Thermal traits, such as upper and lower critical thermal limits, are vital indicators of the vulnerability of populations and species to environmental change. Thus, accurate estimates of these traits are needed to explain biological patterns and forecast responses to the changing thermal environment. However, many thermal trait studies measure relatively few individuals to estimate traits for whole populations or species. To ascertain if, and how, sample size affects the accuracy of reported trait means and variances, we applied a subsampling and equivalency testing approach to empirical and simulated trait data to investigate the accuracy of trait estimates relative to sample size and the skew and variance of the trait distribution in the source population. Simulation results indicated that only 7.9% of the 428 critical thermal limit traits documented in a recent synthesis of thermal trait data reported sufficiently large sample sizes, relative to variance, to ensure confidence in the reported mean trait value with negligible (±0.25°C) error. Greater inter‐individual trait variance in the source population requires a larger number of individuals to be measured to accurately estimate the mean and variance of that trait. This pattern is mitigated somewhat by the tendency of thermal traits to exhibit skew‐normal distributions. As measurements of few individuals from a population are unlikely to provide accurate estimates of thermal traits, the propensity towards small sample sizes in thermal trait studies is concerning. Macrophysiological syntheses often use these data to describe, explain and predict broad‐scale ecological patterns. Thus, insufficient sample sizes in the original studies could diminish the robustness of these patterns and predictions. For future studies, we recommend that preliminary data be used to estimate trait variance and calculate minimum sample sizes. If small sample sizes are unavoidable, larger error around the measured trait mean must be assumed and accounted for in subsequent analyses. A free Plain Language Summary can be found within the Supporting Information of this article.

Two primary patterns of body size variation have been recorded in ectotherms in relation to latitudinal/altitudinal shifts. In some, body size increases with increasing latitude/altitude whereas, in others, body size decreases with increasing latitude/altitude. This clinal variation is generally assumed to be caused by local adaptation to environmental conditions however the selective variable(s) (temperature, humidity, diet quality, etc.) is still heavily debated. Here we investigate geographic variation in body size of dark and pale color morphs of males of the bush-cricket Isophya rizeensis collected from 15 locations along an elevation gradient ranging from 350 to 2 500 m. Using an information theoretical approach we evaluate the relative support of four different hypotheses (the temperature size rule, the moisture gradient hypothesis, the seasonal constraint hypothesis, and the primary productivity hypothesis) explaining body size variation along the altitudinal gradient. Body size variation in pale color morphs showed a curvilinear relationship with altitude while dark color morphs showed no variation in body size. Body size variation in pale color morphs was highly correlated with precipitation and temperature seasonality values thus giving strong support for the moisture gradient and seasonal constraint hypothesis. Our results reinforce the importance of gradients in humidity and seasonality over temperature in the creation of altitudinal body size clines and the role of selection for resistance to stress factors in the establishment of these clines. Whether a body size cline is observed or not might also depend on the phenotypic properties of the individuals, like coloration.

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The hard tick Hyalomma marginatum Koch, 1844 is the main vector of Crimean Congo hemorrhagic fever (CCHF). Although this disease is a serious public health concern in Turkey, there is still no information about population structure and genetic diversity of this tick species. In this study, the genetic structure of H. marginatum populations collected from nine different locations of Turkey were evaluated using five microsatellite markers. A total of 75 H. marginatum samples were collected from domestic animals and genotyped. We hypothesized that localities which have high CCHF incidence rates (Bayburt, Amasya and Tokat) might be genetically distinct from the localities with low incidence rates. All approaches used in this study (DAPC, STRUCTURE and FST) showed low levels of genetic diversity. Although, no genetic pattern was observed between localities that can be associated with CCHF incidence rates, there was moderate genetic differentiation between Igdir and Tekirdag populations (FST = 0.142) and also between Igdir and Mugla populations (FST = 0.128). DAPC confirmed this finding, as Igdir, Mugla and Tekirdag populations were found to be genetically different when compared to other populations. The mechanisms underlying overall observed low genetic variation and only moderate differentiation between some of these populations should be investigated in further studies in the context of other host-parasite-vector system regulating factors such as antropogenic transports of livestock, environmental conditions and the role of migratory routes of birds.

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