title: Coexistence of congeneric native and invasive species: the case of the green algae Codium spp. in northwestern Spain.
abstract: We examined the patterns of distribution and abundance, and reproductive traits (presence of gametophytes and size at time of reproduction) in the invasive Codium fragile ssp. fragile and the native C. tomentosum and C. vermilara on intertidal habitats of NW Spain at two dates. All three species coexist in the locations and habitats studied, although abundances were low. We found a greater proportion of C. fragile ssp. fragile towards the east of the Cantabrian coast and on upper levels on the shore, where conditions are more stressful. The proportion of thalli bearing gametangia in C. fragile ssp. fragile was greater than in the native species in all habitats. The presence of gametangia was size-dependent for all species, with the invasive species maturing at a smaller size, which combined with the previous features, might confer competitive advantages to this species over the native species. We also demonstrated that molecular analyses are necessary for the correct identification of C. fragile subspecies.
authors.affiliation: Dpto. Ecoloxía e Bioloxía Animal, Facultade de Ciencias do Mar, Universidade de Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Pontevedra, Spain. Electronic address: ire.rojo@gmail.com.
authors.forename: Irene
authors.initials: I
authors.lastname: Rojo
authors.affiliation: Dpto. Ecoloxía e Bioloxía Animal, Facultade de Ciencias do Mar, Universidade de Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Pontevedra, Spain.
authors.forename: Celia
authors.initials: C
authors.lastname: Olabarria
authors.affiliation: Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos, C/Tulipán s/n, 28933 Móstoles, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Santamaria
authors.affiliation: School of Biological Sciences/Institute for Global Food Security, The Queen's University of Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK.
authors.forename: Jim
authors.initials: J
authors.lastname: Provan
authors.affiliation: Dpto. Biología Vegetal I, Facultad de Biología, Universidad Complutense de Madrid, c/José Antonio Novais 2, 28040 Madrid, Spain.
authors.forename: Tomás
authors.initials: T
authors.lastname: Gallardo
authors.affiliation: Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos, C/Tulipán s/n, 28933 Móstoles, Spain.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Viejo
mesh_terms: D000460:Chlorophyta / Q000145:classification / Q000235:genetics / Q000502:physiology*; D058865:Introduced Species; D011156:Population Density; D011157:Population Dynamics; D013030:Spain
keywords: Algae; Codium sibling species; Cryptic invasion; Distribution; Exotic species; Morphological and molecular genetic analyses; NW Spain; Reproductive traits