Article

Patterns of Distribution of Acacia in Australia

CSIRO Publishing
Australian Journal of Botany
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Abstract

Patterns of distribution are described for the three subgenera and nine sections that make up the Australian Acacia flora. Subgenus Phyllodineae (833 species) is widespread and contains 99% of the species; subgenus Acacia (six species) and subgenus Aculeiferum (one species) are poorly represented and virtually confined to the north of the continent. The geographic patterns of species-richness are strongly influenced by sections Phyllodineae (352 species), Juliflorae (219 species) and Plurinerves (178 species). Section Phyllodineae has centres of richness south of the Tropic of Capricorn in temperate and adjacent semiarid areas of eastern, south-eastern and south-western Australia. The section is poorly represented in the tropics. The closely related sections Juliflorae and Plurinerves predominate in the north of the continent, semiarid areas of the south-west, many rocky tablelands of the Arid Zone and along the Great Dividing Range and adjacent inland riverine lowland areas in eastern Australia. The remaining four sections contribute little to the overall patterns of species-richness. The principal speciespoor areas are sandy and fluvial lowland regions of the Arid Zone. In eastern Australia, sections Botrycephalae, Juliflorae, Phyllodineae and Plurinerves show discontinuous patterns of species-richness along the Great Dividing Range. All sections have species whose ranges terminate in the area of the McPherson-Macleay Overlap region.

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... Growing across a broad range of climates and edaphic environments, Acacia is morphologically heterogeneous, with a wide diversity of growth form, vegetative and floral morphology, and anatomy (Boughton, 1986(Boughton, , 1990Whinder et al., 2013). Climate and particularly precipitation have been identified as the major factors determining the broad geographic patterns of distribution and abundance of the species of Acacia (Hnatiuk and Maslin, 1988;Maslin and Pedley, 1988). Foliar nervation in Acacia was observed to be strongly influenced by climate, with microneurous phyllodes (numerous, close and parallel) abundant in arid locations and oligoneurous (few, distant) in mesic environments. ...
... Where possible, the species sampled were evenly selected from the four taxonomic sections of Acacia, the Botrycephalae, Juliflorae, Phyllodineae and Plurinerves (Table 2). Full and even coverage of each taxonomic section within each climate region was not achieved, mainly because the more mesic Botrycephalae is scarce in the semi-arid I region, and absent from the arid region, where there are also fewer species from the other three sections (Maslin and Pedley, 1988). ...
... All the species studied have paratracheal parenchyma, which provides further support for questioning of this phenomenon. Pedley, 1988). An alternative speculation is that the inner gelatinous wall retains water and could have a role in maintaining adequate stem capacitance and hence the water balance of trees or shrubs in arid or semi-arid regions (Sonsin et al., 2012). ...
Article
Background and aims: This study investigates the structural diversity of the secondary xylem of 54 species of Acacia from four taxonomic sections collected across five climate regions along a 1200 km E-W transect from sub-tropical [approx. 1400 mm mean annual precipitation (MAP)] to arid (approx. 240 mm MAP) in New South Wales, Australia. Acacia sensu stricto ( s.s. ) is a critical group for understanding the effect of climate and phylogeny on the functional anatomy of wood. Methods: Wood samples were sectioned in transverse, tangential and radial planes for light microscopy and analysis. Key results: The wood usually has thick-walled vessels and fibres, paratracheal parenchyma and uniseriate and biseriate rays, occasionally up to four cells wide. The greater abundance of gelatinous fibres in arid and semi-arid species may have ecological significance. Prismatic crystals in chambered fibres and axial parenchyma increased in abundance in semi-arid and arid species. Whereas vessel diameter showed only a small decrease from the sub-tropical to the arid region, there was a significant 2-fold increase in vessel frequency and a consequent 3-fold decrease in the vulnerability index. Conclusions: Although the underlying phylogeny determines the qualitative wood structure, climate has a significant influence on the functional wood anatomy of Acacia s.s. , which is an ideal genus to study the effect of these factors.
... Acacia s.s. (Leguminosae: Mimosoideae) is the largest vascular plant genus on the Australian continent, with~1020 accepted species in Australia, occurring throughout diverse climate zones, including tropical, temperate, alpine, semiarid and arid, in forest, woodland, grassland and shrubland plant communities (Maslin and Pedley 1988;Thiele et al. 2011). Acacias range from shrubs whose stems never exceed 15 mm in diameter to large trees, and some species can be very variable in size and form, depending on habitat (Maslin 2001). ...
... species fall into the following four sections: Botrycephalae, Juliflorae, Phyllodineae and Plurinerves (Pedley 1978). Members of the Botrycephalae, which contains~40 species, are found mostly in moist, temperate areas of eastern and south-eastern Australia, have compound bipinnate leaves, whereas in the other sections, these are replaced by phyllodes, which are modified petioles with isobilateral anatomy (Maslin and Pedley 1988). The phyllodes, which are the main photosynthetic organ, are generally vertically orientated and widely considered to be an adaptation to dry environments (Elias 1981;Boughton 1986;Brodribb and Hill 1993). ...
... The section Plurinerves contains~180 species, and is widely distributed in inland regions of south-western and south-eastern Australia. The section Juliflorae has~250 species, which are found throughout northern Australia and on the Great Dividing Range of eastern Australia (Maslin and Pedley 1988). Species of the sections Plurinerves and Juliflorae are predominantly found in the arid or semiarid regions, and these two are regarded as the most xeromorphic of the groups. ...
