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Abstract Detail


Finch, Jessamine [1], Seglias, Alexandra [2], Fant, Jeremie [3], Kramer, Andrea [4], Havens, Kayri [5].

Gene flow illuminates patterns in milkweed field recruitment among seed sources.

Plant life history traits influence the extent and degree of gene flow across a species range. The resulting gene flow patterns can influence population differentiation and the scale of local adaptation, with implications for species responses to environmental change and sourcing of plant material for ecological restoration. Broader gene flow may hinder adaptation to local environmental conditions, resulting in wider environmental tolerance ranges as compared to species with more restricted gene flow. Thus, species with broader gene flow may be less sensitive to climate change and amendable to larger seed transfer zones. To investigate the impact of trait variation on gene flow and environmental tolerance, we paired a neutral genetic study of 19 source populations with a field recruitment study of 18 seed sources for two Asclepias spp. (milkweeds; Apocynaceae). Asclepias incarnata (swamp milkweed) is primarily self-compatible, and is largely restricted to wetlands, wet prairies, and shorelines. Conversely, Asclepias syriaca is primarily self-incompatible and is a habitat generalist, commonly found along roadsides, forest edges, and in prairies and old fields. Microsatellite data revealed extremely high gene flow for A. syriaca, with no evidence of isolation by distance. While not universal, results suggest greater habitat-specificity in A. incarnata leads to reduced gene flow and greater genetic differentiation for some populations. Furthermore, allelic richness and heterozygosity displayed positive relationships with the latitude of the population. Field recruitment was evaluated at two field sites (Illinois and Missouri), and results found low to no variation among seed sources within a field site for A. syriaca, while A. incarnata displayed significant effects of seed source, with fluctuating latitudinal patterns across early life stages (germination, emergence, establishment). Analysis of overall fitness derived from aster models, using biomass as a proxy, found a positive relationship with latitude of seed origin for A. incarnata, but no latitudinal trend for A. syriaca. Collectively, these studies support the model that variation in plant traits within genera has implications for gene flow, genetic neighborhood size, and potentially variation in adaptive traits at early life stages. Results of this study are directly relevant to ongoing monarch habitat creation and restoration efforts, as milkweeds are the obligate larval host for the imperiled monarch butterfly (Danaus plexippus).

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1 - Chicago Botanic Garden, Plant Science And Conservation, Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022, United States
2 - Denver Botanic Gardens, 909 York Street, Denver, CO, 80206, United States
3 - Chicago Botanic Gardens, Plant Biology And Conservation , 1000 Lake Cook Rd, Glencoe, IL, 60022, United States
4 - Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022, United States
5 - 1000 Lake Cook Rd, Glencoe, IL, 60022, United States

seed germination
seed sourcing
gene flow
tolernace range.

Presentation Type: Oral Paper
Session: ECO3, Ecology 3: Vegetation, Community and Restoration Ecology
Location: Tucson A/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 3:45 PM
Number: ECO3009
Abstract ID:957
Candidate for Awards:None

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