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Evolutionary Trend (Active, or Driven)

Directional change of traits or features in a lineage, or a discernible pattern of change in a large sample of lineages, caused by forces whose operation over time is relatively homogeneous (i.e., acting in the same direction). Compare to “Evolutionary Trend (Passive).”

References:

McShea, D.W. (1994). “Mechanisms of large-scale evolutionary trends.” Evolution 48(6):1747–1763.

Evolutionary Trend (Passive)

Directional change of traits or features in a lineage, or a discernible pattern of change in a large sample of lineages, caused by forces whose operation over time is heterogeneous (i.e., acting in more than one direction). Compare to “Evolutionary Trend (Active, or Driven).”

References:

McShea, D.W. (1994). “Mechanisms of large-scale evolutionary trends.” Evolution 48(6):1747–1763.

Evolvability

The capacity or potential of a system to evolve, or generate heritable variation.

References:

Kirschner, M. and J. Gerhart. (1998). “Evolvability.” Proceedings of the National Academy of Sciences of the United States of America 95:8420-8427.

Allied Concepts:
Adaptation, Exploratory Behavior, Niche construction, Plasticity

Exploratory Behavior

Activities that are capable of searching out and finding targets in a novel environment. Examples include ambulatory exploration, vertebrate adaptive immunity, and the formation of microtubule structures.

References:

Gerhart and Kirschner (2007). “The theory of facilitated variation.” PNAS 104(suppl. 1):8582–8589.