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Acacia s.s. comprises approximately 1020 species (i.e. just under one-third of all mimosoid legumes) and is almost entirely restricted to, although widespread, on the Australian continent. We investigated variation in the wood anatomy of 12 species from temperate New South Wales in a study concentrating on four recognised taxonomic sections (Botrycephalae, Juliflorae, Phyllodineae and Plurinerves), to elucidate which characteristics are consistent within the sections, having removed climatic effect as much as possible. The sections had great utility in species identification, whereas none of the wood characters reflected the hypothesised phylogeny of the genus. The main consistent difference among species was in ray width (uniseriate versus 1–3 cells wide). All species had distinct growth rings. The vessels had alternate vestured pitting and simple perforation plates. Fibres were generally thick-walled, and many fibres had a gelatinous inner wall (tension wood fibres) and were inconsistently distributed. Axial parenchyma was mainly paratracheal, ranging from vasicentric to confluent and varied greatly in abundance. Prismatic crystals were usually present in chambered fibres and axial parenchyma strands, and also varied in abundance. The variation in these qualitative characters obscures taxonomic differences, but may allow inferences to be made about environmental adaptation.
... ). These Acacia host-species distributions are geographically structured between arid and non-arid areas (Maslin & Pedley 1988; Maslin 2001b; Miller et al. 2003; Murphy et al. 2003; Bowman & Yeates 2006; McLeish et al. 2007b ). Speciation of gall-thrips on each of these host sections is expected to operate under different environmental and ecological contexts that are partitioned by arid/non-arid geographical disjunctions (MJ McLeish in review). ...
... Patterns of Acacia species diversity in Australia are strongly influenced by section Plurinerves that predominates in the north, south-west and eastward along the Great Dividing Range (Hnatiuk & Maslin 1988; Maslin & Pedley 1988). The east-west distributions of Acacia hosts of the K. rugosus complex (Fig. 1 ) reflect the species diversity pattern of Plurinerves generally with the central-south arid region of Eremean Australia being species depauperate. ...
... However, the pattern of gall-thrips host Acacia species richness between east and west defies the usual pattern evident in other taxa of greater species diversity to the west. Of the c. 178 species classified as Plurinerves (Maslin & Pedley 1988), the K. rugosus complex is known to specialise on only 14, which are believed to have radiated during the Quaternary (Byrne et al. 2002; Andrew et al. 2003 ). Divergence time estimates of the split between eastern and western distributed Kladothrips that specialise on Plurinerves is approximately 5 Mya (McLeish et al. 2007b). ...
Data
Phytophagous insects that specialise on broadly distributed plant groups are exposed to host‐species diversity gradients. The gall‐inducing thrips genus Kladothrips (Froggatt) that specialise on Australian Acacia Mill. (Mimosoideae: Leguminosae, subgenus Phyllodineae DC.) is expected to exhibit variation in host range that is dependent on host ecology. Host Acacia species distributions show structuring between the arid Eremean and non‐arid biomes of the monsoonal tropics and temperate south‐western and south‐eastern Australia. We investigate two aspects of host use in: (1) the Kladothrips rugosus species complex that specialises on hosts whose distributions overlap among sibling lineages on different Acacia species; and (2) Kladothrips nicolsoni that specialises on a species that is relatively isolated from hosts of sibling lineages. First, several approaches that use DNA sequence data are combined to infer putative species among K. rugosus lineages collected from multiple Acacia species using: phylogenetic inference; statistical parsimony; amova; maximum likelihood genetic distance relationships; and generalised mixed Yule coalescent likelihood test of lineage delimitation. Second, haplotype network analysis is used to estimate population structuring of K. nicolsoni that specialises on a geographically isolated Acacia host species. Analyses indicated below species‐level relationships among lineages that each induces galls on different Acacia host species. In contrast, haplotype network analysis for a gall‐thrips species that is largely allopatric with hosts of sibling species indicates isolation by distance and range expansion effects. Greater host‐species richness enhances gall‐thrips opportunity to host shift resulting in founder effects that lead to disruptive selection. Restricted gene flow among gall‐thrips populations specialising on a relatively isolated host species implies genetic drift via allopatric mechanisms. The results suggest gall‐thrips speciation is driven by the combined influence of ecologically based selection with genetic drift that is largely determined by variation in host‐species richness between arid and non‐arid Australia.
... from section Plurinerves (Benth.). These Acacia host-species distributions are geographically structured between arid and non-arid areas (Maslin & Pedley 1988;Maslin 2001b;Miller et al. 2003;Murphy et al. 2003;Bowman & Yeates 2006;McLeish et al. 2007b). Speciation of gall-thrips on each of these host sections is expected to operate under different environmental and ecological contexts that are partitioned by arid/non-arid geographical disjunctions (MJ McLeish in review). ...
... Patterns of Acacia species diversity in Australia are strongly influenced by section Plurinerves that predominates in the north, south-west and eastward along the Great Dividing Range (Hnatiuk & Maslin 1988;Maslin & Pedley 1988). The east-west distributions of Acacia hosts of the K. rugosus complex (Fig. 1) reflect the species diversity pattern of Plurinerves generally with the central-south arid region of Eremean Australia being species depauperate. ...
... Of the c. 178 species classified as Plurinerves (Maslin & Pedley 1988), the K. rugosus complex is known to specialise on only 14, which are believed to have radiated during the Quaternary (Byrne et al. 2002;Andrew et al. 2003). Divergence time estimates of the split between eastern and western distributed Kladothrips that specialise on Plurinerves is approximately 5 Mya (McLeish et al. 2007b). ...
