Draft · 2020. 2. 5. · Draft 4 Introduction Biological processes in ectotherms are dependent on body temperature, either directly or indirectly, which depends on the environmental

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Thermal preferences and effects of temperature on fitness parameters of an endemic Argentinean tarantula

(Grammostola vachoni)

Journal: Canadian Journal of Zoology

Manuscript ID cjz-2019-0180.R1

Manuscript Type: Article

Date Submitted by the Author: 09-Oct-2019

Complete List of Authors: Schwerdt, Leonela; CONICET Bahia Blanca, de Villalobos, Ana Elena; Centro de Recursos Naturales Renovables de la Zona Semiarida, CONICET-UNS; Pérez-Miles, Fernando; Facultad de Ciencias, Universidad de la República, EntomologíaFerretti, Nelson; INBIOSUR

Is your manuscript invited for consideration in a Special

Issue?:Not applicable (regular submission)

Keyword: Endemic, Tarantula, Grammostola vachoni<i></i>, Locomotor performance, Thermal sensitivity

https://mc06.manuscriptcentral.com/cjz-pubs

Canadian Journal of Zoology

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Thermal preferences and effects of temperature on fitness parameters of an endemic

Argentinean tarantula (Grammostola vachoni)

1. Schwerdt L.

2. de Villalobos A.E.

3. Pérez-Miles F.

4. Ferretti N.

1. Centro de Recursos Renovables de la Zona Semiárida-CONICET. Bahía Blanca,

Argentina; [email protected]

2. Centro de Recursos Renovables de la Zona Semiárida-CONICET, Departamento de

Biología, Bioquímica y Farmacia. Universidad Nacional del Sur, Bahía Blanca,


3. Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay;

[email protected]

4. Instituto de Ciencias Biológicas y Biomédicas del Sur-CONICET, Bahía Blanca,


Corresponding author: Leonela Schwerdt. San Andrés 850, CERZOS, 8000 Bahía

Blanca, Buenos Aires, Argentina. Phone: +54 291 4566129. Email: lschwerdt@cerzos-

conicet.gob.ar

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mailto:[email protected]




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Thermal preferences and effects of temperature on fitness parameters of an endemic

Argentinean tarantula (Grammostola vachoni)

1. Schwerdt L.

2. de Villalobos A.E.

3. Pérez-Miles F.

4. Ferretti N.

Abstract

Mygalomorphs depend on thermal micro-habitats for successful behavior but their

thermal biology is still poorly known. Grammostola vachoni Schiapelli and Gerschman,

1961 is an endemic tarantula from Argentina and it is listed as vulnerable in the IUCN

Red List. However, little is known about its biology, therefore, we attempted to explore

the thermal biology of juveniles and adult females of G. vachoni under laboratory

conditions. We characterized the preferred temperatures, evaluated the relationship

between temperature and locomotor performance and calculated the thermal sensitivity.

Individuals showed a peak of temperature preference and spent 40% of the total time at

25-29 ºC; we did not find any significant differences in preference between juveniles

and females. We found that locomotor performance is strongly affected by high

temperatures. Different sprint speeds of juveniles and females were found at 5 °C, 35 °C

and 40 °C. The highest thermal sensitivity was recorded in the lowest temperature range

and thermal sensitivity was lowest in the highest ranges. Our results are relevant under a

context of climate change, because thermal parameters constitute a useful tool to

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explore some possible effects of this change on body temperature and thus the

physiological performance and vulnerability of ectotherms, such as G. vachoni.

Key words: endemic; tarantula; Grammostola vachoni; locomotor performance; thermal

sensitivity.

