Table 2.

Examples of studies showing that gene expression is affected by ecological stress. Under the assumption that gene expression allows populations to better persist in stressful environments, these studies indicate that differential gene expression can promote the colonization of, and subsequent persistence in, novel environments

Organism	Study	Method	Environmental stressor	Proportion of genes affected by treatment	Major physiological function affected
Killfish Austrofundulus limnaeus	171	cDNA microarray	Daily and seasonal temperatures regimes	11%	Molecular chaperones, cholesterol and fatty acids synthesis, membrane structure, solute carrier, carbohydrate metabolism, nitrogen metabolism, intermediary metabolism, cytoskeleton elements, protein turnover, complement and innate immunity, and cell growth and proliferation.
Bivalve Argopecten purpuratus	175	Suppression subtractive ESTs library + quantitative RT-PCR (candidate genes)	Copper tolerance	8%	Cell differentiation, cellular communication, cytoskeleton, development and differentiation, energetic metabolism, protein regulation, respiratory chain, stress protein, translation and posttranslation processing, cellulose hydrolysis, and ribosomal protein.
Brazilian flounder Penalichtys orbignyanus	176	Semi-quantitative RT-PCR (candidate gene approach)	Hyperosmosis	2 candidate genes up-regulated	Growth.
Coral fish Pomacentrus moluccensis	177	cDNA microarray	Prolonged heat and hypoxia	2% (down-regulation mostly)	Cell adhesion, cell cycle and growth, cyskeleton, metabolism, protein processing, stress proteins, signal transduction, transcription, translation, and transport.
Arthropod Orchesella cincta	27	cDNA microarray	Cadmium	14% (down-regulation mostly)	Translation, signal transduction, stress protein, redox state, general metabolism, chromatin remodeling, and proteolysis digestion.
Antarctic nematode Plectus murrayi	178	Suppression subtractive hybridization / ESTs library + quantitative RT-PCR	Desiccation resistance	6%	Carbohydrate metabolism, amino-acid metabolism, lipid metabolism, xenobiotic metabolism, membrane transport, signal transduction, transcription, translation, replication, cell growth and death, and cell communication.
Thale cress Arabidopsis spp.	179	Oligo microarray	Salt, osmotic regulation, and temperature	12 to 25% (up-regulation mostly)	Oxidative stress, membrane transport, phosphoregulation, transcription, circadian clock, fatty acid metabolism, stress protein, cytoskeleton, membrane protein, and carbohydrate metabolism.
Black cottonwood Populus trichocarpa	180	cDNA micorarray	Herbivory	5% (up-regulation mostly)	Photosynthesis, general metabolism, transport, transcription, octadecanoid and ethylene signaling, detoxification and redox processes, and secondary metabolism.
Atlantic samon Salmo salar	110	cDNA microarray	Pathogens	17% (up-regulation mostly)	Immunity-related genes, extracellular matrix component, electron and ion-transport chain, signal transduction, transcription, metal-binding protein, pyrimidine biosynthesis, protein degradation, localization and folding, DNA replication, and cell structure and adhesion.
Mycorrhizal involutus	181	cDNA microarray	Fungus Pillus Host specificity	16%	Electron transport, lipid and fatty acid metabolism, transcription, sex determination, regulation of cell cycle, glycolysis, stress protein, protein biosynthesis, and aromatic compounds metabolism.