Human-induced hybridization among congeneric endemic plants on Tenerife, Canary Islands

Abstract

Endemic genera on oceanic islands often evolved striking morphological and ecological differences among species, with weak postzygotic reproductive isolation. Human activities can lead to increased connectivity and can thereby promote secondary contact and hybridization between previously isolated species. We studied this phenomenon in three species of the genus Pericallis (Asteraceae) on Tenerife, Canary Islands. A total of 53 populations was sampled, including morphologically uniform as well as mixed populations containing morphologically diverse individuals. All plants were analyzed both genetically using AFLP markers and morphometrically. As expected, morphological analysis clearly separated the plants from the uniform populations in three clusters, with distinguishing characters corresponding to those used in species identification. The three species were also grouped into distinct genetic clusters in a STRUCTURE analysis, although no private alleles were observed. Adding the mixed population data to the analyses provided evidence for extensive hybridization among species, predominantly between P. cruenta and P. echinata, and between P. cruenta and P. tussilaginis, and morphological and genetic signals were congruent. The mixed populations were geographically located in between the uniform populations and were found in road verges significantly more often than the uniform populations. The observed distribution strongly suggests that hybridization between originally isolated species is recent, promoted by secondary contact due to human disturbance and the construction of roads.

The influence of geological history on diversification in insular species: genetic and morphological patterns of Micromeria Benth. (Lamiaceae) in Tenerife (Canary archipelago)

“…In this context, it could also be possible that some Micromeria species inhabited the third palaeoisland, Adeje, but went extinct during the erosion processes that reduced this palaeoisland to its current extent. A disjointed distribution of species in the three palaeoislands has also been observed in other plant groups such as Convolvulus L. (Convolvulaceae; Trusty et al ., ), Pericallis D. Don (Asteraceae; van Hengstum et al ., ) and in the beetle genus Pimelia (Juan et al ., ), making this inference plausible. Finally, a third diversification event would have given origin to the group of species inhabiting the central area of the island: M. hyssopifolia , M. lachnophylla , M. lasiophylla and M. varia ( c .…”

The silent extinction: climate change and the potential hybridization-mediated extinction of endemic high-mountain plants

“…Anthropogenic hybridization between introduced species and their native congeners occurs frequently and can create serious conservation concerns (Ellstrand and Schierenbeck 2000). Similarly, habitat alterations may cause the eventual contact of related species that have remained separated by inhospitable habitats (Hengstum et al 2012).…”

Monanthes subrosulata, a new species ofM. sect.Sedoidea(Crassulaceae) from La Palma, Canary Islands, Spain

“…It occurs in La Palma, La Gomera, Tenerife, Gran Canaria, Fuerteventura, and Lanzarote. After its discovery and sole citation by Lems & Holzapfel (1974) in La Palma, the species was neglected there by authors (Santos 1983;Nyffeler 1992;Hohenester & Welss 1993;Bramwell & Bramwell 2001 (Fig. 2).…”

“…roads, waterways) reduces ecological separation and natural barriers that originally played an important role in the speciation process (Brochman 1984;van Hengstum & al. 2012).…”

“…Monanthes subrosulata is located in southern and southeastern La Palma at altitudes from 30 m to 570 m, and their populations occupy a total of 37.5 km 2 (Extent of Presence, see IUCN Standards and Petitions Subcommittee 2010) (Fig. 2).…”