Density and intercohort priority effects on larval Salamandra salamandra in temporary pools

Area of Science:

• Ecology
• Evolutionary Biology
• Herpetology

Background:

• Priority effects are typically studied between species, with fewer intraspecific assessments due to methodological challenges.
• Understanding within-species priority effects is crucial for ecological dynamics and population management.

Purpose of the Study:

• To investigate intraspecific priority and density-dependent effects on larval Salamandra salamandra.
• To differentiate between early and late cohorts using individual-specific markings.

Main Methods:

• An outdoor artificial pool experiment manipulated densities of newly born larvae (0-6 per pool).
• A second cohort of larvae was added after 40 days to assess priority effects.
• Individual-specific markings were used to distinguish between cohorts.

Main Results:

• Increasing early-cohort density reduced survival, size, and increased metamorphosis time for the early cohort.
• Late-cohort survival was 100% without early larvae but 13-33% with them.
• Late-cohort metamorphosis time increased with early-cohort density, indicating competition and cannibalism.

Conclusions:

• Early-arriving larvae experience density-dependent effects, while late-arriving larvae face significant negative impacts from early cohorts.
• Competition and cannibalism are key mechanisms driving these priority effects.
• Salamandra females may enhance fitness by strategically adjusting larval deposition to minimize intraspecific conflict.