Multiple origins promote the ecological amplitude of allopolyploid Aegilops (Poaceae)

Abstract

Polyploidy has been ubiquitous in plant evolution and is thought to be an important engine of biodiversity that facilitates speciation, adaptation, and range expansion. Polyploid species can exhibit higher ecological tolerance than their progenitor species. For allotetraploid species, this higher tolerance is often attributed to the existence of heterosis resulting from entire genome duplication. However, multiple origins of allopolyploid species may further promote their ecological success by providing genetic variability in ecological traits underlying local adaptation and range expansion. Here we show in a group of allopolyploid species in the genus Aegilops that range size and abundance are correlated with the number of inferred origins. We found that allopolyploid Aegilops spp. contain multiple chloroplast haplotypes, each identical to haplotypes of the diploid progenitor species, indicating multiple origins as the major source of variation. The number of inferred origins in each allopolyploid species was correlated to the total area occupied by the allopolyploid and the tendency for the species to be common. Additionally, we found differences in ecological tolerance among independent origins in Aegilops triuncialis. These results strongly support the hypothesis that the introduction of genetic variability by multiple origins can increase the ecological amplitude and evolutionary success of allopolyploid species.

Evolutionary Plant Breeding in Cereals—Into a New Era

“…Similarly, including genotypes with broader ecological tolerance will keep the diversity of genotypes longer in the population, since the differential between the performances of different genotypes is less marked than with more specialist genotypes and therefore selection forces act more slowly. The effects of broad tolerance genotypes in evolving populations are of particular importance for wheat, because wheat shows a large tolerance and plasticity already in uniform pure line varieties due to its hexaploid nature and the resulting intergenomic heterosis, providing many triple versions of genes in the overall genome [28,29].…”

Deep sequencing of amplicons reveals widespread intraspecific hybridization and multiple origins of polyploidy in big sagebrush (Artemisia tridentata; Asteraceae)

“…vaseyana and tridentata could produce autotetraploid and allotetraploid progeny ( McArthur et al, 1981 ;Ramsey and Schemske, 1998 ;Van de Peer et al, 2009 ). Approximately half of all big sagebrush samples collected throughout the geographic range ( N = 1103) were identifi ed as tetraploid ( McArthur et al, 1981 ;McArthur and Sanderson, 1999 ), emphasizing the important role polyploids play in this species' geographic distribution and landscape dominance, as has been investigated in other species ( Meimberg et al, 2009 ). It is hypothesized that the frequency of tetraploids in the overall sagebrush population has increased during the Holocene warming as aridity has increased ( McArthur et al, 1981 ;Vallès et al, 2011 ).…”

Cytological status of Allium hookeri Thwaites (2n = 22)

“…These pairing analogies suggest multiple origin of cytotypes with 44 chromosomes. Higher polyploids with multiple origins, in general, are known to have the greater capability to colonize new habitats (Wendel 2000;Levy and Feldman 2002;Meimberg et al 2009). Distribution of cytotypes with 33/44 chromosomes along wider altitudinal range viz.…”