Unwelcome guests: a selective history of weed introductions to arid and semi-arid Australia

Abstract

Following European settlement of Australia, numerous plant species were deliberately introduced for use in crops, pastures, gardens and horticulture, and others arrived by chance. Many subsequently escaped and became weedy. Of the 54 weed species of natural environments of arid and semi-arid Australia that are considered here, 27 were apparently accidentally introduced, 20 were intentionally introduced and 7 were probably introduced both accidentally and intentionally. Livestock including camels and their harness, and contaminated seed and hay were the most common vectors for accidental introduction. Amongst intentional introductions, rather more ornamental species appear to have invaded successfully than pasture species, but the former generally occupy niche habitats. Recent new introductions are few due to pre-border, border and post-border protections, but many current arid zone weeds continue to spread. Understanding the history of weed invasions can help to guide current and future management by clarifying pathways for introduction.

Characterising the herbivore community and its impact on Sonchus oleraceus (Asterales: Asteraceae) in its invaded range in Australia

“…Some surveys have been undertaken to characterise the herbivores on S. oleraceus in Australia; these have been mainly conducted in the south-west of Western Australia and south-east Queensland and focused more on pathogens than phytophagous arthropods (McCarren & Scott 2013, 2017Scott & McCarren 2012). Therefore, the natural enemy's community associated to S. oleraceus in Australia remains poorly understood.…”

“…The common sowthistle, Sonchus oleraceus L. (Asteraceae), is an annual species native to Eurasia and Northern Africa (Boulos 1973), that is now widely distributed around the world (Pyšek et al 2017). In Australia, the species was likely introduced in the 19th century as contaminants of seeds and grain (Friedel 2017) and is now widespread through the country (McCarren & Scott 2013; Peerzada et al 2019).…”

Genomic diversity, chromosomal rearrangements, and interspecies hybridization in the Ogataea polymorpha species complex

“…For example, isolates from the Santa Rita Mountains (Ohag7, Ohag8, Ohag9, Ohag17, and Ohag18) do not form a monophyletic group ( Figure 2C ). The Australian samples do not show a high amount of divergence from the rest of the samples, which likely reflects the introduction of Opuntia species to Australia from their native United States with the last two to three centuries ( Friedel 2020 ).…”