i PATTERNS AND CONSEQUENCES OF DISPERSAL IN ARCTIC CHAR (PISCES: SALVELINUS ...

212 Pages·2012·9.03 MB·English

PATTERNS AND CONSEQUENCES OF DISPERSAL IN ARCTIC CHAR
(PISCES: SALVELINUS ALPINUS) FROM THE CANADIAN ARCTIC

by
Jean-Sébastien Moore

BSc., McGill University, 2004
MSc., McGill University, 2007

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF

DOCTOR OF PHILOSOPHY
in
THE FACULTY OF GRADUATE STUDIES
(ZOOLOGY)

THE UNIVERSITY OF BRITISH COLUMBIA
(Vancouver)
October 2012

© Jean-Sébastien Moore, 2012

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Dispersal can have a multitude of ecological and evolutionary consequences that
can be either positive or negative for population fitness and persistence. In this thesis, I
describe patterns of dispersal in Arctic Char (Salvelinus alpinus), and I explored some of
its consequences. I first examined the consequences of post-glacial dispersal for the
distribution of genetic variation across the Canadian range of the species. MtDNA
sequences and microsatellite markers provided evidence that the populations of Arctic
Char currently inhabiting the Arctic Archipelago probably recolonized from a small
glacial refugium, most likely located in ice-free areas of the Archipelago itself. I also
presented evidence that two glacial lineages of Char (an Arctic lineage and an Atlantic
lineage) probably hybridized post-glacially in the eastern Arctic. Finally, the importance
of contemporary dispersal in redistributing genetic variation was illustrated by the fact
that anadromous populations have greater within-population genetic diversity, and are
less genetically differentiated, than landlocked populations. Second, I used a genetic
assignment approach to study patterns of dispersal among populations distributed around
Cumberland Sound, Nunavut. Estimates of dispersal rates varied extensively depending
on the analysis method used, but all were relatively high compared to other salmonid
species. I also found evidence that overwintering individuals have a greater propensity to
disperse to non-natal habitats than individuals destined to spawn that year. The
consequences of this behaviour for local adaptation among populations was examined
using a population genetic model parameterized with estimates of gene flow obtained
from microsatellite data. Third, I tested alternative hypotheses for the co-existence of
sympatric migratory ecotypes in three lakes of southeast Baffin Island. Microsatellite data
showed that the resident and anadromous components of the population are not
genetically differentiated, suggesting that migratory behavior is not a genetically fixed
trait. Together, the three parts of my thesis provide a general understanding of the
patterns and consequences of dispersal for Arctic Char. Since dispersal will be crucial for
the response of Arctic Char to environmental change, I conclude by discussing how my
work can serve as a foundation for future work on the role of dispersal in adaptation to a
changing Arctic.
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Chapter 2 was a project I conceived and conducted in collaboration with R. Bajno,
J.D. Reist, and E.B. Taylor. The samples were collected by various people working under
J.D. Reist over the years. I collected all the microsatellite data and some of the mtDNA
sequence data. I performed all data analyses, and wrote the original manuscript. All three
other collaborators provided advice and contributed revisions.
Chapter 3 was a project I conceived and conducted in collaboration with L.N.
Harris, R.F. Tallman, and E.B. Taylor. Adult samples used in this study were collected by
various people working under R.F. Tallman over the years, and I collected all samples of
juveniles according to the sampling design I conceived. L.N. Harris and I conducted all
the laboratory work. I performed all data analyses and wrote the original manuscript. All
three collaborators provided advice and contributed revisions.
A version of chapter 4 has been submitted as: “T.N. Loewen, L.N. Harris & R.F.
Tallman (in review) Genetic analysis of sympatric migratory ecotypes of Baffin Island
Arctic Char Salvelinus alpinus: alternative mating tactics or reproductively isolated
strategies?” T.N. Loewen and I collected the samples, and L.N. Harris and I conducted
the laboratory work. I conducted all data analyses and wrote the original version of the
manuscript. All three collaborators provided advice and contributed revisions to the
manuscript.
Permits for Arctic Char collection were obtained from Fisheries and Oceans
Canada (Licenses to fish for scientific purpose S-09/10-1007-NU and S-10/11-1030-NU).
All collections were done according to the Animal Use Protocol of Fisheries and Oceans’
Freshwater Institute’s Animal Care Committee (animal use protocols # FWI-ACC-09/10-
1007-NU and FWI-ACC-10/11-1030-NU).

