Intraspecific ecological niche divergence and reproductive shifts foster cytotype displacement and provide ecological opportunity to polyploids

Abstract

Polyploidy and contrasting reproductive traits between cytotypes have promoted shifts in niche optima, and increased ecological tolerance and niche divergence. Ecologically specialized diploids maintain cytotype stability in core areas by displacing tetraploids, while broader ecological preferences and a shift from sexuality to apomixis favoured polyploid colonization in peripheral areas where diploids are displaced, and fostered the ecological opportunity for autotetraploids supporting range expansion to open southern habitats.

The classification of asexual organisms: Old myths, new facts, and a novel pluralistic approach

“…The classical "Frozen Niche variation model" by Vrijenhoek (Vrijenhoek, 1979), which suggests that broad arrays of clones can use the resource space via niche differentiation among clones better than related sexual species, was supported by many case studies of animals and plants (Vrijenhoek & Parker, 2009). Niche shifts of apomicts have been identified the main causal factor for geographical parthenogenesis in Crataegus (Lo & al., 2013;Coughlan & al., 2014;, in cytotypes of Paspalum intermedium (Karunarathne & al., 2018), and in Ranunculus kuepferi (Cosendai & Hörandl, 2010;. In Crataegus, hybridity plays a major role for range expansions (Coughlan & al., 2014).…”

Difference in reproductive mode rather than ploidy explains niche differentiation in sympatric sexual and apomictic populations ofPotentilla puberula

“…A trend of apomictic plants to occur under more extreme environmental conditions compared to their sexual relatives has been repeatedly reported. Drought was identified as a factor driving the pattern in Draba (Price, ), Antennaria (Bierzychudek, ), Bidens (Crowe & Parker, ), Paspalum intermedium (Karunarathne et al, ), and the Ranunculus auricomus complex (Paule et al, ). The opposite pattern, however, was found in this study: Sexual P. puberula prevailed at drier sites, a tendency also observed in Ranunculus kuepferi (Schinkel et al, ).…”

“…Given the central role that apomixis plays in colonization and range expansion, most studies on amphi‐apomictic systems focus on geographical parthenogenesis, rather than in purely ecological patterns (see Bierzychudek, ). Furthermore, in studies investigating the existence of ecological parthenogenesis, the geographical aspect is often neglected and conclusions on ecological differentiation between sexuals and apomicts are drawn without distinguishing between sympatric and allopatric populations (e.g., Antennaria rosea , Bayer et al, ; Ranunculus carpaticola , Paun et al, ; Pilosella officinarum , Mráz, Šingliarová, Urfus, & Krahulec, ; or Paspalum intermedium , Karunarathne et al, ; see Supporting Information Table A4 in Appendix ). Ecological differentiation of allopatric apomicts may be in fact the result of postcolonization adaptation, or simply an artifact of range boundary disequilibria along ecogeographical gradients (Sexton et al, ).…”

“…Vrijenhoek & Parker, 2009). Ecological differentiation of sexuals and apomicts (i.e., plants reproducing asexually via seeds; Asker & Jerling, 1992) is often studied in the context of geographical parthenogenesis (e.g., Karunarathne et al, 2018;Lo, Stefanović, & Dickinson, 2013;Noyes et al, 2006;Paule et al, 2018). However, differences in the geographical distribution may reflect different biogeographical histories or dispersal limitation rather than differences in ecological preferences (Brown, Stevens, & Kaufman, 1996;Sexton, McIntyre, Angert, & Rice, 2009).…”

“…Such a geographical parthenogenesis is often linked to ecological differentiation among sexual and asexual populations, a phenomenon defined as “ecological parthenogenesis” (Bell, ). Specifically, asexuals tend to (a) inhabit cooler or drier habitats and (b) have broader ecological ranges (e.g., in Erigeron, Noyes, Gerling, & Vandervoort, ; Paspalum intermedium , Karunarathne et al, ; Ranunculus auricomus , Paule, Dunkel, Schmidt, & Gregor, ), albeit examples showing opposite trends (e.g., asexuals inhabit more humid habitats in Limonium , Caperta et al, , and Ranunculus kuepferi , Kirchheimer et al, ; Schinkel et al, ) indicate the idiosyncratic response of taxa.…”