Mating System And Multi-paternity In The Northern Grass Lizard,Takydromus Septentrionalis(Lacertidae)

Although multiple paternity is widespread among reptiles,further research is needed to uncover the potential benefits gained by females mating with multiple males.In general,females mated with multiple males may obtain direct or indirect benefits,but there is currently no evidence directly demonstrating that multiple paternity in lizards is related to direct benefits since lacking parental care in most reptiles.Multiple mating in females is thought to reduce the adverse effects of inbreeding and genetic incompatibilities,and enhance the genetic quality of offspring and maximize genetic diversity.Few studies have been conducted to demonstrate the genetic relationship between parents and offspring in lizards,especially under the known paternal genotype.For now,no clear study reveals the relationship of morphology and genetic inheritance between parents and offspring in Northern grass lizard(Takydromus septentrionalis).In this study,we investigated the mating system,sex selection,and the multiple paternity pattern of the northern grass lizard,and compared the growth and survival of the offspring under different paternity patterns to explore the impact of paternity pattern on the offspring fitness.We chose the northern grass lizard as the experimental subject to organize mating,using microsatellite paternity test and other technical methods to observe their mating behavior and sex selection mechanism and accurately identify the paternity pattern of their offspring.At last we analyzed whether there are differences of offspring fitness under different paternity patterns.The following results were obtained by multiple sets of experimental treatments.Our results showed that the mating system of the northern grass lizard was promiscuity.During the single breeding season.one female can mate four times at most while one male can mate five times at most.Totally,187 times of copulation were accumulated during the experiment.Statistical analysis showed that there was no significant correlation between the mating male and female in morphology(head length,head width,body mass,abdomen length and tail length),thus,they did not conform to the assortative mating,suggesting that both sexes were random in spouse selection.The differences of morphological indicators,including head width and body mass,were significant between the mated males(47)and unmated(69).However,the head length,tail length and snout-vent length had no significant difference.Therefore,we speculated that the bite force and relatively large size of the male northern grass lizards have certain advantages in the competition for mating rights.The results of correlation analysis between female mating number and morphological indicators showed that there was no significant correlation between female mating frequency and body length or body weight,suggesting that the female northern grass lizard is indiscriminate in the choice of mating spouse.Even in the course of the experiment,we observed that the males had forced mating behavior.In addition,the long-term isolated breeding of female and male individuals found that the northern grass lizard maternal sperm storage phenomenon,experimentally documented female longest sperm storage time is 90 days.A total of 779 offspring from 257 clutches from 74 matrixes were identified by paternity test using microsatellite molecular markers,and these newborn larvae were fed together by littermates.The relationship between paternity pattern and fitness of offspring was analyzed.The results showed that 40.1%of nest had multiple paternal phenomenon.There was no significant difference in fitness and survival rates among single-parent and multi-paternal offspring which suggested that at least in a laboratory setting,the patriarchal pattern of the northern grass lizard had little effect on the later growth and survival of the offspring.However,our experiment did not find evidence that females have obtained direct or indirect benefits from multiple mating.Paternity skew in offspring was significantly different between the first and the subsequent clutches,suggesting that there may be cryptic female choice or sperm competition among female northern grass lizards.