Abstract Detail

Molecular Ecology

Cruzan, Mitchell [1], Hendrickson, Elizabeth [2].

Patterns of Seed and Pollen Dispersal Across Human-Modified Landscapes.

With the increasing effects of climate change we expect discordances to develop between species occurrences and the distribution of their suitable habitat. Historically, species distributions have changed via dispersal in response to post-glacial climate changes; however, contemporary conditions pose novel challenges to species as climate change is much more rapid, and large regions of habitat have been converted to agriculture and development. We use landscape genetic models to examine patterns of seed (based on chloroplast haplotypes) and pollen plus seed (based on nuclear SNPs) dispersal across natural and human-modified landscapes for the bee-pollinated annual, Plectritis congesta (aka Valeriana congesta; Caprifoliaceae), which has gravity-dispersed seeds. By using an annual species, we aimed to capture the effects of human landscape modifications on patterns of effective dispersal based on the distribution of genetic markers. We analyzed models for multiple GIS layers for the distribution of agriculture and development, as well as natural geographic features such as rivers, canopy density, elevation, and habitat suitability (based on Environmental Niche Modeling using the ENMTools R package). For seed dispersal based on maternally-inherited chloroplast genomes, models for elevation, habitat suitability, and agricultural development explained > 30% of the variation in genetic distance, while the effect of geographic distance was negligible. Increases in elevation and habitat suitability were associated with reduced seed dispersal, while the presence of croplands acted as a conduit to gene flow. For nuclear markers, genetic distance was negatively associated with geographic distance (explaining 3.3% of variation) and positively associated with intermediate levels of canopy cover (explaining 10.9%). Our results are consistent with the effects of landscape features on biotic pollen (bees) and seed (ungulates) dispersal vectors as well as the effects of an interaction between habitat suitability and effective seed dispersal kernels.

Related Links:
Cruzan lab web site

1 - Portland State University, Department Of Biology, 1719 SW 10th Ave, SRTC Rm 246 - Biology, Portland, OR, 97201, United States
2 - Portland State University, Biology, Portland State University - Biology - SRTC 242, PO Box 751, Portland, OR, 97207, United States

Landsape Genetics
seed dispersal
Pollen Dispersal
Niche Modelling
climate change
population genetics
human impacts.

Presentation Type: Oral Paper
Number: ME1002
Abstract ID:722
Candidate for Awards:None

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