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Abstract Detail

Population Genetics/Genomics

Amici, Autumn [1], Nadkarni, Nalini [2], Seger, Jon [2], DiBlasi, Emily [3].

The effects of spatial isolation on epiphytes in a montane tropical landscape, Monteverde, Costa Rica.

Tropical forests are highly diverse, and epiphytes account for roughly one-third of vascular plant diversity in some neotropical forests. Epiphytes derive water and nutrients from atmospheric, rather than terrestrial, sources as they live on trunks, branches, and in the arboreal soil of trees. When continuous forests are fragmented to create agricultural land, epiphyte population dynamics may be affected because of their dependence on host trees. Although the effects of forest fragmentation on epiphyte diversity have been documented, the impacts of pasture isolation on epiphyte populations is lacking. Does pasture isolation disrupt gene flow? Or conversely, does it create new habitats and opportunities for colonization? The aims of this project were to explore the impacts of short- and long-distance isolation on population structure and genetic differentiation of two species of epiphytic Bromeliaceae, Catopsis nitida and Werauhia tonduziana, in the Monteverde region of Costa Rica. Catopsis nitida is pollinated by small moths and has wind dispersed seeds. Werauhia tonduziana also has wind dispersed seeds but is pollinated by hawkmoths and bats. We searched for both species in primary forest, mixed forest (with mixed land-use history—including some primary and secondary forest trees), and pastures. We found W. tonduziana mostly in primary forest and pasture trees. We did not find C. nitida in primary forest trees but, but it was common in mixed forest and pasture trees. Werauhia tonduziana was more genetically diverse than C. nitida. The genetic differentiation of W. tonduziana among pasture, mixed forest, and primary forest populations was low (FST=0.08). For C. nitida, there was significant genetic differentiation between pasture and mixed forest populations relative to the total genetic variance (FST=0.29). These results suggest that for species of vascular epiphytes that can disperse and establish across habitat types, such as W. tonduziana, isolation in pastures may not act as a barrier to gene flow, and these isolated pasture trees may provide stepping stones for propagule dispersal. These isolated pasture trees may also provide new opportunities for establishment for some species, such as C. nitida that are less commonly found in primary forests. However, for C. nitida, gene flow among patches is low, but is crucial to maintain and genetic diversity. Understanding which epiphyte species may be most (or least) able to maintain genetic diversity in mosaic environments with fragmented patches of forest and pasture is essential to understanding rates of local adaptation, speciation and extinction.

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1 - University Of Utah, Biology, 257 South 1400 East, Room 201, Salt Lake City, UT, 84112, United States
2 - University of Utah, Department of Biology, 257 South 1400 East, Room 201, Salt Lake City, UT, 84112, US
3 - University of Utah, School of Medicine, Department of Psychiatry, Salt Lake City, Utah, USA

population genetics
gene flow
tropical forest
land use change.

Presentation Type: Oral Paper
Session: 38, Population Genetics and Genomics I
Location: 101/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 10:45 AM
Number: 38011
Abstract ID:388
Candidate for Awards:Margaret Menzel Award

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