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. 2017 Aug 5;7(18):7231-7242.
doi: 10.1002/ece3.2940. eCollection 2017 Sep.

Population size, center-periphery, and seed dispersers' effects on the genetic diversity and population structure of the Mediterranean relict shrub Cneorum tricoccon

Ana Lázaro-Nogal  1 , Silvia Matesanz  2 , Alfredo García-Fernández  2 , Anna Traveset  3 , Fernando Valladares  1   2
Affiliations

Population size, center-periphery, and seed dispersers' effects on the genetic diversity and population structure of the Mediterranean relict shrub Cneorum tricoccon

Ana Lázaro-Nogal et al. Ecol Evol. .

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 (HE: 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.

Keywords: genetic diversity; islands; marginal populations; population size; relict plants; seed dispersal.

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Figures

Figure 1
Figure 1
Reproductive individual of the study species, the relict shrub Cneorum tricoccon
Figure 2
Figure 2
Distribution of Cneorum tricoccon (black areas) and location (white dots) of the populations sampled. Letter codes correspond to those listed in Table 1. Codes in italics refer to peripheral populations
Figure 3
Figure 3
(a) Number of genetic clusters (K) detected by Evanno et al. (2005). Mean log probability of the data for the 12 STRUCTURE runs at each K. Error bars are SD; (b) ΔK, rate of change in the log probability of data between successive K values
Figure 4
Figure 4
Population structure inferred by Bayesian cluster analyses (STRUCTURE) for 399 Cneorum tricoccon individuals from 16 central and peripheral populations. Results for K (number of clusters) ranging from 2 to 6. Each individual (grouped by population) is represented by a vertical bar. Letter codes correspond to the population listed in Table 1
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References

    1. Arnaud‐Haond, S. , Teixeira, S. , Massa, S. I. , Billot, C. , Saenger, P. , Coupland, G. , … Serrão, E. A. (2006). Genetic structure at range edge: Low diversity and high inbreeding in Southeast Asian mangrove (Avicennia marina) populations. Molecular Ecology, 15, 3515–3525. - PubMed
    1. Avise, J. C. (2004). Molecular Markers, Natural History, and Evolution (Second Edition). Sinauer: Sunderland, MA.
    1. Awad, L. , Fady, B. , Khater, C. , Roig, A. , & Cheddadi, R. (2014). Genetic structure and diversity of the endangered fir tree of Lebanon (Abies cilicica Carr.): Implications for conservation. PLoS One, 9, e90086. - PMC - PubMed
    1. Babweteera, F. , & Brown, N. (2009). Can remnant frugivore species effectively disperse tree seeds in secondary tropical rain forests? Biodiversity and Conservation, 18, 1611–1627.
    1. Bauert, M. R. , Kalin, M. , Baltisberger, M. , & Edwards, P. J. (1998). No genetic variation detected within isolated relict populations of Saxifraga cernua in the Alps using RAPD markers. Molecular Ecology, 7, 1519–1527.