Variation of Dolly Varden Salvelinus Malma in Northwestern
Total Page：16
File Type：pdf, Size：1020Kb
VARIATION OF DOLLY VARDEN SALVELINUS MALMA IN NORTHWESTERN NORTH AMERICA Laura Groening Supervisors: Dr. Scott Forbes and Dr. Jim Reist A thesis submitted in partial fulfillment of the Honours Thesis Course 05.4111/6 Department of Biology The University of Winnipeg 2008 ii Abstract Dolly Varden (Salvelinus malma (Walbaum)) are native to northwestern North America and northeast Asia. Current taxonomical classifications within S. malma are ambiguous due to the morphological and ecological plasticity observed throughout their range. Uncertainty exists regarding the number and status of geographic variants of S. malma throughout their North American distribution. The objective of this study was to define the number and distribution of natural Dolly Varden taxa below the species level in northern North America, and to assign those taxa to an appropriate level. Morphological characteristics were explored using analysis of variance (ANOVA) and principal component analysis in order to assess the geographic patterns of variation. Allozyme frequency data were collected from the literature and were used to construct trees representative of phylogenetic relationships. The patterns of variation observed correspond to an existing hypothesis that differentiates between a northern and southern form. Phylogenetic analysis indicates the northern and southern forms represent different ancestral clades, which may be indicative of subspecific taxa. The location of the boundary between the northern and southern form suggests the variation may stem from an historic separation during the late Pleistocene glaciation. iii Acknowledgements I would like to thank Jim Reist, for passing on his vision and fascination with Dolly Varden, and instilling in me the power of the scientific method. I would like to thank Dr. Scott Forbes for his guidance and advice throughout this project. I greatly appreciate the opportunity to study evolutionary biology in both the marshes of Manitoba and the rivers of Alaska. It’s been so much fun. I would also like to thank Margaret Docker, for taking the time to be on my committee. Thanks to Jim Johnson, for helping me navigate new programs and many other aspects of this project. Thanks to Dr. Moodie, for his support and guidance and for believing in me. Thanks to Dr. Jens Frank and Kelly Reimer for their assistance with the phylogenetic analysis and emotional support. Also, thanks to my dear family and friends. You listened to me blather without end about this project and were rooting for me from the start. Thank you. iv Table of Contents Table of Contents……………………………………………………………………..iv List of Tables………………………………………………………………………….vi List of Figures………………………………………………………………………...vii List of Appendices……………………………………………………………………ix 1.0 Introduction………………………………………………………………………..1 1.1 Classification of Salmonids………………………………………………..1 1.2 Classification of Dolly Varden…………………………………………….2 1.3 Diversity within S. malma…………………………………………………3 1.4 Life History of North American Dolly Varden……………………………5 1.5 Glacial History of Northern North America………………………………6 1.6 Objectives………………………………………………………………….7 2.0 Methods……………………………………………………………………………9 2.1 Logic of the Study…………………………………………………………9 2.2 Sample Selection…………………………………………………………..10 2.3 Morphometric and Meristic Data………………………………………….13 2.4 Phylogenetic Analysis……………………………………………………..13 2.5 Statistical Analysis………………………………………………………...17 3.0 Results……………………………………………………………………………..19 3.1 Phylogenetic Analysis……………………………………………………..19 3.2 Mophological Data………………………………………………………...19 4.0 Discussion………………………………………………………………………….27 4.1 Phylogenetic Analysis of Genetic Data…………………………………....27 v 4.2 Morphological Diversity…………………………………………………...30 4.3 Phylogeographic Analysis………………………………………………...32 4.4 Future Recommendations…………………………………………………33 5.0 Conclusions……………………………………………………………………….35 References…………………………………………………………………………….36 Appendices……………………………………………………………………………41 vi List of Tables Table 1. Sample location, size, date collected, life history type and suggested geographic form for samples selected from the Freshwater Institute database. Life history types are defined as I = isolated riverine fish, A = anadromous riverine fish, R= resident riverine fish and ? = unknown life history type. Suggested forms are N = Northern form, I = Intermediate form and S = Southern form………………….14 Table 2. Sample location, data type, size, suggested geographic form and source for data collected from the literature. Suggested forms are N = Northern form, I = Intermediate form and S = Southern form………………………………………16 Table 3. Comparison of variable mean values for each location for samples selected from the Freshwater Institute database……………………………………………….21 Table 4. Comparison of variable mean values for each form for samples selected from the Freshwater Institute database……………………………………………….22 vii List of Figures Figure 1. Distribution of Northern and Southern form Dolly Varden as proposed in Behnke (1980, 1984) and Morrow (1980)………………………………………..4 Figure 2. Drainage patterns of Beringia during the Late Wisconsin period. Dashed lines represent Beringian Coastline and dotted lines represent glacial rivers. From DeCicco and Reist (1999). Based on Hopkins (1972) and Lindsey and McPhail (1986)…………..