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Introduction

Biological processes in ectotherms are dependent on body temperature, either directly or

indirectly, which depends on the environmental temperature. In fact, temperature

influences the individual fitness, abundance and geographical distribution of many

species of ectotherms (Huey and Berrigan 2001; Martin and Huey 2008; Taucare Ríos

et al. 2018). Some ectothermic organisms, e.g. female tarantulas, show scarce activity

outside their burrows, and even select those burrows according to the thermal

characteristics of the environment where they live (Riechert and Tracy 1975;

Hammerstein and Riechert 1988; Veloso et al. 2012; Alfaro et al. 2013). Therefore, as

these thermal condition may affect their periods of activity so, consequently, they would

reflect any major impacts on their behavior and ecology (Shillington 2002). Thermal

preferences may vary with the habitat, nutritional state, developmental stage and

acclimation history (Sinclair et al. 2016). Also, individuals within a population may

differ significantly in respect to these preferences, due to both genetic and non-genetic

factors (Kingsolver et al. 2013; Logan et al. 2014). For example, juveniles and males

tend to be more susceptible to thermal/desiccation stress than females, and this could be

due to the differences in body mass, as large spiders are generally less prone to

desiccation than small spiders (Savory 1964; DeVito and Formanowicz 2003).

To accurately describe the thermal biology of an ectotherm organism, the following

features are frequently used: i) thermal preference, i.e. the temperature that an organism

chooses over a range of available temperatures (Light et al. 1966; Stork 2012); ii)

critical thermal limits, i.e. extreme temperatures above which, individuals are not

capable of functioning normally (Hutchison 1961); and iii) locomotor performance, i.e.

the measurement of mobility (e.g.: endurance, sprint speed, strike speed) over a range of

temperatures (Stork 2012).

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These measurements are acquired in different ways, e.g., the temperature value of

thermal preference arises from a gradient selected by organisms and kept over a period

of time. Also, the critical thermal limits are obtained from a thermal performance curve

(TPC) (Huey and Kingsolver 1989; Alfaro et al. 2013), allowing an evaluation of the

effects of body temperature on organismal-level performance or fitness (Huey and

Slatkin 1976). These critical thermal limits are the points at which physiological

performance falls to zero (Woodin et al. 2013). Finally, the locomotor performance can

be measured through the thermal sensitivity, as changes in the whole animal’s

performance that are reflected in changes in the reaction rates of the metabolic

processes involved (Arnold 1983; Stork 2012). Furthermore, locomotor performance is

dependent on the metabolic processes (Arnold 1983) and the factor by which metabolic

processes change over a given range of temperatures is known as the Q10 (Hegarty

1973; Watson 2008). Therefore, evaluation of the Q10 for locomotor performance allows

to estimates the thermal sensitivity of performance and metabolism (Stork 2011).

Understanding the physiological responses of organisms to temperature is of high

priority due to the global climate change events and their consequences (Mydlarz et al.

2010). Basically, air temperature increases and, hence, affects the thermal biology of

terrestrial animals (Huey et al. 2012). For these reasons, recent research on the effect of

temperature on biological processes has experienced a renaissance (Krenek et al. 2011),

particularly in ectotherms that are especially vulnerable to climate warming because

their basic physiological functions are directly influenced by the environmental

temperature (Deutsch et al. 2008).

Studies in this field are imperative for assessing the suitability of thermal habitats and

describing the thermal ecology of ectotherms, that depend on the thermal micro-habitats

for success in many behaviors, such as reproduction or prey capture (Hertz et al. 1993;

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Canals et al. 2007; Figueroa et al. 2010; Veloso et al. 2012; Neethling and Haddad

2019). Specifically, in the case of ectotherms, such as Mygalomorph spiders, that shows

certain biological characteristics (e.g. high mortality rate at the juvenile stage, later

sexual maturity, sedentary females and juveniles) which increase their vulnerability.

Despite its vulnerability, the thermal biology of these taxa is poorly known (Seymour

and Vinegar 1973; Shillington 2002; Alfaro et al. 2012; Veloso et al. 2012; Cubillos et

al. 2018; Montes de Oca et al. 2019).

