Platysace (Apiaceae) of south-western Australia: silent story tellers of an ancient human landscape

Abstract

High gene flow and a population structure corresponding to human rather than geographical drivers are likely to be genetic patterns of human-dispersed plant taxa. We examined variation in geographical structure and gene flow estimates based on three non-coding regions of plastid DNA in three south-west Australian members of the Platysace genus to identify whether a human influence on dispersion of utilized taxa was detectable. Edible tubers of Platysace deflexa and Platysace trachymenioides have been harvested historically by Noongar traditional owners, whereas Platysace effusa has no known cultural significance. We found differences between utilized and non-utilized taxa, particularly when considered against the generally complex phylogeographical patterning in south-west Australian plant taxa. Platysace effusa showed a pattern of high population divergence, low gene flow and multiple refugia, consistent with a long evolutionary history, past climatic oscillations and persistence in a highly fragmented landscape. In contrast, higher gene flow estimates, less divergence between populations and common haplotypes in P. deflexa and in P. trachymenioides over the south-eastern part of its range are consistent with anthropogenic influences. This study contributes to the understanding of human influences on south-west Australian plant taxa that have been present since the late Pleistocene, but to date have received little scientific attention.

Signatures of natural selection in a foundation tree along Mediterranean climatic gradients

“…The LES population, which is the northmost population, displays mixed affinity, being similar to both southern (green) and northern (yellow and red) populations. This is consistent with the northern areas harbouring ancestral variation in other co‐occurring species (e.g., marri; Sampson et al, 2018 ), or could indicate possible historic human influence through Aboriginal movement of plants (Lullfitz et al, 2020 ; Lullfitz, Dabb, et al, 2020 ).…”

First Nations’ interactions with underground storage organs in southwestern Australia, a Mediterranean climate Global Biodiversity Hotspot

“…In an earlier study (Lullfitz et al 2021a), we found that harvest of Platysace deflexa tubers promoted population renewal, which aligns with LK's observation of its prominence in disturbed gravel pits. The many references to Noongar carrying of USOs when travelling also concurs with genetic homogeneity among P. deflexa and P. trachymenioides populations found by Lullfitz et al (2020), and suggests that Noongar use of some USO resources may have influenced current population distributions, and even expanded their range.…”

Extensive Genetic Connectivity and Historical Persistence Are Features of Two Widespread Tree Species in the Ancient Pilbara Region of Western Australia

“…Indigenous Australians have occupied the Pilbara for at least 50 thousand years [ 113 ] and may have been important dispersers of some plant species [ 114 ]. Relatively little recognition has hitherto been given to the potential impacts of this means of dispersal on the present distributions of species and their genetic diversity, but it is likely that people have impacted the current biogeography of plant species, mobilising them for their use as food, medicine or for totemic purposes [ 114 , 115 , 116 , 117 ]. Combined with extreme meteorological events, these features provide a context for understanding the LDD observed in widespread Pilbara plant species and can form the basis of future hypotheses regarding genetic connectivity amongst the Pilbara flora.…”