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University of California Santa Cruz (2018)

Cascading Effects of Climate Stress on Plant–Pollinator Interactions

Ashbacher, Angelita

Titre : Cascading Effects of Climate Stress on Plant–Pollinator Interactions

Auteur : Ashbacher, Angelita

Université de soutenance : University of California Santa Cruz

Grade : Doctor Philosophy (PhD) 2018

Résumé partiel
Plant-pollinator communities vary over landscapes, seasons, and years. This inherently high variation can be linked at least in part to seasonal climates. Early spring temperature and rainfall are important cues for plant germination (Ackerly 2004, Carta et al. 2013, Nonogaki and Nonogaki 2016), flowering (Glover 2008, Tooke and Battey 2010) and other life-cycle events (Chuine et al. 2013). Rearing temperature also influences the growth, development, and consequently emergence time of pollinating insects (Kemp and Bosch 2005, Kingsolver and Huey 2008). While these plant-pollinator cues often align, physiological responses to climate stress in plants or pollinators can induce mismatches that could negatively impact the larger community of interacting species. Recent climate change alters ecologically important mutualistic interactions that may have far-reaching consequences for ecosystems (Tylianakis et al. 2008, Hegland et al. 2009). For instance, increasingly warmer temperatures cue some plant species to flower at unusual times (Wolkovich et al. 2012) that their pollinators do not always track (Inouye 2008, Lambert et al. 2010, Kudo and Ida 2013, Caradonna et al. 2014). Resource-based mismatches may also develop as plants physiologically respond to environmental stress by allocating resources away from reproduction and toward survival (Memmott et al. 2007, Scaven and Rafferty 2013, De la Luz 2018a). On a geographical scale, species’ ranges may shift as pollinators expand their foraging ranges to higher elevations or latitudes over time to escape temperature stress (Kelly and Goulden 2008, Parmesan and Hanley 2015). Resource exchange between plants and pollinators ultimately influences population-level reproductive success for both trophic levels (Wang and Smith 2002, Bascompte and Jordano 2014a). Despite the ecological importance of pollination for both biodiversity and ecosystem function (Potts et al. 2006, Bascompte and Jordano 2007, Albrecht et al. 2012, Hanley et al. 2015, IPBES 2016) there are only a few known plant-pollinator datasets that cover a long enough time frame to specifically address the potential negative impacts of recent climate change or other stressors on those communities in natural ecosystems (reviewed in Burkle and Alarcón 2011, Burkle et al. 2013). My dissertation explores how individual physiological responses to temperature and water stress, scale up to impact plant-pollinator network structure, ecosystem function, and biodiversity. I examine how plant-pollinator networks in two habitats are structured in relation to intrinsic abiotic stressors, and how those habitats have changed over the past twenty years. In the lab and greenhouse, I test how temperature and water availability influence nectar output in three native plant species. Then I follow bumblebee foraging patterns on those plant species in controlled choice trials. In a separate set of experiments, I test how nectar diet influences a bumblebee’s ability to metabolically cool their bodies while under acute heat stress.

Présentation et version intégrale

Page publiée le 9 octobre 2018