DOI: 10.5061/dryad.0p2ngf29d
title: Climate-associated variation in the within-season dynamics of juvenile ticks in California

description: Changing climate has driven shifts in species phenology, influencing a
 range of ecological interactions from plant-pollinator to
 consumer-resource. Phenological changes in host-parasite systems have
 implications for pathogen transmission dynamics. The seasonal timing, or
 phenology, of peak larval and nymphal tick abundance may be an important
 driver of tick-borne pathogen prevalence through its effect on
 cohort-to-cohort transmission. Tick phenology is tightly linked to
 climatic factors such as temperature and humidity. Thus, variation in
 climate within and across regions could lead to differences in
 phenological patterns. These differences may in turn explain regional
 variation in tick-borne pathogen prevalence of the Lyme disease-causing
 Borrelia bacteria in vector populations in the United States (US). For
 example, one factor thought to contribute to high Lyme disease prevalence
 in ticks in the eastern US is the asynchronous phenology of ticks in that
 region, where potentially infected nymphal ticks emerge earlier in the
 season than uninfected larval ticks. This allows the infected nymphal
 ticks to potentially transmit the pathogen to hosts that are subsequently
 fed upon by the next generation of larval ticks. In contrast, in the far
 western US where Lyme disease prevalence is generally much lower, tick
 phenology is thought to be more synchronous with uninfected larvae
 emerging slightly before, or at the same time as, potentially infected
 nymphs, reducing horizontal transmission potential. Yet sampling larval
 and nymphal ticks, and their host-feeding phenology, both across large
 spatial gradients and through time, is challenging, which hampers attempts
 to conduct detailed studies of phenology to link it with pathogen
 prevalence. In this study, we demonstrate through intensive within-season
 sampling that the relative abundance and seasonality of larval and nymphal
 ticks is highly variable along a latitudinal gradient and likely reflects
 the variable climate in the far western US with potential consequences for
 pathogen transmission. We find that feeding patterns were variable and
 synchronous feeding of juvenile ticks on key blood meal hosts was
 associated with mean temperature. By characterizing within-season
 phenological patterns of the Lyme disease vector throughout a climatically
 heterogeneous region, we can begin to identify areas with high potential
 for tick-borne disease risk and underlying mechanisms at a finer scale.
description: This dataset was collected by a single individual from 11 field
 stations in California, USA between January through June in 2021. Field
 data collected includes questing ticks (i.e. collected via drag cloth
 method) and attached ticks (i.e. collected via surveillance of<em>
 Sceloporous occidentalis</em> lizards and removing attached ticks).
 Ticks have been identified to species and life stage in the laborartory
 with a dichotomous key. Only <em>Ixodes pacificus </em>ticks
 were used for this particular manuscript. Remotely sensed climate data
 comes from the Parameter-elevation Regression on Independent Slopes Model
 (PRISM Climate Group, Oregon State University) and can be freely accessed
 online (https://prism.oregonstate.edu).
description: # Climate-associated variation in the within-season dynamics of juvenile
 ticks in California
 [https://doi.org/10.5061/dryad.0p2ngf29d](https://doi.org/10.5061/dryad.0p2ngf29d) ## Description of the data and file structure This dataset was collected by a single individual from 11 field stations in California, USA between January through June in 2021. Field data collected includes questing ticks (i.e. collected via drag cloth method) and attached ticks (i.e. collected via surveillance of *Sceloporous occidentalis* lizards and removing attached ticks). Ticks have been identified to species and life stage in the laboratory with a dichotomous key. Only *Ixodes pacificus *ticks were used for this particular manuscript. Remotely sensed climate data comes from the Parameter-elevation Regression on Independent Slopes Model (PRISM Climate Group, Oregon State University) and can be freely accessed online ([https://prism.oregonstate.edu](https://prism.oregonstate.edu)). ### Files and variables #### File: drag\_climate\_lifestage.csv **Description:** Ticks collected via drag cloth sampling merged with remotely sensed climate data. This format is easier for plotting. ##### Variables * reserve: a unique site in the University of California Natural Reserve System * date: date of collection * life_stage: life stage of ticks (larva, nymph, adult) * count: total ticks collected during a sampling period (reserve-plot-month) * month_numeric: calendar months coded 1-12 * month_name: calendar months name * ppt: precipitation (mm) * tmax: maximum temperature (C) at reserve-plot-month (~4 k resolution) * tmean: mean temperature (C) at reserve-plot-month (~4 k resolution) * tmin: minimum temperature (C) at reserve-plot-month (~4 k resolution) * vpdmax: maximum vapor pressure