Article
Phytophagous insects that specialise on broadly distributed plant groups are exposed to host-species diversity gradients. The gall-inducing thrips genus Kladothrips (Froggatt) that specialise on Australian Acacia Mill. (Mimosoideae: Leguminosae, subgenus Phyllodineae DC.) is expected to exhibit variation in host range that is dependent on host ecology. Host Acacia species distributions show structuring between the arid Eremean and non-arid biomes of the monsoonal tropics and temperate south-western and south-eastern Australia. We investigate two aspects of host use in: (1) the Kladothrips rugosus species complex that specialises on hosts whose distributions overlap among sibling lineages on different Acacia species; and (2) Kladothrips nicolsoni that specialises on a species that is relatively isolated from hosts of sibling lineages. First, several approaches that use DNA sequence data are combined to infer putative species among K. rugosus lineages collected from multiple Acacia species using: phylogenetic inference; statistical parsimony; amova; maximum likelihood genetic distance relationships; and generalised mixed Yule coalescent likelihood test of lineage delimitation. Second, haplotype network analysis is used to estimate population structuring of K. nicolsoni that specialises on a geographically isolated Acacia host species. Analyses indicated below species-level relationships among lineages that each induces galls on different Acacia host species. In contrast, haplotype network analysis for a gall-thrips species that is largely allopatric with hosts of sibling species indicates isolation by distance and range expansion effects. Greater host-species richness enhances gall-thrips opportunity to host shift resulting in founder effects that lead to disruptive selection. Restricted gene flow among gall-thrips populations specialising on a relatively isolated host species implies genetic drift via allopatric mechanisms. The results suggest gall-thrips speciation is driven by the combined influence of ecologically based selection with genetic drift that is largely determined by variation in host-species richness between arid and non-arid Australia.
... Another piece of evidence is from Mulga-banded vegetation in Australia. Mulga is recorded in many regions of Australia but the dominant species across all sites is Acacia aneura (Miller et al., 2002), even though there are ∼1,000 Acacia species in Australia (Maslin and Pedley, 1988). The near-vertical architecture of A. aneura branches, stems, and phyllodes promotes efficient channeling of rainfall to stem bases (Slatyer, 1965;Miller et al., 2002). ...
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Significant effort in the study of self-organized pattern formation has focused on the physical conditions of the ecosystem. But what about the organisms involved? Can just any species form patterns or are certain traits required? I performed a metadata analysis of pattern-forming species in various patterned ecosystems worldwide and analyzed trait values and other biological characteristics to address this question. Results indicate that some species are more likely to form patterns than others, as a result of their possessing a portfolio of traits conducive to pattern formation. There is a conservation of these traits among species forming vegetation patterns across regions of the world. The degree of conservation is high when regular patterns are formed by the mechanism of scale dependent feedbacks. In contrast, when regular patterns arise from intraspecific competition, cross-site variation among pattern-forming species becomes high. Understanding evolutionary implications of pattern formation can be enhanced by this trait-based approach, a perspective that has been lacking to date.
... Studies have now demonstrated that Acacia s.l. is indeed polyphyletic and the genus has been split into seven genera (Acacia Martius, (Kodela & Wilson, 2006;Maslin, 2018). All native Vachellia species are restricted to northern Australia; V. bidwillii is the only species found south of the tropics (Maslin & Pedley, 1988). They occur in both semi-arid and moist-tropical climatic zones. ...
Article
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Plant relationships have implications for many fields including weed biological control. The use of DNA sequencing and new tree building algorithms since the late 1980s and early 1990s have revolutionised plant classification and has resulted in many changes to previously accepted taxonomic relationships. It is critical that biological control researchers stay abreast of changes to plant phylogenies. One of the largest plant genera, Acacia, has undergone great change over the past 20 years and these changes have ramifications for weed biological control projects in a number of countries. Vachellia nilotica (prickly acacia) is a major weed in Australia, originating from the Indian subcontinent and Asia, and it has been a target for biological control since 1980. Once a member of Acacia, a large (>1,000 spp.) and iconic group in Australia, prickly acacia is now part of the genus Vachellia. Current knowledge suggests that Vachellia is more closely related to mimosoid genera than it is to Acacia s.s. There has also been a recent reclassification of legume subfamilies with subfamily Mimosoideae now part of subfamily Caesalpinioideae, and four new subfamilies. In this paper we review the changes that have occurred to this group since the prickly acacia biological control project began and discuss the implications for the project. A new host test list for quarantine testing is proposed. Developed following the modernisation of the centrifugal‐phylogenetic method, it is shorter than past lists, containing 46 species, although still lengthy because of the expectations of regulatory bodies, which are slower to accept advances in scientific knowledge. The list includes five Vachellia species, six “Mimoseae” species and 26 Acacia species. The number species from legume subfamilies other than the new Caesalpinioideae is greatly reduced.
... The genus Acacia comprises of 1,352 species and is the largest genus of family Mimosaceae which can be divided into three genera that is, Acacia has 161 species, Senegalia has 231 species and Racosperma has 960 species (Orchard & Maslin, 2003). The genus Acacia if taken in broad sense includes about 1,450 species (Lewis, 2005) and its species are distributed in Asia, America as well as in Australia and it contains the second most species after Astragallus in Leguminoceae (Mabberley, 1997;Maslin & Pedley, 1988). Tribe Acacieae has been split up in to five genera. ...
Article
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Current research carried out in Pakistan is the first report on spermoderm ornamentation of eight species of tribe Acacieae (Mimosoidae) by using scanning electron microscopic techniques representing two genera, Fedherbia and Acacia were examined. Different spermoderm ornamentation were observed, described and discussed for their taxonomic importance. Seeds surfaces of the studied tribe possess novel variations in macro and micro morphology. Great variations were observed in both qualitative and quantitative characters of seeds. Seeds shape was oblong, ovate to elliptical and spermoderm ornamentation was levigate, rugose, polygonal and discoid, colliculate, and papillose type. These variations in the spermoderm ornamentation can be used as an aid in identification and classification of the members of tribe Acacieae.
... Four of the sections are relatively small (less than 50 species) and three are relatively large (greater than 150 species). Two sections have relatively restricted distributions (Alatae and Pulchellae from south-west Western Australia), whereas the other sections are relatively widespread across Australia (Hnatiuk and Maslin 1988;Maslin and Pedley 1988). Six to 10 species were obtained from all sections except for the Lycopodiifoliae (22 species total) where only two species were available from the supplier ( Table 2). ...
