A Comparative Study On The Patriarchal Pattern Of Snakes In Different Habitat Types

Snakes are the second most speciose group of living reptiles,can be found in diverse habitats,and exhibit a wide variety of ecological strategies.There are fossorial,arboreal,aquatic and terrestrial forms.Snakes are one of the first taxa in which multiple paternity has been detected and,as such,they have been main focal animals of reproductive studies.Owing to their polyandrous or even polygynandrous mating systems,large clutch/litter sizes,intense sexual selection pressures,various phenotypic attributes,and ease of captive maintenance,snakes have become ideal materials for reproductive strategy and multiple paternity studies.I aimed to explore the factors which influenc the paternity and reproductive success in snakes.Sankes involved in this research include seven colubrids(Enhydris chinensis,Enhydris plumbea,Cerberus rynchops,Sinonatrix annularis,Elaphe rufodorsata,Elaphe taeniura and Zaocys dhumnades)and two pit-vipers(Gloydius brevicaudus and Gloydius ussuriensis).I obtained 137 complete clutches/litters and 1550 tissue samples of which 137 were from mothers and 1413 from offspring.Between 8-11 microsatellite DNA loci were used for individual species to assign paternity within clutch/litter.Multiple paternity is common in all studied species,with a frequency ranging from 56%to 94%.I compared patterns of multiple paternity between three aquatic(E.chinensis,S.annularis and E.rufodorsata)and three terrestrial(E.taeniura,Z.dhumnades,and G.brevicaudus)snakes using micro satellite DNA loci.I detected high levels of multiple paternity within litters/clutches for all the six species,yet found little concordance between the number of sires per litter/clutch and the body size of females.The number of fathers per litter ranged from 1 to 6;nearly 70%of litters produced by aquatic snakes were sired by 1-3 males.In contrast,more than 70%of litters/clutches produced by terrestrial snakes were sired by 3-5 fathers.In the polyandrous litters/clutches,the proportion of offspring sired by single male ranged from 5-95%,showing great variation in paternity among different males.It also reflects the key role of post-copulation under female control in multiple paternity.