Grammostola vachoni is an endemic Argentinean tarantula that inhabits mountainous

grasslands in central Argentina (Ferretti and Ferrero 2008). The geographic range which

this species inhabits is characterized by a humid and temperate climate with an average

annual rainfall of 850 mm and a mean annual temperature is 14.5 °C with an annual

amplitude of 14-15 °C. In the summer the average temperature is 20 °C and the records

that reach 40 °C are frequent, while the winter is characterized with a hardest frosts (-

10°C, with 5% of probability) (Michalijos and Uboldi 2013; Kristensen and Frangi

2015). This species strictly occupies shallow burrows constructed under stones (Ferretti

and Pérez-Miles 2011). Adult males of the species do not have fixed home ranges and

from October to December they frequently move in search of females (Ferretti and

Ferrero 2008). This species is characterized by a poor dispersal mechanism with an

aggregated distribution and with late sexual maturity. It is listed as vulnerable in the

IUCN Red List of Threatened Species (International Union for Conservation of Nature

and Natural Resources) (Ferretti and Pompozzi 2012). Although it is a threatened

species of high priority, its thermal biology is unknown. However, some studies have

been published on its reproductive behavior, intraspecific interactions and ecology

(Ferretti and Ferrero 2008; Ferretti and Pérez-Miles 2011; Schwerdt et al. 2018;

Schwerdt et al. 2019a, 2019b).

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To fill this gap, in the present study we attempted to explore the thermal biology of

juveniles and adult females of G. vachoni under laboratory conditions. We hypothesized

that: 1. Preferred temperature and critical thermal limits are different between juveniles

and females; 2. Locomotor performance is strongly affected by temperature, in both

juveniles and females; 3. Thermal sensitivity is higher at the lowest temperature ranges,

that represents temperatures that are less common in the habitats where G. vachoni is

found. To achieve these objectives, in the present study we: 1. Characterized the

preferred temperatures of juveniles and females of G. vachoni under laboratory

conditions; 2. Evaluated the relation between temperature and locomotor performance

through a thermal performance curve; 3. Calculated the thermal sensitivity for all

possible temperature ranges, discerning between juveniles and females.

Methods

Individuals

All the individuals of Grammostola vachoni used in the present study were bred in the

laboratory. Individuals were kept at 22 ± 2 °C under a 12:12 photoperiod and were

housed individually in a subdivided plastic terrarium. Spiders were fed once a week

with cockroaches [Blatella germanica (Linnaeus, 1767)] except during the experimental

period. The body mass (hereafter Mb) of each specimen was measured using a Denver

AA-160 balance with a precision of 0.001 g. We used juveniles of the same

development stage (age = 4 years) and adult females of similar sizes for both

experiments.

Experiments

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Thermal preference. A thermal gradient from 3ºC to 60ºC was generated in a glass cage

of 65 x 13 x 15 cm (length x width x height), with sand on the floor (0.5 cm). The hot

end had a constant heat source under the sand, while the cold end had a cold source (see

Veloso et al. 2012; Barahona‐Segovia et al. 2016). This gradient was calibrated and

checked before and during each experiment. The spiders (juveniles: n = 20, females: n =

13) were introduced individually at the center of the cage where the temperature was

about 30ºC. We avoided disturbing the individuals during the experiments. The spiders

were free to move during four hours in order to select their preferred temperature. The

body temperature of each individual was recorded every 30 min with an infrared

thermometer (EXTECH Instrument, Dual Laser; IR accuracy: ± 0.8 °C); the

measurements were obtained from the midpoint between the carapace and abdomen.

Critical thermal limits and locomotor performance. We considered the sprint speed as

the parameter for the relationship between performance and temperature. To evaluate

the thermal performance, each spider was placed in a sealed plastic tube and submerged

directly into a programmable thermostatic bath (Digital Thermostatic Bath v1.0) for 30

min under different random temperatures (5, 10, 15, 20, 25, 30, 35, 40 and 45 ºC) and

on different days. Each individual was evaluated for only one temperature per day. We

decided not to perform any experiments at the highest temperatures in order to avoid

extremely stressful conditions for the spiders. After removal from the bath, each spider

was immediately placed on an experimental setup to measure its sprint speed

performance [speed from the start in the set up to the first stop (cm sec-1)]. The

experimental setup consisted of a plexiglass cylinder (1 m long and 10 cm wide) with

graph paper in the background. The sprint speed was calculated by the distance

measured on the graph paper and a chronometer. The measurement was considered

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from the starting point of the carapace. All experiments were carried out by the same

operator.

