COS 154-1 - CANCELLED - Temperature niche determines phenological sensitivity of moths to urban heat island effects in a subtropical environment

Abstract: Urbanization is an anthropogenic disturbance that can dramatically disrupt ecological processes and is known to impact biodiversity by advancing the timing of life history events (i.e., the phenology) of organisms due to the urban heat island effect. However, much of the evidence showing that urban warming leads to earlier phenological events comes from research in temperate areas with high temperature seasonality. Plants and animals in low-latitude areas may have phenologies less sensitive to such effects since temperature is likely a weaker phenological cue in tropical areas. Additionally, insects may have phenological sensitivities that vary across life stages. However, sampling across multiple life stages rarely occurs in tandem, limiting our ability to examine phenological effects to the same stressor across two life stages. Here, we use repeated structured surveys across an entire year to test how the timing of peak abundance is impacted by urbanization in a subtropical moth community across caterpillar and adult life stages. We first examine how the timing of abundance peaks are influenced by urbanization variables at the overall adult and caterpillar community-level. We then examine how urbanization responses are mediated across species-specific life history traits for adult macro-moths.



We found strong evidence that urbanization influences the phenology of moths in a subtropical city, and that the phenological sensitivity to urbanization varies across life history traits and life stages. Specifically, we found that urbanization delayed the pooled peak abundance for caterpillars but advanced the pooled peak abundance of macro-moths. This result was contrary to our prediction that urbanization would impact the phenology of moths similarly across life-stage and highlights the need for experiments to disentangle the processes that may lead to differing responses across life stages. For macro-moths, we were able to estimate the timing of peak abundance for individual species. We found that the timing of peak macro-moth abundance is related to the temperature of the site, the temperature niche of the moth species, and the interaction between these variables. Cold adaptive species are more phenologically sensitive to urban warming than warm adaptive ones. These results suggest that evolutionary context is important in predicting which species will shift their phenology in response to urban heat islands in low-latitude, but not fully tropical environments. These results also provide a testable hypothesis to examine if the temperature niche of different groups of organisms, such as plants, describes the variable phenological response of subtropical plants to urbanization.