Article
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Acacia s. str. (Mimosoideae, Fabaceae) is the largest plant genus in Australia (~1000 species). Its seeds have physical dormancy from a hard, water-impermeable testa. Heat from fire (natural systems) and hot water (nursery production) can break this dormancy. It is often reported that these treatments ‘soften’ or ‘crack’ the seed coat, but in practice they only affect a minute part of the seed coat, the lens. We examined lens structure in a wide range of Acacia species to determine what diversity of testa and lens structure was present, if there were differing responses to a hot water dormancy breaking treatment and if there were structural differences between soft- and hard-seeded species. Seed morphology, testa and lens structure were examined before and after hot water treatment (~90°C for one minute), in 51 species of Australian Acacia from all seven sections, from all states and territories of Australia and from a wide range of environments. Five of the species had been noted to produce non-dormant seed (‘soft-seeded’ species). Average seed mass per species ranged from 3.1 to 257.9 mg (overall average 24.2 mg, median 13.8 mg). Almost all species had a relatively thick seed coat (average 132.2 µm) with well-developed palisade cells (average 41.5 µm long) and a lens which ‘popped’ in response to hot water treatment. For 44 species ranging in average seed mass from 3.1 to 43.9 mg (×14 range), the unpopped lens area only ranged ×3 (11480–36040 µm²). The lens was small (in 88% of species the average length of the unpopped lens was <300 µm) and the unpopped lens area was a minute proportion of seed surface area (average 0.10%). A. harpophylla (soft-seeded species) had a thin testa (37.3 µm) without obvious palisade cells and did not have a functional lens. In hard-seeded species the morphology of the popped lens varied widely, from a simple mound to complete detachment. A functional lens is not a universal feature in all genera of the Mimosoideae, including several species in a genus (Senegalia) previously included in Acacia s. lat. On the basis of the 51 investigated species a lens was present in all Australian acacias, although non-functional in two soft-seeded species. Although the lens was, on average, only ~1/1000th of the surface area of an Acacia seed and thus easily overlooked, it can have a profound influence on imbibition and germination. An assessment of lens structure, before and after heat treatment, can be of considerable use when interpreting the results of Acacia germination experiments.
... Tab. 1: Übersicht über die Systemklassifizierung Pedleys 1978und 1986(Quelle: TAME, 1992, MASLIN & PEDLEY, 1988, MASLIN, 1989 (1986( , in MASLIN, 1989 von Acacia in die drei Gattungen Acacia, Senegalia und Racosperma hatte weltweite Auswirkungen. 96 % der australischen Flora, über 850 ...
Thesis
Die vorliegende Arbeit zeigt die Möglichkeiten einer Kultur australischer Akazien als Topfpflanzen. Im ersten Teil werden in einer umfangreichen Literaturübersicht ökologische Standortbedingungen und bisherige nationale und internationale Veröffentlichungen über australische Akazien und zur Kultur weiterer australischer Pflanzen dargestellt. Untersuchungen zur generativen Vermehrung an 12 Akazienarten beinhalten verschiedene Saatgutvorbehandlungsmethoden: mechanische Beschädigung, Vorquellen, Behandlung mit konzentrierter Schwefelsäure, dem Seed Starter "Smoky Water" sowie die Behandlung mit hohen Temperaturen. Die mechanische Beschädigung des Saatgutes erzielt bei der Mehrzahl der untersuchten Akazienarten eine hohe Keimrate bei kurzer Keimdauer. Die Behandlung mit Seed Starter zeigt dagegen keine keimungsfördernde Wirkung. Praktische Versuche zur vegetativen Vermehrung durch Stecklinge beziehen sich auf unterschiedliche Stecklingsarten, Vermehrungstermine, Alter der Mutterpflanzen sowie verschiedene Stecklingsbehandlungen mit Bewurzelungshormonen und die Lagerung der Stecklinge. Es wird gezeigt, dass diese bisher problematische Vermehrungsmethode durch die Verwendung juvenilen Mutterpflanzenmaterials deutlich verbessert werden kann. Ferner konnte ein positiver Einfluss der Lagerung von Stecklingen auf die Bewurzelungsraten dargestellt werden. Vorteile bei der Bewurzelung und teilweise im weiteren Wachstum erzielte die Anwendung von IBS als Bewurzelungshormon. Versuche zur In-vitro-Kultur zeigen die Möglichkeit der In-vitro-Vermehrung und In-vitro-Bewurzelung der Akazienarten sowie die unproblematische Überführung in vivo für Acacia retinodes. Der Einfluss der Vermehrungsmethoden und -arten auf die weitere Entwicklung der Akazien wird im Teil der Wachstumssteuerungsmöglichkeiten untersucht. Es erfolgt die Darstellung der klimatischen Ansprüche und die Wirkung einiger kulturtechnischer Maßnahmen, beispielsweise die Anwendung von Hemmstoffen, Stutzen und Wurzelkürzen. Entscheidend für eine zeitige Blütenknospenbildung ist die Vermehrung über adultes Stecklingsmaterial. Die Kultur unter Zusatzlicht führt zu einem kompakten Habitus und einer verbesserten Blühinduktion. Die Blütenentwicklung kann durch das Absenken der Temperatur gefördert werden. Das Kürzen der Wurzeln beeinträchtigt die weitere Entwicklung der Pflanzen nicht. Durch Stutzen kann der Austrieb nicht gefördert werden; die Wirkung auf die Pflanzenhöhe erfolgt in Abhängigkeit vom Stutztermin. Abschließend werden Kulturschemata ausgewählter australischer Akazien als Blattpflanzen und blühende Topfpflanzen dargestellt.
... and A. auriculiformis A.Cunn. ex Benth are tropical Acacia species native to humid low elevation sites in Australia, Papua New Guinea, and eastern Indonesia (Maslin and Pedley 1988). Due to their wide adaptability, fast growth and utility, A. mangium and A. auriculiformis have been widely planted in South-east Asia (Maslin 2002;Maslin et al. 2003;Midgley and Turnbull 2003) for both short-fibre pulp and sawlogs. ...
