|
|
Society for Conservation Biology 16th Annual Meeting July 14-July 19 2002
co-hosted by DICE and the British Ecological Society
Abstracts for Conservation and Genetics
Session Four
Thursday 18th
July, 10.15 - 12.15, Rutherford Lecture Theatre 1
Chair: Lisette Waits
|
Conference Home Page | Session
timetable
(BLOCK CAPITALS indicate the presenting author)
10.15 - 10.30
FRÉVILLE, HÉLÈNE, Agnès Mignot, Miquel Riba, Bruno
Colas, Eric Imbert and Isabelle Olivieri. Université de Montpellier 2, CC065,
ISEM, Place E Bataillon, 34095 Montpellier Cedex 05, France, <H.Freville@open.ac.uk>(HF,
AM, EI, IO), Centre de Recerca Ecològica i Aplicacions Forestals, Universitat
Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain (MR), Laboratoire
Fonctionnement et Evolution des Systèmes Ecologiques, UMR 7625, CC 237, Université
de Paris VI, 7 quai Saint-Bernard, 75252 Paris cedex 05, France (BC).
MATING SYSTEM AND RARITY: A CASE STUDY IN CENTAUREA CORYMBOSA (ASTERACEAE)
The evolution of self-incompatibility (SI) in plants has been intensively studied.
In small populations, one expects a breakdown of the SI system if inbreeding depression
is small enough. Centaurea corymbosa Pourret (Asteraceae) is endemic to the
Massif de la Clape in southern France. The species is known from only six small populations
growing in a three km2 area. Previous work has suggested that its rarity would be
the consequence of its low colonisation ability, due to limited seed dispersal and
self-incompatibility. Here, we addressed two questions: 1) is there any evidence
of dissolution of the SI system in C. corymbosa, 2) how does inbreeding depression
affect its reproductive success? We analysed the success of selfing and outcrossing
by hand-pollinations and investigated the effect of intermate distances. The species
is shown highly self-incompatible. There is no evidence of evolution toward self-compatibility
in either population. No inbreeding depression at early stages was detected when
comparing selfing and outcrossing treatments. In contrast, fertilisation rate increased
with pollen donor distance, indicating a spatial structure of incompatibility alleles
and/or deleterious alleles. Not surprisingly given the small geographic scale, no
outbreeding depression was detected. These results allow us to give new guidelines
for in situ management.
10.30 - 10.45
Shi, Xiujie, HELEN J. MICHAELS and Randall J. Mitchell. Department of Biological
Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA, <hmichae@bgnet.bgsu.edu>
(XJS, HJM), Department of Biology, University of Akron, Akron, Ohio 44325, USA (RJM).
EFFECTS OF INBREEDING DEPRESSION, GENETIC VARIATION, AND POPULATION SIZE ON REPRODUCTION
IN PERENNIAL LUPINE.
In the threatened herbaceous perennial Lupinus perennis (Fabaceae), small
populations have lower seed and fruit production. We investigated the contributions
of inbreeding depression, population size, and genetic variation to reduced reproductive
success in 8 populations of this long-lived species, a host plant for threatened
or US Federally Endangered butterflies. The effects of inbreeding depression on germination,
survival, and biomass in a common greenhouse environment were estimated by comparing
the performance of crossed, selfed and open-pollinated progeny from a field pollination
experiment. Progeny from selfing had reduced germination, survival, and biomass.
Population size effects were evident only in the earliest life stage of germination.
We screened 10 populations for variation at 7 microsatellite loci. Preliminary analysis
of microsatellite variation indicates that although small and large populations were
similar in heterozygosity, small populations had lower allelic diversity. We conclude
that inbreeding depression resulting from increased levels of self-pollination and
genetic erosion are likely to have contributed to reduced reproduction of small populations.
10.45 - 11.00
Lipow, Sara R., KEN VANCE-BORLAND, and J. Bradley St. Clair. Department of Forest
Science, 321 Richardson Hall, Oregon State University, Corvallis, OR 97331, USA,
<ken.vance-borland@orst.edu> (KV-B, SRL), USDA Forest Service, PNW Research
Station, Forestry Sciences Laboratory, Corvallis, OR 97331, USA (JBS).
