Transcript A FRAMEWORK FOR COMMUNITY AND ECOSYSTEM GENETICS

A FRAMEWORK FOR COMMUNITY AND ECOSYSTEM GENETICS:
4.
Conservation
Implications
FROM
GENES
TO
ECOSYSTEMS
1. The Concept of Community& Ecosystem
Phenotypes
Just as the genotype may have a
‘traditional’ phenotype that is expressed
within the individual and its population,
gene expression that leads to interactions
with other species extends to levels above
the population to produce community and
ecosystem phenotypes (all illustrations
from Nature Reviews Genetics 2006, in
press).
2. Demonstrating Community & Ecosystem
Phenotypes
Using experimental crosses of Populus angustifolia x P. fremontii, we
found that a single QTL (Quantitative Trait Locus) is significantly
correlated with the phenotypic variation in condensed tannins among
cross types (Fig. a). These compounds have been extensively studied
and are well known for their generally inhibitory effects on diverse
organisms from microbes to vertebrates. The variation in condensed
tannins is associated with different community phenotypes of terrestrial
arthropods living in tree canopies (Fig. b), endophytic fungi inhabiting tree
bark (Fig. c), and aquatic macroinvertebrates feeding on the leaves that
fall into an adjacent stream (Fig. d). Similarly, we found significant
ecosystem phenotypes; the effects of condensed tannins explained 65%
of the variation in net nitrogen mineralization in the soil (Fig. e) and 97% of
the variation in decomposition of leaves in the stream (Fig. f).
PI - Tom Whitham ([email protected]), Northern Arizona Univ. (Lead
Institution); NAU Co-PIs - Steve Shuster, Catherine Gehring, Gery Allan, Jane
Marks, Steve Hart, & Randy Bangert; Rick Lindroth & Stuart Wooley, Univ.
Wisconsin; Stephen DiFazio, West Virginia Univ.; Brad Potts, Univ. Tasmania,
Australia; Carri LeRoy & Dylan Fischer, Evergreen State College, Jen Schweitzer
& Joe Bailey, Univ. of Tennessee; Eric Lonsdorf, Lincoln Park Zoo, Chicago.
Abstract. Heritable traits in a single species can affect an entire
ecosystem. Recent studies show that such traits in a common
tree have predictable effects on community structure and
ecosystem processes. Because these ’community and ecosystem
phenotypes’ have a genetic basis and are heritable, we can begin
to apply the principles of population and quantitative genetics to
place the study of complex communities and ecosystems within
an evolutionary framework. This framework may allow us to
understand the genetic basis of ecosystem processes, and the
impacts such phenomena as climate change and introduced
transgenics may have on entire communities.
Because individual plant genotypes support different community and
ecosystem phenotypes and these phenotypes are heritable, the genetic
diversity in a foundation species affects the diversity of the dependent
community in two ways. First, genetically similar plants support similar
communities. The left panel shows that the genetic differences among
individual trees based on molecular markers are strongly associated with
differences in the arthropod communities they support both within a
common garden and among trees in the wild. Second, based on genetic
similarity, increased genetic diversity within the plant population is
positively correlated with increased species diversity of the dependent
community. The right panel B shows that genetic variation in individual
poplar stands accounts for nearly 60% of the variation in an arthropod
community of 207 species.
3. Heritability of Community Phenotypes - Genetic Variation
Within Tree Species Structures Arthropod Communities
When species comprising ecological communities are summarized using a multivariate
statistical method (non-metric multidimensional scaling; NMDS), the resulting univariate
scores can be analyzed using standard techniques for estimating the heritability of
quantitative traits. Our estimates of the broad-sense community heritability (H2C) of
arthropod communities on known genotypes of cottonwood trees in common gardens have
explained 56-63% of the total variation in community phenotype. Furthermore, genetic
variation within, rather than between, individual tree species structures the dependent
arthropod community in the cottonwood system. Line cross and joint scaling analyses of
communities on Populus angustifolia, P. fremontii, their F1s and their backcross hybrids
could not reject the simplest additive model (χ2 = 1.68, df = 2, p = 0.43) indicating nonsignificant additive and dominant effects among parental and hybrid lines. Yet broad-sense
heritability estimates for communities within each parental type (P. fremontii H2C = 0.65; P.
angustifolia H2C = 0.60), and on backcross hybrids (H2C = 0.80) were all significant; only H2C
on F1 hybrids was not. Larger, filled circles represent adjusted means of the arthropod
community for each cross type ±S.E. from a nested ANOVA. Replicated clones of the same
genotype are indicated by the same symbol within each of the four cross types. Different
symbols within each of the four cross types indicate different genotypes; similar symbols in
different cross types do not represent similar genotypes.
