title: Salt- and alkaline-tolerance are linked in Acacia.
abstract: Saline or alkaline soils present a strong stress on plants that together may be even more deleterious than alone. Australia's soils are old and contain large, sometimes overlapping, areas of high salt and alkalinity. Acacia and other Australian plant lineages have evolved in this stressful soil environment and present an opportunity to understand the evolution of salt and alkalinity tolerance. We investigate this evolution by predicting the average soil salinity and pH for 503 Acacia species and mapping the response onto a maximum-likelihood phylogeny. We find that salinity and alkalinity tolerance have evolved repeatedly and often together over 25 Ma of the Acacia radiation in Australia. Geographically restricted species are often tolerant of extreme conditions. Distantly related species are sympatric in the most extreme soil environments, suggesting lack of niche saturation. There is strong evidence that many Acacia have distributions affected by salinity and alkalinity and that preference is lineage specific.
authors: CSIRO Land and Water, Canberra, Australian Capital Territory, Australia elisabeth.bui@csiro.au.
authors: Elisabeth N
authors: http://orcid.org/0000-0001-7632-1992
authors: EN
authors: Bui
authors: Centre for Australian National Biodiversity Research, CSIRO Plant Industry, Canberra, Australian Capital Territory, Australia Australian Tropical Herbarium, James Cook University, Cairns, Queensland, Australia.
authors: Andrew
authors: A
authors: Thornhill
authors: Centre for Australian National Biodiversity Research, CSIRO Plant Industry, Canberra, Australian Capital Territory, Australia.
authors: Joseph T
authors: JT
authors: Miller
mesh_terms: D000045:Acacia / Q000145:classification* / Q000502:physiology*; D000222:Adaptation, Physiological; D001315:Australia; D005075:Biological Evolution; D017753:Ecosystem; D006863:Hydrogen-Ion Concentration; D010802:Phylogeny; D054712:Salinity; D055049:Salt Tolerance; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil
keywords: salt-tolerance; soil pH; stress-tolerance