Variation in mating systems of salamanders: mate guarding or territoriality?

Area of Science:

• * Vertebrate reproductive strategies and behavioral ecology.
• * Amphibian biology and evolutionary morphology.

Background:

• * Mate guarding and territoriality are common vertebrate mating tactics, but research often overlooks non-traditional systems.
• * The Eurycea bislineata complex of North American stream salamanders offers a unique model due to varied male morphologies and mating strategies.

Purpose of the Study:

• * To investigate the hypothesized link between robust male morphology in Eurycea aquatica and benefits in territorial or mate defense.
• * To compare the mating and defensive behaviors of Eurycea aquatica (robust morph) and Eurycea cirrigera (slender morph).

Main Methods:

• * Observational study comparing aggressive behaviors of males from two Eurycea species in different contexts (territorial vs. mate defense).
• * Morphological comparison focusing on head size and musculature differences between the two species.

Main Results:

• * Neither Eurycea aquatica nor Eurycea cirrigera males exhibited aggression when defending territories.
• * Eurycea aquatica males showed significantly higher aggression towards intruding males when a female was present, indicating mate guarding.
• * Eurycea cirrigera males did not display this mate-guarding aggression.

Conclusions:

• * Mate guarding behavior is confirmed in Eurycea aquatica, with enlarged male heads likely aiding in rival deterrence.
• * This study provides the first evidence of mate guarding in the Plethodontidae family, the most diverse salamander family.
• * Morphological variations in male salamanders are linked to specific mating strategies like mate guarding.