Sexual Size Dimorphism Depends Drastically on Environment: The Case Study in Ground Beetles

Area of Science:

• Evolutionary Biology
• Zoology
• Ecology

Background:

• Sexual size dimorphism (SSD) is crucial for understanding animal adaptation to environmental changes.
• Analyzing SSD variation provides insights into evolutionary mechanisms and population dynamics.

Purpose of the Study:

• To investigate the geographical patterns of SSD variation in the ground beetle Carabus granulatus.
• To assess how SSD differs across various traits and populations within the species' extensive range.

Main Methods:

• Utilized a large dataset of over 8000 Carabus granulatus individuals from Russia and Europe.
• Employed Analysis of Variance (ANOVA) to statistically analyze size variation between sexes and across different regions.
• Calculated SSD values for individual traits and populations to identify regional trends.

Main Results:

• Statistically significant size variation was observed between males and females across different geographical regions.
• SSD was highest in southern parts of the range (e.g., Bulgaria, Italy) and showed a monotonic decrease towards the north.
• Elytra length and pronotum width exhibited the highest SSD values (0.08-0.09), while other traits showed lower values (0.05).

Conclusions:

• Geographical location significantly influences sexual size dimorphism in Carabus granulatus.
• SSD patterns suggest potential adaptive responses to varying environmental conditions across the species' range.
• The study highlights the importance of considering regional and trait-specific SSD variations for a comprehensive understanding of evolutionary processes.