Hybridization and competition between the endangered sea marigold (Calendula maritimaAsteraceae) and a more common congener

Abstract

Hybridization and competition between the endangered sea marigold (Calendula maritima, Asteraceae) and a more common congener ARTICLE in PLANT BIOSYSTEMS · FEBRUARY 2015 Impact Factor: 1.91 · AbstractOccurrences of hybridization between the rare, endangered Sicilian endemic, Calendula maritima, and other congeners in the wild have been suspected by several authors, but never demonstrated. In San Cusumano (Trapani), one of the only three Sicilian mainland populations, C. maritima occurs in close proximity to the more common congener C. suffruticosa subsp. fulgida, and individuals morphologically intermediate between the two taxa have been observed. In order to determine whether hybridization is occurring at this site, and, if so, begin to assess the impact it could have on C. maritima, two independent tests of hybridity were conducted by studying (1) the pollen morphology and viability and (2) sequence variation in one chloroplast marker (atpI-atpH) and in the nuclear ribosomal internal transcribed spacer region (ITS). Both palynological and molecular data provided evidence of hybridization between C. maritima and C. suffruticosa subsp. fulgida, and suggest that although fertility of hybrids appeared to be reduced, they are likely capable of back-crossing with parents. Thus, hybridization may be putting C. maritima at risk of extinction via introgression. Anthropogenic habitat disturbance and expansion of C. suffruticosa subsp. fulgida into remaining populations of C. maritima could pose a serious threat to its successful conservation.

Inflorescence Scents of Calendula maritima, Calendula suffruticosa subsp. fulgida, and Their Hybrid

“…From mainly May to June it produces yellow inflorescences, though inflorescences can be found throughout the year (De Montmollin and Strahm 2005). Calendula maritima is an endemic species that grows in Sicily (near Trapani) and in some surrounding islets (Isola Grande dello Stagnone, La Formica, Maraone, and Colombaia; Plume et al 2013). It is found on sand and rock in open areas near the sea and in Posidonia oceanica (L.) Delile seagrass litter, called "banquettes" (Plume et al 2013).…”

“…Calendula maritima is an endemic species that grows in Sicily (near Trapani) and in some surrounding islets (Isola Grande dello Stagnone, La Formica, Maraone, and Colombaia; Plume et al 2013). It is found on sand and rock in open areas near the sea and in Posidonia oceanica (L.) Delile seagrass litter, called "banquettes" (Plume et al 2013). Its natural habitat is under threat from urban development as well as by competition with invasive species (e.g., Carpobrotus edulis (L.) N.E.…”

“…This study focuses on a hybrid and its two parental taxa in Mediterranean Calendula, a genus being at least partially selfincompatible and depending on insect pollen vectors for outcrossing (Plume et al 2013). In particular, our study plants were the yellow-flowered C. maritima Guss, the orange-flowered C. suffruticosa Vahl.…”

“…fulgida (Raf.) Guadagno (henceforth, C. fulgida), and an intermediate form (hybrid) that has leaf properties in common with C. maritima (leaves entire and fleshy) and inflorescence properties in common with C. fulgida (inflorescences orange or pale orange; Plume et al 2013). Early in 1919, Lanza reported that hybrids between C. maritima and C. fulgida were rare.…”

Genetic analysis based on plastidial and ribosomal sequences of the endemic bi-edaphic taxonJurinea pinnata(Lag.) DC. (Compositae) in the Guadix-Baza Basin

“…nrDNA sequences are useful in the detection of hybridization events (Emshwiller & Doyle 1998;Widmer & Baltisberger 1999). In this case, nucleotide additive patterns, which combine parental ribotypes differentially inherited in the hybrid genome as a result of a recent hybridization event, can emerge (Fuertes-Aguilar et al 1999a;Plume et al 2013). nrDNA sequences have also been used in the study of plants adapted to different types of substrates (Cecchi et al 2011) and ecotypes (Schechter & Bruns 2008).…”