The thermal performance curve (TPC) and their parameters were calculated with a

polynomial quadratic regression: critical thermal limits minimum and maximum (CTmin

and CTmax, respectively), maximal performance (Pmax), thermal optimum (Topt), thermal

performance breadth (Tbr) and tolerance range (TR). The ecophysiological

characteristics of CTmin and CTmax were derived numerically as the intersection points of

the resulting TPC on the temperature axis (µ=0) (Martin and Huey 2008; Gaitán-Espitia

et al. 2014). The Topt comprises the temperature at which an individual sprinted the

fastest; so Pmax is the sprint speed at Topt. The Tbr is an index that represents the

amplitude of performance and it was calculated using the following equation (Gilchrist

1996): ; where N equals the number of 𝑇𝑏𝑟 = √∑𝑁𝑖 = 1[𝑃𝑖(𝑇𝑖 ― 𝑇𝑜𝑝𝑡)/𝑃𝑚𝑎𝑥]2

temperatures and Pi is the sprint speed at temperature Ti. The tolerance range (TR) was

calculated as .𝑇𝑅 = 𝐶𝑇𝑚𝑎𝑥 ― 𝐶𝑇𝑚𝑖𝑛

In the thermal sensitivity (Q10), the subunit 10 only makes reference to a 10-degree

temperature range. However, in the present study we analyzed thermal sensitivity over a

5-degree temperature range, which, we will refer to as Q5 hereafter. The Q5 was

calculated using the sprint speed and comparing seven five-degree intervals (5-10, 10-

15, 15-20, 20-25, 25-30, 30-35 and 35-40°C) using the formula 𝑄5 = (𝑅2𝑅1)

(10

𝑇2 ― 𝑇1)

(Schmidt-Nielsen 1997). In this equation, R1 is the performance at temperature 1 of

range (T1), and R2 is the performance measured at temperature 2 of the same range

(T2).

Statistical analyses. The normality of data was evaluated by the Shapiro-Wilk test (Zar

1999). The locomotion performance (sprint speed) at the different temperatures was

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estimated using repeated measures ANOVA and the means were compared with the

Tukey test. Thermal parameters between juveniles and females and thermal sensitivity

of the sprint speed over a 5-degree range (Q5) were compared through ANOVA. We

used the Pearson correlation to explore the possible linear relationships between Mb

with thermal parameters and Q5. Data are presented as mean ± 1 standard deviation

(SD), except where otherwise indicated.

Results

The 13 adult G. vachoni used for the study weighed 14.13 ± 1.18 g (mean ± SD),

whereas the 20 juveniles weighed 6.55 ± 1.13 g (mean ± SD).

Thermal preference

Individuals of G. vachoni were able to move freely during the experiments until they

remained in a thermally preferred zone. We did not find any significant differences in

the preferred temperatures of juveniles and females (juveniles = 26.98 ± 0.9 °C and

females = 25.95 ± 0.7 °C; ANOVA, F = 0.69, p > 0.05) (Figure 1). All individuals

showed a preference peak and spent 40% of the total time in the 25-29 ºC range (Figure

2). We did not find any significant correlation between Mb and the preferred temperature

(Pearson, r = 0.21, p > 0.05; r = -0.26, p > 0.05; females and juveniles respectively).

Critical thermal limits and locomotor performance

We recorded an average Topt of 25.75 ± 2.0 °C (N = 33), and CTmin and CTmax showed

values of 5.39 ± 0.78 °C and 46.11 ± 4.26 °C, respectively. The Pmax was 4.87 ± 1.33

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cm sec-1, while values obtained for Tbr and TR were 14.74 ± 3.19 °C and 40.72 ± 4.63

°C, respectively. The significant differences in Topt, CTmax, Tbr and TR between the

juveniles and females are shown in Table 1.

The TPC showed that sprint speeds from spiders were significantly different between

the different temperatures (ANOVA repeated measure: F = 26.92; p < 0.0001 and F =

19.73; p < 0.0001; juveniles and females respectively) (Figure 3). Different speeds

between the juveniles and females were found at 5 °C, 35 °C and 40°C, but for the

remaining temperatures, the sprint speed values were almost equal (Figure 4).

