- Award ID(s):
- 2019323
- PAR ID:
- 10448519
- Date Published:
- Journal Name:
- Journal of The Royal Society Interface
- Volume:
- 20
- Issue:
- 205
- ISSN:
- 1742-5662
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Synopsis Our article describes the explosive seed dispersal of the Hura crepitans fruit. Through high-speed video analysis of an exploding fruit, we observe that the seeds fly with backspin as opposed to topspin, which was previously assumed. Backspin orients seeds to minimize drag during flight and consequently increases dispersal distance. The seeds’ dispersal distance is estimated by using results from the seeds of Ruellia ciliatiflora, which are similarly shaped but ∼10 times smaller than those of H. crepitans. We note that the effects of lowering drag on the dispersal distance are more pronounced at higher speeds. We also see that the effect of launch height on the dispersal distance of the seeds becomes less consequential at higher launch speeds. We conclude that the increased dispersal distance due to flying with backspin should improve fitness in colonizing new habitats or escaping disease or predation and that comparisons of the seed dispersal mechanisms across species within the Euphorbiaceae and Acanthaceae might help reveal the adaptive significance of this behavior.more » « less
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Overwintering monarch (Danaus plexippus) populations have declined since the 1990s. In response, restoration of milkweeds, including Asclepias syriaca (common milkweed), an important host plant in their breeding grounds, has become increasingly common. However, latitudinal variation in milkweed populations suggests the possibility of regional adaptation and the potential for seed provenance to affect restoration success. Using seeds from 20 populations throughout the range of A. syriaca, we tested whether seed mass, germination success, and germination time in the greenhouse demonstrate geographic clines consistent with available evidence for this species from other studies. In addition, we tested for patterns in germination traits consistent with adaptation to spring thermal conditions by planting seeds from 10 populations in growth chambers simulating Minnesota and Kentucky spring temperatures. Even after accounting for seed mass, seeds from higher latitudes germinated faster on average under all conditions. Elevated temperatures accelerated germination time and leaf development time; however, we did not detect geographic patterns in leaf development time, indicating that the processes underlying the latitudinal cline in germination time may be unique to the germination stage. In the thermal adaptation study, high-latitude populations produced larger seeds and seeds that germinated at a higher rate; however, neither latitudinal trend was observed in the geographic clines study, even though individual seed mass predicted germination success. High-latitude populations express more favorable germination traits in every setting measured, perhaps due to reduced dormancy. Consequently, we conclude that latitudinal clines are more consistent with adaptation to growing season length than to spring temperatures.more » « less
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