Morphological and isozyme variation in Cerastium arvense (Caryophyllaceae) in the southern Andes

Abstract

We tested the hypothesis that South Andean populations of the highly polymorphic and mostly Northern Hemisphere perennial forb Cerastium arvense L. show ecotypic variation along distinct habitats. We compared differences in morphology and flowering phenology among six natural populations occurring in different environments. Genetic differences were analyzed by a common-garden experiment and isozyme electrophoresis. Several of the morphological differences observed in the field were maintained after more than a year of cultivation in the common garden (e.g., plant height and leaf width). Mean tests and multivariate analyses on morphological traits generally distinguished high-elevation populations from the rest, and a similar grouping of populations was obtained from isozyme data at 10 loci. Cerastium arvense had genetic polymorphism levels of >50% in all populations and an average genetic diversity (HT = 0.254) of which approximately 20% was distributed among populations. These marked genetic differences are probably maintained by restricted gene flow due to variation in flowering time. Morphological and genetic differences suggest ecotypic variation in C. arvense in the southern Andes, which seems to have originated by disruptive selective pressures in different environments and the effect of genetic drift in response to the extreme climatic changes occurring during the Pleistocene.Key words: common-garden experiment, ecotypic variation, elevation and precipitation, genetic diversity, Patagonian Andes, phenology.

Life-history variation in agricultural and wild populations of Erucastrum nasturtiifolium (Brassicaceae)

“…In order to discriminate between environmental and genetic effects on intra-specific variability, common garden experiments (Hauser and Weidema, 2000;Quiroga et al, 2002;Zopfi, 1998) have been carried out since the early studies by Turesson in 1922 andClausen et al in 1948. Moreover, growing distinct populations, or individuals from a population, over an environmental gradient allows us to detect genetic variation in phenotypic plasticity related to life-history traits among or within populations, respectively (Clauss and Aarssen, 1994;Kittelson and Maron, 2001;Schlichting, 1986;Schlichting and Levin, 1990;Schlichting and Pigliucci, 1994).…”

Genetic variation relevant for the conservation of the narrow endemic Senecio carbonensis (Asteraceae) from the southern Andes

“…For example, in Cerastium arvense (Caryophyllaceae) from the Patagonian Andes, populations at higher altitudes are low plants with larger flowers, whereas those that grow below 1000 m a.s.l. are taller plants with smaller flowers (Quiroga et al 2002). In addition, within-species comparisons show that populations of the range-restricted S. carbonensis were more similar to each other in their morphology than the studied populations of S. peteroanus.…”

“…For example, in Cerastium arvense (Caryophyllaceae) from the Patagonian Andes, populations at higher altitudes are low plants with larger flowers, whereas those that grow below 1000 m a.s.l. are taller plants with smaller flowers (Quiroga et al . 2002).…”

A revision of Cerdia (Caryophyllaceae)

“…Some Caryophyllaceae taxa, for example groups of species in Cerastium , have been recognized as variable (Brysting & Elven, 2000; Quiroga, Premoli & Ezcurra, 2002), and the variation has been attributed to polyploidy. However, chromosome information for Cerdia has not yet been determined to establish whether this could be one the possible causes of morphological variation within the same populations.…”