738 The Condor 115(4):738–749  The Cooper Ornithological Society 2013 4 E-mail: laurafinnegan@trentu.ca Manuscript received 13 July 2012; accepted 2 May 2013. FINE-SCALE ANALYSIS REVEALS CRYPTIC PATTERNS OF GENETIC STRUCTURE IN CANADA GEESE LAURA FINNEGAN 1,4 , SARRAH CASTILLO 1 , JACK HUGHES 2 , KEN F. ABRAHAM 3 , RODNEY W. BROOK 3 AND CHRISTOPHER J. KYLE 1 1 Natural Resources DNA Profiling and Forensics Centre, Trent University, Peterborough, ON, Canada 2 Canadian Wildlife Service, Ottawa, ON, Canada 3 Wildlife Research and Development Section, Ontario Ministry of Natural Resources, Peterborough, ON, Canada Abstract. In migratory birds, population-genetic structure is generally low, but philopatric species can have fine-scale patterns of differentiation. We investigated the population-genetic structure of the Canada Goose (Branta canadensis) across multiple spatial scales to determine whether genetic data support current delineations of subspecies and populations for management. We collected samples from two subspecies (B. c. interior and B. c.maxima) and four management populations across Ontario and Quebec. Using 7 microsatellites and 442 base pairs of mtDNA we found that genetic structure varied with scale. F ST revealed low levels of genetic differentiation between subspecies and management populations, and individual-based clustering revealed no genetic differen- tiation. However, fine-scale spatial autocorrelation revealed significant levels of relatedness at distances <85 km. The lack of clear genetic structure may reflect recent human management. That our fine-scale analysis revealed significant genetic relationships suggests that genetic structure may increase and in time reflect that revealed by banding data. As our markers were unable to accurately distinguish between subspecies they will be of little use in estimating subspecific contribution to harvested stock. Alternative molecular markers under selective pressure may be more informative in assess targets for harvest. Key words: Branta canadensis, migration, subarctic, temperate, mtDNA, wildlife management, microsatel- lite DNA. Análisis de Escala Fina Revelan Patrones Crípticos de Estructura Genética en Branta canadensis Resumen. En las aves migratorias, la estructura genética poblacional es generalmente baja, pero las especies filopátricas pueden tener patrones de escala fina de diferenciación. Investigamos la estructura genética poblacional de Branta canadensis a lo largo de múltiples escalas espaciales para determinar si los datos genéticos apoyan las delimitaciones actuales de subespecies y poblaciones para manejo. Colectamos muestras de dos subespecies (B. c. interior y B. c. maxima) y de cuatro poblaciones de manejo a través de Ontario y Quebec. Usando 7 microsatélites y 442 pares de bases de ADNmt encontramos que la estructura genética varió con la escala. F ST reveló bajos niveles de diferenciación genética entre subespecies y poblaciones de manejo, y los grupos de base individual no reve- laron diferenciación genética. Sin embargo, la autocorrelación espacial de escala fina reveló niveles significativos de relación a distancias <85 km. La falta de estructura genética clara puede reflejar un manejo antrópico reciente. El hecho de que nuestro análisis de escala fina revelara una relación genética significativa sugiere que la estruc- tura genética puede aumentar y en el tiempo reflejar aquella revelada por los datos de anillado. Dado que nuestros marcadores fueron incapaces de distinguir con precisión entre subespecies, serán de poca utilidad para estimar la contribución de cada subespecie a las existencias cosechadas. Marcadores moleculares alternativos bajo presión de selección pueden ser útiles para evaluar objetivos de cosecha. INTRODUCTION Long-distance movement facilitates gene flow across broad geographic scales (Webster et al. 2002) and may drive a cor- respondingly weak population genetic structure (McCracken et al. 1994, Boulet et al. 2007, Ball et al. 2010, Reudink et al. 2011). However philopatric behavior and life-history strate- gies may produce fine-scale genetic relationships that can be masked during wider-scale assessments of population The Condor, Vol. 115, Number 4, pages 738–749. ISSN 0010-5422, electronic ISSN 1938-5129.  2013 by The Cooper Ornithological Society. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Rights and Permissions website, http://www.ucpressjournals.com/ reprintInfo.asp. DOI: 10.1525/cond.2013.120117 structure (Miller-Butterworth et al. 2003, Lecomte et al. 2009). Genetic assessments that account for a species’ biology, and that consider gene flow at appropriate geographic scales, are essential for accurate monitoring of the genetic relation- ships among individuals and populations for conservation and management. The Canada Goose (Branta canadensis) is a wide- ranging migratory species. Its taxonomy is complex, with six