Predation of Threespine Stickleback by Dragonfly Naiads

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Aquatic Ecology

Background:

• Threespine stickleback populations with reduced pelvic girdles are often found in environments with low ions, few predators, and abundant macroinvertebrates.
• It is hypothesized that macroinvertebrates may use stickleback pelvic spines for prey capture and manipulation.

Purpose of the Study:

• To investigate if dragonfly naiads differentially prey on threespine stickleback with complete versus reduced pelvic fins.
• To document the hunting and capturing behaviors of dragonfly naiads towards stickleback with different pelvic phenotypes.

Main Methods:

• Arena experiments were conducted to observe naiad predation on stickleback with complete and reduced pelvic fins.
• Naiads were presented with single stickleback phenotypes and then with paired stickleback of differing phenotypes to assess prey choice.

Main Results:

• Dragonfly naiads did not show a higher predation rate on stickleback with one pelvic phenotype over the other when presented individually.
• When offered a choice, naiads preyed more heavily on small stickleback with pelvic spines and large stickleback without pelvic spines.
• Naiads demonstrated adaptive predatory behavior, adjusting their prey selection based on the pelvic phenotype of the stickleback.

Conclusions:

• Pelvic spine presence alone does not determine naiad predation preference in stickleback.
• Dragonfly naiad predation on threespine stickleback is influenced by a complex interaction between prey size and pelvic fin morphology, suggesting adaptive foraging strategies.