Phenotypic Variation in Adaptive Traits Among Western Populations of Showy Milkweed (\u3cem\u3eAsclepias speciose\u3c/em\u3e)

Monarch butterfly (Danaus plexippus) populations have suffered extensive declines due to habitat loss and fragmentation in wintering, migrating, and breeding ranges. Urbanization and intensive agricultural practices have reduced populations of milkweeds which monarchs depend on for reproduction. With increasing conservation concern and a prospective Endangered Species Act listing, there is increased motivation for habitat restoration projects that enhance milkweeds. Our project seeks to describe variation in adaptive traits and phenology among populations of showy milkweed from the Western US. We conducted common garden experiments, in which we propagated and grew individuals from 36 populations ranging from California to South Dakota. We used remotely sensed climate data in conjunction with morphological measures and plant growth data to identify variation in adaptive traits and correlate them to elevation and climate variation. Here we present the results of our analyses and their implications for defining seed transfer zones for showy milkweed in the context of monarch butterfly habitat restoration

Milkweed Common Garden

As Monarch Butterfly (Danuas plexippus) populations decrease, habitat restoration has become a concern. To restore habitat new populations of Showy Milkweed (Asclepias speciosa) will need to be planted. Areas may lack local, new propagules and using non-native A. speciosa in the effort to restore habitat may have detrimental effects. Non-native individuals could have poorly adapted genes for the area and hybridize with native populations creating negative effects. Here, we seek to determine the extent of putative adaptive traits among seedlings from 35 populations of A. speciosa that originate from eight provisional seed zones across the Intermountain West. We germinated seeds, propagated seedlings in a greenhouse and recorded phenotypic characteristics, survival, and germination. Adaptive traits were correlated (linear regressions) to elevation and climate variation. Trait variations were detected using ANOVAs. Here we present the results of our analyses and their implications for defining Showy Milkweed seed transfer zones in the context of monarch butterfly habitat restoration

Phenological Variation Among Western Populations of Showy Milkweed (\u3cem\u3eAsclepias speciosa\u3c/em\u3e)

Western monarch butterflies (Danaus plexippus) have declined ~97% from historic abundances in the early 1980s and are being evaluated for listing under the Endangered Species Act. Habitat loss and fragmentation in wintering, migratory, and breeding areas are considered key causes. Since monarchs depend on milkweeds (Asclepias sp.) for reproduction, there is increased interest among conservationists to plant milkweeds as habitat restoration. Showy milkweed (Aslceipias speciosa) is the most common and abundant milkweed species in the Western US. Successful habitat restoration will require germplasm that is adapted for target restoration environments and seasonal phenology. Phenological traits are adaptive, easily observable, and shaped by climate; making them helpful in genecological applications for determining seed transfer zones. We evaluated phenological variation among 35 showy milkweed populations from across the Intermountain West to determine geographic patterns of adaptive traits and their relationships to local climates using a common garden approach. We used remotely sensed climate data in conjunction with growth and reproductive phenology data to identify variation in adaptive traits and correlate them to elevation and climate variation. Here we present the results of our analyses and their implications for defining seed transfer zones for showy milkweed in the context of monarch butterfly conservation

Variation in Adaptive Traits and Seed Zone Evaluation of Showy Milkweed (\u3cem\u3eAsclepias speciosa\u3c/em\u3e)

Monarch butterfly (Danuas plexippus) populations are imperiled and in review for listing under the Endangered Species Act. Among many contributors to the decline is the loss of breeding, migratory, and overwintering habitat. Showy milkweed (Asclepias speciosa) and other obligate milkweeds are essential for monarch reproduction and have thus been cornerstones of monarch habitat restoration efforts in the Intermountain West. However, many potential restoration areas lack convenient seed sources to supply prospective efforts. Furthermore, because certain populations may be better adapted to specific local climates and selective pressures, the introduction of non-native, poorly adaptive genotypes may have negative consequences for restoration efforts and milkweed-dependent species. We used a genecological approach to identify adaptive traits among 35 showy milkweed populations from the Intermountain West to inform seed transfer zones for A. speciosa. We used morphological measures and plant growth data in conjunction with remotely sensed climate data to identify putative adaptive traits and determine how they relate to local climate variation. Here we present the results of our analyses and their implications for classifying showy milkweed seed transfer zones and maximizing restoration and conservation benefit for monarch butterflies

Do Showy Milkweed (\u3cem\u3eAsclepias speciosa\u3c/em\u3e) Leaf Characteristics Respond to Environmental Conditions?

Monarch butterfly populations have declined since the 1970s due to habitat loss and fragmentation caused by human activities. Monarch conservation efforts call for the obligate host plants, milkweeds, to be replenished across the Western US. By quantifying phenological and morphological variations of Showy Milkweed across the Intermountain West, our study will delineate seed transfer zones to maximize restorations success. Successful habitat restoration will require germplasm that is adapted for target restoration environments and seasonal phenology. We recorded leaf length, width, surface area, specific leaf area, and trichome densities from ten individuals among 35 populations raised in a common garden to inform photosynthetic capabilities, water use-efficiency, and defense against herbivory. By modeling relationships among leaf characteristics, climate and known herbivore responses, we can restore milkweed that is both best adapted to the environment, and best suited to host Monarch larvae. As existing monarch butterfly populations represent less than 1% of historic abundance, effective conservation is needed to restore numbers to sustainable levels. Here we present our methodological approach for assessing leaf characters, and evaluate the implications that leaf traits have for both plant fitness and host plant suitability for monarch butterflies