……………………………………...8 Figure 3. Location of morphological samples from Fisheries and Oceans (Numbered 1 through 9) and samples selected from the literature (Numbered 10 though 30)......................................................................................12 Figure 4. Morphometric measurements used for analysis. Description of acronyms found in the text. From Reist et al. (1991)………………………………………………14 Figure 5. Bootstrapped consensus tree for loci IDDH, sAAT1,2, LDH-C, PGDH and SOD. Auke Creek, Fish Creek and Osprey Lake samples are located south of the Alaskan Peninsula, therefore represent Southern form. All other samples represent locations north of Seward Peninsula, thereby represent Northern form. See table 2 for detailed sample locations…………………………………………………….20 Figure 6. Pairwise comparison of the number of significant variables out of 21 meristic and morphometric variables. The numbers within cells indicate the number of significant meristic variables (out of eight) (left number), and morphometric variables (out of 13) (right number). The legend shows the total number of significant morphological variables ranked into colored categories…………… 23 Figure 7. Scatter plot of principal component one (28.1% of variance) by principal component two (15.5% of variance) for meristic variables by sample location……………………………………………………………….25 Figure 8. Scatter plot of principal component one (28.1% of variance) by principal component three (13.1% of variance) for meristic variables by sample location………………………………………………………………25 Figure 9. Scatter plot of principal component one (30.1% of variance) by principal component two (19.4% of variance) for ratioed morphometric variables by sample location……………………………………………………………………...……26 Figure 10. Scatter plot of principal component one (30.1% of variance) by principal component three (12.9% of variance) for ratioed morphometric variables by sample location……………………………………………………………...........26 viii Figure 11. Location of ice-free refugia during Wisconsin glaciation. Based on Rogers et al. (1991)………………………………………………………………………31 ix List of Appendices Appendix 1. Enzyme loci and sources. Tissues used for extraction (M = muscle, L = liver, E = eye). Buffer systems as described in Crane et al. (1994). Enzyme names follow IUBNC (1984)……………………………….…………………………..41 Appendix 2. Allozyme frequency for polymorphic loci in populations of Dolly Varden. Samples numbers correspond to locations in Figure 3………………………….42 1 1.0 Introduction 1.1 Classification of Salmonids Classification of fishes within the Salmonid family remains problematic for taxonomists despite thorough investigation (Grewe et al. 1990, Phillips and Pleyte 1991, Phillips and Oakley 1997). Members of the Salmonidae display a high frequency of hybridization and introgression, which complicates phylogenetic analysis (Taylor 2004, Phillips and Oakley 1997). In addition, there are few shared derived characters between branches of Salmonids, due to the rapid radiation following tetraploidization (Allendorf and Thorgaard 1984, Phillips and Oakley 1997, Grewe et al. 1990). Salmonids also display a wide range of genetic and phenotypic variation, both between and within species (reviewed in Willson 1997). The classification of Salmonids is further complicated by glacial history, particularly in their north Pacific range. Repeated glacial events and subsequent recolonization of glaciated areas often results in low genetic divergence between species, creating taxa that do not fit the strict requirements of the biological species concept (Bernatchez and Wilson 1998). The high degree of variation within Salmonid taxa, coupled with low genetic divergence, can greatly complicate attempts to decipher intraspecific relationships. These complications have resisted attempts at establishing a general agreement as to relationships within the Salmonid family, perhaps most notably in the intensely debated genus Salvelinus, which includes the Dolly Varden (Salvelinus malma (Walbaum)) (Phillips and Oakley 1997). The objective of this study is to attempt 2 to define the presence, or absence, of subspecific taxa within North American Dolly Varden by describing the geographic pattern of genetic and morphological variation. 1.2 Classification of Dolly Varden Dolly Varden, a