Abstract Detail

Ecology

Panko, Rebecca [1], Bunker, Daniel [2].

Urban plant evolution: A case-study with Capsella bursa-pastoris in New York City.

Urban areas present a suite of environmental changes to colonizing plant species, including habitat fragmentation, high proportion of impervious surface, and increased salinity. Despite this, some plant species have reached global distributions via success in human-dominated landscapes. Mounting evidence suggests that urbanization is driving evolutionary processes in wild plants, yet the relative roles of natural selection and genetic drift remain unclear. Shepherd’s purse (Capsella bursa-pastoris) is a cosmopolitan, early-colonizing weed commonly found in disturbed sites in urban areas. We hypothesize that urban populations have undergone adaptive evolution in abiotic stress tolerance via prolonged exposure to urban abiotic stress. Due to the highly fragmented landscape in cities, we also hypothesize that genetic drift randomly accelerates adaptation in some urban populations while stunting adaptation in others. We predict 1) plants from urban populations will demonstrate overall higher relative fitness in urban environments compared to plants from less-urban populations in reciprocal transplant and laboratory trials and 2) variation in average relative fitness will be higher among urban populations than among less-urban populations. We collected seeds from 23 populations found within 50km of Lower Manhattan, using proportion impervious surface to quantify urbanization. We conducted reciprocal transplant experiments with plants reared from 4 urban and 4 less-urban populations. Transplants at urban sites had high mortality rates due to random events (e.g., truck wheels, lawn mowers, homeless encampments). Of the transplants that survived the experiments, relative fitness (e.g., flower, seedpod, and leaf number) was not significantly different between urban and less-urban populations. Lab stress trials began in fall 2018 and are on-going. These trials subject plants reared from seed from 15 populations (8 urban; 7 rural) to extreme moisture variability. Initial data show a difference in plant growth per treatment type, but urban and less-urban populations do not currently demonstrate differences in growth within treatments. Future stress trials will measure relative fitness of plants under different soil salinity treatments. Urban areas present many abiotic challenges to wild plants, and it is difficult to predict which stressor (e.g., drought/flood, salinity, metal pollution, soil compaction) plays the largest role in shaping plant populations. Further complicating matters is the fact that C. bursa-pastoris predominantly self-pollinates, increasing the effects of genetic drift in isolated urban populations. In the future, we hope to perform population genomics on C. bursa-pastoris populations in the NYC metropolitan area to better estimate and understand the role of drift in this urban species.

1 - Rutgers University and NJIT, 195 University Ave, Newark, NJ, 07102, United States
2 - Rutgers University and NJIT, 100 Summit St, Newark, NJ, 07103, United States

Keywords:
Urban Ecology
evolution
Anthropocene.

Presentation Type: Poster
Session: P, Ecology Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PEC023
Abstract ID:787
Candidate for Awards:Ecological Section Best Graduate Student Poster