resource allocation to each sex (Charnov 1982). Under limited seed dispersal, ferent offspring may be sired by the same father.where interacting individuals are likely sibs, it may also Within maternal progeny arrays it is often referred to act on the type of competitive interactions involved (e.g., as "correlated mating" and can be expressed by the kin selection; Hamilton 1964; Schuster and Mitton fraction of full-sib pairs (e.g., Ritland 1989; El-Kassaby 1991; Rousset and Billiard 2000), the average fitness and Jaquish 1996) or by the number of different fathers of competing siblings (Young 1981; Schmitt and Ehrinvolved (e.g., Campbell 1998). In this context, pure hardt 1987; Karron and Marshall 1990, 1993), or half-sib and pure full-sib families represent the extreme the success of mating events between nearby individuals alternatives of a continuum from uncorrelated to totally when inbreeding depression or self-incompatibility occorrelated mating events (e.g., polyads of mimosoid lecurs. Second, together with the outcrossing rate, the gumes and tropical figs; Nason et al. 1998). Correlated pattern of correlated mating is a key parameter of the paternity can also be considered between maternal mating system (Ritland 1988 and can provide progeny arrays, where it can be expressed by the relative valuable information on pollination biology because it proportions of (paternal) half-sibs and non-sibs.depends on a set of biological factors related in particuIn plant populations, correlated paternity is impor...

Centaurea corymbosa (Asteraceae) is endemic to a small area (<3 km 2 ), and <500 individuals reproduce in any given year. Nevertheless, enzyme polymorphism was found within and among the six local extant populations, the most distant at 2.3 km. Levels of gene f low among populations and seed and pollen dispersal data indicated very low dispersal capacity. Rarity of long distance dispersal events coupled with traits such as prolonged juvenile period, monocarpy, and self-incompatibility precludes the establishment of new populations and thus the evolution toward colonization ability through increased dispersal rate, polycarpy, or selfcompatibility. The species thus appears to be trapped on an evolutionary dead-end toward extinction, even though, from a preliminary introduction experiment, we conclude that several nearby unoccupied sites would be suitable for the species.

Despite recent efforts to develop the science of reintroduction biology, there is still no general and broadly accepted definition of reintroduction success. We investigate this issue based on the postulates (1) that successful reintroduction programs should produce viable populations and (2) that reliable assessments of ultimate success require that populations have reached their regulation phase. We assessed if the viability of these reintroduced populations could be evaluated using the same criteria as for remnant populations, such as the Internation Union for Conservation of Nature (IUCN) Red List criteria. Using modeling, we projected the viabilities of theoretical populations with various life history and environmental characteristics and we tested whether population sizes (criterion D of the IUCN) and other potential predictors are relevant proxies of the risk of extinction (criterion E of the IUCN) in the case of remnant populations with an unknown past history and in the case of reintroduced populations that have reached their carrying capacity. We found that, as for remnant populations, population size can be used as a relevant indicator (although subject to considerable uncertainty) of the viability of reintroduced populations. However, the results demonstrate the importance of the reintroduction failure filter, that is, the fact that the reintroduced populations that have successfully reached their carrying capacity are those with the highest and more stable growth rates, especially if populations have been reintroduced with a few individuals. As a consequence, the general relationship between the current size of a population and its projected viability will, most likely, differ considerably between remnant and reintroduced populations. Overall, our results demonstrate that there are no theoretical limitations on the application of some of the criteria widely used for remnant populations to define reintroduction success, although these criteria are very conservative for reintroduced populations and might be rescaled to account for the demographic filter that early extinction constitutes for these populations.