5. Training & Outreach
• Our faculty are involved with the new IGERT program at NAU to train
graduate students in “Integrative Bioscience: Genes to Environment”.
Photo credit: Gery Allan
Photo credit: zsuzsi Kovacs
• EnGGEN: The Environmental Genetics & Genomics facility was
independently established in 2003 with NSF funding and is being used to
train graduate and undergraduate students conducting FIBR research.
Photo credits: Tom Whitham & Carri LeRoy
Photo credit: Carri LeRoy
25 Selected Publications Since 2004
Whitham, T.G, J.K. Bailey, J.A. Schweitzer, S.M. Shuster, R.K. Bangert, C.J. LeRoy, E. Lonsdorf, G.J. Allan, S.P. DiFazio, B.M. Potts, D.G.
Fischer, C.A. Gehring, R.L. Lindroth, J. Marks, S.C. Hart, G.M. Wimp, and S.C. Wooley. 2006. A framework for community and ecosystem
genetics: From genes to ecosystems. NATURE REVIEWS GENETICS (in press).
Chapman, S.C., J.A. Schweitzer and T.G. Whitham. Herbivory differentially alters plant litter dynamics of evergreen and deciduous trees.
OIKOS (in press).
Rehill, B., T.G. Whitham, G.D. Martinsen, J.A. Schweitzer, J.K. Bailey, and R.L. Lindroth. Developmental trajectories in cottonwood
phytochemistry. JOURNAL OF CHEMICAL ECOLOGY (in press).
Fischer, D.G., S.C. Hart, B.J. Rehill, R.L. Lindroth, P. Keim, and T.G. Whitham. Do high tannin leaves require more roots? OECOLOGIA (in
press).
Gehring, C.A., R.C. Mueller, and T.G. Whitham. 2006. Environmental and genetic effects on the formation of ectomycorrhizal and arbuscular
mycorrhizal associations in cottonwoods. OECOLOGIA (in press).
Gitlin, A., C.M. Stultz, M.A. Bowker, S. Stumpf, K. Ecton, K. Kennedy, A. Munoz, J.K. Bailey, and T.G. Whitham. 2006. Mortality gradients
within and among dominant plant populations as barometers of ecosystem change during extreme drought. CONSERVATION BIOLOGY
(in press).
Bailey, J.K., S.C. Wooley, R.L. Lindroth, and T.G. Whitham. 2006. Importance of species interactions to community heritability: A genetic
basis to trophic-level interactions. ECOLOGY LETTERS 9:78-85.
Shuster, S.M., E.V. Lonsdorf, G.M. Wimp, J.K. Bailey, and, T.G. Whitham. 2006. Community heritability measures the evolutionary
consequences of indirect genetic effects on community structure. EVOLUTION 60(5):991-1003.
Bailey, J.K., and T.G. Whitham. 2006. Interactions between cottonwood and beavers positively affect sawfly abundance. ECOLOGICAL
ENTOMOLOGY (in press).
Bangert, R.K., R.J. Turek, B. Rehill, G.J. Allan, G.M. Wimp, J.A. Schweitzer, J.K. Bailey, G.D. Martinsen, P. Keim, R.L. Lindroth, and T.G.
Whitham. 2006. A genetic similarity rule determines arthropod community structure. MOLECULAR ECOLOGY 15:1379-1392.
LeRoy, C.J., T.G. Whitham, P. Keim, and J.C. Marks. 2006. Plant genes link forests and streams. ECOLOGY 87:255-261.
Loeser, M.R., B.H. McRae, M.M. Howe, and T.G. Whitham. 2006. Litter hovels as havens for riparian spiders in an unregulated river.
WETLANDS 26:13-19.
Schweitzer, J.A., J.K. Bailey, S.C. Hart, and T.G. Whitham. 2005. Nonadditive effects of mixing cottonwood genotype on litter decomposition
and nutrient dynamics. ECOLOGY 86:2834-2840.
