Presentation Title

Santa Monica Mountain Chaparral Ferns May Exhibit Reduced Genome Size

Faculty Mentor

Dr. Thomas L. Vandergon

Start Date

17-11-2018 12:30 PM

End Date

17-11-2018 2:30 PM

Location

HARBESON 24

Session

POSTER 2

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

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. These strategies include; being summer or dry deciduous, developing desiccation tolerance using a resurrection strategy, or “toughing it out” and staying evergreen with deep rhizomes and tolerating very low xylem pressures. Many SMM fern species, also have close relatives that reside in wetter habitats and therefore experience much less water related stress. 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 drought stress 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. We measured vegetative cell genome sizes in seven species of chaparral ferns to determine if genome sizes were different from sister species or closely related ferns living in less water stressed environments. We found that at least for three species of chaparral ferns, their genome sizes are significantly smaller than their closest wet habitat relatives. The smaller genomes in some chaparral ferns may represent a survival strategy by lowering energy costs in cell replication.

Summary of research results to be presented

We measured vegetative cell genome sizes in seven species of chaparral ferns to determine if genome sizes were different from sister species or closely related ferns living in less water stressed environments. We found that at least for three species of chaparral ferns, their genome sizes are significantly smaller than their closest wet habitat relatives. However one species exhibited a larger genome size; this larger size could potentially be the result of a polyploidy event which is the focus of ongoing research. The smaller genomes in some chaparral ferns may represent a survival strategy by lowering energy costs in cell replication.

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Nov 17th, 12:30 PM Nov 17th, 2:30 PM

Santa Monica Mountain Chaparral Ferns May Exhibit Reduced Genome Size

HARBESON 24

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. These strategies include; being summer or dry deciduous, developing desiccation tolerance using a resurrection strategy, or “toughing it out” and staying evergreen with deep rhizomes and tolerating very low xylem pressures. Many SMM fern species, also have close relatives that reside in wetter habitats and therefore experience much less water related stress. 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 drought stress 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. We measured vegetative cell genome sizes in seven species of chaparral ferns to determine if genome sizes were different from sister species or closely related ferns living in less water stressed environments. We found that at least for three species of chaparral ferns, their genome sizes are significantly smaller than their closest wet habitat relatives. The smaller genomes in some chaparral ferns may represent a survival strategy by lowering energy costs in cell replication.