Presentation Title

Genome Size Comparison Reduction found in Some Santa Monica Mountain Chaparral Ferns

Faculty Mentor

Thomas L. Vandergon

Start Date

23-11-2019 10:45 AM

End Date

23-11-2019 11:30 AM

Location

54

Session

poster 4

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Genome Size Comparison Reduction found in Some Santa Monica Mountain Chaparral Ferns

Authors: Xingyue Zhu, Talia Cao and Samantha Fiallo, Pepperdine University; Logan Meeks, Carroll College, Helena, Montana

Mentor: Thomas L. Vandergon, Natural Science Division, Pepperdine University

The Santa Monica Mountains (SMM) are home to two main vegetative zones, oak/sycamore dominated creek beds or riparian zones and shrub dominated chaparral zones. Eight fern species from across three families of ferns occupy niches in these riparian zones, but also may be found in the understory of the dryer chaparral. Research by Holmlund et al, has shown that some of these ferns are under extreme water stress and adaptations to very dry conditions are observed. Adaptations include; being summer or dry deciduous, developing desiccation tolerance using a resurrection strategy, or staying evergreen with deep rhizomes and tolerating very low xylem pressures. Many SMM fern species, also exist on the Channel Islands where some species exhibit differences in foliar water uptake mechanisms. Organismal stress, such as drought stress, in plants may be associated with whole genome responses that can result either in increased genome size from ploidy events, or reduction in genome size by processes involving removal of repetitive sequences. Within the fern phylum (Pteridophyta) there is a large range of known genome sizes and ploidy events are common. We wonder if stresses related to water acquisition may have induced changes in genomes within chaparral fern species. We hypothesized that the chaparral ferns will have significant genomic size differences compared to their wet habitat relatives. In addition, we hypothesis that island species may have genome size shifts relative to their mainland counterparts. We measured vegetative cell genome sizes in six species of chaparral ferns from the SMM and compared them to close sister species as well as Santa Cruz Island samples when available. We found that for three species of chaparral ferns, genome sizes were significantly smaller than their closest wet habitat relatives. There were no significant differences found between SMM and island fern genome sizes in our samples. The smaller genomes in some chaparral ferns may represent a survival strategy by lowering energy costs in cell replication.

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Nov 23rd, 10:45 AM Nov 23rd, 11:30 AM

Genome Size Comparison Reduction found in Some Santa Monica Mountain Chaparral Ferns

54

Genome Size Comparison Reduction found in Some Santa Monica Mountain Chaparral Ferns

Authors: Xingyue Zhu, Talia Cao and Samantha Fiallo, Pepperdine University; Logan Meeks, Carroll College, Helena, Montana

Mentor: Thomas L. Vandergon, Natural Science Division, Pepperdine University

The Santa Monica Mountains (SMM) are home to two main vegetative zones, oak/sycamore dominated creek beds or riparian zones and shrub dominated chaparral zones. Eight fern species from across three families of ferns occupy niches in these riparian zones, but also may be found in the understory of the dryer chaparral. Research by Holmlund et al, has shown that some of these ferns are under extreme water stress and adaptations to very dry conditions are observed. Adaptations include; being summer or dry deciduous, developing desiccation tolerance using a resurrection strategy, or staying evergreen with deep rhizomes and tolerating very low xylem pressures. Many SMM fern species, also exist on the Channel Islands where some species exhibit differences in foliar water uptake mechanisms. Organismal stress, such as drought stress, in plants may be associated with whole genome responses that can result either in increased genome size from ploidy events, or reduction in genome size by processes involving removal of repetitive sequences. Within the fern phylum (Pteridophyta) there is a large range of known genome sizes and ploidy events are common. We wonder if stresses related to water acquisition may have induced changes in genomes within chaparral fern species. We hypothesized that the chaparral ferns will have significant genomic size differences compared to their wet habitat relatives. In addition, we hypothesis that island species may have genome size shifts relative to their mainland counterparts. We measured vegetative cell genome sizes in six species of chaparral ferns from the SMM and compared them to close sister species as well as Santa Cruz Island samples when available. We found that for three species of chaparral ferns, genome sizes were significantly smaller than their closest wet habitat relatives. There were no significant differences found between SMM and island fern genome sizes in our samples. The smaller genomes in some chaparral ferns may represent a survival strategy by lowering energy costs in cell replication.