The extended phenotype of Eucalyptus globulus B Potts 1 , R Barbour 1 , J O’Reilly-Wapstra 1 , S Baker 2 , L Forster 1 , J Schweitzer 3 , J Bailey 3 , T Whitham 4 , J Humphreys 1 , J Freeman 1 and R Vaillancourt 1 1 School of Plant Science and CRC for Forestry, University of Tasmania, Australia 2 School of Zoology and CRC for Forestry, University of Tasmania, Australia 3 Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, USA 4 Department of Biological Sciences & the Merriam-Powell Center for Environmental Research, Northern Arizona University, USA
The extended phenotype “The effects of genes at levels higher than the population” (Dawkins 1982; Whitham et al. 2003) Foundation species Dominant or keystone species that have a disproportionate influence on the ecosystem in which they occur from Whitham et al. 2006
Trees as foundation species Populus in USA • Conservation and management of biodiversity • Restoration ecology • Predict the broader impacts of anthropogenic changes (e.g. GMOs) • Community structure & evolution Whitham et al 2003, 2006
The case of Eucalyptus globulus • Dominant of lowland forest in SE Australia and Tasmania • A major plantation species in temperate regions of world • Extensive genetic resources available • Extensive quantitative and molecular studies of gene pool
Significant spatially structured genetic variation in numerous traits Localities from the1987/88 CSIRO range-wide collection of 600+ OP seedlots and racial classification Partition of variation within Gunns Ltd trials (46 traits, 13 races, 46 localities, 450+ families) genetic + environmental genetic 21% residual 5 trials race locality 74% between between within 9% plots plots 3% family two-tree 9% 8% 8% plots 68% block 5% Potts et al. 2004 Dutkowski & Potts 1999
Dependent herbivores respond to genetic variation in tree traits Autumn gum moth Brush tail possum Sawfly ( Perga affinis ) (Mnesampela privata) Oviposition is affected by Foliage intake is affected by Foliage damage greater genetic variation in genetic variation in formylated on thick barked trees the aliphatic ester (C 24 ) phloroglucinol compounds (r g = 0.44 ***) benzyl n-tetracosanoate (FPCs) [sideroxylonal A and macrocarpal G ] Dutkowski & Potts 1999 Jones et al. 2002 Jordan et al. 2002 O’Reilly-Wapstra et al . 2002, 2004, 2005a,b Rapley et al. 2004a,b,c Kelly 1997
Significant racial differences in defensive chemistry Adult foliage condensed tannins O’Reilly-Wapstra et al. submitted
How far does the effect of genetic variation at the race level flow through the ecosystem?
The experiment Gunns Ltd E. globulus base population field trial at West Ridgley, NW Tasmania (CSIRO 1988/89 OP seedlots) 1. 160 felled trees • age 15 years • 8 races across 2 replicates • 20 trees per race (10 families per race, 2 trees/ family) 2. 100 standing trees • age 16 years • 5 races across 2 replicates • 20 trees per race (10 families per race, 2 trees/ family)
Defining the extended phenotype Genetic Tree canopy communities (fungi, variation CHO CHO invertebrates, HO HO OH OH marsupials, [birds],) OHC OHC OH OH O O Canopy & leaf Log & disc decay decay rates & rates & communities communities Seedling recruitment (invertebrates, fungi) Bark communities (invertebrates) Chemical and Soil nutrients & nutrient leaching into micro-biota soil
Race of decaying canopy can affect soil quality Linseed bioassay of soil extracts taken from beneath decaying canopies after 7 months 60 % germination radical length 15 Radicle length (mm) length (mm) 50 % germination 10 % 40 5 30 0 20 Strz EO WO KI WT FI SET ST Strz EO WO KI WT FI SET ST
Race of decaying canopy affects litter invertebrate community Species richness Abundance Non-collembolan Pitfall traps beneath decaying Total invertebrates invertebrates canopies of trees from Southern 50 160 n individuals n species Tasmania and Strzelecki Ranges 35 110 60 20 S Tas Strzelecki S Tas Strzelecki Community NMDS ordination ▲ Strzelecki Ranges ○ Southern Tasmania Significant (P<0.05) variation in community traits was found
Tree race affects soil nutrient availability NO 3 levels in soil at base of standing trees 2.5 – 3 (ug/g OD resin/d) a a 2.0 ab ab 1.5 ab ab ab 1.0 b b NO 0.5 0.0 NE S W Flinders Is. Jeeralong NE Tas Southern Tas Westerrn Tas Flinders Strzelecki Tas Tas Tas Island Provenance Resin bags at Race base of tree
Tree race affects bark community Height of loose bark All loose bark & … Bark retention 6 c associated invertebrates Height (m) c c bc 4 removed from the trunk ab c a a of 100 trees 2 0 Flinders Northeast Southern Western Island Tasmania Tasmania Tasmania Arthropod abundance Species abundance 60 b n individuals b b 40 b a 20 0 30-50% of individuals are STRZ FI NE S W spiders and other TAS TAS TAS predators Race
Conclusion There is increasing evidence for extended community and ecosystem effects of genetic variation at the racial level in E. globulus , but their stability and extent are as yet unclear . Community and ecosystem genetics is an emerging field in ecology. Forest trees are key study organisms and studies will increasingly focus on lower levels of genetic variation with community heritability H 2c / h 2c estimates and QTL c studies appearing.
