Tail Display Intensity is Restricted by Food Availability in an Asian Agamid Lizard(Phrynocephalus vlangalii)

To ascertain the function of signals,we have to first uncover the reasons behind signal variation.There are several potential driving forces,including background noise,predation cost,receiver perception,and energy limitations.The energy limitation hypothesis assumes that individuals trade off signal intensity and energy expenditure according to resource condition,while variation of signal intensity likely associates with food availability.This hypothesis has been evidenced by a great number of researches on vocal signals,but no studies evaluated the influence of food availability on motion visual signal in lizards.Here we used an Asian agamid lizard Phr ynocephalus vlangalii and examined the effect of food availability on tail display intensity.We designed two food restriction treatments as well as a nature control treatment,and quantified individual tail display speed and display duration under different food availability conditions.Consistent with our prediction,our results showed that males significantly reduced their average tail display speed and maximum display speed in both food restriction treatments when compared to nature control condition.Therefore,our study provides direct evidence that lizards would trade off their display intensity according to the food condition,suggesting tail display is energetically costly and likely provides honest information on individual body condition and resource hold potential.

Tail Waving Speed Affects Territorial Response in the Toad-headed Agama Phrynocephalus vlangalii

Territorial response affects a resident＇s access to resources and mates, but the response level is likely flexible

Tail display is regulated by anaerobic metabolism in an Asian agamid lizard

Understanding the mechanism underlying signal variation is an important goal in the study of animal communication.Several potential causes have been proposed for signal variation,including environmental noise(e.g.wind,sound),energy limitation,and predation risk,among others,but the physiological control of many signals are often unclear.Here,we examined the correlation between tail display signal variation and energy metabolic activity using an Asian agamid lizard Phrynocephalus vlangalii.Individual tail display signals were observed in the field,and blood lactate concentration as well as 2 energy metabolic enzymes was assayed.Our results showed that average tail coil speed was positively associated with blood lactate concentration,while tail coil duration was negatively associated with LDH activity.We also found that average tail lash speed was positively associated with blood lactate concentration,suggesting that the tail display behavior of P.vlangalii was regulated by anaerobic metabolism.Furthermore,the correlation between tail display behavior and energy metabolism was not sex-dependent.Taken together,our research provides insight into the physiological mechanisms underlying tail display variation in lizards,and suggests that tail display variation likely transmits important information on individual body condition and resource holding potential.