Sympatric diploid and hexaploid cytotypes of Senecio carniolicus (Asteraceae) in the Eastern Alps are separated along an altitudinal gradient

Abstract

We explored the fine-scale distribution of cytotypes of the mountain plant Senecio carniolicus along an altitudinal transect in the Eastern Alps. Cytotypes showed a statistically significant altitudinal segregation with diploids exclusively found in the upper part of the transect, whereas diploids and hexaploids co-occurred in the lower range. Analysis of accompanying plant assemblages revealed significant differences between cytotypes along the entire transect but not within the lower part only, where both cytotypes co-occur. This suggests the presence of ecological differentiation between cytotypes with the diploid possessing the broader ecological niche. No tetraploids were detected, indicating the presence of strong crossing barriers.

Divergence in Eco-Physiological Responses to Drought Mirrors the Distinct Distribution of Chamerion angustifolium Cytotypes in the Himalaya–Hengduan Mountains Region

“…The results of our study illustrate the distinct natures of physiological tolerance in the different ploidy levels, with diploids being less sensitive to drought stress than hexaploids. Thus, the occurrence of diploids in more open habitats at higher altitudes may be the result of adaptation that provides greater resistance to abiotic stress (Körner, 2003; Sonnleitner et al, 2010), whereas the predominance of polyploids in dense and nutrient-rich vegetation at lower altitudes may be due to greater competitiveness compared with the surrounding vegetation (Schönswetter et al, 2007; Ståhlberg, 2009). An earlier study indicated that differences in physiological tolerances in C. angustifolium probably evolved through natural selection acting on plant water relations after polyploidization (Maherali et al, 2009) and thus induced the adaptation of cytotypes to their native habitats (Martin and Husband, 2013).…”

No evidence for a role of competitive capabilities of adults in causing habitat segregation of diploid and hexaploid Senecio carniolicus (Asteracaeae)

“…The most frequent cytotypes are diploids and hexaploids and they frequently co-occur in mixed populations within narrow contact zones (Sonnleitner et al 2010; Suda et al 2007). Previous studies found cytotypes of S. carniolicus segregating along an ecological gradient with diploids occurring mainly in open vegetation on rocky micro-sites, whilst the hexaploids were more abundant on sites with high vegetation cover (Hülber et al 2009; Schönswetter et al 2007; Sonnleitner et al 2010). As underlying causes, different competitive abilities of cytotypes have been hypothesized (Sonnleitner et al 2010): due to lower vigor and resulting lower competitiveness diploids would be forced into more open habitats.…”

Ecological studies of polyploidy in the 100 years following its discovery

“…By the early 2010s, the floodgates had opened and ecological studies were published about polyploid complexes in more than a dozen other genera. For the most part, the emphasis of recent projects is on classical questions in polyploid ecology, but the diversity of topics and methodological approaches is impressive-the work encompasses analyses of spatial and environmental distributions of cytotypes, including niche modelling [75,147,[195][196][197][198][199][200][201][202][203][204][205][206]; gene flow and reproductive barriers, including ecologically mediated components of isolation [151,[207][208][209][210][211]; detailed phenotypic and fitness measurements of plants in natural habitats [212][213][214][215][216][217][218][219]; phenotypic attributes of plants cultured in controlled greenhouse or garden conditions [29][30][31]143,150,[220][221][222][223][224][225][226]; and field transplant experiments [14,[227][228]…”