Genetic conservation and management of the California endemic, Torrey pine ( Parry): Implications of genetic rescue in a genetically depauperate species.

Rare species present a challenge under changing environmental conditions as the genetic consequences of rarity may limit species ability to adapt to environmental change. To evaluate the evolutionary potential of a rare species, we assessed variation in traits important to plant fitness using multigenerational common garden experiments. Torrey pine, Parry, is one of the rarest pines in the world, restricted to one mainland and one island population.

Missing Rings, Synchronous Growth, and Ecological Disturbance in a 36-Year Pitch Pine (Pinus rigida) Provenance Study.

Provenance studies are an increasingly important analog for understanding how trees adapted to particular climatic conditions might respond to climate change. Dendrochronological analysis can illuminate differences among trees from different seed sources in terms of absolute annual growth and sensitivity to external growth factors. We analyzed annual radial growth of 567 36-year-old pitch pine (Pinus rigida Mill.

Postglacial migration and adaptation for dispersal in pitch pine (Pinaceae).

Premise Of The Study: Variation in a species is a blend of adaptive, random, and migratory responses. Pitch pine (Pinus rigida), a highly variable eastern conifer, has occupied multiple glacial refugia, whose harsh conditions favored adaptations enhancing subsequent dispersal and recolonization of newly deglaciated sites. We assessed phenotypic diversity in long-term growth trials to elucidate both the adaptations and likely refugia.

The evolution of the New Jersey Pine Plains.

Premise Of The Study: Fire in the New Jersey Pine Plains has selectively maintained a dwarf growth form of pitch pine (Pinus rigida), which is distinct from the surrounding tall forest of the Pine Barrens and has several other inherited adaptations that enable it to survive in an environment dominated by fire.

Methods: Pitch pine progeny from two Pine Plains sites, the West and East Pine Plains, were grown in common garden environments with progeny from two Pine Barrens stands, Batsto and Great Egg Harbor River. The tests were replicated in five locations: in New Jersey, Connecticut, two sites in Massachusetts, and Korea.

Projections of suitable habitat under climate change scenarios: Implications for trans-boundary assisted colonization.

Premise Of The Study: Climate change may threaten endemic species with extinction, particularly relicts of the Arcto-Tertiary Forest, by elimination of their contemporary habitat. Projections of future habitat are necessary to plan for conservation of these species.

Methods: We used spline climatic models and modified Random Forests statistical procedures to predict suitable habitats for Brewer spruce (Picea breweriana), which is endemic to the Klamath Region of California and Oregon.

Projections of suitable habitat for rare species under global warming scenarios.

Premise Of The Study: Modeling the contemporary and future climate niche for rare plants is a major hurdle in conservation, yet such projections are necessary to prevent extinctions that may result from climate change. •

Methods: We used recently developed spline climatic models and modified Random Forests statistical procedures to predict suitable habitats of three rare, endangered spruces of Mexico and a spruce of the southwestern USA. We used three general circulation models and two sets of carbon emission scenarios (optimistic and pessimistic) for future climates.

Decoupled mitochondrial and chloroplast DNA population structure reveals Holocene collapse and population isolation in a threatened Mexican-endemic conifer.

Chihuahua spruce (Picea chihuahuana Martínez) is a montane subtropical conifer endemic to the Sierra Madre Occidental in northwestern México. Range-wide variation was investigated using maternally inherited mitochondrial (mtDNA) and paternally inherited chloroplast (cpDNA) DNA markers. Among the 16 mtDNA regions analysed, only two mitotypes were detected, while the study of six cpDNA microsatellite markers revealed eight different chlorotypes.

Genic diversity, genetic structure, and mating system of Brewer spruce (Pinaceae), a relict of the Arcto-Tertiary forest.

Brewer spruce (Picea breweriana), a relict of the widespread Arcto-Tertiary forests, is now restricted to a highly fragmented range in the Klamath Region of California and Oregon. Expected heterozygosity for 26 isozyme loci, averaged over 10 populations, was 0.121.

Genetic variation at allozyme and RAPD markers in Pinus longaeva (Pinaceae) of the White Mountains, California.

We compared genetic diversity estimated from allozymes and from random amplified polymorphic DNA (RAPDs) in a sample of 210 Great Basin bristlecone pines (Pinus longaeva Bailey) from three groves in the White Mountains, California, USA. The White Mountains are the most westerly extension of bristlecone pine and home to the oldest known living trees. We assayed two forks of each tree to determine whether they originated from multiple seed caches of the Clark's nutcracker.

Genetic diversity and the mating system of a rare Mexican pinon, Pinus pinceana, and a comparison with Pinus maximartinezii (Pinaceae).

Weeping piñon (Pinus pinceana) has a restricted and fragmented range, trees are widely scattered within populations, and reproduction is limited. Nevertheless, genetic diversity was high; based on 27 isozyme loci in 18 enzyme systems, unbiased expected heterozygosity averaged 0.174.

Founder effects and the genetic structure of Coulter pine.

Mean expected heterozygosity at 33 isozyme loci decreased with latitude from 0.193 near the southern extreme of Coulter pine's range to 0.107 at its northern extreme.

EVIDENCE FOR AN EXTREME BOTTLENECK IN A RARE MEXICAN PINYON: GENETIC DIVERSITY, DISEQUILIBRIUM, AND THE MATING SYSTEM IN PINUS MAXIMARTINEZII.

Maxipiñon (Pinus maximartinezii Rzedowski), which is confined to a single population of approximately 2000 to 2500 mature trees, covers about 400 ha in southern Zacatecas, Mexico. Genetic diversity measured by expected heterozygosity was 0.122, which is moderate for pines.

RECENT EVOLUTION AND DIVERGENCE AMONG POPULATIONS OF A RARE MEXICAN ENDEMIC, CHIHUAHUA SPRUCE, FOLLOWING HOLOCENE CLIMATIC WARMING.

Fragmentation and reduction in population size are expected to reduce genetic diversity. However, examples from natural populations of forest trees are scarce. The range of Chihuahua spruce retreated northward and fragmented coincident with the warming climate that marked the early Holocene.

THE FITNESS CONSEQUENCES OF MULTIPLE-LOCUS HETEROZYGOSITY: THE RELATIONSHIP BETWEEN HETEROZYGOSITY AND GROWTH RATE IN PITCH PINE (PINUS RIGIDA MILL.).

Positive correlations between measures of "fitness" and the number of electrophoretic loci for which an individual is heterozygous have been observed in many species. Two major hypotheses have been proposed to explain this phenomenon: inbreeding depression and overdominance. Until recently, there has been no way to distinguish between these hypotheses.