COS 155-5 - Assessing the role of climatic niche shifts in facilitating the spread of Brassica tournefortii

Wednesday, August 17, 2022

11:00 AM – 11:15 AM EDT

Location: 516D

Presenting Author(s)

CR

Clarissa Rodriguez

University of California, Riverside
Whittier, California, United States

Coauthor(s)

JF

Janet Franklin

Distinguished Professor and Biogeographer
University of California, Riverside, United States
LL

Loralee Larios

Faculty advisor
University of California, Riverside
Riverside, California, United States

Background/Question/Methods

To reduce the ecological impacts associated with plant invasions, managers must be able to identify areas vulnerable to the spread of invasive species. Species distribution modeling can be used to create spatial predictions for suitable habitat of invasive species by using occurrence data to assess a species’ breadth of climatic tolerances (i.e. realized climatic niche). However, the climatic distribution of a species in its native range may not accurately predict the distribution in the introduced range if the species is only occupying a subset of viable conditions in its home range, or is expanding its niche in the introduced range. Reconciling these discrepancies is essential to improve the accuracy of predictions for invasive spread. We used global occurrence records, climate, and soils data to quantify and model the realized niche of Brassica tournefortii, in its home range (Middle East and Eurasia) and introduced range (Southwestern United States). We asked: 1) Are there differences in B. tournefortii’s realized climatic niche between its native and introduced range? If so, what abiotic drivers are most important in shaping the distribution of B. tournefortii in its introduced range? 2) What areas within the invaded range are likely to be occupied by B. tournefortii?

Results/Conclusions

Our models detected that only 79.06% of B. tournefortii’s occupied niche was stable across regions. Within the introduced range, 20% of suitable habitat remained unoccupied, and it experienced a 28.63% niche expansion into a more arid climate compared to its native range. Altogether these results suggest B. tournefortii’s realized climatic niche is different between the native and introduced ranges. We found this species was positively associated with warm and dry temperatures, along with soils with high sand and bulk density content, consistent with habitat commonly found in North American drylands. We also found this species was negatively associated with precipitation of the wettest month, soil available water content, and soil organic carbon, suggesting that this species does well in areas that may be resource-limited. These results indicate that species distribution models based only on the introduced range may be underestimating areas at risk for invasion from this species. This research provides insights into why this species continues to invade drylands and provides an improved spatial prediction model of invasion to be used for management.