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Population genetics of self-incompatibility in a clade of relict cliff-dwelling plant species

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ABSTRACT

This study highlights the value of performing detailed mating system studies in plant species of high conservation value, such as the rare and relict species of Sonchus section Pustulati described here. This study adds to the evidence that outcrossing mating systems based on SSI are highly resilient even under long-term conditions of small, fragmented, and isolated populations, possibly due to mating system flexibility with the presence of some selfing and the fact that high cross-compatibility is achieved for relatively modest dominantly expressed S allele polymorphism. We highlight the importance of taking mating system factors into account as part of conservation efforts.

No MeSH data available.


Distribution range of the species of Sonchus section Pustulati, locations of all known populations, and area of occupancy (Silva et al. 2015b). Sampled populations are in bold.
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plw029-F1: Distribution range of the species of Sonchus section Pustulati, locations of all known populations, and area of occupancy (Silva et al. 2015b). Sampled populations are in bold.

Mentions: Sonchus pustulatus, S. fragilis and S. masguindalii constitute the well-supported clade Sonchus section Pustulati (Asteraceae, Cichorieae; Boulos 1973; Kim et al. 2007; Silva et al. 2015a). These species are narrow endemics restricted to both sides of the western Mediterranean Basin (Spain and Morocco) occurring on localized cliffs at low altitude (Fig. 1; Silva et al. 2015b). All three species are found in North Africa, where they are considered to be very rare (Fennane and Ibn Tattou 1998). S. pustulatus also occurs in the SE Iberian Peninsula, where it is categorized as ‘critically endangered’ (Cueto et al. 2003; Silva et al. 2015b). Phylogenetic and phylogeographic data suggest that these taxa are relicts of the late Tertiary (Silva et al. 2015a). Their restricted and disjunct distribution seems to be related to old geological events of large biogeographic impact: the Messinian Salinity Crisis and the subsequent Zanclean reflooding of the Mediterranean Basin 5.96–3.60 million years ago (Krijgsman et al. 1999; Rosenbaum et al. 2002; Fauquette et al. 2006), and the subsequent establishment of the Mediterranean climate (3.2–2.8 Ma; Suc, 1984). These relict and endemic taxa seem to have suffered from erosion of genetic diversity by genetic drift during long periods of small population size that is reflected in previous observations of relatively low genetic diversity (HE = 0.088–0.177; Silva et al. 2015a). Therefore, it is also of interest to investigate their SI mating systems. These species are pollinated by generalist insects (Silva 2014) and preliminary hand pollinations suggested that S. pustulatus in Spain is SI (Mejías 1992). We predict that strong long-term genetic drift could have led to limited S allele diversity, capacity of selfing or frequent dominance interactions among remaining S alleles.Figure 1.


Population genetics of self-incompatibility in a clade of relict cliff-dwelling plant species
Distribution range of the species of Sonchus section Pustulati, locations of all known populations, and area of occupancy (Silva et al. 2015b). Sampled populations are in bold.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4940477&req=5

plw029-F1: Distribution range of the species of Sonchus section Pustulati, locations of all known populations, and area of occupancy (Silva et al. 2015b). Sampled populations are in bold.
Mentions: Sonchus pustulatus, S. fragilis and S. masguindalii constitute the well-supported clade Sonchus section Pustulati (Asteraceae, Cichorieae; Boulos 1973; Kim et al. 2007; Silva et al. 2015a). These species are narrow endemics restricted to both sides of the western Mediterranean Basin (Spain and Morocco) occurring on localized cliffs at low altitude (Fig. 1; Silva et al. 2015b). All three species are found in North Africa, where they are considered to be very rare (Fennane and Ibn Tattou 1998). S. pustulatus also occurs in the SE Iberian Peninsula, where it is categorized as ‘critically endangered’ (Cueto et al. 2003; Silva et al. 2015b). Phylogenetic and phylogeographic data suggest that these taxa are relicts of the late Tertiary (Silva et al. 2015a). Their restricted and disjunct distribution seems to be related to old geological events of large biogeographic impact: the Messinian Salinity Crisis and the subsequent Zanclean reflooding of the Mediterranean Basin 5.96–3.60 million years ago (Krijgsman et al. 1999; Rosenbaum et al. 2002; Fauquette et al. 2006), and the subsequent establishment of the Mediterranean climate (3.2–2.8 Ma; Suc, 1984). These relict and endemic taxa seem to have suffered from erosion of genetic diversity by genetic drift during long periods of small population size that is reflected in previous observations of relatively low genetic diversity (HE = 0.088–0.177; Silva et al. 2015a). Therefore, it is also of interest to investigate their SI mating systems. These species are pollinated by generalist insects (Silva 2014) and preliminary hand pollinations suggested that S. pustulatus in Spain is SI (Mejías 1992). We predict that strong long-term genetic drift could have led to limited S allele diversity, capacity of selfing or frequent dominance interactions among remaining S alleles.Figure 1.

View Article: PubMed Central - PubMed

ABSTRACT

This study highlights the value of performing detailed mating system studies in plant species of high conservation value, such as the rare and relict species of Sonchus section Pustulati described here. This study adds to the evidence that outcrossing mating systems based on SSI are highly resilient even under long-term conditions of small, fragmented, and isolated populations, possibly due to mating system flexibility with the presence of some selfing and the fact that high cross-compatibility is achieved for relatively modest dominantly expressed S allele polymorphism. We highlight the importance of taking mating system factors into account as part of conservation efforts.

No MeSH data available.