Locomotor performance is strongly affected by high temperatures, especially in the

juveniles (N = 20) that showed the greatest sprint speed between 25 ºC and 30 ºC and

the slowest speeds at 5 ºC, 10 ºC and 40 ºC (Post Hoc Tukey, p < 0.05); while the

females (N = 13) showed the greatest sprint speeds at 35 °C and the slowest speeds at 45

°C and 5 °C. We did not find any significant correlations between Mb and the thermal

parameters.

The thermal sensitivity (Q5) evaluated for all spiders showed a mean value of 3.32 ±

6.80. Significant differences were found between the temperature ranges (ANOVA: F

= 5.95; p < 0.01) (Table 2). The highest thermal sensitivity was recorded in the lowest

temperature ranges, for 5-10 °C and 10-15 °C ranges, for both the juveniles and

females. However, the lowest Q5 values were obtained in the 25-30 °C, 30-35 °C and

35-40 °C ranges (Figure 5). In the latter temperature ranges reported, significant

differences were found between the juveniles and females (Table 2). The juveniles

showed the lowest values of Q5 in relation to females under those temperature ranges

(Figure 5). We did not find any significant correlation between Mb and Q5.

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Discussion

De Vito and Formanowicz (2003) reported that large spiders are generally less prone to

desiccation than small spiders and likewise, in previous studies, size-related differences

in the preferred temperature were reported (Sevacherian and Lowrie 1972; Humphreys

1975, 1978). However, we did not find any differences in the preferred temperature

between the different developmental stages studied in G. vachoni. The acclimation of

individuals under laboratory conditions could explain this similarity in the

developmental stages involved. The fact that body mass does not affect the preferred

temperature agrees with previous studies on other tarantula species (Alfaro et al. 2012;

Veloso et al. 2012). In addition, other studies showed that thermal preferences would

match the Topt for maximizing the fitness and in ectotherms, the thermal preferences

would be close to the body temperature (Huey and Bennett 1987; Angilletta et al. 2002;

Martin and Huey 2008). In fact, in this study we observed that the preferred temperature

is actually close to Topt for both the juveniles and females.

Martin and Huey (2008) suggested that ectotherms would avoid body temperatures that

approach CTmax, maintaining a broad “thermal-safety margin” (i.e., the distance

between Topt and CTmax) and our results agreed with this idea. Moreover, we observed

that the upper limit of preferred temperatures (about 32-34 °C) was much lower than the

CTmax (approximately 44 and 49 °C in juveniles and females, respectively). Similarly,

the lowest thermal limit chosen by G. vachoni (about 13 and 18 °C) was higher than

CTmin (approximately 5 ºC in juveniles and females). Our results showed that when the

breadth of thermal performance and the tolerance range showed a wide thermal

spectrum and the individuals are able to select temperatures from a gradient, they

preferred to remain under middle temperatures. Also, females a showed wider

temperature amplitude of performance than juveniles, with a higher CTmax. However,

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this result could not be explained by differences in the body mass of the spiders, since

no correlations between thermal parameters and body mass were found.

Extremely high temperatures negatively affect the individual performance or activity,

reaching zero performance at CTmax (Storks et al. 2017). The juveniles of G. vachoni

showed a reduced locomotion after being exposed to 40 ºC whereas the females showed

the same symptom at 45 °C. In these cases, some spasmodic movements were observed

in some cases. Krakauer (1972) reported muscular spasms prior to death during thermal

stress in Nephila clavipes (Linnaeus, 1767) (Araneidae). Lutterschmidt and Hutchison

(1997) suggested muscular spasms as a good CTmax limit point.

According to Nespolo et al. (2003), there is a lot of information on the Q10 regarding

metabolic rate in insects and the values reported usually ranged from 1.5 to 3 (Davis et

al. 1999; Rourke 2000; Rogowitz and Chappell 2000), that are in agreement with results

provided in other studies on tarantulas and other arachnids (Punzo 1991; Shillington