deficit (kPA) at reserve-plot-month (~4 k resolution) * vpdmin: minimum vapor pressure deficit (kPA) at reserve-plot-month (~4 k resolution) * ppt_month: total precipitation (mm) per month at reserve-plot-month (~4 k resolution) * ppt_prior_month: total precipitation (mm) of previous month at reserve-plot-month (~4 k resolution) * region: latitudinal region gradient (northern, central, southern) * location: climatic location gradient (coastal, inland) #### File: drag\_climate\_nolifestage.csv **Description:** Ticks collected via drag cloth sampling merged with remotely sensed climate data. This format is easier for analysis. ##### Variables * reserve: a unique site in the University of California Natural Reserve System * date: date of collection * count: total ticks collected during a sampling period (reserve-plot-month) * month_numeric: calendar months coded 1-12 * month_name: calendar months name * ppt: precipitation (mm) * tmax: maximum temperature (C) at reserve-plot-month (~4 k resolution) * tmean: mean temperature (C) at reserve-plot-month (~4 k resolution) * tmin: minimum temperature (C) at reserve-plot-month (~4 k resolution) * vpdmax: maximum vapor pressure deficit (kPA) at reserve-plot-month (~4 k resolution) * vpdmin: minimum vapor pressure deficit (kPA) at reserve-plot-month (~4 k resolution) * ppt_month: total precipitation (mm) per month at reserve-plot-month (~4 k resolution) * ppt_prior_month: total precipitation (mm) of previous month at reserve-plot-month (~4 k resolution) * region: latitudinal region gradient (northern, central, southern) * location: climatic location gradient (coastal, inland) #### File: liz\_climate\_nolifestage.csv **Description:** Ticks collected via lizard surveillance where visible ticks were removed and labeled 'lizard_ticks' and merged with remotely sensed climate data. This format is easier for plotting. ##### Variables * reserve: a unique site in the University of California Natural Reserve System * month_numeric: calendar months coded 1-12 * lizard_num: individual lizard identifier collected at reserve-plot-month (up to 15 lizards were sampled per sampling) * count: total attached ticks per lizard * month_name: calendar months name * date: date of collection * ppt: precipitation (mm) * tmax: maximum temperature (C) at reserve-plot-month (~4 k resolution) * tmean: mean temperature (C) at reserve-plot-month (~4 k resolution) * tmin: minimum temperature (C) at reserve-plot-month (~4 k resolution) * vpdmax: maximum vapor pressure deficit (kPA) at reserve-plot-month (~4 k resolution) * vpdmin: minimum vapor pressure deficit (kPA) at reserve-plot-month (~4 k resolution) * ppt_month: total precipitation (mm) per month at reserve-plot-month (~4 k resolution) * ppt_prior_month: total precipitation (mm) of previous month at reserve-plot-month (~4 k resolution) * region: latitudinal region gradient (northern, central, southern) * location: climatic location gradient (coastal, inland) #### File: liz\_climate\_lifestage.csv **Description:** Ticks collected via lizard surveillance where visible ticks were removed and labeled 'lizard_ticks' and merged with remotely sensed climate data. This format is easier for analysis. ##### Variables * reserve: a unique site in the University of California Natural Reserve System * date: collection date * lizard_num: individual lizard identifier collected at reserve-plot-month (up to 15 lizards were sampled per sampling) * count: total attached ticks per lizard * lifestage: life stage of ticks (larva, nymph, adult) * month_numeric: calendar months coded 1-12 * month_name: calendar months name * ppt: precipitation (mm) * tmax: maximum temperature (C) at reserve-plot-month (~4 k resolution) * tmean: mean temperature (C) at reserve-plot-month (~4 k resolution) * tmin: minimum temperature (C) at reserve-plot-month (~4 k resolution) * vpdmax: maximum vapor pressure deficit (kPA) at reserve-plot-month (~4 k resolution) * vpdmin: minimum vapor pressure deficit (kPA) at reserve-plot-month (~4 k resolution) * ppt_month: total precipitation (mm) per month at reserve-plot-month (~4 k resolution) * ppt_prior_month: total precipitation (mm) of previous month at reserve-plot-month (~4 k resolution) * region: latitudinal region gradient (northern, central, southern) * location: climatic location gradient (coastal, inland) #### ## Code/software Data were cleaned and analyzed in RStudio version 4.1.0 The following R packages were used for cleaning and analysis: ggplot2, lme4, MASS, prism, tidyverse, psych. ## Access information Other publicly accessible locations of the data: * data and code to run analyses and make figures can be found: [https://github.com/sbsambado/UCNRS_Phenology](https://github.com/sbsambado/UCNRS_Phenology)  Data was derived from the following sources: * Climate data for each reserve was accessed from the Parameter-elevation Regression on Independent Slopes Model (PRISM Climate Group, Oregon State University, [https://prism.oregonstate.edu](https://prism.oregonstate.edu)), which provides estimates of primary climate elements such as mean temperature (tmean, °C), precipitation (ppt, mm), and maximum vapor pressure deficit (vpdmax, kPA)