The Evolution of Genetic Networks and Complex Adaptations

Complex Adaptations

Coexpressed traits selected for a novel function.

Bryan Fry

Biologist studying snake venom evolution.

Snake Venom

Complex adaptation involving toxic proteins and fangs.

Venom Glands

Produce toxic proteins for snake venom.

Fangs

Inject venom into prey during attack.

Muscular Mechanisms

Help deliver venom effectively to prey.

Regulatory Networks

Control gene expression in complex adaptations.

Master Regulatory Genes

Activate or repress over 300 other genes.

Hox Genes

Control body part development location in embryos.

Gene Duplication

Produces homologous genes with potential new functions.

Promiscuous Proteins

Proteins capable of performing multiple functions.

Paralog

Homologous gene resulting from gene duplication.

Gene Recruitment

Co-option of genes for new functions.

Citrate Metabolism

Novel trait in E. coli for consuming citrate.

Microbes

Ideal for studying complex adaptation evolution.

Dorsal-Ventral Patterning

Conserved patterning across different animal species.

Tetrapod Limbs

Evolved from fish fins through gene expression changes.

Complex Eyes

Evolved independently in various animal lineages.

Opsins

Photoreceptor proteins evolved from a common ancestor.

Crystallins

Evolved from heat-shock proteins for light focusing.

Antagonistic Pleiotropy

Single gene affects multiple traits, causing trade-offs.

Recurrent Laryngeal Nerve

Inefficient nerve pathway inherited from aquatic ancestors.

Convergent Evolution

Similar traits evolve independently due to similar pressures.

Parallel Evolution

Similar traits evolve from a common ancestral condition.

Deep Homology

Shared developmental mechanisms from a common ancestor.

Natural Selection

Retools existing traits for fitness advantages.

Evolutionary Constraints

Physical laws limit the potential for evolution.

Gene Expression Changes

Alterations can dramatically change phenotypes.

Novel Traits

Arise from gene duplication and regulatory changes.

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