2005; Lardies et al. 2008). However, the thermal sensitivity is variable, depending on

the process being tested, e.g. a value of 5.3 was found for the excretion rate in a species

of grasshopper (Harrison and Fewell 1995). Animals tend to exhibit higher Q10 values at

the extremes of the metabolic tolerance and, species that exhibit a low metabolic

response at low temperatures tend to exhibit a high metabolic response at high

temperatures (Nespolo et al. 2003; Watson 2008). Therefore, a higher Q10 indicates

greater temperature sensitivity of processes over the range, whereas a lower Q10 would,

therefore, indicate stability and would be considered more favorable (Watson 2008). For

some thermodynamic considerations in many ectotherm processes, Q10 is predicted to

be higher at lower temperatures (Schmidt-Nielsen 1995). Our results have shown a

similar trend, by obtaining Q5 values higher at lower temperatures and decreasing as

temperatures increased, as reported in other studies (Punzo 1991; Nespolo et al. 2003;

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Stork 2012). Thermal sensitivity at both the 5-degree range and the 10-degree range is

the same, with the difference that Q5 provides more information than Q10, because it

shows the factor by which metabolic processes change over a given 5-degree range of

temperature and, hence, offers a larger number of more precise measurements. Our

results showed that the greater sensitivity was related to temperatures that are not

usually recorded inside the burrows of G. vachoni, for example, the temperature inside

the burrow is close to 13 °C during the coldest months it the field (Schwerdt 2018). It

was observed that the species fitness and some behavior were unsuccessfully displayed

over a temperature range and could be indicative of the temperature acting as an

ecological factor that limits the species distribution. According to Booster et al. (2015)

the thermal sensitivity of tarantula locomotion is directly relevant to their field ecology.

For example, in this study, the sprint speed can be a good measurement by which to

integrate the physiology and ecology of the species. This is because the sprint speed has

been shown to significantly affect vital life processes, such as predation, escape from

predators and intraspecific interaction in the mating season (Huey and Stevenson 1979).

However, in other spider species, such as Rabidosa rabida (Walckenaer, 1837), the

temperature does not seem to be a limiting factor for its geographical distribution (Stork

2012).

In this study, a significant variation was found in the thermal performance of speed

sprint in G. vachoni. Also, the CTmax recorded is probably greater than any temperature

experienced at night by the spiders, the time at which they are most active, even during

the warmest time of year (Schwerdt et al. 2018). Like other tarantulas, G. vachoni can

avoid unfavorable thermal conditions primarily through nocturnal activity patterns and

fossoriality (Punzo 1991; Schwerdt 2018). However, the air temperature has often been

higher as a direct effect of climate change (Huey et al. 2012). Hence, under a context of

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global warming, the thermal performance curve constitutes a useful tool for exploring

some possible effects of this change on body temperature and thus the physiological

performance and vulnerability (Huey et al. 2012; Sinclair et al. 2016). In addition,

tarantulas are especially susceptible since they have poor dispersal mechanisms,

aggregated distribution and long periods at the juvenile stage, implying that climate

change might actually constitute a relevant threat, affecting their thermal biology, as

found in other ectotherms (Punzo 1991; Huey et al. 2012; Nori et al. 2017; Ferretti et al.

2018; Montes de Oca et al. 2019).

Acknowledgements

The authors thank Viviana Echenique and Rodrigo Batista for making a Digital

Thermostatic Bath available. Also, we sincerely thank Pablo Rodriguez and Claudio

Veloso for assistance in the experimental design. We also thank Matias Gaviot for

making an infrared thermometer available. L.S was supported by a CONICET

scholarship.

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Tables

Table 1. Thermal parameters of the thermal performance curve for juveniles and females

of Grammostola vachoni. Data are expressed as the mean ± SD. Significant results

(ANOVA) are in bold.

Parameter Juveniles Females F p

CTmin 5.59 ± 0.17 5.09 ± 0.21 3.5 0.07

CTmax 44.05 ± 0.77 49.33 ± 0.95 18.48 <0.001

Topt 24.82 ± 0.35 27.2 ± 0.46 16.35 <0.001

Pmax 4.64 ± 0.29 5.24 ± 0.32 1.64 0.21

Tbr 12.99 ± 0.52 17.45 ± 0.65 28.77 <0.001

TR 38.46 ±0.83 44.2 ± 1.03 18.95 <0.001

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Table 2. Thermal sensitivity over the temperature range analyzed for juveniles and

females of Grammostola vachoni. Different letters indicate the mean significant

differences between the temperature ranges (p < 0.05, Tukey test). Data are expressed

as the mean ± SD. Significant comparisons between juveniles and females (ANOVA)

are in bold.

