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<p>Answering conservation-related questions about rare or extinct plants can be challenging given the difficulty in obtaining samples for genetic analysis, but herbarium specimens can offer historic genetic samples to address these questions. One outstanding question in Western Australia relates to the species distinction of a conservation-listed plant, <i>Adenanthos eyrei</i> E.C.Nelson, which was collected once in the 1970s but never again despite survey efforts. We set out to assess whether <i>A. eyrei</i> represented a morphological variant of the sympatric <i>A. forrestii</i> F.Muell., a hybrid between <i>A. cuneatus</i> Labill. and <i>A. forrestii</i>, or a distinct species. Given the lack of recent collections, we sequenced genomic DNA from two fifty-year-old specimens: the type of <i>A. eyrei</i> and a putative hybrid <i>A. cuneatus</i> × <i>forrestii</i>. We used genome skimming for the herbarium samples and 74 fresh samples from populations of six <i>Adenanthos</i> species to assemble full chloroplast genomes (cpDNA) and the nuclear ribosomal DNA (nrDNA) region. We also assembled Angiosperms353 (A353) loci from the skimming data to improve phylogenetic resolution, and we called A353 SNPs for clustering. Our results showed that <i>A. eyrei</i> and the putative hybrid (1) shared cpDNA with nearby <i>A. forrestii</i> populations, (2) were heterozygous at nrDNA positions of fixed difference between <i>A. cuneatus</i> and <i>A. forrestii</i>, and (3) were placed intermediately between the putative parents in A353 trees and SNP-based clustering analyses, consistent with a hybrid origin for both specimens. The finding that <i>A. eyrei</i> is a hybrid has implications for its taxonomy and conservation. We transfer the name to recognise it as a nothotaxon, <i>A.</i> × <i>eyrei</i>, and suggest that its conservation listing needs to be re-evaluated.</p>

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Sequencing of historic specimens helps to clarify the long uncertain species distinction of a rare plant, Adenanthos eyrei E.C.Nelson (Proteaceae)

  • 期刊论文

  • 发表日期：

    2026年5月27日

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  • Benjamin M. Anderson,
  • Emma D. Adams,
  • Brendan J. Lepschi,
  • Katherine M. Taylor,
  • Rachel M. Binks

摘要

Answering conservation-related questions about rare or extinct plants can be challenging given the difficulty in obtaining samples for genetic analysis, but herbarium specimens can offer historic genetic samples to address these questions. One outstanding question in Western Australia relates to the species distinction of a conservation-listed plant, Adenanthos eyrei E.C.Nelson, which was collected once in the 1970s but never again despite survey efforts. We set out to assess whether A. eyrei represented a morphological variant of the sympatric A. forrestii F.Muell., a hybrid between A. cuneatus Labill. and A. forrestii, or a distinct species. Given the lack of recent collections, we sequenced genomic DNA from two fifty-year-old specimens: the type of A. eyrei and a putative hybrid A. cuneatus × forrestii. We used genome skimming for the herbarium samples and 74 fresh samples from populations of six Adenanthos species to assemble full chloroplast genomes (cpDNA) and the nuclear ribosomal DNA (nrDNA) region. We also assembled Angiosperms353 (A353) loci from the skimming data to improve phylogenetic resolution, and we called A353 SNPs for clustering. Our results showed that A. eyrei and the putative hybrid (1) shared cpDNA with nearby A. forrestii populations, (2) were heterozygous at nrDNA positions of fixed difference between A. cuneatus and A. forrestii, and (3) were placed intermediately between the putative parents in A353 trees and SNP-based clustering analyses, consistent with a hybrid origin for both specimens. The finding that A. eyrei is a hybrid has implications for its taxonomy and conservation. We transfer the name to recognise it as a nothotaxon, A. × eyrei, and suggest that its conservation listing needs to be re-evaluated.