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Floral phenology and morphology of colchicine-induced auto-tetraploid trees of Acacia mangium Willd. (AM-4x) growing in Vietnam were compared with adjacent diploid A. mangium (AM-2x) and A. auriculiformis A.Cunn. ex Benth (AA-2x). Flowering lasted for several months with a slightly later peak flowering period for A. auriculiformis (December–January), than for A. mangium (November–December). Flower spikes of AM-4x were shorter and had fewer flowers per spike than those of AM-2x, but were longer and had more flowers than AA-2x. Percentages of male to hermaphrodite flowers were less than 23% for all three species/ploidy combinations. Flowers of AM-4x had slightly shorter styles than did AM-2x, but AM-4x stigma and polyad diameters were greater. For all polyad-stigma combinations among species/ploidy levels, at least one polyad could be accommodated. AM-4x had fewer (13) ovules per ovary, compared with AM-2x and AA-2x (14–16). AM-4x set fewer (less than 3) seeds per pod than did AM-2x and AA-2x (7–8 and 5–6, respectively). Foraging behaviour of the main insect pollinators (honeybees) and examination of polyads collected from them suggested interspecific and interploidy pollination would occur. There appeared to be no phenophase or flower structure barriers to interploidy pollination.
... Acacia mangium and A. auriculiformis are tropical species in the subgenus Phyllodineae, the largest monophyletic group of the genus Acacia (Maslin et al. 2003a). They occur naturally in northern Queensland, Australia and adjacent regions of Papua New Guinea and eastern Indonesia (Maslin & Pedley 1988, Maslin et al. 2003b). Together with their natural hybrid (A. ...
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Pollen–pistil interactions between autotetraploid and diploid Acacia mangium and diploid A. auriculiformis. Development of sterile triploid (3x) planting stock could help manage the risk of invasivity of widely planted Acacia species. Triploids may be derived from crosses of diploid and tetraploid plants. This study investigated the effect of cytotype on pollen–pistil interaction following mating between colchicine-induced tetraploid A. mangium (AM-4x), diploid A. mangium (AM-2x) and A. auriculiformis (AA-2x). Following controlled pollinations, pollen tubes grew well in the style, entered the ovary and penetrated ovules within 72 hours, regardless of the mating type. However, mean number of penetrated ovules per ovary was lower for AM-4x than for AM-2x or AA-2x maternal parents for all cross combinations except for self-pollination. Considering crosses between cytotypes, interspecies had significantly greater number of ovules penetrated than intraspecies. However, yields of pods (1.03%) and filled seeds (5.3%) following all inter-cytotype crosses were extremely poor compared with intra-cytotype (7.59 and 76.3% respectively). Thus, there were strong barriers to production of viable 3x seeds, despite the demonstrated absence of pre-zygotic isolation.
... Acacia shows a similar pattern (Hnatiuk and Maslin 1988;Maslin and Pedley 1988) with different sections of the genus predominating in the tropical and temperate areas. Triodia likewise shows a similar pattern (Jacobs 1982). ...
Article
Patterns in the distribution of Australasian species of freshwater aquatic plants were sought, to determine whether vicariance, distance dispersal, local speciation, or a mixture of these could best explain the distribution. The distribution was recorded from 10 regions of Australasia that include sizeable areas of wetland: Papua New Guinea, Cape York Peninsula, south-east Queensland, eastern New South Wales, Victoria, Tasmania, New Zealand, northern Northern Territory, the Kimberley, and south-west Western Australia. Matrices of 553 species by 10 regions, 139 genera by 10 regions, and 56 families by 10 regions were analysed using hierarchical fusion, nearest neighbour and ordination techniques. The results indicate that there are two distinct elements in the aquatic flora, tropical and temperate. The diffuse boundary between these two climatic zones could be interpreted as a barrier in the sense used in definitions of vicariance. There is little effective spread between tropical and temperate areas but, within each of these climatic zones, the species are mobile and many spread reasonably readily between regions, provided suitable habitats and dispersal opportunities are available. Where geographic barriers to distance dispersal have been great then these may become as important as the climatic barrier. This is demonstrated, at least in part, by the differences between some of the generic and species dendrograms. Local speciation (not shown by our PATN analyses because of the endemic species being ignored in them) has been important where some primarily aquatic genera have proliferated when conditions have been suitable. Local speciation has occurred in cosmopolitan aquatic genera that have presumably arrived in regions via long distance dispersal. The significance of bird migration and dispersal patterns are discussed. The aquatic flora of the monsoon tropics has evolved mainly from long distance dispersal but with significant local speciation in some genera such as Nymphoides, Utricularia, Nymphaea and Vallisneria. The pattern of distribution was compared with those recorded from other ecologically defined groups such as the Australian arid and alpine floras.
... Section Botrycephalae (Pedley 1978) is endemic to eastern Australia (Fig. 1), with the highest species diversity recorded for the central and South Coast regions of New South Wales (Maslin and Pedley 1988). Botrycephalae was originally classified at a high rank within Acacia, as one of only six series (Bentham 1842(Bentham , 1875. ...
Article
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A phylogenetic analysis of Acacia subg. Phyllodineae sect. Botrycephalae, endemic to eastern Australia, is presented based on a combined dataset of ITS and ETS sequences of nrDNA. A smaller set of species was sequenced also for the cpDNA trnK region. A limited number of morphological characters was also combined with the ITS+ETS dataset for most taxa. Thirty-eight of 41 Botrycephalae species were sequenced, together with a sample of ten uninerved phyllodinous species (sect. Phyllodineae). Although these DNA regions showed limited sequence divergence, bootstrap supported nodes of the consensus ITS+ETS tree indicate that Botrycephalae as currently defined is polyphyletic. Eight bipinnate species fell outside the main clade of Botrycephalae species while seven phyllodinous species were nested within it, near the base. The few derived but homoplasious morphological characters that were discovered included: presence of appressed unicellular hairs, presence of jugary and interjugary glands, number of pinnae > 7 and the funicle half–fully encircling the seed. Section Botrycephalae requires redefinition.
