Modelling the dynamics of introduced populations in the narrow‐endemic Centaurea corymbosa: a demo‐genetic integration

Abstract

Summary1. In the context of the restoration of an endangered species, population viability analysis represents a useful tool for assessing the effectiveness of different possible management strategies before implementation. However, despite the consensus that demographic and genetic mechanisms are both involved and interact in the process of extinction, few attempts have been made to examine their combined impacts on population viability in a particular species. 2. We integrated specific data resulting from 10-year multidisciplinary investigations into a descriptive model to simulate the dynamics of an introduced population of the rare self-incompatible plant species Centaurea corymbosa . The model allowed us to examine the interplay between demographic processes and genetic self-incompatibility in the particular habitat conformation of the species, alternating suitable and unsuitable sites within a population along cliffs. Population growth and extinction risk were compared for different introduction strategies. 3. Population persistence mainly depended on the number of introduced seeds and on their initial spatial distribution within the population (single vs. multisite introduction). In most cases, a multisite introduction resulted in faster population growth and higher viability than a single-site introduction. 4. As expected, a strong negative impact of the self-incompatibility system was observed on population dynamics and viability. However, because of positive feedback between demographic and genetic processes, this impact differed among introduction strategies: it was less severe when seeds were distributed among suitable sites, which also limited the loss of self-incompatibility alleles. Moreover, self-incompatibility contributed to the positive relationship between flowering plant density and fertilization rate. 5. Synthesis and applications. Our results provide strong management guidelines for future introductions of C. corymbosa regarding the number of seeds required (> 800) and the benefits of introducing them into several sites to achieve population persistence. Further, the study highlights the general importance of integrating demography and genetics to compare the effectiveness of different management strategies.

Effect of balancing selection on spatial genetic structure within populations: theoretical investigations on the self-incompatibility locus and empirical studies in Arabidopsis halleri

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Population size, self-incompatibility and genetic rescue in diploid and tetraploid races of Rutidosis leptorrhynchoides (Asteraceae)

“…Even though fecundity selection is thought to counteract the reduction in mate availability in small populations by helping to maintain high allelic diversity at the SI locus Castric and Vekemans, 2004), the loss of rare S-alleles through genetic drift, especially in systems where there are strong dominance relationships, means that there can be a marked reduction in compatible mates in generations immediately following a decrease in population size. These effects can have important implications for long-term population viability, especially for species where seed production is the primary factor limiting recruitment (either within populations, or between them in a meta-population context), rather than other demographic processes such as the availability of suitable microsites or negative density dependence (Kirchner et al, 2006). For example, in some populations of the endangered Lakeside Daisy (Hymenoxys acaulis var.…”

Interaction of climate, demography and genetics: a ten-year study of Brassica insularis, a narrow endemic Mediterranean species

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