Spatial asynchrony and cross-scale climate interactions in populations of a coldwater stream fish
Date
2023
Authors
Valentine, George P., author
Kanno, Yoichiro, advisor
Hooten, Mevin B., advisor
Morrison, Ryan R., committee member
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Abstract
Climate change affects animal and plant populations over broad geographic ranges due to spatially autocorrelated abiotic conditions known as the "Moran Effect". However, populations do not always respond to broad-scale environmental changes synchronously across a landscape. We used a retrospective analysis of time-series count data (5-28 annual samples per site) at 170 stream segments dispersed over nearly 1,000 km to characterize the population structure and scale of spatial population synchrony in a coldwater stream fish (brook trout, Salvelinus fontinalis), which is sensitive to temperature and flow alterations, across its southern native range. Spatial synchrony differed by life stage and geographic region: it was stronger in the juvenile life stage than the adult life stage and in the northern sub-region than the southern sub-region. Spatial synchrony of trout populations extended to 100-150 km but was much weaker than that of climate variables such as temperature, stream flow, and precipitation. Early life stage abundance changed over time due to annual variation in summer temperature and winter and spring stream flow conditions. Climate effects on abundance differed between sub-regions and among local populations, indicating multiple cross-scale interactions where climate interacted with local habitat to generate only a modest pattern of population synchrony over space. We conclude that heterogeneous responses to climate variation lead to only a modest level of spatial synchrony among local trout populations, which leads to varying susceptibility to climate change. This response heterogeneity indicates that some local segments characterized by population asynchrony and resistance to climate variation could represent unique populations of this iconic native coldwater fish that warrant attention in their conservation planning in a changing climate. Identifying such priority populations and incorporating them into landscape-level conservation planning is imperative to their conservation. Our approach is applicable to other widespread aquatic species sensitive to climate change.
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Subject
brook trout
Portfolio Effect
synchrony
climate
Bayesian
stream fish