Phylogenomics Reveals Deep Divergences and Cryptic Species Within a Rare Sand-Dwelling Milkweed, Asclepias tomentosa Elliott
Duran DP, Ksepka JE, Davis SA and others. Ecology and evolution, August 2025.
Read the paper Free to read · doi:10.1002/ece3.71942
What this paper is about
Asclepias tomentosa is a rare sand-dwelling milkweed of the southeastern United States, with populations in Texas, Florida and the Carolinas separated by long gaps. The authors used genome-scale data alongside morphology and ecology to test whether it is one species.
The analyses found deep divergences between those disjunct population sets, consistent with cryptic species hidden inside the current name. Work of this kind is what adds or removes names from a flora.
Summarised here from the abstract below. Not the authors’ words.
Abstract
Integrative taxonomy incorporates multiple data types to delineate and describe species and discovers hidden biodiversity (i.e., 'cryptic' species) previously undetected when relying solely on morphology. Phylogenomic data, when combined with morphological and ecological data, have revealed many cryptic species in animal and plant taxa with large geographic ranges and disjunct distributions. In the present study, we examined the genetic structure of the rare milkweed species, Asclepias tomentosa Elliott, found in the southeastern USA, with disjunct sets of populations occurring in Texas, Florida, and the Carolinas. Using multiple analyses, including a phylogenomic tree, population structure analysis, principal component analysis of SNP data, calculations of FST, and a Bayesian species delimitation model, we uncovered three well-separated genetic lineages, each corresponding to the major geographic areas. Populations from Texas were most deeply separated from the rest and were differentiated in every analysis, including previously unrecognized morphological characters. Herein, we describe these Texas populations as a new species, Asclepias tonkawae sp. nov., and discuss the conservation implications of this discovery.
Abstract reproduced from the published paper, which is licensed CC BY. Copyright remains with the authors.
Key terms
Milkweeds in this paper
- Velvetleaf Milkweed Asclepias tomentosa
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"Phylogenomics Reveals Deep Divergences and Cryptic Species Within a Rare Sand-Dwelling Milkweed, Asclepias tomentosa Elliott (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/phylogenomics-reveals-deep-divergences-and-cryptic-species-within-a-2025/. Accessed DATE.
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title = {Phylogenomics Reveals Deep Divergences and Cryptic Species Within a Rare Sand-Dwelling Milkweed, Asclepias tomentosa Elliott (listing)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/research/phylogenomics-reveals-deep-divergences-and-cryptic-species-within-a-2025/},
note = {Accessed DATE}
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