Distance decay is uncommon in large‐scale population synchrony of common moths: does it promote vulnerability to climate change?

Abstract

1. Large-scale spatial synchrony is common in population dynamics. In nearly all empirical data sets, population synchrony decays with distance.2. Large-scale spatial population synchrony of 20 common moth species was studied using 367 separate light-trap time series of 3-27 years, at 13-19 localities in southern Finland. The maximum distance between trap sites was ca 1075 km. The degree of spatial synchrony in three weather variables (daily mean and minimum temperature, and daily total precipitation) from 15 weather stations was also studied. Data were analysed with spatial non-parametric correlation functions (Sncf).3. Statistically significant large-scale spatial synchrony in population fluctuations occurred in 85% of the species (Scotopteryx and Diarsia mendica), as well as in all weather variables.4. Spatial synchrony decreased with distance (=distance decay) in 45% of the species, and there was no indication of distance decay in the remaining species.5. Climate change is likely to cause an increasing frequency of extreme weather events, and insects are strongly affected by such environmental stochasticity. In combination with the high frequency of large-scale spatial synchrony, which did not show distance decay as a rule in these data, even currently common moth species may become threatened in the near future.

Geographic variation in forest composition and precipitation predict the synchrony of forest insect outbreaks

“…Many studies have investigated the spatial synchrony of animal abundances or mast seed production by measuring the region-wide average strength of synchrony as a function of distance between sampled locations (Hanski and Woiwod 1993, Haynes et al 2009, Nieminen 2015. However, this approach fails to capture information about the drivers and inhibitors of synchrony that can be gleaned from spatial heterogeneity in the strength of synchrony (Walter et al 2017).…”

Interactions between body size, abundance, seasonality, and phenology in forest beetles

“…For example, less abundant species emerging in relative synchrony are likely to encounter mates more often than if their flight is spread across the season. However, the more abundant and less seasonal small‐ and intermediate‐sized species are more likely to exhibit stability within meta‐populations in the event of variable weather events and other perturbations, because neighboring populations may be dispersing during different overlapping time periods (Abbott, ; Nieminen, ). Furthermore, in this study smaller species tended to increase the length of the flight activity period during warmer years, perhaps due to an increase in bivoltinism (Altermatt, ).…”

“…While size and abundance are related to many traits, little is known about how they are associated with many other aspects of species ecology. For example, phenology, the timing of life‐history events such as adult emergence, is one of the aspects of species ecology that helps to determine species coexistence, species interactions, and community structure (Nieminen, ; Pozsgai & Littlewood, ). For many species, phenology has been shown to change over time in response to warming global temperatures (Root et al., ), and for mammals, body size has been found to scale positively with phenological sensitivity to climate change (McCain & King, ).…”

Related herbivore species show similar temporal dynamics

“…Global change including habitat degradation and fragmentation have been shown to drive changes in species distributions, abundance and spatial synchrony (Chen, Hill, Ohlemüller, Roy, & Thomas, 2011;Jiguet et al, 2010;McCarty, 2001;Nieminen, 2015;Parmesan & Yohe, 2003). However, it is unclear whether species and communities inhabiting the same habitat in a system at equilibrium would be stable.…”