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

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.

On the winter enhancement of adaptive humoral immunity: hypothesis testing in desert hamsters (Phodopus roborovskii: Cricetidae, Rodentia) kept under long-day and short-day photoperiod.

We tested the winter immunity enhancement hypothesis (WIEH) on male desert hamsters (Phodopus roborovskii) kept under long-day (LD) and short-day (SD) photoperiods. We assumed that under SD in a laboratory, the adaptive humoral immune responsiveness to the antigenic challenge would be enhanced due to the lack of winter physical stressors and food shortages and/or because of the action of an endogenous winter bolstering mechanism, while under LD the immune responsiveness would be suppressed by the activity of the reproductive system. The results support the WIEH in part.

Females choose gentle, but not healthy or macho males in Campbell dwarf hamsters ( Thomas 1905).

Androgen-dependent male sexual traits (STs) as well as immunocompetence are theoretically assumed to be key indicators of a male's quality for the mate-choosing female. We studied mate choice by sexually motivated (SM) females of Campbell's dwarf hamsters. Females chose between 2 tethered male siblings that differed in expression of STs.

[Female mate choice, male-male competition, and male sexual traits: Experimental study of sexual selection directedness in Campbell's dwarf hamster (Phodopus campbelli Thomas 1905)].

We studied the relationship between female mate choice and male-male competition in Campbell's dwarf hamster. Sexually motivated (SM) females chose between two tethered male siblings that differed in expression of sexual traits. Males were unrelated to the female and able to contact and copulate with her.

[Testosterone and Induced Humoral Immunity in Male Campbell Dwarf Hamsters (Phodopus campbelli, Thomas, 1905, Rodentia, Cricetidae): Experimental Manipulation of Testosterone Levels].

In this paper we report the results of testosterone manipulation in the blood of male Campbell dwarf hamsters Phodopus campbelli Thomas, 1905 through castration, followed by testosterone treatment. Under these conditions, we studied antibody production rates in response to injection with sheep red blood cells (SRBC). It was shown that castration induced a dramatic decrease in blood testosterone but had no effect on the humoral response to SRBC.