GENE CONSERVATION OF PACIFIC NORTHWEST CONIFERS: A GAP ANALYSIS APPROACH
Genetic diversity is a major determinant of the ability of forest tree populations
to maintain adaptability and respond to changing ecological conditions and, as such,
is recognised as an indicator of sustainability. We used gap analysis to evaluate
whether the genetic resources conserved in situ in protected areas are adequate
for eight species of conifers in the Pacific Northwest. The analysis involved intersecting
in a GIS data layers showing: 1) the location of various types of protected areas,
2) the distribution and abundance of each tree species, and 3) a system of ecoregions
or seed zones used to stratify species’ distributions into genetically meaningful
units for analysis. The results show that for most species in most seed zones and
ecoregions, at least 5000 reproducing individuals occur in protected areas, indicating
that the strata are well protected in situ. Species and areas with fewer protected
trees include noble fir in the Willapa Hills of southwest Washington and western
white pine throughout the Puget lowlands. Additional conservation measures may be
warranted for these populations.
11.00 - 11.15
TERO, NIINA, Jouni Aspi, Pirkko Siikamäki, Anne Jäkäläniemi
and Juha Tuomi. Department of Biology, P.O. Box 3000, 90014 University of Oulu, Finland,
<niina,tero@oulu.fi>.
GENETIC STRUCTURE AND GENE FLOW IN A METAPOPULATION OF A ENDANGERED PLANT SPECIES,
SILENE TATARICA
Silene tatarica is an endangered, perennial plant species growing along periodically
disturbed riverbanks of two rivers in Finland. In order to study the population structure
and gene flow of the species, we sampled thirty plants from seven sites along the
River Oulankajoki, and used AFLP-markers to characterise the genetic diversity within
and amongst sample sites. The results of Pritchard et al.’s (2000) software "structure"
suggested that each sample site formed a distinct subpopulation. FST estimates averaged
over all polymorphic loci indicated that significant genomic differentiation occurs
among subpopulations. AMOVA-analysis suggested no regional structure among subpopulations.
Genetic variation was greater within (63.1%) than amongst (36.9%) subpopulations.
There was no significant association between pairwise genetic (FST) and geographic
distances separating pairs of subpopulations, suggesting no regional equilibrium
between genetic drift and gene flow (predicted by the stepping stone model of population
structure). Direct estimate of gene flow based on assignment tests indicated a low
level of migration between subpopulations. There were significant differences in
genetic diversity between subpopulations. Allele frequency distributions suggested
recent population bottlenecks in most subpopulations. The genetic analysis supported
the metapopulation structure of the species.
11.15 - 11.30
KRAUSS, SIEGY, Bob Dixon and Kingsley Dixon. Botanic Gardens and Parks Authority,
Kings Park and Botanic Garden, West Perth, Western Australia 6005, Australia, <skrauss@kpbg.wa.gov.au>.
RAPID GENETIC DECLINE IN A TRANSLOCATED POPULATION OF THE THREATENED PLANT GREVILLEA
SCAPIGERA
Translocation is an important tool for conserving rare species existing in vulnerable
populations. The Corrigin Grevillea, Grevillea scapigera, is one of the world's
rarest plants, occurring in vulnerable roadside remnants in the Western Australian
wheatbelt. In 1995, 10 plants were selected as genetically representative founders,
propagated vegetatively and translocated into secure sites. By 1998, 266 plants were
producing copious seed, which were artificially germinated ex situ and 161
returned as seedlings in 1999. We used AFLP to (i) assess genetic fidelity of clones
through propagation; (ii) contrast genetic variation and distance of founders to
the F1's to assess genetic decline, and (iii) assign paternity to the F1's. We found
that (i) eight clones, not ten, were present in the translocated population, and
that 54% of all plants were a single clone; (ii) the F1's were 22% more inbred and
20% less heterozygous than their parents, largely because (iii) 85% of F1's were
the product of only four clones. We assess the fitness consequences of this genetic
decline, as well as genetic decline in the F2's. Our results highlight the difficulty
of maintaining genetic fidelity and variation through a species recovery, but identify
strategies to prevent genetic decline in plant translocations.
11.30 - 11.45
DeWOODY, JENNIFER A., John D. Nason, and Marian Smith. Department of Botany,
Iowa State University, Ames, IA 50011, USA, <jdewoody@iastate.edu> (JAD, JDN),
Department of Biological Sciences, Southern Illinois University at Edwardsville,
Edwardsville, IL, USA (MS) .
