Abstract Detail

Macroevolution

Spear, Marissa [1], Etterson, Julie [2], Gross, Briana [3].

Resurrecting an urban sunflower population: phenotypic and molecular changes over 36 years.

Resurrection experiments, in which dormant propagules (e.g. seeds) of ancestral populations are collected, stored, and grown alongside contemporary populations, provide a unique opportunity to directly evaluate phenotypic and molecular adaptation to environmental change. To understand evolution of an urban population of Helianthus annuus (Asteraceae) over 36 years, we resurrected samples obtained from a 1980 USDA National Plant Germplasm System accession, then returned to the original collection sites in 2016 to gather the contemporary descendants. After a refresher generation in greenhouse conditions, we grew the refreshed individuals from the ancestral 1980 families alongside individuals from the modern 2016 families in an outdoor common garden under varied water availability (well-watered and 25% water) and temperature conditions (ambient and elevated >3°C) to observe phenotypic differences and plastic response. Growth patterns differed between the ancestral and modern groups. The modern population was 11 cm taller than the ancestral population and had a larger stem diameter, while the ancestral population produced more branches than the modern population. As a result of more intensive branching architecture, the ancestral population produced 1.4 times more flowers over the growing season than the modern population. Flowering time was 14 days later on average in the modern population compared to the ancestral population, and individuals under drought conditions flowered later than well-watered individuals. Drought and elevated temperature also had a negative effect on leaf production and height. RNA-seq transcriptome analysis revealed differential expression of genes that may underlie these phenotypic changes. Some of these differentially expressed genes include psaA, which is associated with photosystem I and might contribute to differences in growth. Evolutionary response to environmental pressures, gene flow from cultivated H. annuus, or some combination could be driving the differences in gene expression and phenotype we observed between the 1980 and 2016 populations, and our future work will focus on distinguishing between these causal factors.

1 - 1921 E 3rd St, Apt 2, Duluth, MN, 55812, United States
2 - University Of Minnesota Duluth, 207 Swenson Science Building, 1110 Kirby Drive, 6770 Haugen Lane, 1035 Kirby Drive, Duluth, MN, 55803, United States
3 - University Of Minnesota Duluth, Department Of Biology, 207 Swenson Science Building, 1035 Kirby Drive, Duluth, MN, 55812, United States

Keywords:
evolution
crop wild relative
climate change
Plasticity
Resurrection
Sunflower
Helianthius annuus.

Presentation Type: Oral Paper
Session: MACRO1, Macroevolution I
Location: Tucson B/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 11:15 AM
Number: MACRO1012
Abstract ID:806
Candidate for Awards:None