The Evolution of Functionally Redundant Species; Evidence from Beetles

Area of Science:

• Ecology
• Evolutionary Biology
• Biodiversity

Background:

• Ecosystems rely on species fulfilling diverse roles.
• The concept of functional redundancy, where multiple species share similar ecological functions, remains debated.
• Understanding functional redundancy is crucial for assessing ecosystem stability and resilience.

Purpose of the Study:

• To investigate the existence and patterns of functional redundancy in diving beetles (Dytiscidae).
• To determine if body size variation among co-existing diving beetle species supports functional redundancy.
• To explore the evolutionary processes driving species clustering and functional similarity.

Main Methods:

• Analysis of extensive global data on 4168 species of diving beetles.
• Examination of body size distributions and evolutionary patterns.
• Statistical analysis of size differences between locally co-existing species.

Main Results:

• Diving beetles globally show a tendency towards a few regularly spaced body size groups.
• Locally co-existing species are either very similar in size or differ by at least 35%, with intermediate sizes being rare.
• Body size is a strong indicator of functional traits, particularly diet, for these generalist predators.

Conclusions:

• Diving beetles form distinct clusters of functional 'look-alikes', supporting the hypothesis of functional redundancy.
• The observed global regularity in body size patterns suggests a self-organizing evolutionary process.
• Functional redundancy, driven by evolutionary clustering, likely enhances ecosystem resilience through an 'insurance effect'.