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Kunkel, David [1], Fishbein, Mark [2].

Niche Partitioning Between Two Closely Related Milkweeds, Asclepias viridis and A. asperula.

The ecological niche describes the conditions under which a species can occur and makes predictions about the coexistence of species. Assessing niche differences between closely related species is important for understanding how these species diverged, as well as for how they may coexist across a landscape. To examine niche differences between closely related species, I utilized Asclepias viridis and A. asperula, two sister milkweeds. These milkweeds share similar pollinators and are observed to coexist in the southcentral United States and are distributed to the southeast and southwest, respectively. There is also observational evidence that these two species inhabit substrate composed of different proportions of sand, silt, and clay. Based on the distributions of Asclepias viridis and A. asperula and their apparent soil preferences, I hypothesized that the modeled climatic and substrate niches of these species are different, with A. viridis occupying more mesic conditions with higher % clay and silt content and A. asperula being associated with more xeric conditions with higher % sand. I used ecological niche modelling, an approach for predicting species occurrences based on niche components, with 19 bioclimatic variables, elevation, % clay content, % silt content, % sand content, pH, and electrical conductivity to characterize their climatic and substrate niches. I found that there were significant differences between the climatic and substrate niches of these two species. However, I did not find differences in the pH and electrical conductivity of the substrate. I conclude that these closely related milkweeds, A. viridis and A. asperula, have undergone complete niche divergence in their climatic and substrate characters, with a few exceptions related to the acidity and ion content of the soils in which they are found.

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1 - 208 S Duncan St, Apt 3, Stillwater, OK, 74074, United States
2 - Oklahoma State University, Dept Of Plant Biology, Ecology & Evolution, 301 Physical Science, Stillwater, OK, 74078, United States

Niche Modeling
climatic niche
edaphic niche

Presentation Type: Oral Paper
Location: Virtual/Virtual
Date: Tuesday, July 20th, 2021
Time: 10:30 AM(EDT)
Number: BIOGII003
Abstract ID:629
Candidate for Awards:None

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