INTRODUCTION

1. Population Genetics and Ex situ Gene Conservation of Eastern Hemlocks (Tsugacanadensis) Threatened by the Hemlock Woolly Adelgid (Adelgestsugae) Robert M. Jetton1, Kevin M. Potter2, William S. Dvorak1, W. Andrew Whittier1, and James “Rusty” Rhea3 1Camcore, Dept. of Forestry & Environmental Resources, NC State University, Raleigh, NC 2Dept. of Forestry & Environmental Resources, NC State University & USDA Forest Service EFETAC, RTP, NC 3USDA Forest Service, Forest Health Protection, Region 8, Asheville, NC INTRODUCTION Since its introduction to the eastern Untied States in 1951, the invasive hemlock woolly adelgid (AdelgestsugaeAnnand) has caused widespread mortality and localized extinction among populations of Eastern hemlock (TsugacanadensisCarriére). In 2005, as part of the larger integrated effort to manage the adelgid’s impact on hemlock forests utilizing silvicultural, chemical, and biological controls, Camcore (an international tree breeding and conservation program at NC State University) and the USDA Forest Service began collaboration on a multi-year effort to study the population genetic structure and conserve the genetic resources of Eastern hemlock across it geographic range. This poster presents a brief synopsis of the progress we have made in these research areas. (This work has been supported by the following USDA Forest Service grants and agreements: 05-DG-11083150-210; 06-PA-11083150-002; 08-DG-11083150-014; 09-DG-11083150-008) • POPULATION GENETIC STRUCTURE & DIVERSITY • ResearchObjectives & Goals • The overall goal of this study is to conduct the first range-wide population genetic assessment of Eastern hemlock utilizing highly polymorphic, co-dominant, consistent microsatellite markers. The primary objectives of the research are to identify areas of high and low genetic variation across the species’ geographic range to help guide ex situ conservation efforts, compare the genetic variation present in interior versus peripheral disjunct populations to assess the genetic effects of isolation, and evaluate regional (north vs. south) differences in genetic variation to better understand biogeographical processes. • Preliminary Results • Between 2006 and 2009, foliage samples for genetic analysis were collected from 1,182 individual Eastern hemlock trees distributed across 61 populations in 21 eastern US states and 2 Canadian provinces. DNA from these samples was screened across 13 microsatellite loci developed for hemlock. • Genotyping and data analysis are ongoing, but some of our preliminary findings based on results from 8 microsatellite loci are: • Overall, Eastern hemlock has moderate levels of genetic variation (Observed Heterozygosity = 0.532) and moderate genetic differentiation among populations (~6%; FST = 0.063). • Greater genetic variation is present in interior versus disjunct populations (Observed Heterozygosity = 0.550 and 0.439, respectively). • The number of unique alleles per locus is higher for disjunct (0.40) versus interior (0.31) populations. • Based on several measures, Eastern hemlock appears to have two main centers of genetic diversity. This is reflected in the results for Observed Heterozygosity presented in Figure 1. • EX SITU GENE CONSERVATION • Project Objectives & Goals • The primary objectives of the ex situ gene conservation portion of this project are to develop a framework plan for Eastern hemlock genetic conservation, make genetically representative seed collections from hemlock populations distributed across the species’ geographic range, place seeds into cold storage in multiple seed storage facilities for long-term preservation, and establish national and international hemlock conservation seed orchards in places such as the Ozark Mountains of Arkansas and on Camcore Cooperative member lands in Chile and Brazil. • The overall goal of the gene conservation effort is to maintain viable populations of Eastern hemlock in perpetuity that will be available for breeding and restoration activities if these ecologically vital species are functionally eliminated from the forests of eastern North America. • Progress in Seed Collection & Long-term Conservation • Seeds for conservation have been collected from 237 mother trees representing 35 Southern Region populations and 32 mother trees representing 4 Northern Region populations (Figure 2). • Seeds representing 84 mother trees from 19 Southern Region populations have been submitted to the USDA Forest Service National Seed Laboratory (NSL) in Dry Branch, Georgia for long-term preservation and accession in the Germplasm Resources Information Network (GRIN). • The first conservation seed orchard representing Southern Region seed sources of Eastern hemlock was established by Camcore Cooperative member Rigesa (MeadWestvaco) in Santa Catarina, Brazil in November 2010. Figure 1. Map depicting levels of Obs. Heterozygosity in the 61 Eastern hemlock populations sampled. Results suggest two main centers of genetic diversity, one in the Southern Appalachians and a second along the northeast Atlantic seaboard. Figure 2. Map depicting the locations of seed collections from Eastern hemlock in the eastern United States.