Pregnancy interruption in Microtus ochrogaster: laboratory artifact or field phenomenon?

Area of Science:

• Behavioral Ecology
• Reproductive Biology
• Rodent Behavior

Background:

• Pregnancy interruption (block) by novel male exposure is documented in laboratory rodents.
• The adaptive significance of this phenomenon in natural settings remains less understood.
• Previous studies primarily used small laboratory cages, limiting female interaction options.

Purpose of the Study:

• To investigate pregnancy interruption in prairie voles (Microtus ochrogaster) under semi-natural conditions.
• To determine if pregnancy block occurs when females have opportunities to avoid or confront strange males.

Main Methods:

• Prairie voles were housed in large, outdoor enclosures simulating semi-natural environments.
• Experimental groups included: original pair, male replacement with a strange male, or addition of a second male.
• Control groups were housed in small laboratory cages with male replacement.

Main Results:

• Pregnancy interruption was observed in prairie voles even when females could potentially avoid or repel strange males.
• The presence of the original male (stud male) did not prevent pregnancy block when a strange male was introduced.
• Pregnancy block occurred across various social contexts, including those with potential for female agency.

Conclusions:

• Pregnancy block in prairie voles is not solely dependent on female confinement or inability to interact with males.
• The findings suggest that pregnancy interruption may serve adaptive roles in prairie vole reproductive strategies.
• Further research is needed to fully elucidate the ecological and evolutionary significance of pregnancy block in rodents.