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transcript
Ex Situ Plant Conservation
Certificate Program in
Native Plant StudiesDecember 12, 2009
Johnny Randall
North Carolina Botanical GardenUniversity of North Carolina at Chapel Hill
Topics covered:
Ex situ, definition, history, and global context
Prioritization
Components of an ex situ capability
Seed collection
Seed storage
Reintroduction
Ecotypes and seed zones
Some further examples
Definitions
Situ is from Latin and refers to place
In situ means „in the place‟
Ex situ means from, or away from the place,
Saving seeds off site, out of nature, as a means of conserving the sampled populations and taxa in the wild can seem like a contradiction in terms (but, properly used, it is not)
From BGCI web page…
Ex Situ Conservation
Ex situ conservation is the conservation
and maintenance of samples of living
organisms outside their natural habitat,
in the form of whole plants, seed, pollen,
vegetative propagules, tissue or cell
cultures.
Evolution of ex situ conservation
• Botanic garden as repository for academic study – 1400s to 1900s
• Botanic gardens first mentioned as “Jardin Conservatoire,” supporting wild plant diversity by Cugnac in 1953
• Botanic gardens as “Arks” – 1970s
• Botanic gardens as partners in “Integrated Plant Conservation” –1980s to present
Off site, or Ex situ
Conservation resources are...
1. A means to an end (enhanced
survival prospects in nature, and)
2. A part of a whole (Integrated
conservation strategies, in which
ex situ methods support in situ
efforts)
Seed Bank History
Vavilov first to recognize value of genetic diversity,
created first modern seed bank in St Petersburg, Russia
USDA NCGRP – crop and other seed bank back up
Doomsday Seed Bank
Millennium Seed Bank – RBG Kew
Seeds Of Success/BLM – US native species
Center for Plant Conservation - for rare plant species
Kuijt I, Finlayson B PNAS 2009;106:10966-10970
©2009 by National Academy of Sciences
Oldest known granaries 11,000 years ago in Jordan
River Valley, predating domestication by 1,000
years or so, and together set scene for sedentary
life style and dramatically increased local
population sizes.
Structure 4, phase 1, Dhra′, Jordan looking north
©2009 by National Academy of Sciences
Success is what me make of the
mess we‟ve made of things.
T.S. Elliot
The mess being the current state of the global
environment: massive loss of habitat and biodiversity,
degradation and fragmentation of habitat, rapidly
increasing rates of extinction, invasives, etc. All of
which are a consequence of the huge human
population – which itself was made possible by
agriculture, which in turn was made possible by seed
storage. Thus, seed banks contributed to what got us
into this mess...
Scientists in Kabul reported the loss of Afghanistan's
principal agricultural insurance policy: two stores of
carefully collected seeds, materials selected to
represent the genetic diversity of native crops.
It was a looting of the worst kind - a theft of that
agrarian country's stockpiled agricultural heritage. In it
were seeds to help that nation's 22 million people
rebuild the capacity to feed themselves.
Ironically, the stores were not plundered for those
plant materials; the seeds were dumped in disarray
onto the floor of ransacked buildings in two cities. The
looters merely ran off with the airtight plastic and
glass jars in which the seeds had been kept.
N.I. Vavilov• First to recognize value of genetic diversity.
• Established first modern seed bank in St Petersurg (now
Leningrad)
Centers of origin for food plants
The USDA seed storage effort, used to be called
National Seed Storage Laboratory. Historically, their
main focus has been on agriculturally important plants
and their wild relatives. Leading laboratory for seed
storage science.
Millennium
Seed Bank
Project
15 Oct 2009
Kew‟s Millennium Seed Bank
partnership is celebrating
collecting, banking and conserving
10% of the world‟s wild plant
species by banking its 24,200th
plant species.
Seeds of Success
BLM originally in conjunction with
Millennium Seed Bank.
Attempting to gather
large samples of more
commons species.
Millennium Seed Bank /
Seeds of Success Project
Wiregrass collection in NC
Coastal Plain with TNC
and NC Plant Conservation
Program partners
Seed
Processing
Sending
seeds and
vouchers
to Kew…
The CPC Participating Institutions
Components of an Ex situ (off site)
Conservation Capability
I. Collect genetically representative seed samples
II Keep seeds alive for a long time, and learn to germinate and grow them
III. Use samples as population founders when needed
19911996
2004
1. Collect genetically representative samples.
2. Maintain samples off site in good
condition for a long time, and be
able to use them if needed.
3. Use samples to
reintroduce genetic
material to the wild if
necessary.
