• Genetic Considerations in Restoration Ecology

• Linhart, Y.B. 1995. Restoration, revegetation and the importance of genetic and evolutionary perspectives. Proceedings: Wildland Shrub and Arid Land Restoration Symposium. USDA Intermountain Research Station

• Linhart proposed very restrictive guidelines:

– Use nearby local native species

• Within 100 m for herbs

• Within 1 km for woody plants

• Precise local adaptations:

– “Plant genomes show very precise adaptations to local conditions. Introduction of non-local materials may lead to failure of revegetation projects and endanger long-term health of nearby populations.”

• Studies of genetic variability show:

– Geographic range accounts for largest variation

– Species with large ranges are more variable than endemics

– Breeding system:

• Outcrossers more variable

– Variability is within populations

• Inbreeders less variable

– Variability is among populations (populations differ)

• Genetic variability

– Primary factors affecting genetic variability:

• Breeding systems

• Selective pressure

– Natural selection, heterogeneity of environment

• Genetic drift

• Gene flow

• Some arguments against restrictive genetic guidelines

– Precise adaptations? Niche displacement

– “No organism is perfectly adapted; all fail to adapt to their environments in some ways and to differing degrees” Fisher, 1930

– Competitive advantage may be conferred on a less optimally adapted genotype because it has less competition where it finds the opportunity to flourish.

• Some arguments against restrictive genetic guidelines 2

– Genetic variation is variation between plants

• One plant does not have variation

• One seed has a different genetic makeup than another seed

– The place where a plant is most common may be the place that has the most poorly adapted genotypes.

– Precise adaptation may be occurring at the ends of a plant’s range

• Some arguments against restrictive genetic guidelines 3

– Plants can adapt to the environment genetically, or by plasticity

• Some species have high geographic variability (Douglas fir, loblolly pine)

• Some species do not (western red cedar, white pine)

• What is identified as geographic variation may actually be a response to an environmental gradient

– Which could occur over a 1000 km or 1 km.

• “Why do we care about genetics?”

• 12 factsheets from Genetic Resources Conservation Program, U.C. Davis

• Why is genetic diversity important?

– It may gauge a species ability to adapt to changing environment.

– Populations may be able to occupy different ecological niches.

• How can genetic information be valuable in natural resource management?

– For establishing taxa.

– To assess normal levels of diversity.

– To assess gene flow.

– To determine where to collect seeds.

– To understand how the ecology of a species has evolved (bottlenecks, dispersers).

– To track human-assisted plant movement.

• Why is genetic diversity dynamic?

– Migration

– Mutation

– Genetic drift

– Selection

• Are patterns of genetic diversity important?

– Broadly distributed pollen and seeds suggest little local genetic differentiation.

– Selfing, heavy seeds, quick germination suggest differences from one population to another.

– Strong selection pressures (climate) may result in locally differentiated populations.

• What are the genetic risks associated with a planting decision?

– Genetic consequences can be because of the amount and type of diversity introduced.

• Lower amount can lead to genetic erosion.

– Collect from adequate number of well-spaced donors.

• Wrong kind can lead to loss of local adaptations.

– Match site conditions.

• Can genetic diversity be influenced by nursery practices?

– Nursery plants are a sub-sample of natural diversity.

– Subsequent filtering (for size, speed of germination, etc.) further reduces sample.

– Supplying adequate water, moisture and light is essentially diversity-neutral.

• What is genetic erosion and how can it be managed?

– May occur quickly with a large population or habitat loss.

– May occur slowly

• Fragmentation

• Selective harvest

• Re-planting with material with narrow genetic range.

– Addressing genetic erosion

• Collect materials that represent the genetic diversity of the geographic area.

• Obtain geographic source information when buying nursery plants.

• Use caution when planting cultivars.

• Encourage nurseries that use practices that maximize genetic diversity.

• Is genetic management important in urban landscapes?

– Choosing appropriate geographical source insures that plants are well-adapted to planting site. (?)

– Also provides continuity with neighboring populations and bridges to disjunct populations.

– Habitat for native specialist animals (esp. insects).