BRC-BIO: Using analysis of historical and contemporary samples to elucidate mechanisms of altitudinal range expansion by plants

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Species distributions changes over time and space, often in association with environmental conditions. Due to climate change, environments are rapidly and dramatically changing. These changes have consequences for plants. The magnitude of the environmental change and the ability of plants to respond to such changes will determine their long-term fate. One way plants may respond to climate change is moving to better suited environments. Thus, range-shifts may be an important coping mechanism for plant populations when environments change. This project uses non-native populations of the model species Arabidopsis thaliana to understand the evolutionary mechanisms behind altitudinal range expansion. Non-native species are ideal, non-planned experiments useful in understanding responses to new environments. This work will leverage historical samples stored in herbaria, to directly explore changes over time. Historical samples will also be combined with samples from contemporary populations. Together, these samples will be used to explore adaptation patterns along altitudinal gradients. Integrated with the research is a long-term community outreach program at the California State University, San Bernardino (CSUSB) herbarium. This program targets campus students, their families, and K-12 students. The program aims to showcase the richness and ecological relevance of the local plant community. The herbarium also strives to bring awareness of the cultural relevance of plants. Finally, the research data will be incorporated in a Course-based Undergraduate Research Experience (CURE) to provide students with hands-on research experience. Typically, inferences about past eco-evolutionary events are based on existing populations. Unfortunately, this offers only a snapshot of long-term processes. Historical herbaria samples allow direct observation of changes over time and space. This project uses historical and contemporary samples to study the eco-evolutionary mechanisms over ~150 years of altitudinal movement in California by Arabidopsis thaliana. Data from herbaria records show that A. thaliana stayed at low altitudes for approximately 40 years. Subsequently, in the next 60 years, A. thaliana spread to elevations above 2,000m. These movement patterns, along with its status as model organism, makes A. thaliana great to investigate various questions. Including, how much of the upward elevational shift is due to adaptation? And, which traits were important? Two complementary approaches will be used to answer these questions. First, investigation of historical A. thaliana samples will identify temporal changes in distribution. Parallel study of contemporary populations across altitudinal gradients will explore patterns of local adaptation. Whole genome sequencing data of both herbaria and contemporary samples will explore what genetic changes occurred across time and space. Further, the data will be used to test for signatures of adaptation. Genomic data will also inform genome association studies. Data on fitness-related traits will identify morphological changes across time (historical samples) and space (contemporary samples) and test if they are indicative of altitude adaptation. Quantitative data will be combined with genomic data. Together, these data will be used to investigate adaptation and determine how much phenotypic plasticity is environmentally vs. genetically controlled.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.