Center for Plant Conservation
Berry Botanic Garden Seed VaultVented exterior door with exhaust fan
Freezer
Fluorescent lights
Fluorescent lights
Wire shelving
Ceiling mounted low profile
condensing unit for temperature
control
Fire doorInsulated door
Vestibule Entry
Scale 5 feet (ca 1.5 m)
Steel reinforced Concrete shell
Insulated shell
Compressors:
Vault
Freezer *
**
* Thermostat for Power Cut-Off Safety
** Hygrostat
Dehumidifier
Vault temperature controller
Biodiversity Concentration in US
• Total U.S. plant species ~20,000
• Extinct >200
• Fed. listed endangered, 889
threatened, or qualify (~5%)
• Species of concern (25%) > 5,000
Mountain Sweet
Pitcher Plant
(Sarracenia jonesii)
Vulnerability in the U.S. Flora
Condition of Listed Plant Species
(survey of recovery plans 1982-1998)
Solidago plumosa
One Site Remaining
•65% of listed species had < 10 sites remaining;
49% had < 5 sites
•74% had less than 100 individuals per site. These
populations are VERY vulnerable to chance events
and genetic erosion—they could be extinct within 20
years or less without intervention
Botanic gardens and arboreta:
• Develop and manage a documented
collection of plants…they represent
some of the most concentrated sites
of species richness
• Are evolving from “collections of
curiosities” to centers of research and
conservation
• Serve as “windows to the plant world”
• Collectively host over 150 million
visitors per year…serving as centers
for outreach on plant conservation is
an area where we can make a unique
and significant impact
The ex situ/in situ continuum• Cryopreservation
• Seed Banking
• Tissue Culture Storage
• Tissue Culture Propagation
• Cultivation in dedicated conservation facility
• Specialist cultivation in controlled environment
• Cultivation in mixed display or reference collections
• Field gene bank
• Commercial Cultivation
• Community Garden
• Inter situ
• In situ - horticulturally managed individuals
• In situ - managed wild populations
What is ex situ delivering?
• 1800 botanic gardens hold 2.5 million accessions, representing 18,000 taxa
• About 100 taxa exist only in botanic gardens
• Many ex situ collections vastly outnumber surviving wild populations
• In the US, over 80 rare taxa are being reintroduced
Why isn‟t ex situ delivering
more?
• A perception that it undermines
in situ conservation efforts
• A lack of professional confidence
that gardens can hold diverse
samples for long periods of time
• Conservation “liabilities” - source
of pathogens, genetic change,
etc.
Characteristics of many botanical
garden collections
• Small, often from a few closely related founders
• Subject to fluctuating population size
• Little or no ecological/biological information
• Little information on the history of the taxa in cultivation
• Individuals susceptible to artificial selection, genetic drift, inbreeding and hybridization with congeners
• Persistence in collections highest for horticulturally amenable taxa
Ex Situ Target from the Global
Strategy for Plant Conservation
• TARGET 8: 60 per cent
of threatened plant
species in accessible ex
situ collections, preferably
in the country of origin,
and 10 per cent of them
included in recovery and
restoration programs.
CPC National Collection at
The North Carolina Botanical Garden• Amaranthus pumilus
• Arabis serotina
• Asplenium heteroresiliens
• Buckleya distichophylla
• Carex lutea
• Clematis socialis
• Clematis viticaulis
• Coreopsis latifolia
• Echinacea laevigata
• Eupatorium resinosum
• Geum geniculatum
• Helianthus schweinitzii
• Iliamna corei
• Isoetes tegetiformans
• Kalmia cuneata
• Leiophyllum buxifolium
• Liatris helleri
• Lilium grayi
• Lobelia boykinii
• Lysimachia asperulifolia
• Oxypolis canbyi
• Parnassia caroliniana
• Paxistima canbyi
• Pityopsis ruthii
• Ptilimnium nodosum
• Rhexia aristosa
• Rhus michauxii
• Sagittaria fasciculata
• Sarracenia jonesii
• Sarracenia oreophila
• Solidago spithamaea
• Solidago verna
• Solidago villosicarpa
• Stylisma pickeringii var. pickeringii
• Thalictrum cooleyi
• Vaccinium sempervirens
Carex lutea – Golden Sedge
Solidago villosicarpa
Recent additions
to CPC National
Collection taxa
in need of study
Clematis viticaulis
Buckleya distichophylla
Paxistima canbyi
Prunus alleghaniensis
Leiophyllum buxifolium
Collections transferred
from The Arnold Arboretum
of Harvard University
Seed collection and
storage projects
CPC and NPS Collections•Geum radiatum
•Liatris helleri
•Aster georgianus (Symphyotrichum georgianum)
•Amaranthus pumilus
•Sarracenia oreophila
•Ptilimnium nodosum
• Lilium pyrophilum
Alex Reynolds
USFWS Flex Grant•Liatris helleri
•Hudsonia montana
•Parnassia caroliniana
•Amaranthus pumilus
•Delphinium exaultatum
•Asplenium heteroresiliens
•25 collections scheduled for 2008 in 8 states.