... The six recorded host-plants of Kladothrips rugosus form a group of closely related species within the Plurinerves. These species are characterised by having 'microneurous' phyllodes; the longitudinal nerves are very fine, close together and without any anastomosing nerves in between (see Maslin and Pedley 1988). The host-plants of four of the other five members of the K. rugosus species-group are also quite closely related within the Plurinerves, although the host-plant of the fifth species, K. maslini, is more distantly related and although currently placed in the Plurinerves possibly belongs elsewhere. ...
Article
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The available biological information on the association, unique to Australia, between gall-inducing thrips and the phyllodes of Acacia species is summarised. Identification keys to the three genera and 21 gall-inducing species involved are presented, together with descriptions of nine new species (Kladothrips harpophyllae, Kladothrips maslini, Kladothrips xiphius, Oncothrips morrisi, Oncothrips schwarzi, Oncothrips sterni, Oncothrips torus, Onychothrips pilbara and Onychothrips zygus).
... Acacia species (Mimosaceae) are woody shrubs and small trees that are widely distributed in temperate woodlands in south-eastern Australia (Maslin and Pedley, 1988), and are commonly recorded in many roadside environments (McBarron, 1955;Schabel and Eldridge, 2001). Most Acacia species are highly adapted to fire, through hard-coated seed and resprouting ability, and Ôthe prevalence of young wattles after a bush fire is a fact that must have struck the most unobservantÕ (Hamilton, 1892, p. 201). ...
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Disturbances from road management activities are often considered to be a major threat to plants in roadside environments, however effects may not be deleterious to all plants. The post-disturbance response of three Acacia species with different life-history attributes was compared in four road reserves impacted by soil disturbance from grading activities. Recovery of acacias to grading was variable, however basal resprouting, root suckering and seedling emergence led to a 6.2% population increase for all road reserves combined. In two road reserves, there was significant resprouting of the facultative seeder A. decora, and 2 years after disturbance, resprouts reached mean heights of 71 and 74 cm. One year after disturbance, 71% of A. decora resprouts flowered and 49% also set viable seed, and there was a significant positive relationship between flowers produced and viable seed set. Similarly, 65% of resprouts of the facultative seeder A. montana flowered but only 10% set viable seed. In contrast, there was patchy seedling emergence of the obligate seeder A. pycnantha and to a lesser extent A. montana, and seedlings did not reach reproductive maturity 1 year after disturbance. Drought most likely reduced seedling numbers, as seedlings were only recorded in shaded road reserves, where additional water was applied from roadworks activities. Grading of roadside environments appears to favour plants with strong resprouting ability, and persistence of Acacia populations will depend on the timing of soil disturbances from grading activities in relation to species life-history attributes.
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This bibliography, based on an electronic database of material authored by state government department staff since 1896, contains 9138 items on the flora, fauna and forests of Western Australia. An extensive search of stafflists, publications and library catalogues was undertaken to build a comprehensive database and as a result the bibliography provides a history of government research. Only 28 items were produced pre 1920, with 405 produced in the 1920s. After a decline during the 1930s and 1940s, the number of titles has steadily increased to 5122 titles produced in the 1990s.
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The aim of this study is to identify and map the spatial distribution of species richness and endemism of the genus Acacia in Australia. A database of 171 758 geo-referenced herbarium records representing 1020 Acacia species was assembled and aggregated to a 0.25° grid cell resolution. A neighbourhood analysis of one-cell radius was applied to each of the grid cells to map the spatial patterns of species richness and endemism. The primary centres of species richness are in accordance with previous results, occurring in the South-West Botanical Province in Western Australia, the MacPherson-Macleay overlap and the Central Coast of the Sydney Sandstone region. We identify 21 centres of endemism, of which six were previously unrecognised. The primary centres of endemism are located in South-West Western Australia, the Kimberley District and the Wet Tropics in Queensland. The South-West Botanical Province in Western Australia contained the greatest number of regions with the highest number of endemic species of Acacia. A randomisation test showed that our 21 centres of endemism were significantly different from random. The majority of centres of Acacia endemism were incongruent with the centres of species richness, with only three grid cells in the top 1% for both measures. We also confirm that South-West Western Australia is a region of very high species richness and endemism, in accordance with its status as a global hotspot of biodiversity.
Article
A number of factors potentially affect flowering and fruiting of Acacia species in arid central Australia. Three phenological data sets were examined to determine the influence of edaphic, climatic and inherent evolutionary factors. Data for three intensively-studied common species showed that soil moisture over various lag periods was the best predictor of flowering, while site differences and temperature were of secondary importance. Soil moisture, site differences and daylength (time of year) were better predictors of fruiting. According to long-term records of a wider selection of species, the persistence of temperate-zone spring flowering patterns was apparent in one section of Acacia; the same patterns were also more common in shorter-lived species. Species from other sections and longer-lived species were more opportunistic in their flowering. Fruiting commonly occurred in the second half of the year, peaking in October, regardless of opportunistic or seasonal flowering. Phenological patterns are mixed, in keeping with the unreliable rainfall and environmental diversity of the Australian arid zone.
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Phyllodes of species of Acacia from the sections Julflorae, Plurinerves, Lycopodiifoliae and Phyllodineae are described in respect of the disposition of the stomates relative to the phyllode surface, size of the substomatal cavities, outline of the phyllode as seen in transverse section, and disposition of the smaller vascular bundles. The first three of these characters are shown to be related to stickiness and the third and fourth to the relative humidity or aridity of the environment. The geographical distribution of sticky species in central and eastern Australia is determined. Sticky species occur throughout the region but are commoner in the more arid interior than in the more humid coastal regions. No relationship is apparent between stickiness and membership of the sections.