Thank you We thank the Gunns Ltd and Forestry Tasmania for inkind support and access to field trials Funding is provided by Australian ARC Discovery and USA National Science Foundation FIBR grants Photo: S Foster
References Dutkowski GW, Potts BM (1999) Geographic patterns of genetic variation in Eucalyptus globulus ssp. globulus and a revised racial classification. Australian Journal of Botany 47 , 237-263. Jones TH, Potts BM, Vaillancourt RE, Davies NW (2002) Genetic resistance of Eucalyptus globulus to autumn gum moth defoliation and the role of cuticular waxes. Canadian Journal of Forest Research 32 , 1961-1969. Jordan GJ, Potts BM, Clarke AR (2002) Susceptibility of Eucalyptus globulus ssp globulus to sawfly ( Perga affinis ssp insularis ) attack and its potential impact on plantation productivity. Forest Ecology and Management 160 , 189-199. Kelly CM (1997) Natural variation and genetic control of relative bark thickness in Eucalyptus globulus ssp. globulus . BSHonours thesis, University of Tasmania. O'Reilly-Wapstra JM, McArthur C, Potts BM (2002) Genetic variation in resistance of Eucalyptus globulus to marsupial browsers. Oecologia 130 , 289-296. O'Reilly-Wapstra JM, McArthur C, Potts BM (2004) Linking plant genotype, plant defensive chemistry and mammal browsing in a Eucalyptus species. Functional Ecology 18 , 677-684. O'Reilly-Wapstra JM, Potts BM, McArthur C, Davies NW, Tilyard P (2005) Inheritance of resistance to mammalian herbivores and of plant defensive chemistry in an Eucalyptus species. Journal of Chemical Ecology 31 , 357-375. O'Reilly-Wapstra JM, Potts BM, McArthur C, Davies NW (2005) Effects of nutrient variability on the genetic-based resistance of Eucalyptus globulus to a mammalian herbivore and on plant defensive chemistry. Oecologia 142 , 597-605. Potts, B.M., Vaillancourt, R.E., Jordan, G., Dutkowski, G., Costa e Silva, J. McKinnon, G., Steane, D., Volker, P., Lopez, G., Apiolaza, L., Li, Y. Marques, C. and Borralho, N. (2004). Exploration of the Eucalyptus globulus gene pool. Plenary paper In ‘ Eucalyptus in a changing world’ (Eds. N.M.G. Borralho, J.S. Periera, C. Marques, J. Coutinho, M. Madeira and M. Tomé) pp. 46-61. Proc. IUFRO Conf., Aveiro, 11-15 Oct. 2004 (RAIZ, Instituto Investigação de Floresta e Papel, Portugal). Rapley, L, Allen, GR & Potts, BM (2004). Oviposition by autumn gum moth ( Mnesampela privata ) in relation to Eucalyptus globulus defoliation, larval performance and natural enemies. Agricultural and Forest Entomology 6, 205-213 Rapley LP, Allen GR, Potts BM (2004) Genetic variation of Eucalyptus globulus in relation to autumn gum moth Mnesampela privata (Lepidoptera: Geometridae) oviposition preference. Forest Ecology and Management 194 , 169-175. Rapley LP, Allen GR, Potts BM (2004) Susceptibility of Eucalyptus globulus to Mnesampela privata defoliation in relation to a specific foliar wax compound. Chemoecology 14 , 157-163. Whitham TG, Bailey JK, Schweitzer JA, Shuster SM, Bangert RK, LeRoy CJ, Lonsdorf E, Allan GJ, DiFazio SP, Potts BM, Fischer DG, Gehring, CA, Lindroth RL, Marks J, Har SC, Wooley SC and Wimp, GM. (2006) Community and ecosystem genetics: a framework for integrating from genes to ecosystems. Nature Reviews Genetics 7, 510-523. Whitham TG, Young WP, Martinsen GD, Gehring CA, Schweitzer JA, Shuster SM, Wimp GM, Fischer DG, Bailey JK, Lindroth RL, Woolbright S, Kuske CR (2003) Community and ecosystem genetics: A consequence of the extended phenotype. Ecology 84 , 559-573.
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