Limited impact of fragmentation and disturbance on the mating system of tuart (Eucalyptus gomphocephala, Myrtaceae): implications for seed-source quality in ecological restoration

Abstract

Variation in patterns of mating within and among plant populations can be impacted by habitat disturbance and have significant implications for offspring fitness. An understanding of this variation will inform predictions of seed genetic quality, benefiting ecological restoration through better seed-sourcing guidelines. We assessed mating system variation in six populations of tuart (Eucalyptus gomphocephala DC.), an iconic tree of significance to ecological restoration in Western Australia. A mixed mating system was observed with predominant outcrossing (tm = 0.76 ± 0.05) and low biparental inbreeding (tm–ts = 0.03 ± 0.02). We detected some evidence of increased inbreeding in a naturally fragmented population (tm–ts = 0.10 ± 0.04) and in a disturbed urban remnant (tm = 0.52 ± 0.12), including a family with complete selfing. However, most variation in outcrossing rate occurred among individuals within populations (82%), rather than among populations (2.6%) or among groups of populations defined by fragmentation or disturbance (15.4%). Genetic diversity was not consistently lower in offspring from fragmented, smaller and/or disturbed populations. These data reinforce the importance of sourcing seeds from multiple trees for ecological restoration, and emphasise that tuart’s mating system and the genetic diversity of offspring is robust to some habitat disturbance and/or fragmentation.

Clonality, interspecific hybridisation and inbreeding in a rare mallee eucalypt, Eucalyptus absita (Myrtaceae), and implications for conservation

“…However, this rate is very low compared to widespread eucalypts (Millar et al 2000;Byrne 2008;Mimura et al 2009;Bradbury and Krauss 2013;Breed et al 2015a, b) but comparable with, or lower than, some other rare and restricted species (Butcher et al 2005;Sampson and Byrne 2015). Eucalypts often maintain high outcrossing rates in seed progeny despite small population size or even clonality, due to post-zygotic barriers against inbreeding and selection in the seed capsule acting against selfed seeds (James and Kennington 1993;Gauli et al 2013).…”

Biodiversity hotspots and Ocbil theory

“…caesia (Proteaceae) -linear remnants prone to inbreeding depression Llorens et al (2013) x Eucalyptus gomphocephala (Myrtaceae) Bradbury and Krauss (2013) x Ironstone inselberg shrub Acacia woodmaniorum ( Bond (2015) x x Mad Fire-stimulated flowering Lamont and Downes (2011) x Erica coccinea (Ericaceae) Segarra-Moragues and Ojeda (2010) x Protea neriifolia, P. repens, P. nitida (2012) glob Floras of fire-prone habitats, mainly Australian Bradstock et al (2012) 9. Other major topics in conservation biology raised by OCBIL Theory 9 (a) Providing space -small and isolated may be sufficient for persistence, edge-effects aside…”

“…x Amphisopus (Isopoda : Amphisopidae) Gouws and Stewart (2013) x T w o r a r e Eremophila (Scrophulariaceae: Myoporeae) Llorens et al (2013) x Eucalyptus gomphocephala (Myrtaceae) Bradbury and Krauss (2013) x Calothamnus quadrifidus (Myrtaceae) Nistelberger et al (2015) x Eucalyptus gomphocephala (Myrtaceae) Nevill et al (2014) x Species-specific phylogeography of five west coast sand-dune and sand-plain reptiles Edwards et al (2014) x Flora reviewed Byrne et al (2014) x Millar et al (2014) Plant Soil Tapper et al (2014a) x Granite inselberg perennial herb Stypandra glauca (Hemerocallidaceae) Tapper et al (2014b) x Terrestrial fauna and flora with dated phylogenies reviewed Rix et al (2014) x Eucalyptus wandoo (Myrtaceae) Dalmaris et al (2015) x Bird-pollinated, inselberg endemic Grevillea georgeana (Proteaceae) Nistelberger et al (2015a) x Banksia sphaeorcarpa var. caesia (Proteaceae) Nistelberger et al (2015b) x Drakaea elastica (Orchidaceae) pollination ecotypes Menz et al (2014) x Erica coccinea (Ericaceae) Segarra-Moragues and Ojeda (2010) x Fossorial skinks Scelotes (Squamata: Scincidae)…”

“…x Eucalyptus gomphocephala (Myrtaceae) Bradbury and Krauss (2013) x Ironstone inselberg shrub Acacia woodmaniorum ( x Nuytsia floribunda (Loranthaceae) Ashbolt et al (2012) x Thermal tolerances Caddisflies, mayflies, dragonflies Stewart et al (2013) x PPunCC (Plant Persistence under Climate Change) model-assisted migration called for Renton et al (2012) x Granite outcrop vegetation -climate refugia Schut et al (2014) x Eucalyptus gomphocephala (Myrtaceae) Nevill et al (2014) x Resistance and resilience to changing climate and fire regime -plant functiona traits kwongkan Enright et al (2014) x Eucalyptus wandoo (Myrtaceae) Dalmaris et al (2015) x Aust Invasion hotspots for weeds in Australia O'Donnel et al (2012) x A u s t Eucalyptus, Corymbia (Myrtaceae) Butt et al (2013) x Aust Arid Zone/ semiarid refugia freshwater wetland fish and invertebrates Davis et al (2013) Aust Letten et al (2013) Plant Soil Gouramanis et al (2012) x x Whole floras Cowling et al (2015) x Berkheya cuneata (Asteraceae) Pleistocene refugia Potts et al (2013) x Amphibians Schreiner et al (2013) x Whole flora of tepui highlands and Gran Sabana uplands Rull et al (2013) x Grassland flora x Vegetation cover biomes invaded by Phytophthora cinnamomi. Shearer et al (2012a) x Threatened flora susceptibility to Phytophthora cinnamomi.…”

“…x Eucalyptus gomphocephala (Myrtaceae) Bradbury and Krauss (2013) x x Whole floras Arianoutsou et al (2013) x Grassland flora Le Stradic et al (2014a, b) x Grassland flora …”