The expansion history of a sexual and asexual species of Cortaderia in California, USA

Lambrinos, JG

Jg. Lambrinos, The expansion history of a sexual and asexual species of Cortaderia in California, USA, J ECOLOGY, 89(1), 2001, pp. 88-98

61

INGLESE

Article

Environment/Ecology

JOURNAL OF ECOLOGY

0022-0477 → ACNP

89

1

2001

88 - 98

ISI

0022-0477(200102)89:1<88:TEHOAS>2.0.ZU;2-F

1 The expansion histories of two South American species of Cortaderia, simi lar in morphology but differing profoundly in their breeding systems, were compared in California, USA. 2 Both species were introduced to California in the mid-1800s, but herbariu m records indicate that the sexual C. selloana has expanded spatially at tw ice the rate of the asexual C. jubata. 3 The invasiveness of C. selloana has increased over time, whereas that of C. jubata has remained relatively constant. Populations of C. selloana now occupy more vegetation types and more non-ruderal habitats than C. jubata. 4 Populations of C. selloanu have experienced directional morphological cha nge, whereas the morphology of C. jubata has been constant over the 90 year s for which preserved specimens are available. 5 The invasion of an alien species appears to be a malleable process, rathe r than a singular event. Species traits, such as inbreeding, can be advanta geous at some stages but disadvantageous at others. Alien species also adju st over time to the novel and diverse selective regimes that they encounter as they expand spatially. Sexual species may have a greater ability to adj ust to diverse selective landscapes relative to asexual species.