GENETIC ANALYSIS OF A METAPOPULATION OF BOLTONIA DECURRENS, A THREATENED FLOODPLAIN
HERB
The historical flooding cycles of the Illinois River have been altered by human activity
over the past century. One species negatively affected by these changes, Boltonia
decurrens, requires regular flooding for the production of suitable habitat and
the dispersal of seeds. Populations as ephemeral as B. decurrens are out-competed
for light within 3-5 years. Previous research has focused on factors contributing
to local extinction events and species decline, but a better understanding of the
processes influencing the founding of new populations would aid in the conservation
of this and co-occurring water-dispersed species. We investigated the process of
population establishment in B. decurrens using neutral genetic markers (isozymes).
Results reveal high levels of genetic variation within and indicate significant structuring
among populations, with no evidence of isolation by distance. Population assignment
tests indicate that a limited number of populations contribute founders to colonisation
events. Genetic bottlenecks occur during or subsequent to population founding. These
results found no exceptionally variable populations, nor evidence of ecotypic variation.
We recommend that restoration efforts use seed from a limited number of not necessarily
local populations, and that future conservation efforts maintain potential habitat
across the range of the species.
11.45 - 12.00
WHELAN, ROB, David Ayre and David Roberts. Institute for Conservation Biology,
Department of Biological Sciences, University of Wollongong, NSW 2522, Australia,
<rob_whelan@uow.edu.au>.
ECOLOGY AND GENETICS OF A RARE AUSTRALIAN GREVILLEA IN AN URBANISED ENVIRONMENT
Urban expansion threatens plant populations by habitat removal and increased fragmentation.
We asked how plants that occur in urban gardens might contribute to overall genetic
diversity and how they interact with surrounding natural populations. Using microsatellite
markers with a rare shrub, Grevillea macleayana, in gardens in Hyam's Beach
Village and two adjacent National Park populations at Jervis Bay (southeastern Australia),
we found that garden plants contributed substantially to overall genetic diversity.
They contained more alleles per locus and more unique alleles than the National Park
populations. Most of the unique alleles occurred in nine garden plants with atypical
morphology, inferred to be horticultural stock. Allele frequencies differed among
the three populations and all showed significant deficits of heterozygotes. Fixation
indices were higher for seeds (current year's reproduction) than for adults. There
was significant genetic structuring in adult plants across the populations. Assigning
seeds to their most likely father indicated some pollen dispersal from garden to
National Park, despite the fact that the foraging movements of pollinators were mostly
within plants. We conclude that garden plants can contribute to conservation of genetic
diversity but genes in horticultural varieties could be contaminating the gene pool
in adjacent natural vegetation.
12.00 - 12.15
MILLER, CRAIG R., Paul Joyce, and Lisette P. Waits. College of Natural Resources,
Deptartment of Fish and Wildlife, University of Idaho, Moscow ID, 83844, USA, <mill8560@uidaho.edu>
(CRM, LPW), Deptartment of Mathematics, Division of Statistics, University of Idaho,
Moscow, ID 83844, USA (PJ).
BAYESED AND CONFUSED: COMPARING ALLELIC DIVERSITY IN THE FACE OF UNEQUAL SAMPLE SIZES,
SAMPLING ERROR AND OTHER HEADACHES
Allelic diversity (A, the number of alleles/locus) is routinely used to quantify
and compare levels of genetic diversity between populations or within a population
over time.
Unfortunately, these comparisons are confounded and confused by a number of issues:
1) observed A is very sensitive to sample size and sample sizes are commonly
uneven; 2) the A observed in a sample of a given size is a random variable
that will differ across sampling events; 3) there is a tendency to confuse the relative
numbers of alleles in two samples with the relative numbers of alleles in two populations.
We argue that it is impossible to estimate relative allelic diversity in two populations
without including information about the population sizes. This is because the population’s
As depend on the numbers of unobserved alleles, which depend on the numbers
of unsampled individuals. Current methods for addressing these quandaries include
bootstrap subsampling and rarefaction curve fitting. We propose a Bayesian method
for estimating the relative allelic diversity in two populations that incorporates
uneven sample sizes, sampling variance and uncertainty in population sizes. Using
simulated and empirical data, we evaluate the accuracy and power of our approach
and compare it with those currently available.
The SCB2002 pages are maintained by Christine Eagle
email: C.M.Eagle@ukc.ac.uk
Conference email: scb2002@ukc.ac.uk
Last updated: 30.06.02