Final answer:
Life-history theory, costly signaling theory, and cultural influences are three ecological/evolutionary dimensions of personality differentiation that play a role in how personality traits are expressed and evolve.
Step-by-step explanation:
The three ecological/evolutionary dimensions of personality differentiation that are important in evolutionary psychology and trait theory include life-history theory, costly signaling theory, and cultural influences on personality. Life-history theory examines how individuals allocate resources to growth, maintenance, reproduction, and parenting. Costly signaling theory deals with the honesty and deception in signals that individuals send about their quality as a mate or friend. Lastly, cultural influences are crucial as they determine the strength and manifestation of personality traits such as conscientiousness, neuroticism, openness, and extraversion across different cultures.