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Table 1.1 Some definitions of dispersal from recent reviews on the topic. ..................... 27!
Table 1.2 Estimates of dispersal rates from tagging studies performed on Arctic Char,
Salvelinus alpinus, and Dolly Varden, S. malma. ..................................................... 28!
Table 1.3 Summary of evidence for increased propensity to disperse when overwintering
in Arctic Char, Salvelinus alpinus, and Dolly Varden, S. malma. ............................ 28!
Table 1.4 Summary of studies examining the marine migrations of Arctic Char,
Salvelinus alpinus, and Dolly Varden, S. malma. ..................................................... 29!
Table 2.1. Results of the historical demography analyses using neutrality tests (Fu’s F
s
and Tajima’s D) and mismatch distribution analysis on mitochondrial DNA
sequence variation (D-loop) in Arctic Char, Salvelinus alpinus. .............................. 58!
Table 2.2. Differences in genetic diversity (allelic richness and expected heterozygocsity)
and average pairwise F between landlocked and anadromous populations of Arctic
ST
Char, Salvelinus alpinus, assayed at nine microsatellite DNA loci. ......................... 58!
Table 3.1. Information regarding the sampling locations used in this study, and measures
of genetic diversity at each location for anadromous Arctic Char (Salvelinus alpinus)
assayed at fourteen microsatellite DNA loci. ........................................................... 91!
Table 3.2. Results of discriminant function analysis testing for trait differences between
philopatric and dispersing individuals of anadromous Arctic Char (Salvelinus
alpinus) sample from Cumberland Sound. ............................................................... 93!
Table 4.2. Details of the primers and PCR reactions used for each of the four multiplexes
used to assess genetic variation of resident and anadromous Arctic Char (Salvelinus
alpinus). .................................................................................................................. 117!
Table 4.3. Summary statistics of microsatellite variation for each ecotype of Arctic Char
(Salvelinus alpinus) per sampling location.. ........................................................... 118!
Table 4.4. Semi-matrix of pairwise F (Weir & Cockerham, 1984) values between all
ST
sampling locations and ecotypes of Arctic Char (Salvelinus alpinus). ................... 119!
Table 4.5. Results of the analysis of molecular variance (AMOVA) examined among
sampling locations and ecotypes of Arctic Char (Salvelinus alpinus). ................... 119!
viii
Table A.1. Name and geographic coordinates of sampling locations where specimens of
Arctic Char (ARCH, Salvelinus alpinus) and Dolly Varden (DVCH, Salvelinus
malma) used for mtDNA sequencing were collected. ............................................ 171!
Table A.2. Sampling location information for the samples used in the microsatellite
analysis of Arctic Char (Salvelinus alpinus) ........................................................... 174!
Table A.3. Frequency of haplotypes of Arctic Char (Salvelinus alpinus) in each sampling
locations. ................................................................................................................. 175!
Table A.4. Summary population statistics for the microsatellite analysis across nine loci
in Arctic Char (Salvelinus alpinus). ........................................................................ 179!
Table B.1. Details of the primers and PCR reactions used for each of the 4 multiplexes.
................................................................................................................................. 183!
Table B.2. Heterozygosity (observed and expected) and F (Weir & Cockerham 1984)
IS
per locus in samples of Arctic Char (Salvelinus alpinus) ....................................... 185!
Table B.3. Pairwise F (Weir and Cockerham 1984) between each Arctic Char
ST
(Salvelinus alpinus) sample used in the study. ....................................................... 189!
Table B.4. Summary of sibship reconstruction among samples of juvenile Arctic Char
(Salvelinus alpinus) using the program COLONY ................................................. 192!

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Figure 1.1. Arctic Char, Salvelinus alpinus. The drawing is based on an anadromous
specimen in spawning colours from Anderson Bay Lake in the Cambridge Bay
Region of Nunavut, Canada. ..................................................................................... 30!
Figure 1.2 Map of the northern hemisphere showing the Holarctic distribution of Arctic
Char, Salvelinus alpinus, in dark shaded areas surrounded by dashed lines. ........... 31!
Figure 2.1. Map of the Northern Hemisphere showing the distribution and names of the
five major mitochondrial DNA lineages of Arctic Char (Salvelinus alpinus)
identified in the Holarctic phylogeography study of Brunner et al. (2001). ............. 59!
Figure 2.2. Maximum likelihood phylogenetic tree of Arctic Char (Salvelinus alpinus)
mtDNA haplotypes generated using GARLI (Zwickl 2006). ................................... 60!
Figure 2.3 (Next page) Map showing the geographical distribution of the two mtDNA
lineages identified in North American Arctic Char (Salvelinus alpinus) and Dolly
Varden (S. malma). ................................................................................................... 61!
Figure 2.4. Results of the pairwise mismatch analysis done on the mtDNA data for two
lineages of Arctic Char (Salvelinus alpinus). ........................................................... 63!
Figure 2.5. Neighbour-joining tree of Cavalli-Sforza’s chord measure genetic distance
from nine microsatellite loci assayed in samples of Arctic Char (Salvelinus alpinus).
................................................................................................................................... 64!
Figure 2.6. Variation in expected heterozygosity as a function of waterway distance from
a putative glacial refugium (Banks Island) in samples of Arctic Char (Salvelinus
alpinus) assayed at nine microsatellite DNA loci. .................................................... 65!
Figure 2.7. Results of the STRUCTURE analysis based on the most likely (sensu Evanno
et al. 2005) number of genetic cluster: K = 4 in samples of Arctic Char (Salvelinus
alpinus) assayed at nine microsatellite DNA loci. .................................................... 66!
Figure 2.8. Relationship between pairwise genetic distance measured as linearized F
ST
(Rousset 1997) and geographical distance (km) in samples of Arctic Char
(Salvelinus alpinus) assayed at nine microsatellite DNA loci. ................................. 67!
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