Impacts of land cover data selection and trait parameterisation on dynamic modelling of species' range expansion

Peer reviewedPublisher PD

A regionally informed abundance index for supporting integrative analyses across butterfly monitoring schemes

1. The rapid expansion of systematic monitoring schemes necessitates robust methods to reliably assess species' status and trends. Insect monitoring poses a challenge where there are strong seasonal patterns, requiring repeated counts to reliably assess abundance. Butterfly monitoring schemes (BMSs) operate in an increasing number of countries with broadly the same methodology, yet they differ in their observation frequency and in the methods used to compute annual abundance indices. 2. Using simulated and observed data, we performed an extensive comparison of two approaches used to derive abundance indices from count data collected via BMS, under a range of sampling frequencies. Linear interpolation is most commonly used to estimate abundance indices from seasonal count series. A second method, hereafter the regional generalized additive model (GAM), fits a GAM to repeated counts within sites across a climatic region. For the two methods, we estimated bias in abundance indices and the statistical power for detecting trends, given different proportions of missing counts. We also compared the accuracy of trend estimates using systematically degraded observed counts of the Gatekeeper Pyronia tithonus (Linnaeus 1767). 3. The regional GAM method generally outperforms the linear interpolation method. When the proportion of missing counts increased beyond 50%, indices derived via the linear interpolation method showed substantially higher estimation error as well as clear biases, in comparison to the regional GAM method. The regional GAM method also showed higher power to detect trends when the proportion of missing counts was substantial. 4. Synthesis and applications. Monitoring offers invaluable data to support conservation policy and management, but requires robust analysis approaches and guidance for new and expanding schemes. Based on our findings, we recommend the regional generalized additive model approach when conducting integrative analyses across schemes, or when analysing scheme data with reduced sampling efforts. This method enables existing schemes to be expanded or new schemes to be developed with reduced within-year sampling frequency, as well as affording options to adapt protocols to more efficiently assess species status and trends across large geographical scales

Effects of Natura 2000 on nontarget bird and butterfly species based on citizen science data

ABSTRACT The European Union's Natura 2000 (N2000), is one of the largest international networks of protected areas. One of its aims is to secure the status of a pre-determined set of (targeted) bird and butterfly species. However, also non-target species may benefit from N2000. We evaluated how the terrestrial component of this network relates to the abundance of non-targeted, more common bird and butterfly species using data from long-term volunteer-based monitoring programs in 9,602 sites for birds and 2,001 sites for butterflies. In almost half of the 155 bird species assessed, and particularly among woodland specialists, abundance increased with the proportion of N2000 sites in the landscape. The corresponding positive relationship was found for 27 of the 104 butterfly species, although most of these species were generalists. These positive relationships disappeared for most of the species when land-cover covariates were taken into account, hinting that land-cover is a primary factor defining the positive effects of the N2000 network. The increase in abundance with N2000 was correlated with the specialization index for bird species, but not for butterfly species. Although the N2000 network supports higher abundance of a large spectrum of species, the low number of specialist butterfly species showing a positive association stresses the need to implement management plan improving the quality of habitats of N2000 areas potentially harboring openland butterfly specialists. For a better understanding of the processes involved, we advocate for a standardized collection of data on N2000 sites. Article impact statement: Across Europe the abundance of a majority of nontarget birds and a quarter of nontarget butterflies increased with Natura 2000 coverage. This article is protected by copyright. All rights reservedpeerReviewe

Urbanization extends flight phenology and leads to local adaptation of seasonal plasticity in Lepidoptera

Abstract Urbanization is gaining force globally, which challenges biodiversity, and it has recently also emerged as an agent of evolutionary change. Seasonal phenology and life cycle regulation are essential processes that urbanization is likely to alter through both the urban heat island effect (UHI) and artificial light at night (ALAN). However, how UHI and ALAN affect the evolution of seasonal adaptations has received little attention. Here, we test for the urban evolution of seasonal life-history plasticity, specifically changes in the photoperiodic induction of diapause in two lepidopterans, Pieris napi (Pieridae) and Chiasmia clathrata (Geometridae). We used long-term data from standardized monitoring and citizen science observation schemes to compare yearly phenological flight curves in six cities in Finland and Sweden to those of adjacent rural populations. This analysis showed for both species that flight seasons are longer and end later in most cities, suggesting a difference in the timing of diapause induction. Then, we used common garden experiments to test whether the evolution of the photoperiodic reaction norm for diapause could explain these phenological changes for a subset of these cities. These experiments demonstrated a genetic shift for both species in urban areas toward a lower daylength threshold for direct development, consistent with predictions based on the UHI but not ALAN. The correspondence of this genetic change to the results of our larger-scale observational analysis of in situ flight phenology indicates that it may be widespread. These findings suggest that seasonal life cycle regulation evolves in urban ectotherms and may contribute to ecoevolutionary dynamics in cities

The total population abundance and range dynamic statistics for <i>Maniola jurtina.</i>

<p>The statistics include projected total number of <i>Maniola jurtina</i> individuals (A–B), number of 200×200 m cells occupied (C–D) and maximal range shift of the butterfly (E–F) at the end of a 50 year dynamic simulation period. Simulations were conducted using RangeShifter, a dynamic and individual-based modelling platform, and either summed cover of CORINE classes ‘Pastures’ and ‘Natural grassland’ (A, C, E) vs. open grasslands included in the National Survey of Traditional Rural Biotopes and grasslands managed via Agri-environment Scheme (B, D, F). All nine different simulation settings included 100 replicate runs. Species parameterisation: BASE = the default model parameterisation (K = 250; DL = 3000 m; DP = 0.90; GR = 2.0); alternative values for mean distance of long-distance dispersal events (DL1 = 1500 m, DL2 = 5000 m), probability of short-distance events (DP1 = 0.80, DP2 = 0.95), growth rate (GR1 = 1.5, GR2 = 2.5) and carrying capacity (K1 = 200, K2 = 300).</p

Difference in the amount of estimated suitable grasslands between the two land cover datasets.

<p>The distribution of differences was calculated by subtracting the amount of open grasslands in the National Survey-AES(-SLICES) databases from the amount of CORINE land cover types deemed as suitable for the two study species. The differences are shown in hectares across the 10×10 km grid cells of the simulation area. (A) <i>Maniola jurtina</i>: National Survey-AES grasslands were subtracted from the summed cover of the CORINE types ‘Pastures’ and ‘Natural grassland’; (B) <i>Issoria lathonia</i>:, National Survey-AES-SLICES grasslands were subtracted from the CORINE types ‘Pastures’, ‘Natural grassland,‘Land principally occupied by agriculture, with significant areas of natural vegetation’, ‘Abandoned arable land’ and field margins measured based on the CORINE class ‘arable land’.</p

Example output for the simulated range expansion of <i>Issoria lathonia</i> in S Finland.

<p>Probability of a 200×200 m grid cell to be occupied after a 50-year simulation run is depicted with a colour ramp from red (high) to orange (intermediate) and yellow (low), with areas in dark blue having a probability of zero. Simulations were done using (A) CORINE data and default values for species traits, (B) CORINE data and increased carrying capacity value, and (C) AES – National Survey – SLICES data and default values for species traits. In (B), areas in pink indicate 200×200 m cells projected to have a population only when the higher carrying capacity is assumed.</p