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Abstract Extreme heat events are becoming more frequent and intense as climate variability increases, and these events inherently vary in their timing. We predicted that the timing of a heat wave would determine its consequences for insect communities owing to temporal variation in the susceptibility of host plants to heat stress. We subjected common milkweed (Asclepias syriaca) plants to in‐field experimental heat waves to investigate how the timing of heat waves, both seasonally and relative to a biotic stressor (experimental herbivory), affected their ecological consequences. We found that heat waves had multiyear, timing‐specific effects on plant–insect communities. Early‐season heat waves led to greater and more persistent effects on plants and herbivore communities than late‐season heat waves. Heat waves following experimental herbivory had reduced consequences. Our results show that extreme climate events can have complex, lasting ecological effects beyond the year of the event—and that timing is key to understanding those effects.
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Demographic consequences of an extreme heat wave are mitigated by spatial heterogeneity in an annual monkeyflower
Abstract Heat waves are becoming more frequent and intense with climate change, but the demographic and evolutionary consequences of heat waves are rarely investigated in herbaceous plant species. We examine the consequences of a short but extreme heat wave in Oregon populations of the common yellow monkeyflower (Mimulus guttatus) by leveraging a common garden experiment planted with range‐wide populations and observational studies of 11 local populations. In the common garden, 89% of seedlings died during the heat wave including >96% of seedlings from geographically local populations. Some populations from hotter and drier environments had higher fitness, however, others from comparable environments performed poorly. Observational studies of local natural populations drastically differed in the consequences of the heat wave—one population was completely extirpated and nearly half had a >50% decrease in fitness. However, a few populations hadgreaterfitness during the heat wave year. Differences in mortality corresponded to the impact of the heat wave on soil moisture—retention of soil moisture throughout the heat wave led to greater survivorship. Our results suggest that not all populations experience the same intensity or degree of mortality during extreme events and such heterogeneity could be important for genetic rescue or to facilitate the distribution of adaptive variants throughout the region.
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- Award ID(s):
- 2045643
- PAR ID:
- 10495332
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 13
- Issue:
- 8
- ISSN:
- 2045-7758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract When thermal tolerances differ between interacting species, extreme temperature events (heat waves) will alter the ecological outcomes. The parasitoid waspCotesia congregatasuffers high mortality when reared throughout development at temperatures that are nonstressful for its host,Manduca sexta. However, the effects of short‐term heat stress during parasitoid development are unknown in this host–parasitoid system.Here, we investigate how duration of exposure, daily maximum temperature, and the developmental timing of heat waves impact the performance ofC.congregataand its host¸M.sexta. We find that the developmental timing of short‐term heat waves strongly determines parasitoid and host outcomes.Heat waves during parasitoid embryonic development resulted in complete wasp mortality and the production of giant, long‐lived hosts. Heat waves during the 1st‐instar had little effect on wasp success, whereas heat waves during the parasitoid's nutritionally and hormonally critical 2nd instar greatly reduced wasp emergence and eclosion. The temperature and duration of heat waves experienced early in development determined what proportion of hosts had complete parasitoid mortality and abnormal phenotypes.Our results suggest that the timing of extreme temperature events will be crucial to determining the ecological impacts on this host–parasitoid system. Discrepancies in thermal tolerance between interacting species and across development will have important ramifications on ecosystem responses to climate change.more » « less
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Abstract PremiseTheory predicts that mixed ploidy populations should be short‐lived due to strong fitness disadvantages for the rare ploidy. However, mixed ploidy populations are common, suggesting that the fitness costs for rare ploidies are counterbalanced by ecological benefits that emerge when rare. We investigated whether differences in ecological interactions with soil microbes help to maintain a tetraploid–hexaploid population ofLarrea tridentata(creosote bush) in the Sonoran Desert, California, United States, where prior work documented ploidy‐specific root‐associated microbes. MethodsWe used a plant–soil feedback (PSF) experiment to test whether host‐specific soil microbes can alter the outcomes of intraploidy vs. interploidy competition. Host‐specific soil microbes can build up over time; thus, distance from a host plant can affect the fitness of nearby plants. ResultsSeedlings grown in soils from near plants of a different ploidy produced greater biomass relative to seedlings grown in soils from near plants of the same ploidy. Moreover, seedlings grown in soils from near plants of a different ploidy produced more biomass than those grown in soils that were farther from plants of a different ploidy. These results suggest that the ecological consequences of PSF may facilitate the persistence of mixed ploidy populations. ConclusionsThis is the first evidence, to our knowledge, that is consistent with plant–soil microbe feedback as a viable mechanism to maintain the coexistence of multiple ploidy levels in a single population.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/ece3.10397
