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- Title
Potentially adaptive significance of genome size diversity across ecological gradients and seed size in Ivesia (Rosaceae).
- Authors
BOROKINI, ISRAEL T.; BRODERICK, SHAUN R.; ZHI GAO; HALLAS, JOSHUA M.; BIRCHLER, JAMES A.; PEACOCK, MARY M.
- Abstract
Variation in genome size across taxa has been explained using neutral and nonadaptive theories; however, genome size variation among taxonomic groups can also be shaped by natural selection if it correlates with functional traits. This study investigated the potential adaptive significance of genome size in Ivesia, a radiating genus distributed in the western North American desert ecosystems. We estimated the genome size of 34 taxa (including 31 Ivesia taxa, 2 Potentilla taxa, and 1 Horkelia taxon) using flow cytometric methods. For each taxon, leaf samples were collected from 6 individuals in 1 location each; intraspecific genome size variation was investigated using samples collected from 11 Ivesia webberi populations. The results showed an 8.1-fold variance in genome size, ranging from 0.73 pg/2C in I. baileyi var. beneolens to 5.91 pg/2C in I. lycopodioides var. megalopetala. Only 6 taxa, with a genome size >1.5 pg/2C, significantly differed from the remaining taxa. Genome size in Ivesia is relatively small, which is typical of plants living in stressful environments. Also, genome size was significantly correlated with seed size and actual evapotranspiration both within I. webberi and among Ivesia taxa, thus supporting the predictions of the nucleotype theory and suggesting an adaptive significance of genome size in the genus. Genome size in I. webberi is mostly statistically nonsignificant; however, populations near the center of the species’ known range have significantly larger genomes, which decrease in size toward the marginal populations. This intraspecific genome size gradient from range center toward range margins could be attributed to patterns of gene flow and geographic isolation.
- Subjects
GENOME size; SEED size; NATURAL selection; ROSACEAE; PREDICTION theory; PLANT genomes; SPECIES diversity; LOQUAT
- Publication
Western North American Naturalist, 2023, Vol 83, Issue 3, p301
- ISSN
1527-0904
- Publication type
Article
- DOI
10.3398/064.083.0301