Urban Plants as Genetic Reservoirs or Threats to the Integrity of Bushland Plant Populations

1. Urban Plants as Genetic Reservoirs or Threats to the Integrity of Bushland Plant Populations Presented by Shannon Slivinske

2. Urban plants- contributing to plant conservation, or further threatening the gene pool? Habitat fragmentation- increase in isolation and decrease in (population) size of natural resource patches, inevitably isolated remnants of natural forests. Species with patchy distribution and rare classification, more susceptible, esp. to "edge effects"

3. Grevillea macleayana McGillivray • New South Whales South coast • Lifespan: decades undisturbed, senescence after 20-30 yrs. • No obvious seed dispersal mechanism • Germination after disturbance • Flowers year round • Inflorescences of 50 hermaphroditic, self-compatible flowers

4. Four bushland stands isolated by 1 km (except CB) • Six stands within Hyams Beach Village Jervis Bay National Park (CB, Chinamans Beach; GB, Greenfields Beach; ILL, Illowra Lane; HB, Hyams Beach) and stands within an adjacent urban setting (HBV, Hyams Beach Village).

5. Examined: • Reproductive effort and success • Pollinator visitation and behavior • Genetic diversity and population differentiation • Outcrossing and gene flow

6. 1.Reproductive effort (flowering intensity) and success (seeds set per plant) Methods • 15 plants from 3 stands • # inflorescences every 3 weeks Mar. ’01-Sept. ’01 • Crown volume (NS) • 1-12 inflorescences, seed initiation after 3 weeks and every 3 weeks until maturation

7. 2. Pollinator Visitation and Behavior • Grevillea provide important resources for native nectarivores and insectivores in suburban areas • Pollinators- honeybee and honey-eaters observed on same sites • Visitor rate of pollinators- # inflorescences and # visits/inflorescence per 15-min • % foraging movement that were inter vs. intraplant- # plants visited per pollinator and # inflorescences per plant

8. 3. Genetic Studies • Leaf material from all adult plants was collected and 4-15 seeds from 5-9 plants in each stand (3 from remnant and 3 from exotic in HBV) • DNA extraction using CTAB extraction protocol of Doyle and Doyle

9. 4. Statistical Analysis • ANOVA to analyze Pollinator data • Principal Coordinates Analysis- genetic distance matrix • POPGENE- standard population genetic parameters Weir and Cockerham's formulation of Wright's F statistics- partition genetic variation • MLTR- level of outcrossing in each stand • Biparental inbreeding level versus inbreeding • CERVUS- scale and pattern of gene flow from urban-bushland and assign paternity from seed sets

10. Results 1. Plant Reproductive Effort and Success • Inflorescence production: Peak July-Sept • Urban- 1180, Bush- 753 and 892 • Fruit initiation/inflorescence: Urban 1-12, Bush 1-6 • Seed maturation: Urban 1-2, 11.1%, Bush 1-3, 12.1%(CB) and 2.4%(GB)

11. 2. Pollinator Visitation and Behavior

12. Foraging movement: • Honeyeaters- 80% b/w inflorescences on same plant • Honeybees- 90% b/w inflorescences on same plant • Observed honeyeaters flying between gardens and bushland, including between exotic stand and bush

13. 3. Genetic Diversity and Population Differentiation • All stands varied for at least 9 of 10 studied loci • # alleles for GmE, Gm10 and Gm25 were 13-14, 2-8 for remainder • 89% all alleles present in Urban, only 39%-52% for Bush • 27/30 private alleles within Urban, 17 in 19 with unusual morphology

15. 4. Outcrossing and Gene Flow • Low-intermediate outcrossing in all stands • 157/358 seeds selfed • 95/358 outcrossed, 62% within same stand • 7-29 seeds outcrossed between stands • No exotic alleles in bushland or remnant

16. HBV plants: • Genetic diversity indicates disturbance resistance/resilience • Aesthetically pleasing as garden plants, less susceptible to drought/fire threat • Buffer loss of genetic diversity from bushland stands • Low-moderate outcrossing indicates regional functionality • Retained most alleles, contained most variation • While about 77% adults in HBV contained 10 private alleles,

17. 19 exotics/cvs with 17-27 private alleles (possibly deleterious) • Reduce fitness, outbreeding depression, possible extinction • Remnants may worsen as bridges • Protection from fire also reduces future generation germination potential Honeybees: • Introduced, potential gene-flow suppressant • Increase inbreeding and reduce gene flow Honey-eaters: • patchy nature of nectar resources encourages nomadism, less so in urban environments

18. Questions and Discussion

19. Works Cited • Eastern Spine-billed honey-eater photo by Brett Donald on Wikipedia • Goosem, S. and N.I.J. Tucker (1998) Theory. Chapter 1 in: Repairing the rainforest -- theory and practice of rainforest re-establishmnet in north Queensland's Wet Tropics. Wet Tropics Management Authority, Cairns. • Jean Clarke. 2002. Grevillea macleayana. Growing Native Plants, Australian National Botanic Gardens. • http://www.anbg.gov.au/gnp/interns-2002/grevillea-macleayana.html. October 13, 2008. • French, K., Major, R. and K. Hely. Use of Native and Exotic Garden Plants by Suburban Nectarivorous Birds. Biological Conservation 121 (4): 545-559, 2005. • Roberts, David G., Whelan, R. J., Ayre, D. J. and Phillip R. England. The Potential for Genetic Contamination vs. Augmentation by Native Plants in Urban Gardens. Biological Conservation 128 (4): 493-500, 2005. • Roberts, David G., Ayre, D. J. and Robert J. Whelan. Urban Plants as Genetic Resevoirs or Threats to the Integrity of Bushland Plant Populations. Conservation Biology 21 (2): 842-852, 2006.