Data file is created with Microsoft Excel 2010. Data are acquired experimentally by rearing offspring of wild-caught
females (column heading: Family) sampled from 18 locations (column heading: Population) forming a cline from
southern Estonia to northern Finland (exact locations given under column headings Longitude and Latitude in the
data). Three populations originated from a region where the study species (Chiasmia clathrata, Geometridae,
Lepidoptera) expresses strictly univoltine phenology (i.e. one generation per season), 10 populations from a partially
bivoltine region and five populations from a predominantly bivoltine region (i.e. two generations per season)
(column heading: Region). Length of the season favorable for insect development and growth (column heading:
Seasonlength) for each location was derived from data provided by Finnish Meteorological Institute and Estonian
Meteorological Institute for years 2001–2008. Sampling site-specific season length was estimated as the number of
days when average daily temperature had been either above or equal to 10°C by fitting a generalized additive model
[function gam (Wood, 2006) in R 2.10.1 (R Development Core Team, 2009)] to the data on average daily
temperatures in a particular location. Five offspring (column heading: Individual) of each wild-caught female were
reared under standardized laboratory conditions (continuous light at 20ºC) on the natural host plant Lathyrus
pratensis.
The duration of larval period (column heading: Development_time_(days)) was determined as days since the egg
hatched until the larval ceased feeding and started to pupate. Five days later, the pupa was weighed to the nearest
0.01 mg with a precision balance (Mettler Toledo MT 5) to determine its acquired mass (column heading:
Pupalmass_(mg)) and sexed based on the cuticular genital scars (see Scoble, 1992) (column heading: Sex). The pupae
were maintained under the same conditions as larvae. Individuals that did not eclose within a month were
considered as diapausing ones, whereas the ones that eclosed had entered the direct developmental pathway
(column heading: Developmental_pathway).
An index of larval growth rate (c) was derived from the growth model by Tammaru and Esperk (2007):
c
m pupa
1 /(1b )
t larva
,
(1)
where mpupa is pupal mass, tlarva is larval development time and b is an allometric exponent relating anabolism to
body mass. We used a b value of 0.8, which seems a reasonable estimate for a species of this size (Tammaru &
Esperk, 2007. To test sensitivity of the results, the analyses of growth rate variation were repeated with b = 0.75 and
b = 0.85. Absolute growth rates were standardized for analysis by subtracting the mean and dividing by the standard
deviation because the R function lme (Pinheiro et al., 2009) was unable to estimate the variance components
reliably when absolute values were used. The respective standardized growth rate values are given under column
headings “Standardized_growth_rate_b_0.85”, “Standardized_growth_rate_b_0.8” and
“Standardized_growth_rate_b_0.75”
NA’s in the data stand for missing measurements as some larvae died or did not manage to pupate properly making
estimation of the above variables unreliable.
Pinheiro, J., Bates, D., DebRoy, S.,Sarkar, D. & the R Core team. 2009. nlme: Linear and Nonlinear Mixed Effects
Models. R package version 3.1-96. URL http://www.r-project.org/.
Scoble, M.J. 1992. The Lepidoptera – form, function and diversity. The Natural History Museum / Oxford Univ. Press,
Suffolk, UK.
Tammaru, T. & Esperk, T. 2007. Growth allometry in immature insects: larvae do not grow exponentially. Funct. Ecol.
21: 1099–1105.
R Development Core Team 2009. R: A language and environment for statistical computing. R Foundation for
Statistical Computing, Vienna, Austria. URL http://www.r-project.org/.
Wood, S.N. 2006. Generalized Additive Models: An Introduction with R. Chapman and Hall ⁄ CRC, Boca Raton, US.