Mean Seed Mass Variation
in Amaranthus pumilus
•Throughout geographic range
•18% from NJ-SC
•Among populations within
states
•21% within NJ
•31% within NC
•Among plants within a
population
•21% among plants at
Indian Beach, NC
Ex situ capacity vs. need -
hotspots
Ex situ load for selected
countries
Country Plant
endemics
(mean)
60%
stored
10%
managed
# BGs Required
BGs (@25
taxa /BG
for 10%)
Brazil 17,500 10,500 1750 29 70
Indonesia 16,650 9990 1665 5 67
Madagascar 9200 5520 920 2 37
China 10,000 6000 1000 106 40
USA 4000 2400 400 296 16
Practical recommendations
• Improve professional
capacity
• Refine species selection
• Support in situ management
• Improve fund raising and
outreach
• Manage ex situ “liabilities”
The challenges of prioritization!
Prioritization – Broad Scale
• The five “E‟s”
– Endangerment
– Endemism
– Ecological
– Economic
– Emblematic/Education
Prioritization – fine scale
• New England model
(Farnsworth, et al., Biological
Conservation, 2006)
• A set of 3 decision matrices
that rank species and
populations for ex situ
activity
Ex situ usually not 100% efficient.
Original
PopulationEx situ
New,
Reintroduced
Population
Gen
etic D
ivers
ity
Time?
Genetic Loss
?What are sources and magnitude of losses?
Matrix 1
• Are seeds/spores orthodox?
• Is vegetative propagation possible?
• Can seeds be germinated and grown?
• If no, is collaboration with research facility
arranged?
• Are there 5 or fewer populations?
• Is current reproduction sufficient?
Matrix 2
• G-rank
• Flora Conservanda rank
• Range outside of NE
• Total EO‟s in NE
• In NEPCoP seedbank?
• # EO‟s in seedbank?
• Proportion of accessions confirmed viable
Matrix 3
• Reproduction consistent
• Population outlier or middle of range
• Protection status
• Habitat typical?
• Imminent threat
• Landowner permission expected
• Collection possible given current
reproduction
Developing species
conservation plans• Are ex situ activities
appropriate and needed?
• If so, what techniques?
Seed banking as an “insurance policy” for orthodox taxa?
Alternative techniques for recalcitrant taxa?
Reintroduction/translocation?
Clues that ex situ activities are
needed:
• Small populations (size and/or number decreasing)
• Increased fragmentation/isolation
• Variable environment or current stress (drought)
• Threats imminent
• Habitat highly degraded
• Genetic or demographic problems
• High priority species
Plants aren‟t reproducing…why?
• No seeds….
– Lack of pollinators
– Lack of compatible mates
• No seedlings…
– Poor conditions for
establishment
– Fruit dispersal agent important
– Severe inbreeding
Talking it out
Sampling for diversity
• Capturing genetic
diversity is important for
conservation programs
• Genetic diversity allows
plants to avoid inbreeding
and is a buffer against:
changing environment
pathogen attack
demographic stochasticity
How many populations should be
sampled?
• Usually 1-5, more if:
High diversity,
limited gene flow
between populations
Destruction of
population imminent
Recent or
anthropogenic rarity
How many individuals should be
sampled?
• Usually 10-50, more if
high genetic diversity
among individuals
within populations
• Sampling follows law
of diminishing returns
How many seeds/individual should
be sampled?
• Usually 1-20, more
if:
high attrition rates
planned
reintroduction
Multi-year collections are indicated
if:
• Low annual
reproductive output
• High year to year
variation in population
size or structure
• Multi-year collections
may capture more
genetic variation
First do no harm
• Sample=trample
• Permits and landowner
permission must be in
place
• Site confidentiality
• Unintentional introduction
of weeds/diseases
• Sample size
considerations
Avoiding harm to native
populations
• Menges, Guerrant and Hamze (2004) modeled demographic consequences of 36 patterns of seed harvest:– 10, 50, and 100% of fecundity for
10, 50, and 90% of years on populations of 10, 50, 100, and 500 plants
– used published projection matrices from a range of taxa with different life histories
Avoiding harm - conclusions
• Menges, Guerrant and Hamze suggest 3 rules:– harvesting 10% of seeds in 10% of
years (or less) is generally safe
– harvesting 50% of seeds in 50% of years (or more) is generally unsafe
– less intense, frequent harvests are safer than more intense, infrequent harvests
• Long-lived woody taxa and large populations are less sensitive to seed harvest
Seed collection conclusions
• Assess extent of population and estimate fecundity, 5-10% of fecundity should be maximum collection amount
• Collect 1000+ seeds (20 seed from each of 50 plants) if population can withstand it (if it makes more than 20,000 seed)
• Sample in a stratified random fashion
• High attrition rates are the rule, rather than the exception
• Consider a multi-year collection strategy
• Adjust as needed depending on purpose of collection (Reintroduction? Long-term storage? Research?)
