Frugivore behavior and plant spatial genetics
by Tiziana A. Gelmi-Candusso
Date of Examination:2017-11-03
Date of issue:2019-03-13
Advisor:Prof. Dr. Eckhard W. Heymann
Referee:Dr. Oliver Schülke
Referee:Prof. Dr. Pierre-Michel Forget
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Description:Dissertation_Gelmi-Candusso
Abstract
English
Spatial genetics aims to understand the influence of environmental features and biological interactions on gene flow and genetic structure. In plants, spatial genetics is determined by the rate, pattern and spatial extent of gene dispersal within and between populations. Gene dispersal in plants is composed by seed dispersal and pollination. Seed dispersal increases the probabilities of mating between spatially distant, non-related, individuals, reducing the probability of biparental inbreeding, decreasing the incidence of unfavorable traits and increasing genetic diversity. In animal seed dispersal, foraging behavior and post-feeding movement range affect seed dispersal pattern and distance, with consequences in plant spatial genetics. This thesis aims to understand the relationship between frugivore behavior and spatial genetics while strengthening the current knowledge on seed dispersal by tamarins and using their dispersal of Leonia cymosa as a case study for a finer analysis of the effect of frugivore behavior on spatial genetics. Leonia cymosa Mart. (Violaceae), a small Neotropical understory tree, is exclusively dispersed at our study site by tamarins, Saguinus mystax, and Leontocebus nigrifrons. Leonia cymosa is, therefore, a good model for understanding the effects of frugivore behavior and plants spatial genetics. First, I analyzed the presence and strength of SGS in animal-dispersed plants studied in the last 20 years. I found animal behavior has an effect on spatial genetic structure, but pollination and marker type used could also have an influence on the strength of SGS. Second, I analyze seed dispersal distance of Leonia cymosa by tamarins, using plant genetics and animal behavior data in parallel. Methods for estimating seed dispersal distance did not differ significantly and mean seed dispersal distance for Leonia cymosa was between 218 and 304m. Third, I analyze spatial genetic structure (SGS) in Leonia cymosa through its life stages and put it in the context of tamarin behavior. SGS was present in seedlings, and weaker in juveniles and absent in adults of Leonia cymosa, likely due to tamarin seed dispersal patterns and extent. Clumped seed dispersal patterns might have a strong influence on SGS of seedlings, while the combination of-density-dependent mortality and relatively long seed dispersal distance likely reduces this effect in adulthood. Fourth, I analyzed the genetic composition of Leonia cymosa individuals growing on different tamarin home ranges. Home ranges were expected to create a seed dispersal barrier influencing overall gene flow. However, even though the parentage analysis showed no seed exchange across home ranges, genetic makeup shows no difference between individuals located in different home ranges, at all life stages, giving evidence that pollination or small shifts in time of home ranges, could have a strong effect in maintaining gene flow across home ranges. The results of this thesis give evidence that seed dispersal patterns and distance can strongly and differently affect plant spatial genetic structure, while, pollination might play an important role in maintaining gene flow in case of seed dispersal constraints.
Keywords: Seed dispersal, tamarins, primates, population genetics, tropical rainforest, Peru, GIS, seed dispersal distance, spatial genetic structure, territoriality, microsatellites, FTA plantsaver cards