Dr. Lema’s research examines the neural and hormonal mechanisms that generate phenotypic variation in the wild, and explores the importance of these mechanisms for evolution and conservation.  His research approach is integrative and ranges from molecular endocrine studies in the laboratory to observations of natural behaviors in the wild. 

Recent studies have emphasized the idea that integrating molecular and endocrine approaches into questions about phenotypic development can illuminate how behavior and the brain are shaped by experiences earlier in life.  Ongoing studies with pupfish in the Death Valley region of California and Nevada, USA, have identified differences in brain expression of the hormone arginine vasotocin (AVT) that mirror changes in social behavior and osmoregulatory function among allopatric populations.  This work is revealing how the environmental sensitivity, or plasticity, of key neuroendocrine pathways that regulate behavior can evolve rapidly in ecologically dissimilar habitats in the wild. 

In other lines of research, Dr. Lema has studied how habitat structure influences brain development in Pacific salmon, and is currently using molecular approaches to assess the effects of chemical pollutants on hormonal pathways associated with brain development in teleost fishes.  Pollution, habitat degradation and climate change pose immediate threats to wildlife and human health, and physiological and behavioral studies that approach these problems from an ecological perspective can generate novel approaches for preserving biodiversity. 

Lema, S.C.  2008. The phenotypic plasticity of Death Valley’s pupfish. American Scientist 96: 28-36.

Lema, S.C., Schultz, I.R., Scholz, N.L., Incardona, J.P. and Swanson, P.  2007. Neural defects and cardiac arrhythmia in fish larvae following embryonic exposure to 2,2',4,4'-tetrabromodiphenyl ether (PBDE 47). Aquatic Toxicology 82: 296-307.

Lema, S.C.  2006. Population divergence in plasticity of the AVT system and its association with aggressive behaviors in a Death Valley pupfish. Hormones and Behavior 50: 183-193. 

Lema, S.C. and Nevitt, G.A.  2006. An ecophysiological mechanism for morphological plasticity in pupfish and its relevance to conservation efforts for endangered Devils Hole pupfish. Journal of Experimental Biology 209: 3499-3509.

Kihslinger, R.L., Lema, S.C. and Nevitt, G.A.  2006. Environmental rearing conditions produce differences in the relative forebrain size in wild Chinook salmon, Oncorhynchus tshawytscha. Comparative Biochemistry and Physiology A 145: 145-151.

Lema, S.C., Hodges, M.J., Marchetti, M.P. and Nevitt, G.A.  2005. Proliferation zones in the salmon telencephalon and evidence for environmental influence on proliferation rate. Comparative Biochemistry and Physiology A 141: 327-335.

Lema, S.C. and Nevitt, G.A.  2004. Exogenous vasotocin alters aggression during agonistic exchanges in male Amargosa River pupfish (Cyprinodon nevadensis amargosae). Hormones and Behavior 46: 628-637.

Lema, S.C. and Nevitt, G.A.  2004. Evidence that thyroid hormone induces olfactory cellular proliferation in salmon during a sensitive period for imprinting. Journal of Experimental Biology 207: 3317-3327.

Lema, S.C. and Nevitt, G.A.  2004. Variation in vasotocin immunoreactivity in the brain of recently isolated populations of a Death Valley pupfish, Cyprinodon nevadensis. General and Comparative Endocrinology 135: 300-309. 

Watters, J.V., Lema, S.C. and Nevitt, G.A.  2003. Phenotype management: A new approach to habitat restoration. Biological Conservation 112: 435-445.