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trees, North America, migration, genetic diversity, historical biogeography, climate change, species distribution model

Roberts, David R.

Supervisor and department: Andreas Hamann Renewable Resources

Examining committee member and department: Andrew Bush Earth and Atmospheric Science Glen Armstrong Renewable Resources Jack Williams Geography, University of Wisconsin at Madison Erin Bayne Biological Science Scott Nielsen Renewable Resources

Department: Department of Renewable Resources

Specialization: Conservation biology

Date accepted: 2013-04-23T14:55:14Z

Graduation date: 2013-11

Degree: Doctor of Philosophy

Degree level: Doctoral

Abstract: Over the last two million years, the evolution of North American tree species, subspecies, and genetic varieties has taken place in a constantly changing landscape often dominated by extensive ice sheets and restricted temperate climate environments. Here, I approximately reconstruct post-glacial vegetation histories and glacial refugia of western North American trees using species distribution models to test biogeographic hypotheses regarding the existence of glacial refugia in Beringia, the evolution of subspecies in widespread conifers, the origin of Pacific Northwest inland rainforests, and levels of modern genetic diversity. The first two chapters have a methodological emphasis, where I select and test a variety of species distribution models for their accuracy and robustness. Validations against 3,571 pollen and fossil records from 835 study sites indicated fair accuracy for most techniques AUCs around 0.75. Ecosystem-based modelling approaches outperformed in specificity statistics and robustness against extrapolations far beyond training data, suggesting that they are well suited to reconstruct historical biogeographies. Evaluations at the biome level indicated that species distribution models could approximately reconstruct biomes for the mid- to late-Holocene but became unreliable in the Late Pleistocene due to the emergence of no-analogue climates. However, the limitation applied primarily to non-forested biomes. Using a set of three robust species distribution modelling techniques, I investigate how modern genetic diversity and genetic structure was shaped by refugial history, using published estimates of allelic richness and expected heterozygosity for 473 populations of 22 tree species. Species with strong genetic differentiation into subspecies and varieties had widespread and large glacial refugia, while species with restricted refugia showed no differentiation and little genetic diversity. In a regression tree analysis, 66% of allelic richness could be explained by the total size of glacial refugia, while expected heterozygosity was best explained by the number of glacial refugia. A comparison of projected past and future habitats showed that future migration requirements were much faster than, but highly correlated with, past migration requirements a cross 24 tree species. Populations in certain localities may be at risk of maladaptation due to the inability of gene flow to keep pace with the migration of climate habitats.

Language: English

DOI: doi:10.7939-R3Q974

Rights: Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.





Autor: Roberts, David R.

Fuente: https://era.library.ualberta.ca/


Introducción



We are now faced with the fact that tomorrow is today.
We are confronted with the fierce urgency of now.
In this unfolding conundrum of life and history there is such a thing as being too late .
We may cry out desperately for time to pause in her passage, but time is deaf to every plea and rushes on.
Over the bleached bones and jumbled residue of numerous civilizations are written the pathetic words: “Too late.” - Martin Luther King, Jr. I wouldn’t have seen it if I hadn’t believed it. - Marshall McLuhan University of Alberta Biogeographic histories and genetic diversity of western North American tree species: implications for climate change by David Roxburgh Roberts A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Conservation Biology Department of Renewable Resources © David Roxburgh Roberts Fall 2013 Edmonton, Alberta Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author’s prior written permission. For Bridget, with whom I can see it clear, out to the end. For Finlay, who inspires me to just go and play. And for Richard, for your enthusiasm: here’s to blue skies, no flat tires, and no blisters. Abstract Over the last two million years, the evolution of North American tree species, subspecies, and genetic varieties has taken place in a const...





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