Bailey, J.K., R. Deckert, J.A. Schweitzer, B.J. Rehill, R.L. Lindroth, C.A. Gehring, and T.G. Whitham. 2005. Host plant genetics affect hidden
ecological players: Links among Populus, condensed tannins and fungal endophyte infection. CANADIAN JOURNAL OF BOTANY 83:356361.
Whitham, T.G., E. Lonsdorf, J.A. Schweitzer, J.K. Bailey, D.G. Fischer, S.M. Shuster, R.L. Lindroth, S.C. Hart, G.J. Allan, C.A. Gehring, P. Keim,
B.M. Potts, J. Marks, B.J. Rehill, S.P. DiFazio, C.J. LeRoy, G.M. Wimp, and S. Woolbright. 2005. “All effects of a gene on the world”:
Extended phenotypes, feedbacks and multi-level selection. ECOSCIENCE 12:5-7.
Schweitzer, J.A., J.K. Bailey, S.C. Hart, G.M. Wimp, S.K. Chapman, and T.G. Whitham. 2005. The interaction of plant genotype and herbivory
decelerate leaf litter decomposition and alter nutrient dynamics. OIKOS 110:133-145.
Rehill, B., A. Clauss, L. Wieczorek, T.G. Whitham, and R.L. Lindroth. 2005. Foliar phenolic glycosides from Populus fremontii, Populus
angustifolia, and their hybrids. BIOCHEMICAL SYSTEMATICS AND ECOLOGY 33:125–131.
Wimp, G.M., G.D. Martinsen, K.D. Floate, R.K. Bangert, and T.G. Whitham. 2005. Plant genetic determinants of arthropod community
structure and diversity. EVOLUTION 59:61-69.
*Cox, G., D. Fischer, S.C. Hart, and T.G. Whitham. 2005. Nonresponse of native cottonwood trees to water additions during summer
drought. WESTERN NORTH AMERICAN NATURALIST 65:175-185.
Bangert, R.K., R.J. Turek, G.D. Martinsen, G.M. Wimp, J.K. Bailey, and T.G. Whitham. 2005. Benefits of conservation of plant genetic
diversity on arthropod diversity. CONSERVATION BIOLOGY 19:379-390.
Wimp, G.M., W.P. Young, S.A. Woolbright, G.D. Martinsen, P. Keim, and T.G. Whitham. 2004. Conserving plant genetic diversity for
dependent animal communities. ECOLOGY LETTERS 7:776-780.
Bailey, J.K., R.K. Bangert, J.A. Schweitzer, R.T. Trotter III, S.M. Shuster, and T.G. Whitham. 2004. Fractal geometry is heritable in trees.
EVOLUTION 58:2100-2102.
Fischer, D.G., S.C. Hart, and T.G. Whitham, G.D. Martinsen, and P. Keim. 2004. Ecosystem implications of genetic variation in water-use of a
dominant riparian tree. OECOLOGIA 139:288–297.
Bailey, J.K., J.A. Schweitzer, B.J. Rehill, R.L. Lindroth, G.D. Martinsen, and T.G. Whitham. 2004. Beavers as molecular geneticists: A genetic
basis to the foraging of an ecosystem engineer. ECOLOGY 85:603-608.
Schweitzer, J.A., J.K. Bailey, B.J. Rehill, G.D. Martinsen, S.C. Hart, R.L. Lindroth, P. Keim, and T.G. Whitham. 2004. Genetically based trait in
a dominant tree affects ecosystem processes. ECOLOGY LETTERS 7:127-134.
*indicates undergraduate as the lead author
Photo credit: Carri LeRoy
• A 40-acre common garden planted in
collaboration with the Bureau of Reclamation,
USFW & at Cibola National Wildlife Refuge in
2005 involved 17 graduate students and 5
undergraduates.
• FIBR PhD students include Native
American and Hispanic minorities.
• FIBR is now linked to an REU Site at NAU
in Behavioral and Conservation Sciences.
• We are involved in outreach to all ages
at the Ogden Nature Center (UT), Swaner
Nature Preserve (UT), the Arboretum at
Flagstaff (AZ) & the Flagstaff Festival of
Science.
• We have restored over 75 acres of critical
riparian habitat jointly with the BOR, Utah DNR,
USFW, Ogden Nature Center, Swaner Nature
Reserve and the Arboretum at Flagstaff.
Photo credits: Dylan Fischer
• Undergraduates at Evergreen State College
trained in a 2-week Field Ecology program at
common garden sites in Arizona & Utah.