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Abstract Detail

Population Genetics/Genomics

Steven, Janet [1], Decatur, George [2], Murasaki, Ryo [2].

Clonal growth and outcrossing in the fern Osmunda claytoniana.

Population-level genetic diversity in homosporous ferns is influenced by life history traits in both the sporophyte and the gametophyte. Intra- and intergametophytic selfing can increase homozygosity, while mechanisms that promote outcrossing among gametophytes will favor heterozygosity. Frequent establishment from outcrossing gametophytes would also contribute to greater genetic diversity, while extensive clonal growth and long-lived genets could result in reduced genetic diversity in a population. We developed microsatellite markers for the homosporous fern Osmunda claytoniana and used them to estimate clonal growth and clone age, outcrossing rates in gametophytes, and genetic diversity within and among populations. We grew gametophytes at varying densities on agar plates, and found that plates with the highest densities had proportionally fewer gametophytes with archegonia, indicating the potential for population-level influences on sex expression and a consequent reduction in inbreeding. In pots with a mix of gametophytes from two different spore parents, two-thirds of the sporophyte offspring were a product of outcrossing. Genotypes of mapped individuals in a natural population of sporophytes suggest extensive clonal growth and very low genetic variation, although a survey of four populations showed greater genetic variation in some populations. We estimated that rhizomes grow about a centimeter a year, and survival of ramets from year to year is 99%. We estimate that the mapped clone is a minimum of a thousand years old. While gametophytes appear to be predominantly outcrossing, extreme longevity and high survival can result in low genetic diversity in populations of Osmunda claytoniana.

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1 - Christopher Newport University, Department Of Organismal And Environmental Biology, 1 Avenue Of The Arts, Newport News, VA, 23606, United States
2 - Christopher Newport University, 1 Avenue of the Arts, Organismal and Environmental Biology, Newport News, Virginia, 23606, United States

clonal growth

Presentation Type: Oral Paper
Session: PGG1, Population Genetics and Genomics I
Location: /
Date: Tuesday, July 20th, 2021
Time: 3:45 PM(EDT)
Number: PGG1004
Abstract ID:588
Candidate for Awards:Margaret Menzel Award

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