Transcriptome Sequencing And Analysis Of Dominant And Subordinate Males In The Omei Treefrog(Rhacophorus Omeimontis)

Animal behaviors are regulated by genes.Animals display various and complex behaviors.The expression of a given behavioral trait generally involves the regulation of several genes except that a few behaviors are regulated by single gene.For a species,the variation of expression level of genes results in the difference of expressed behaviors.Therefore,the study of genes with discrepancy on expression is vital for understanding the difference of animal behaviors.The reproductive behaviors of amphibians are complicated and diversified,and studies about its genetic regulatory mechanism are scarce.In the Omei treefrog,Rhacophorus omeimontis,for example,during the breeding season,populations display polygynandry mating system,and the populations exist a phenomenon that more than one male frequently take amplexus with one female.In these mating groups,males can display two different amplectant behaviors:dominant amplectant behavior(i.e.on the back of the females)and subordinate amplectant behavior(i.e.in lateral position).But,the genetic mechanisms of these two kinds of reproductive behaviors are still unknown in R.omeimontis.Here,using R.omeimontis as research species,in 2011-2014,we conducted field observation on reproductive behaviors,and recorded reproductive data on marked individuals.For transcriptome analyses,we sampled brain and testis tissues of males caught in three randomly chosen mating groups(each of them involving one female,one dominant and one subordinate male).Our aim was to determine whether there are genes on different expression level that regulate dominant and subordinate amplectant behaviors,and thus provide the theoretical foundation for further research on reproductive behavior evolution.The following results were obtained:(1)During breeding seasons,dominant and subordinate amplectant behaviors appeared stable in R.omeimontis.(2)Transcriptome results showed that in brain and testis,in total,there were 14 genes differentially expressed between dominant and subordinate male individuals,and there were 4 genes functional annotated.These genes were the growth hormone(GH)gene,the Phosphatidyl ethanolamine binding protein 1(PEBP-1)gene,Oocytes ribonuclease precursor gene and MGC84082 protein gene.Among these genes,the GH gene(highly expressed in the brain of dominant males)and PEBP-1 gene(highly expressed in testis of subordinate males)can be considered as involved in the regulation of the two studied amplectant behaviors.GH is involved in several functions including the regulation of spermatogenesis,body's sugar and lipid metabolism.A higher expression of the GH gene in the brain of dominant males is consistent with the previous studies of R.omeimontis that showed that dominant males dispense more energy and sire more offspsperm capacitation and sperm-egg fusion.The high expression of the PEBP-1 gene in rings.PEBP-1 is responsible of testis of subordinate males may increase the amount of capacitated sperm and improves sperm-egg fusion,so that,the reproductive fitness of subordinate males can be enhanced.