Recurring seasonal changes can lead to the evolution of phenological cues. For example, many arthropods undergo photoperiodic diapause, a programmed developmental arrest induced by short autumnal day length. The selective mechanisms that determine the timing of autumnal diapause initiation have not been empirically identified. We quantified latitudinal clines in genetically determined diapause timing of an invasive mosquito, Aedes albopictus, on two continents. We show that variation in diapause timing within and between continents is explained by a novel application of a growing degree day (GDD) model that delineates a location-specific deadline after which it is not possible to complete an additional full life cycle. GDD models are widely used for predicting spring phenology by modeling growth and development as physiological responses to ambient temperatures. Our results show that the energy accumulation dynamics represented by GDD models have also led to the evolution of an anticipatory life-history cue in autumn.

Diapause incidence data collected in a common garden experiment used to calculate critical photoperiods, historical climate data, and code used for analysis and figure generation.

Files of greatest interest for reuse by diapause researchers indicated with *.

File descriptions

Ae_albopictus_CPP_experiment_data_collated.csv: experimental data
PaperID - individual oviposition paper
CageID - unique number for each mosquito cage
Cabinet - number of photoperiod cabinet
Block - first or second experimental block
Population - population name, location from which mosquitoes were collected (described in more detail in mapping_pops_cpp_expt.csv)
Country - Japan (JP) or U.S.
Lat - Latitude
Long - Longitude
Photoperiod - number of hours of light in cabinet
Generation - number of generations population reared in lab
NumPupae - number of pupae added to cage
BFDate - cage date of blood meal
OvipositionDate - date oviposition paper was collected
InitialEggs - number of eggs counted on oviposition paper
Subsampled - yes/no whether oviposition paper was subsampled prior to counting eggs
H1IndDate - date of induction of first hatch
H1CtDate - date of counting larvae in first hatch
H1Count - number of larvae in first hatch
H2IndDate - date of induction of second hatch
H2CtDate - date of counting larvae in second hatch
H2Count - number of larvae in second hatch
EmbryoCtDate - date on which embryos were counted on oviposition paper
EmbryoCount - number of embryonated eggs (pharate larvae) counted on oviposition paper
TotalHatch - (H1Count + H2Count)
TotalLarvaeEmbryos (H1Count + H2Count + EmbryoCount)

Aealbopictus_CPP_analysis.Rmd: code used to analyze data and generate figures
Place Rmd file in the same directory as data files and run script to generate figures and statistics. Note that some of the R figures were subsequently edited in Inkscape for clarity of annotations, but data presentation is substantively identical to published figures.

CPP_2008.csv
Diapause photoperiod response data from 2008 iteration of experiment; collated from https://doi.org/10.5061/dryad.68277435

* cpp_calcs_filtered.csv
Critical photoperiods from all populations from 2008 and 2018, filtering out unreliable data points, generated by R script.
pop -  population name
Estimate - critical photoperiod (hours)
StdError - standard error of critical photoperiod
Country - Japan (JP) or U.S.
lat - Latitude
year - year of mosquito population collection

cpp_calcs_unfiltered.csv
Same data as cpp_calcs_filtered.csv, but not applying filtering criteria to oviposition papers

DI_2015_FIELD.csv
Diapause incidence data from 2015 field study in Washington DC.
WeekDate - date of collection week
DOY - date converted to day of year (ordinal day)
DI - diapause incidence

FF_JP.csv
Date of first frost for all population locations in Japan, 1998-2018. Dates are given as ordinal day of the year.

FF_US.csv
Date of first frost for all population locations in the USA, 1998-2018. Dates are given as ordinal day of the year.

GDD400_JP.csv
Deadline for 400 growing degree days (GDD) remaining in the year at each population location in Japan,  1998-2018. Dates are given as ordinal day of the year.
GDD400_US.csv
Deadline for 400 growing degree days (GDD) remaining in the year at each population location in USA,  1998-2018. Dates are given as ordinal day of the year.
* GDD465_JP.csv
Deadline for 465 growing degree days (GDD) remaining in the year at each population location in Japan,  1998-2018. Dates are given as ordinal day of the year.
* GDD465_US.csv
Deadline for 465 growing degree days (GDD) remaining in the year at each population location in USA,  1998-2018. Dates are given as ordinal day of the year.

gdd_alternate_deadlines.csv
Deadlines calculated using GDD values from 300 to 600, 1998-2018. Includes deadlines calculated for an additional location in France (FRA).

MAN_2014_meantemp.csv
Daily mean temperatures (C) in Manassas location (MAN) in 2014. DOY is ordinal day of the year. CountDegrees are degrees above 10 degrees C (count toward growing degree day accumulation); UncountDegrees are temperatures below 10 degrees.

MeanTemp_replocations_2017.csv
Daily mean temperatures (C) in latitude-matched subset of population locations in 2017. DOY is ordinal day of the year.

climate_variables folder: files containing information about average monthly minimum, mean and maximum temperatures, and number of total frost days, in all locations in US and Japan, 1998-2018.