Thermal sensitivity (Q5)Temperature range (°C)

Tukey test

All spiders Juveniles Females F p

5-10 C 7.65 ± 6.95 7.18 ± 1.17 3.96 ± 1.45 2.29 0.09

10-15 BC 5.91 ± 5.01 9.01 ± 3.26 7.89 ± 4.04 0.05 0.82

15-20 AB 3.02 ± 2.34 3.53 ± 0.51 2.23 ± 0.64 2.5 0.12

20-25 AB 2.97 ± 2.56 4.19 ± 1.25 2.48 ± 1.55 0.73 0.39

25-30 A 1.33 ± 1.09 1.47 ± 0.47 1.11 ± 0.58 0.28 0.62

30-35 A 1.04 ± 0.98 0.52 ± 0.30 1.83 ± 0.37 7.41 0.01

35-40 A 0.41 ± 0.37 0.19 ± 0.09 0.76 ± 0.11 16.03 0.0004

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Figure captions

Figure 1. Comparison of the temperature preferred (°C) by juveniles and females of

Grammostola vachoni. The temperature preferred was significantly different (ANOVA,

F = 0.69, p > 0.05; 25.95 ± 0.7 °C and 26.98 ± 0.9 °C (mean ± SD); for females and

juveniles respectively). The median line in each box represents the median temperature

and the cross indicates the mean for juveniles and females.

Figure 2. Time of permanence (% of all recordings) at different temperatures in

juveniles and females of Grammostola vachoni.

Figure 3. The thermal performance curve shown as the effect of temperature on the

locomotor performance, sprint speed, of juveniles (dark gray) and females (light gray)

of Grammostola vachoni.

Figure 4. Mean sprint speed ± standard error at different temperatures. * indicates

significant differences between juveniles and females (ANOVA: F = 17.88, p ≤ 0.001;

F = 15.08, p ≤ 0.001; F = 23.58, p ≤ 0.001; 5, 35 and 40 °C respectively).

Figure 5. Comparison of the thermal sensitivity (Q5) of Grammostola vachoni over

different temperature ranges. The median line in each box represents the median

thermal sensitivity. * indicates significant differences for Q5 between juveniles and

females (ANOVA, F = 7.41, p < 0.01; F = 16.03, p < 0.01; at 30-35 and 35-40 °C

respectively).

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Figure 1. Comparison of the temperature preferred (°C) by juveniles and females of Grammostola vachoni. The temperature preferred was significantly different (ANOVA, F = 0.69, p > 0.05; 25.95 ± 0.7 °C and

26.98 ± 0.9 °C (mean ± SD); for females and juveniles respectively). The median line in each box represents the median temperature and the cross indicates the mean for juveniles and females.

220x163mm (300 x 300 DPI)

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Figure 2. Time of permanence (% of all recordings) at different temperatures in juveniles and females of Grammostola vachoni.

310x175mm (300 x 300 DPI)

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Figure 3. The thermal performance curve shown as the effect of temperature on the locomotor performance, sprint speed, of juveniles (dark gray) and females (light gray) of Grammostola vachoni.

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Figure 4. Mean sprint speed ± standard error at different temperatures. * indicates significant differences between juveniles and females (ANOVA: F = 17.88, p ≤ 0.001; F = 15.08, p ≤ 0.001; F = 23.58, p ≤

0.001; 5, 35 and 40 °C respectively).

291x150mm (300 x 300 DPI)

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Figure 5. Comparison of the thermal sensitivity (Q5) of Grammostola vachoni over different temperature ranges. The median line in each box represents the median thermal sensitivity. * indicates significant

differences for Q5 between juveniles and females (ANOVA, F = 7.41, p < 0.01; F = 16.03, p < 0.01; at 30-35 and 35-40 °C respectively).

244x170mm (300 x 300 DPI)

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Graphical Abstract

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Documents

Draft · 2020. 2. 5. · Draft 4 Introduction Biological processes in ectotherms are dependent on body temperature, either directly or indirectly, which depends on the environmental