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This paper reports on the kinds of geographic patterns encountered in the distribution of Australian species of Acacia and on some climatic correlates of these patterns. The analyses were based on distribution data of 837 species mapped on a 1° x 1.5° grid. The area of highest density of species was the south-west corner of the continent, especially adjacent to the major boundary separating the Arid Zone from the more humid South West Botanical Province. The second major centre of richness occurred in eastern Australia south of the Tropic of Capricorn along the topographically heterogeneous Great Dividing Range. Secondary centres of species-richness occurred in northern and north-eastern Australia, a number of rocky tablelands of the Arid Zone and in western Victoria. The principal species-poor areas were located in sandy and some riverine areas of the Arid Zone, in temperate forests of Tasmania and in coastal areas of the north of the continent. The geographic patterns of each section of Acacia, when combined with those of species density, highlighted the tropical (section Juliflorae) v. temperate areas (sections Phyllodineae, Pulchellae, Botrycephalae and Alatae). The numerical classification of grids resulted in the recognition of eight major Acacia areas, arranged under four Acacia regions: (1) South-west; (2) Eastern, comprising a southern and a northern area; (3) Northern, comprising an eastern and a western area; (4) Central, comprising a south-east, a central and a north-west area. A discriminant function analysis indicated that precipitation was more important than temperature in distinguishing between areas. Discussion of the potential evolutionary significance of these findings and brief comparison with other biogeographic studies are given.
Article
The utility of isozyme analysis in elucidating the relationship between Australian tree taxa is reviewed. Although little exploited to date, isozyme analysis is shown to be a rapid and relatively powerful method of examining relationships, if used at an appropriate taxonomic level. For Eucalyptus and Acacia, isozymes appear to be the most informative at the lower taxonomic levels. In Eucalyptus delegatensis and Casuarina cunninghamiana, isozyme data strongly support subspecies erected on the basis of morphological characteristics. In Acacia holoserocea, isozyme data predicted the existence of two subspecies, which prediction as later supported by morphological characters. An isozyme study of the phylogenetic relationships within the 'green ash' group of eucalypts yielded a phylogenetic hypothesi comparable to one derived from morphological characters, but also highlighted areas of discrepancy requiring further research. At the generic level, isozyme data for the Australian species of Litsea and Neolitsea successfully separated the two genera and allowed phylogenetic relationships within genera to be hypothesised. For the larger tree genera such as the Eucalyptus and Acacia, however, the utility of isozymes at the higher taxonomic levels is likely to be low, because of the difficulty in establishing homologies between taxa, or insufficient phylogenetic information when taxa being compared have few alleles in common.
Article
The morphology of seedlings, leaves, flowers and inflorescences, anatomy of the pod, the occurrence of extra-floral nectaries, free amino acids of the seeds, flavonoid compounds in heartwoods, cyanogenic compounds and porate, colporate and extraporate pollen, and susceptibility to rusts, all indicate that three genera, Acacia Miller, Senegalia Raf. and Racosperma Martius, should be recognized. These correspond to currently accepted subgenera of Acacia. The size of these more narrowly circumscribed genera is in keeping with the size of genera of other tribes of low diversity in Leguminosae. Acacia and Senegalia arose independently from the Ingeae, with Racosperma being derived from Senegalia. Section Filicinae is more advanced than section Senegalia of Senegalia, and sections Racosperma and Pukhella, both with at least some species with bipinnate foliage, are the most advanced of Racosperma, while the other sections Pleurinervia and Lycopodiifolia have only phyllodinous species. Long-range dispersal of Racosperma from the Australian region has occurred, but the broad pattern of distribution is interpreted in terms of plate tectonics. Racosperma was present in Australia in the late Cretaceous but did not become widespread until the general drying of the continent in the Miocene. The flora of SW Australia has been isolated from the rest of the continent by climatic barriers since the late Tertiary and has a high proportion of endemic species. Barriers to plant migration in the east have operated only intermittently and there is no area comparable in endemism to the southwest.
Article
This paper reports on the kinds of geographic patterns encountered in the distribution of Australian species of Acacia and on some climatic correlates of these patterns. The analyses were based on distribution data of 837 species mapped on a 1° x 1.5° grid. The area of highest density of species was the south-west corner of the continent, especially adjacent to the major boundary separating the Arid Zone from the more humid South West Botanical Province. The second major centre of richness occurred in eastern Australia south of the Tropic of Capricorn along the topographically heterogeneous Great Dividing Range. Secondary centres of species-richness occurred in northern and north-eastern Australia, a number of rocky tablelands of the Arid Zone and in western Victoria. The principal species-poor areas were located in sandy and some riverine areas of the Arid Zone, in temperate forests of Tasmania and in coastal areas of the north of the continent. The geographic patterns of each section of Acacia, when combined with those of species density, highlighted the tropical (section Juliflorae) v. temperate areas (sections Phyllodineae, Pulchellae, Botrycephalae and Alatae). The numerical classification of grids resulted in the recognition of eight major Acacia areas, arranged under four Acacia regions: (1) South-west; (2) Eastern, comprising a southern and a northern area; (3) Northern, comprising an eastern and a western area; (4) Central, comprising a south-east, a central and a north-west area. A discriminant function analysis indicated that precipitation was more important than temperature in distinguishing between areas. Discussion of the potential evolutionary significance of these findings and brief comparison with other biogeographic studies are given.
Article
The Australian acacias have been examined in considerable detail, via extensive morphological and anatomical observation and numerical analyses involving 171 species. This work has provided further evidence of the need -to divide Australian Acacia taxonomically into two main series, associating the bipinnate-leaved Botryocephalae closely with the uninerved phyllodinous species and separating them from the Pulchellae. It has also made available a large body of morphological and anatomical data, suitable for generating special purpose keys and potentially useful for other purposes.
