Phenotypic Seasonal Difference And The Stress Tolerance Of The Wolf Spider Pardosa Astrigera

Pardosa astrigera is a wandering spider widely distributed across China's Yangtze River and the Yellow River.P.astrigera usually has two generations a year which are called overwintering generation and the first generation.In this paper,we used the spider P.temperature on the spider's seasonal phenotypicastrigera to study its phenotypic variation and stress resistance,and to explore effects of variation.We first collected 30 overwintering female spiders with egg sacs from field.When spiderlings hatched out,we divided them into two groups equally.One group of spiderlings were reared at the temperature of 18 ± 0.5 ? and the other 28 ± 0.5?.We compared phenotypic differences(e.g.spider size,body color,cuticular lipid content,water content and spectral reflectance)of mature male and female spiders treated with two different temperatures.We found there existed significant differences in size of female individuals at both temperatures.Females at 28? were significantly larger than 18 ?,while there were no significant differences in body size of males between the two temperatures.Cuticular lipid content of Male spiders at 18 ? were significantly higher than that at 28 ?,while female spiders were of no significance;Males matured at 28 ? owned higher water content than that at 18 ?,while the comparison between the two female groups showed no statistical difference.We compared the reflectance spectra of different body parts of male and female between the two temperatures using the spectrometer.The results showed that the spectral reflectance of different body parts of male and female differed significantly between the two temperatures.The spectral reflectance of different body parts of spiders at 28 ? is significantly higher than those at 18 ? in terms of light brightness,chroma and hue,respectively.In addition,we collected sub-adult and adult P.astrigera spiders of the overwintering generation in March and the first generation in July,respectively.Their seasonal phenotypic variations(e.g.spider size,body color,cuticular lipid content,water content and reflectance spectroscopy)were measured.We found that spiders of the overwintering generation were significantly larger than those of the first generation,and the males of the first generation have significantly higher lipid content than those of the overwintering generation;there were no differences in water content between the two generations.We used the spectrometer to compare the reflectance spectra of different body parts of male and female between the two generations.The results showed that the spectral reflectance of different body parts of male and female differed significantly between the overwintering and first generations.In general,the spectral reflectance of different body parts of the overwintering generation is significantly lower than those of the first generation in terms of light brightness,chroma and hue,respectively.Our present findings held the therm-regulating hypothesis.The wolf spiders Pardosa pseudoannulata and P.astrigera are two common wandering spiders belonging to Lycosidae family,Pardosa genus,both of which widely distributed in China.Under natural conditions,their environmental distribution is significantly different.The wolf spider P.pseudoannulata mainly distributes in wet environments,whereas P.astrigera distributes mainly in the arid and sunny land.We predicted there may exist significant differences in drought and hunger stress tolerance between the two spider species.In the present study,we first measured the spider water content and lipid content,respectively,and compared their surviving time between the two spider species under the stress conditions without water or food.We aim to shed some light on the relationship between the spiders'water and lipid content and their stress tolerance.Our results showed that the body water content and lipid content of P.astrigera were significantly higher than those of the spider P.pseudoannulata.In addition,the survival time of the spider P.astrigera was significantly longer than that of the spider P.pseudoannulata under the stress conditions without water or food.Meanwhile,female lipid content and survival time under the stress conditions without water or food were significantly higher than those of the corresponding male spiders.Our results indicated that the body higher lipid content of the wolf spiders may to some extent account for their higher surviving duration under the tress conditions without water or food.Besides,we determined the differences of survival time of male wolf spiders of P.astrigera when they were exposed to the draglines from conspecific females or males and the blank treatments,but no significant differences were detected.