In recent human evolution, gene duplication has occurred producing related genes of gene families.  This seems to be the rule rather than the exception.  Genomes contain many related genes—some very closely related, some more distantly related, some more distantly related still.  Drawing trees based on sequence comparisons depicts gene families which have produced more and more member genes throughout time.


ABC CASSETTE TRANSPORTER Gene Family members in yeast; (after Decottignies, 1997).



























A Family of taste receptors (T2R) with first four lines representing related opsin and 3 vomeronasal receptors (after Adler, 2000)

























































Human MHC I alleles and genes after Nei 1997 (last two branches from mouse MHC I).







































Various MHC I genes from a variety of vertebrate species (human, gorilla, orangutan, tamarin, cat, mouse, wallaby, chicken frog, and fish) after Nei, 1997.







































Two phylogenetic trees of immunoglobulin light chain C (upper tree) and V (lower tree) sequences from a variety of vertebrates, including humans; after Greenberg, 1993.






































Cadherin Gene family, after Wu, 2000.














Vertebrate globins, after Goodman, .





















vertebrate and invertebrate opsin genes (plus the related RGR genes from humans and cows); after Blackshaw, 1999.



































Human olfactory receptors after Fuchs, .



















































Homeodomain Gene Family after Bharathan, 1997.































































Dlx genes in various vertebrates, after Stock, 1996.





























Cellular Retinol Binding Protein (Werten, 2000).


Gecko i-crystallin/
















P2y purinoceptor family (Somers, 1997).