Geographical and environmental range expansion through polyploidy in wild potatoes (SolanumsectionPetota)

Abstract

Aim To assess evidence for geographical and environmental range expansion through polyploidy in wild potatoes ( Solanum sect. Petota ). There are diploids, triploids, tetraploids, pentaploids and hexaploids in this group.Location Wild potatoes occur from the south-western USA (Utah and Colorado), throughout the tropical highlands of Mexico, Central America and the Andes, to Argentina, Chile and Uruguay. MethodsWe compiled 5447 reports of ploidy determination, covering 185 of the 187 species, of which 702 determinations are presented here for the first time. We assessed the frequency of cytotypes within species, and analysed the geographical and climatic distribution of ploidy levels.Results Thirty-six per cent of the species are entirely or partly polyploid. Multiple cytotypes exist in 21 species, mostly as diploid and triploid, but many more may await discovery. We report the first chromosome count (2 n = 24) for Solanum hintonii . Diploids occupy a larger area than polyploids, but diploid and tetraploid species have similar range sizes, and the two species with by far the largest range sizes are tetraploids. The fraction of the plants that are polyploids is much higher from Mexico to Ecuador than farther south. Compared with diploids, triploids tend to occur in warmer and drier areas, whereas higher-level polyploids tend to occur in relatively cold areas. Diploids are absent from Costa Rica to southern Colombia, the wettest part of the group's range. Main conclusionsThese results suggest that polyploidy played an important role in this group's environmental differentiation and range expansion.

The time lag between introduction and escape from cultivation of alien woody plant species decreases with polyploidization

“…Polyploids are on average more successful invaders (e.g. Stebbins, 1971;Lee, 2002;Pandit et al, 2006Pandit et al, , 2011Hijmans et al, 2007;Stenberg et al, 2003;Schlaepfer et al, 2008). A number of mutually non-exclusive mechanisms have been proposed to explain this observation (Soltis and Soltis, 2000): (i) polyploid species generally maintain higher levels of heterozygosity than their diploid relatives providing the evolutionary potential to evolve adaptive and competitive genotypes.…”

“…Grant, 1963;Goldblatt, 1980) with subsequent diploidization., "apparent" polyploids point to evolutionary recent polyploidization events. Polyploids often exhibit broader ecological tolerances than their diploid ancestors (Otto and Whitton, 2000;te Beest et al, 2012) and therefore may be able to cope with unfavourable environmental conditions (Hijmans et al, 2007). This advantage associated with polyploidization has been explained by the larger number of non-linked gene duplicates which increase genetic variance and therefore the speed of adaptive evolution (Lee, 2002;Soltis et al, 2003a, b).…”

Phytophthora infestans induced defense response in calli of wild and cultivated potato genotypes: Pathogen induced cell death in cultures - a marker for resistance

“…The Resistant genotypes grouped together with higher percent cells accumulated H2O2 and higher percent Cell death. (Hijmans et al, 2007). These wild species can be used to breed potato against biotic stress like Late Blight and abiotic stresses such as salt, heat and cold stresses.…”

Revisiting the Dioecy-Polyploidy Association: Alternate Pathways and Research Opportunities

“…to habitats more extreme in salinity or cold) or novel environments compared to their diploid progenitors [Stebbins, 1950]. Evidence for a change in geographic range associated with WGD is extensive, ranging from individual case studies [Hijmans et al, 2007] to floristic analyses [Clausen et al, 1945] and meta-analyses [Stebbins and Dawe, 1987;Petit and Thompson, 1999;Martin and Husband, 2009] of geographic/ecological ranges. These shifts necessarily expose populations to new and more extreme environments, some of which are conducive to the evolution of separate sexes, e.g.…”

“…Specifically, physiological or morphological changes associated with polyploidy, such as greater vegetative size, slower development or drought tolerance [Maherali et al, 2009;Hodgson et al, 2010;Herben et al, 2012], could lead to invasion of new or marginal habitats [Stebbins, 1950;Hijmans et al, 2007;Ainouche et al, 2009]. Polyploid species have long been associated with geographic range shifts (e.g.…”