Environmental threshold model for tick questing behaviour.

<p><b>a</b>) Theoretical expressions of the fitness functions (straight lines) for questing and resting ticks and the frequency distributions of temperatures (bars) in a tick population. We assume that resting ticks face declining fitness from missing opportunities to find a host as temperature increases (solid line). As temperature declines, we assume that questing ticks face costs such as an increased probability of wasting resources searching for hosts when they are too cold to move rapidly enough to grasp them, as well as increased predation risk when they can only move slowly (dashed line). The combination of these effects results in selection for switch points distributed around the temperature at which fitness from questing first begins to exceed the fitness from resting (arrow). <b>b</b>) A difference or change in the distribution of temperatures (pale bars vs dark bars) should be accompanied by a parallel shift in the fitness functions (black vs grey lines) and therefore a proportional change in the mean of the switch point distribution (arrows). <b>c</b>) Temperature-dependent effects on the fitness of one of the phenotypic states (e.g. questing), will alter the slope of the fitness function (from solid black line to solid grey line) this will alter the switch point favoured by selection and result in an evolutionary shift in the switch point distribution to the new average switch point temperature (from solid arrow to dashed arrow). <b>d</b>) Temperature independent effects e.g. a reduction in host numbers, will affect the fitness of both phenotypes equally (dashed lines) and will not alter the switch point temperature (arrow) that is favoured by selection.</p

Curves fitted to the predicted values from the Richards equation, for the cumulative % of <i>I. ricinus</i> in each population to initiate questing over the course of the hourly temperature increase experiments.

<p>Curves fitted to the predicted values from the Richards equation, for the cumulative % of <i>I. ricinus</i> in each population to initiate questing over the course of the hourly temperature increase experiments.</p

Results of Tukey-Kramer comparisons of the least square mean temperature at initiation of questing between tick populations.

<p>Significance level <i>P</i><0.05.</p><p>Results of Tukey-Kramer comparisons of the least square mean temperature at initiation of questing between tick populations.</p

Mean ±95% CI temperature at which questing was initiated in each tick population during the hourly temperature increase experiments.

<p>H and L =  High and Low altitude.</p

Summary statistics for the distributions (and shape of the curve) of “temperature at first questing” (°C) for five populations of <i>I. ricinus</i> from Scotland southward to France.

<p>Mean and standard deviation of the initiation of questing (Sdev.) controlling for experimental blocks, Shapiro Wilk test for the normality of the temperature at questing, Skewness and Kurtosis and their respective standard errors (SE).</p><p>Summary statistics for the distributions (and shape of the curve) of “temperature at first questing” (°C) for five populations of <i>I. ricinus</i> from Scotland southward to France.</p

Location and climate details of the five geographic locations from which ticks were collected (see methods for estimation of metabolically significant maximum temperature).

<p>“Estimated yearly mean max. temp.” refers to the annual averages of the maximum temperatures recorded for each month for the period 1971–2000.</p><p>Location and climate details of the five geographic locations from which ticks were collected (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0110028#s2" target="_blank">methods</a> for estimation of metabolically significant maximum temperature).</p

Population genetic statistics for <i>Ixodes ricinus</i> mtDNA lineages.

<p>Population genetic statistics for <i>Ixodes ricinus</i> mtDNA lineages.</p

Sampling sites of <i>Ixodes ricinus</i>.

<p>Locations given as black dots. Pie diagrams show the proportion of the three mtDNA lineages for each site, with the GB lineage colored in burgundy, the WNo lineage in orange and the Eu lineage in green. Numbers within pie diagrams refer to the site number as given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0167450#pone.0167450.t001" target="_blank">Table 1</a>. (Map made from <a href="http://www.naturalearthdata.com/" target="_blank">www.naturalearthdata.com</a>).</p

Pairwise genetic differences in concatenated fragment of mtDNA CR and cyto <i>b</i> between samples of <i>Ixodes ricinus</i> from different locations in northwest Europe.

<p>Pairwise genetic differences in concatenated fragment of mtDNA CR and cyto <i>b</i> between samples of <i>Ixodes ricinus</i> from different locations in northwest Europe.</p

Description of the fixed effects and model types used to analyse each reproductive parameter.

<p>Fixed effects (in order of appearance in table). trt  =  treatment (fed or control), HD  =  standardized hatching date of earliest brood for that individual or pair, yr  =  year, maleage  =  male age (young (yearling) or old (2+)), chicks  =  number of nestlings alive at time of measurement, chickage  =  age of chicks (7 or 8 days old), found  =  standardized date nest found. Male ID/Female ID  =  individual identity of male/female. GLMM  =  Generalized linear mixed model fit by maximum likelihood, GLM  =  General linear model, LME  =  Linear mixed model fit by maximum likelihood.</p><p>Description of the fixed effects and model types used to analyse each reproductive parameter.</p