Mate Choice Based On Morphological, Genetic And Behavior In Eurasian Kestrel(Falco Tinnunculus)

Raptors are at the top of the food chain,with a small population.Most raptors are thought to be socially monogamous,because both sexes play important roles in parental care,and occasionally polygyny has been observed in some raptor species.Reversed sexual dimorphism(RSD),which occurs when the female of a species is larger than the male,is the rule for most raptors.Many studies suggested that RSD is related to mate choice.However,there are few studies on mate selection of raptors based on genetic characteristics as limited by population size and availability in the wild.In this study,Eurasian kestrel(Falco tinnunculus),a small raptor,was taken as the research object,and its mate choice pattern was analyzed based on morphology,behavior,microsatellite(or simple sequence repeats,SSR)and major histocompatibility complex IIB class 2 exon(MHC IIB2).The study on mate choice of Eurasian kestrel based on morphological and behavioral characteristics found that: there was no significant difference between pairs and random mating pairs in dimorphism index(D.I.),however,D.I.with pairs was positively correlated with the female PC1(PC 1 value in principal component analysis of body size),and was negatively correlated with male PC1,was independent of other morphological and behavioral parameters.The body condition index(BCI)of female of Eurasian kestrel was positively correlated with male partners.Larger females have a higher BCI index,and the female with higher BCI index have a longer nest-sitting time.Moreover,the female nest-sitting time was positively correlated with the male provisioning rate.Which results suggested that Eurasian kestrel may have a certain preference for RSD of its mate,but prefers the mate with good body condition.The female's body condition and the male's feeding behavior can directly affect the female's incubation time.The study on mate choice of Eurasian kestrel based on SSR found that: The difference of SSR heterozygosity between pairs was significantly lower than that between random pairs,and the difference of SSR heterozygosity between pairs was only negatively correlated with males' SSR heterozygosity of and females' PC1,and was independent of female SSR heterozygosity and other morphology and behavior parameters.There was no significant difference between the Pairwise relatedness between pairts and the random pairs,but the Pairwise relatedness between pairts was negatively correlated with the female SSR heterozygosity,and was independent of female SSR heterozygosity and other morphology and behavior parameters.Mediation analysis showed that male BCI index could mediate female mate choice based on the similarity of SSR heterozygosity.Which results suggested that Eurasian kestrel may have a certain inbreeding avoidance preference,but prefer mates with more similar SSR heterozygosity.females could “see” SSR heterozygosity via male body condition and chose mate with similar SSR heterozygosity.The study on mate choice of Eurasian kestrel based on MHC found that: The difference of MHC IIB2 genotypes between pairs was significantly lower than that between random pairs,and the amino acid distance of PSS(Positively selected sites)between pairs was lower than that between random pairs,while the difference of MHC IIB2 diversity between pairs was not significantly different from that between random pairs;The difference of MHC IIB2 Couple Allele Dissimilarity was positively correlated with the female nest-sitting time,and the amino acid distance of positive selection site was positively correlated with the male provisioning rate;The difference of MHC IIB2 genotype and the amino acid distance of PSS between pairs were not related to morphological behavior parameters.There was a significant positive correlation between the female BCI index and the number of MHC IIB2 alleles,and a significant negative correlation between the male PC1 and the number of MHC IIB2 alleles.Which results suggested that Eurasian kestrel may prefer a mate with a more similar MHC IIB2 genotype,or prefer a mate with a similar amino acid distance of PSS.But this preference is relative,the difference in a certain range is more favored by the individual in pairs.Females with Good body condition and males with small body size have greater MHC IIB2 gene diversity.The study of two cases of bigamy in Eurasian kestrel shows that the provisioning rates of bigamous male is significantly higher than that of monogamous males,and preferred to feed primary females;Compared with monogamous males,the bigamous males tended to have shorter wing chord,but the secondary females were smaller than primary females,and compared with other females,tended to have shorter bill length,tarsus length and lower body mass,in particular,their wing chord were significantly shorter;The two secondary females were < 2 yrs old,while,all primary females and bigamous males were >2 yrs,93% of monogamous males,and 97% of monogamous females were >2 yrs;There was no significant difference in SSR heterozygosity between monogamous and bigamous individuals,but close relatedness may play a role in reducing the aggression between bigamous females in Eurasian kestrel.