Comparison of ultrasonic isolation calls of pure-breeding and interspecies hybrid Phodopus dwarf hamster pups

Abstract

In mammalian cross-species hybrids, parameters of voice calls, produced by vocal fold vibrations, are intermediate between parental species. Inheritance of ultrasonic calls, produced by whistle mechanism, is unstudied for hybrids. We examined 4000 pup ultrasonic isolation-induced calls for peak power of call fundamental frequency and for call duration in 4–8-day-old captive hamsters of four Study Groups: pure Phodopus sungorus; pure P. campbelli of two populations (Mongolian and Kosh-Agach) and hybrids between male P. sungorus and female P. campbelli (Kosh-Agach). All Study Groups produced two categories of ultrasonic calls: Low-Frequency centered around 41 kHz and High-Frequency centered around 60 kHz, but in different percentages. Between populations, only Low-Frequency calls were shorter and higher-frequency in Mongolian P. campbelli. Between species, only High-Frequency calls were shorter and higher-frequency in P. sungorus. In hybrids, Low-Frequency calls were shorter and lower-frequency than in either parental species, whereas High-Frequency calls were longer and lower-frequency in hybrids than in pure P. sungorus but similar with another parental species. We discuss that interspecific hybridization may give rise to offspring with new properties of ultrasonic calls.