Article
The Australian phytogeographic region is defined as including the Australian mainland and Tasmania. This region may be subdivided into the Tropical Zone in the north and east, the Temperate Zone in the south and east, and the Eremaean Zone in the arid centre. Delineation of these zones is closely linked with present day climates but their floristic constituents also reflect selection resulting from past climatic and geographic conditions. The following areas are of special phytogeographic interest: South-West Province of Western Australia, Tasmania, Sorth-East Queensland, and the MacPherson–Macleay Overlap where the Tropical and Temperate Zones coincide. Three interzone areas have been defined where special circumstances prevent the drawing of zonal boundaries. In Parts A and B floristic analyses covering the distribution of Australian phanerogamic genera are provided for the Australian Region and for the special areas listed above. The analyses deal with family representation, endemism, and the estimated number of species present. The flora of the South-West Province reveals the highest proportion of endemism though there is a close relationship with the flora of the eastern part of the Temperate Zone. The existing west-east affinities and discontinuities are discussed in relation to climatic changes. The Province is not regarded as the "cradle" of the autochthonous elements of the Australian flora though it is apparently an asylum for many relict forms. Affinities with the flora of South Africa are not higher than those for other areas of the Australian Region. the Temperate Zone. The existing west-east affinities and discontinuities are discussed in relation to climatic changes. The Province is not regarded as the "cradle" of the autochthonous elements of the Australian flora though it is apparently an asylum for many relict forms. Affinities with the flora of South Africa are not higher than those for other areas of the Australian Region. The flora of Tasmania is not highly endemic at the generic level but it is of special interest because of certain affinities with the flora of Malaysia and with genera otherwise found along the Malaysia–New Zealand arc or genera also in South America. In some cases the genera are unknown on the mainland, in others they are known from Australian Tertiary deposits. The Tasmanian flora is considered to include (1) relicts from early Tertiary floras, (2) survivors from the cold climate regimes of the Pleistocene, and (3) Australian elements which have mingled with the flora during periods of land continuity. The North-East Queensland area is defined as including the high rainfall habitats of the eastern parts of Cape York Peninsula. An outstanding number of families, genera, and species are restricted to this area so far as the Australian Region is concerned. Many genera are limited to a single representative which may also occur in Malaysia. It is suggested that a proportion of these may be recent arrivals while others, known as fossils from southern deposits, have a more restricted distribution than in the past. The close affinity with the flora of New Guinea is obvious but there are certain affinities with the floras of New Caledonia and New Zealand which may be independent of those of other parts of the Australian Region. Consideration is given to the problems of migration of temperate elements between the northern and southern hemispheres and the passage of such elements through the tropical belt. The MacPherson–Macleay Overlap is defined as that area of eastern Australia where the Tropical and Temperate Zones overlap. It includes part of south-east Queensland and part of north-east New South Wales. Within this area tropical elements predominate in the wetter habitats of the eastern slopes of the ranges and temperate elements in the drier or cooler and more open sites. Many of the tropical elements are to be found in discontinuous areas to the south of the Overlap but there is no similar pattern of temperate communities to the north. The Overlap is of special interest in the discussion of discontinuous distributions in eastern Australia and the significance of these. The development of the Australian flora is discussed in Part C. Its present composition is regarded as primarily due to climatic selection both within the region and from the biotypes available as a result of migration. Migration by communities rather than by chance dispersal of individuals is considered a prime factor. Though the data concerning Tertiary floras are not extensive certain significant facts emerge. First there is a stronger affinity with the flora of South America and this must be contrasted with the marked lack of data suggesting a similarly increased relationship with southern Africa. The relationship between fossil and modern representatives of such genera as Podocarpus, Dacrydium, and Nothofagus suggests that there has been a northward migration or a withdrawal to warmer latitudes since the Tertiary. All the main elements of the present day flora are represented In the Tertiary assemblages. If current views on the "Malaysian" or "tropical" nature of some affinities and the "Antarctic" nature of others be accepted then there is no indication that the major migration into the Australian Region came from one particular direction. Possible climatic regimes and changes are discussed. It is suggested that the occurrence of cold pluvial conditions in southern Australia implies a contraction of the arid centre rather than a northward shift of the dry tropical belt. Under such circumstances northern Australia could still have enjoyed a warm wet climate. This opinion is supported by certain distribution patterns and by the pedological data concerning laterite formation. Apart from the Australian, Malaysian, and Antarctic elements in the Australian flora there are also temperate elements with northern hemisphere affinities. Some of these are found in temperate communities in both hemispheres but others are endemic to and characteristic of the Eremaean Zone. The Eremaean flora may have originated from a coastal sand dune and littoral type. It is suggested that it developed from elements that migrated to the Australian Region as early as the Cretaceous when there may have been a coastal continuity with the Tethys Sea. It is further postulated that these plants remained in coastal habitats but moved inland, possibly along southern estuarine coasts, and became isolated under arid conditions during the Pleistocene or Recent Times. The evidence is that eastern Australia has been a very important migration route for a very long period, being linked with the northern hemisphere through Malaysia. Northward migration of Australian elements has apparently been less successful than southward migration of Malaysian elements. It is considered that the ecological barrier formed by dense tropical communities must have inhibited northward movement of the light-requiring Australian types. The significance of such a barrier would be dependent on the climatic conditions during periods of land continuity between Australia and Malaysia and between Australia and New Guinea. Relationships between the Australian Region and Kew Zealand are either linked with those between Australia and South America, i.e. related to some unknown southern route, or they concern genera with distribution patterns involving New Guinea or New Guinea and New Caledonia. The opinion that Australia and New Zealand belong together in a biogeographic region is unacceptable unless such a, region includes a portion of the island arc in the north-east. The long-standing floristic relationship between Australia and Malaysia, a relationship which from geological evidence apparently extends back as far as the Cretaceous at least, coupled with the affinities among both fossil and modern plants with the flora of South America but not with southern Africa, militates against unqualified acceptance of any of the hypotheses, such as that of continental drift, which have been proposed to explain biological affinities between the major land masses. Plant distribution patterns are facts which can be demonstrated and at this stage of our knowledge further critical analysis is more important than the correlation between available facts and proposed explanations.