Natural Inter-subgeneric Hybridization Between Eucalyptus acmenoides Schauer and Eucalyptus cloeziana F. Muell (Myrtaceae) in Southeast Queensland

Stokoe, R L; Shepherd, Mervyn; Lee, David J; Nikles, D. G.; Henry, Robert J.

doi:10.1006/anbo.2001.1507

Cited by 25 publications

(16 citation statements)

References 23 publications

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“…However, the present study reports the discovery of a new hybrid entity within the Tasmanian biota. Eucalypt species are often highly differentiated in seedling morphology and the general intermediacy of their hybrids makes detection relatively easy (Pryor 1976;Potts andReid 1988, 1990;Tibbits 1988;Delaporte et al 2001;Stokoe et al 2001;Barbour et al 2002). Certainly, all the F 1 hybrid cross-types that were identified appeared to be generally intermediate on visual inspection, although the level of intermediacy varied between trait and hybrid combinations.…”

Section: Discussionmentioning

confidence: 99%

Gene flow between introduced and native Eucalyptus species: exotic hybrids are establishing in the wild

Barbour¹,

Potts²,

Vaillancourt³

2003

Aust. J. Bot.

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Abstract. F 1 hybrids between exotic Eucalyptus nitens plantations and native E. ovata have previously been reported among seedlings grown from open-pollinated seed collected from E. ovata, on the island of Tasmania. Such exotic hybrid seedlings have now been found in the wild adjacent to plantations at three locations. The proportion of exotic hybrids in open-pollinated seed collected from nearby mature E. ovata was 5.5%. This level compares with only 0.4% for natural hybrids between native species at these sites (E. ovata, E. viminalis and E. rodwayi). Detection of hybrids was initially based on their deviant morphology, which was generally intermediate between parental species. This subjective classification was then successfully verified by morphometric and allozyme analyses. Pure E. nitens seedlings (wildlings) were restricted to within 30 m of these plantations, whereas established hybrids were found up to 310 m from the plantations. This pattern of establishment reflects dispersal of exotic seed and pollen respectively. It is likely that the recent expansion of the eucalypt plantation estate in Australia will cause an increase in the frequency of exotic hybrids. However, the long-term impact of such hybridisation is yet to be assessed. B T 0 3 0 1 6 G e n e f l o w b e t w e e n i n t r o d u c e d a n d n a t i v e e u c a l y p t s R . C . B a r b o u r e t a l .

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Section: Discussionmentioning

confidence: 99%

Gene flow between introduced and native Eucalyptus species: exotic hybrids are establishing in the wild

Barbour¹,

Potts²,

Vaillancourt³

2003

Aust. J. Bot.

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“…Previous work on other hybrid systems have reported a wide range of morphological expression between parentals, from 0% to 88% of traits expressed as intermediate in F 1 hybrids, and cases of biased parental traits, and extreme characters not present in either pure-bred parent (Rieseberg and Ellstrand 1993). Other studies in Eucalyptus have found that hybrids tend to express intermediate morphology in the first generation (Pryor 1976;Hopper et al 1978;Tibbits et al 1991;Delaporte et al 2001;Stokoe et al 2001;Barbour et al 2002;Barbour et al 2003). However, there have also been exceptions with hybrid expression varying depending on the traits examined and the species involved (Potts and Wiltshire 1997;Delaporte et al 2001).…”

Section: Morphological Variationmentioning

confidence: 94%

“…The majority of these estimates are based on morphological intermediacy and, apart from some notable exceptions (Delaporte et al 2001;Stokoe et al 2001; Barbour et al 2003), surprisingly few studies have assessed hybrid combinations in detail using both morphological and molecular techniques. The lack of extensive molecular and genetic studies in Eucalyptus is of concern in the context of conservation biology because there is growing evidence that human activities increase levels of hybridization.…”

Section: Introductionmentioning

confidence: 99%

Molecular and morphological evidence of natural interspecific hybridization between the uncommon Eucalyptus aggregata and the widespread E. rubida and E. viminalis

et al. 2008

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Human activities can promote increased hybridization in the genus Eucalyptus with potentially detrimental consequences for the persistence of rare species. However, many hybrid combinations have not been investigated with combined use of genetic markers and morphology. We assessed the efficiency of the STRUC-TURE program and morphological intermediacy for identifying hybrids between the uncommon tree, Eucalyptus aggregata, which putatively hybridizes with the common congeners, E. rubida and E. viminalis in south-eastern Australia. We sampled 1,005 seedlings across 27 populations, all seedlings were genotyped at 6 allozyme loci and scored for 22 stem and leaf characters. Both marker sets confirmed that E. aggregata is hybridizing with both E. rubida and E. viminalis. Allozymes revealed hybrids from E. aggregata trees in 88% of populations and hybrids comprised 7.3% of all seedlings. Both genetics and morphology indicated that *50% were likely to be F 1 hybrids, and both simulations and morphological characteristics indicated that the remainder were mostly backcrosses. Morphological analysis correctly distinguished 71% of F 1 hybrids from parentals and was least accurate when dealing with potential backcrosses (50% success). Hence, techniques using genetic data (no prior information) and the assessment of appropriate admixture thresholds through simulations provided the most accurate estimates of hybrid frequency. In this study, potential introgression and the high frequency of hybrids in small populations (*30%), suggests that hybridization should be considered in the management and conservation of E. aggregata.

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“…As hybrids with E. viminalis are rare it is possible that mean levels of flowering synchrony of less that 0.2 (Whole-species assessment), as also observed for E. barberi, E. cordata, E. dalrympleana, E. morrisbyi and E. urnigera, would result in the production of very few hybrid offspring when growing adjacent to E. nitens plantations. However, these low levels of exotic F 1 hybridisation in E. viminalis may have been accentuated by cross-specific effects such as protandry (the release of pollen prior to stigmatic receptivity) (Potts and Wiltshire, 1997;Stokoe et al, 2001;Barbour et al, 2002), or post-pollination interactions such as pollen competition (Vanden Broeck et al, 2003b;Barbour et al, 2005b).…”

Section: Risk Assessment Of Exotic Gene Flow From E Nitens Based On mentioning

confidence: 97%

Gene flow between introduced and native Eucalyptus species: Flowering asynchrony as a barrier to F1 hybridisation between exotic E. nitens and native Tasmanian Symphyomyrtus species

Barbour

Potts

Vaillancourt

et al. 2006

Forest Ecology and Management

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Natural Inter-subgeneric Hybridization Between Eucalyptus acmenoides Schauer and Eucalyptus cloeziana F. Muell (Myrtaceae) in Southeast Queensland

Cited by 25 publications

References 23 publications

Gene flow between introduced and native Eucalyptus species: exotic hybrids are establishing in the wild

Gene flow between introduced and native Eucalyptus species: exotic hybrids are establishing in the wild

Molecular and morphological evidence of natural interspecific hybridization between the uncommon Eucalyptus aggregata and the widespread E. rubida and E. viminalis

Gene flow between introduced and native Eucalyptus species: Flowering asynchrony as a barrier to F1 hybridisation between exotic E. nitens and native Tasmanian Symphyomyrtus species

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