Seed curation for orthodox
seeds Collect into paper or cloth bags, keep cool and
dry
Clean as soon as possible
Keep maternal lines separate
Dry seeds – drying temperature influences
appropriate RH for desiccation chamber
• At 25C, desiccate at RH = ~38%
• At 15C, desiccate at RH = ~46%
• At 5C, desiccate at RH = ~32%
Store in airtight containers at –18C
Test viability immediately & at 10 yr. intervals
Relationship between drying
temperature and humidity
• Drying relative humidity and temperature combinations to achieve 20% relative humidity at storage temperatures (Walters, 2004)
Dealing with recalcitrance
• Cryopreserve large
numbers of individuals if
possible
• Alternatively, consider
slow growth tissue
culture, inter situ
techniques, field gene
banks
Redbay Ambrosia Beetle,
Xyleborus glabratus
Eichhoff (Scolytinae:
Curculionidae)
Laurel Wilt Disease
Butternut Canker(Sirococcus clavigignenti-juglandacearum)
Hemlock
wooly
adelgid
Tissue culture projects with Cincinnati
Zoo and Botanical Garden
-Sagittaria fasciculata
-Isoetes tegetiformans
-Lobelia boykinii
-Parnassia caroliniana
-Asplenium heterosiliens
Maintaining genetic integrity
• The genetic structure
of a group of plants in
a garden will change!
• Minimizing genetic
change is crucial for
conservation
programs.
Three major genetic risks in ex situ
collections
• Genetic Drift
• Adaptation to
cultivation
• Mutation
accumulation
Genetic drift
• Random loss of alleles in
small populations
• Homozygosity increases,
some alleles become fixed
• Worsens as Ne decreases
How do we counter effects of
drift?
• Increase effective population size (Ne)
– Equalize family size
– Equalize sex-ratios
– Equalize numbers in different generations
• Provide immigration from wild
populations
Evidence for local adaptation
• Fertilizer dependence in Anthoxanthum
• Herbicide resistance in many taxa
• Moisture/temperature morphotypes in Avena
barbata
• Sun/shade differences in Plantago lanceolata
• Competition-induced differences in Veronica
peregrina
• “Loss of drought tolerance in Solidago
plumosa”…
When can unconscious
selection occur?
• Seed collection
• Seed storage
• Germination
• Propagation
• Growth in nursery or
greenhouse
How can we minimize effects of
artificial selection?
• Equalize family size (relaxes selection)
• Minimize time in captivity
• Immigration from wild populations
Mutation accumulation
• Relaxing selection can allow
deleterious mutations to
accumulate
• Mutations accumulate
independent of pop. size, but
fixation by drift depends on Ne
• Fitness declines depend on
shape of fitness function
Minimizing genetic change
• Equalize founder representation
• Minimize generations in captivity; avoid grow outs when possible
• Maintain large population size
• Provide periodic immigration from wild
Genetic guidelines for
reintroductions• Create large, genetically-diverse
populations
• Equalize founder representation
• Use stock from the same
ecoregion and/or evolutionary
lineage
• Consider the taxon‟s breeding
system and historic patterns of
gene flow
• Design restoration as an
experiment
Multiple vs. single source stock
• Introductions
– Use multiple sources
• Reintroductions
– Use propagules from that site unless
they lack diversity
• Augmentations
– Use only propagules from that site
unless circumstances are
extraordinary
Ecological Connections
• Pollinators
Are they present?
Is population large enough to
attract sufficient numbers?
• Seed dispersal agents
• Mycorrhizae
• Others (rhizobia, host plants,
nurse plants)
Other factors to consider
• Abiotic ecological
considerations
Soils
Disturbance regime
Hydrology
• Political considerations
Land ownership
Land management
Outplanting
• Consider benefits of hard
vs. soft release
• Develop an experimental
design
• Monitor, Monitor, Monitor!
• Share results and
celebrate successes!