California Botanical Society

2022 Botany Speaker Series

The CalBotSoc botany speaker series aims to showcase and promote the work of early career botanists. If you are an early career botanist interested in giving a talk of general interest to our members, please email us at

Christopher_Cosma_Photo (portrait) Christopher Cosma

7689aaf3-4210-d7c1-ff51-f1642dc2786a Noah Teller

HelenFernSCI Helen Holmlund

headshot4 Avery Hill

43D1AB04-EA15-48F1-9C96-8F2C836F2EB9_1_105_c Claire Willing

image Ryan Buck

Snyder_Kristine Kristy Snyder

Coleman Mitchell Coleman

Thursday, November 10, 2022 7-8pm PT
Christopher T. Cosma, UC Riverside

"Prioritizing California Native Plants for Butterfly and Moth Conservation"

The migratory monarch butterfly—which has captivated generations of people with its perilous annual journey and its special relationship with milkweed—was recently declared endangered by the IUCN. As native habitat is increasingly degraded by climate change, urbanization, herbicides, and other stressors, the monarch’s dependence on its obligate host plant is part of what puts the species at risk. Conservation efforts have revealed that planting milkweed is critical to protect the monarch from extinction in the face of these threats. However, it is time for Lepidoptera conservation in the Western US to move beyond this narrow focus on one species. Hundreds of other Western US butterfly species are in decline, including some even more at risk of extinction than the monarch. Like the monarch, each species requires specific native plants to survive. Here, I analyze interaction data between thousands of butterfly and moth species and their native host and nectar plants to find the right plants for the right places to support entire communities of threatened Lepidoptera in California. I find that relatively few plant species support the majority of Lepidoptera species, that Lepidoptera species use discrete host and nectar plants, and that which plants are the most important varies significantly between California ecoregions and habitat types. I have integrated these analyses into a web application that helps users find the best native host and nectar plants to support butterflies and moths anywhere in California. Future work will incorporate climate change predictions to guide climate-resilient habitat design for Lepidoptera conservation.

Chris is a PhD candidate in Dr. Nicole Rafferty's lab in the Evolution, Ecology, and Organismal Biology Department at UC Riverside. His research focuses on how climate change is affecting moths and their interactions with native plants in California. He has developed a tool called The Butterfly Net that helps people find the best native host and nectar plants for butterflies and moths anywhere in California.

Moths of California

Cosma_The Butterfly Net

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2022 Schedule of Talks

13-Jan: Mitchell Coleman, Tejon Ranch Conservancy and University of California, Riverside

10-Feb: Kristy Snyder, Eastern Washington University

10-Mar: Ryan Buck, San Diego State University

12-May: Claire Willing, Stanford University

9-June: Avery Hill, Stanford University

11-Aug: Helen Holmlund, Pepperdine University

13-Oct: Noah Teller, UC Riverside

10-Nov: Christopher T. Cosma, UC Riverside

8-Dec: Brooke Rose, UC Riverside

View Recordings of Past Talks on our YouTube Channel:

Botany Speaker Series Playlist

California Botanical Society
c/o Jepson Herbarium
1001 Valley Life Sciences Building
Berkeley, California 94720-2465