Year-end Sale % OFF 
Abstract
The effect of population size on population genetic diversity and structure has rarely been studied jointly with other factors such as the position of a population within the species’ distribution range or the presence of mutualistic partners influencing dispersal. Understanding these determining factors for genetic variation is critical for conservation of relict plants that are generally suffering from genetic deterioration. Working with 16 populations of the vulnerable relict shrub Cneorum tricoccon throughout the majority of its western Mediterranean distribution range, and using nine polymorphic microsatellite markers, we examined the effects of periphery (peripheral vs. central), population size (large vs. small), and seed disperser (introduced carnivores vs. endemic lizards) on the genetic diversity and population structure of the species. Contrasting genetic variation (H E: 0.04–0.476) was found across populations. Peripheral populations showed lower genetic diversity, but this was dependent on population size. Large peripheral populations showed high levels of genetic diversity, whereas small central populations were less diverse. Significant isolation by distance was detected, indicating that the effect of long‐distance gene flow is limited relative to that of genetic drift, probably due to high selfing rates (FIS = 0.155–0.887), restricted pollen flow, and ineffective seed dispersal. Bayesian clustering also supported the strong population differentiation and highly fragmented structure. Contrary to expectations, the type of disperser showed no significant effect on either population genetic diversity or structure. Our results challenge the idea of an effect of periphery per se that can be mainly explained by population size, drawing attention to the need of integrative approaches considering different determinants of genetic variation. Furthermore, the very low genetic diversity observed in several small populations and the strong among‐population differentiation highlight the conservation value of large populations throughout the species’ range, particularly in light of climate change and direct human threats.
Highlights
We addressed the following questions: (1) Are there differences in genetic diversity and structure among populations in relation to the population’s position in the distribution range or population size? (2) Are introduced mammals effective dispersers promoting greater genetic and structural diversity compared to the native lizards?
To define the two levels of population size, we considered small populations those with 200 individuals (Frankham, 1996; Frankham, Briscoe, & Ballou, 2002), a relatively conservative threshold used in several studies
Genetic diversity varied significantly across populations. These differences were not related to population location or disperser type; that is, there were no significant differences in the genetic diversity indices when peripheral versus central populations were compared or when populations were grouped according to disperser type (Table 3)
Summary
KEYWORDS genetic diversity, islands, marginal populations, population size, relict plants, seed dispersal We addressed the following questions: (1) Are there differences in genetic diversity and structure among populations in relation to the population’s position in the distribution range (i.e., center vs periphery) or population size (large vs small)?
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
