Habitat Differentiation between Diploid and Tetraploid <i>Galax urceolata</i> (Diapensiaceae)

Johnson, Marc T. J.; Husband, Brian C.; Burton, Tracy L.

doi:10.1086/376813

Cited by 63 publications

(63 citation statements)

References 38 publications

(58 reference statements)

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“…Habitat diVerentiation has been inferred from comparison of habitats in Dactylis glomerata (Lumaret et al 1987) and Cardamine pratensis (Arvanitis et al 2007), from comparison of associated vegetation in Anthoxanthum alpinum (Felber-Girard et al 1996) and Galax urceolata (Johnson et al 2003) or from diVerent performances of two cytotypes in the common garden in D. glomerata (Bretagnolle and Thompson 2001). It has been argued that studies based on habitat comparisons may confound competitive displacement with niche diVerentiation and that only reciprocal transplant experiments provide a direct test of diVerences in fundamental niches (Baack and Stanton 2005).…”

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confidence: 99%

Niche differentiation between diploid and hexaploid Aster amellus

2008

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The maintenance of separated diploid and polyploid populations within a contact zone is possible due to both prezygotic and postzygotic isolation mechanisms. Niche differentiation between two cytotypes may be an important prezygotic isolating mechanism and can be studied using reciprocal transplant experiments. We investigated niche differentiation between diploid and hexaploid Aster amellus in their contact zone in the Czech Republic. Diploid populations are confined to habitats with low productivity, whereas hexaploid populations occur in habitats with both low and high productivity. Thus, we chose three diploid populations and six hexaploid populations, three in each of the two different habitat types. We analyzed habitat characteristics and carried out reciprocal transplant experiments in the field using both seeds and adult plants. Sites of diploid and hexaploid populations differed significantly in vegetation and soil properties. The mean number of juveniles was higher at sites of home ploidy level than at sites of foreign ploidy level, suggesting niche differentiation between the two cytotypes. On the other hand, transplanted adult plants survived at all sites and juvenile plants were able to establish at some sites of the foreign cytotype. Furthermore, the mean number of juveniles, survival, and flowering percentages were higher at home sites than at foreign sites, indicating local adaptation. We conclude that niche differentiation between the two cytotypes and local adaptation within each cytotype may contribute to the maintenance of diploid and hexaploid populations of A. amellus in their contact zone. Moreover, further factors, such as differences in flowering phenology and exclusion of minority cytotypes, should also be considered.

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confidence: 99%

Niche differentiation between diploid and hexaploid Aster amellus

2008

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“…Morphological differences between different ploidy levels resulted from genetic differences. However, it remains unclear how such differences affect the spatial distribution of cytotypes (Johnson et al, 2003). The explanation suggested herein is that ecological and genetic variations contribute to the establishment of polyploids (Husband, 2000), thus permitting the spread of species with different levels of ploidy.…”

Section: Discussionmentioning

confidence: 92%

“…Johnson et al (2003) noted that little is known about the mechanisms that maintain cytotype separation, despite their importance. The way in which polyploidy affects the tolerance of individuals to environmental factors and the geographical pattern of diploids and polyploids remain unclear (Johnson et al, 2003;Soltis et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…The way in which polyploidy affects the tolerance of individuals to environmental factors and the geographical pattern of diploids and polyploids remain unclear (Johnson et al, 2003;Soltis et al, 2010). Researchers reinforce the importance of quantitative and statistical inferences to provide evidence of the differences between diploids and polyploids (Johnson et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Abiotic factors such as temperature and water stress modify the frequency of unreduced gametes (Ramsey and Schemske, 1998). However, it is unknown whether there is a pattern of environmental conditions that are related to the occurrence of polyploidy, or which environmental conditions influence the persistence and natural distribution of polyploids (Johnson et al, 2003). The study of widely distributed species enables us to understand how polyploidy influences the diversification and geographical distribution of closed related taxa, permitting the determination of a pattern of local environmental conditions in which the polyploids are found.…”

Section: Introductionmentioning

confidence: 99%

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Environmental variations drive polyploid evolution in neotropical Eugenia species (Myrtaceae)

et al. 2016

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ABSTRACT. Polyploidy is one of the most important mechanisms of speciation and diversification in plant evolution. Polyploidy results in genetic variation among individuals of the same species and even between populations, and may be responsible for differences in environmental tolerance between populations of the same species. This study determined chromosome numbers of Eugenia L. (Myrtaceae, x = 11) for 26 populations of 14 species by conventional cytogenetic techniques. Nine species (13 populations) were diploid (2n = 2x = 22), but diploid and/or polyploid cytotypes were found in the other five species (13 populations), with 2n = 33, 2n = 44, and 2n = 55. Data on chromosome number/ploidy level for other Eugenia species/populations were collected from the literature and included in this cytogeographic analysis. For each collection point (32 species and 62 populations), environmental variables were recorded using georeferencing techniques through the DIVA-GIS v.7.5 program. Environmental variables such as temperature, altitude, rainfall, solar radiation, soil type, and vegetation were analyzed with the R program, using MannWhitney and chi-square tests, principal component analysis, and graphic analyses, such as scatterplots, boxplots, and barplot. Polyploid and diploid populations had different spatial distribution patterns and were found in areas subjected to different environmental conditions. Polyploid individuals were collected from locations with more adverse environmental conditions, usually at higher elevations than the diploid individuals. Polyploidy allows species to occur at locations with varying environmental conditions. As diploidy and polyploidy occur under different environmental conditions, species with cytotypes exhibit wide environmental tolerance.

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