Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Click to edit Master subtitle style 1/12/13 Chapter 10Adaptation: from genes to traits1/12/13 Evolution of novel traits The ability to consume citrate is a complex adaptation1/12/13 Regulatory networks are often involved in complex adaptations1/12/13 Gene duplication can produce novel functionsPromiscuous proteins are especially likely to take on new functions after duplication1/12/13 Gene duplication and snake venoms1/12/131/12/13 Venom evolved before snakes themselves1/12/13 Key Concepts•Promiscuous proteins are often the starting point for novel traits–Duplication can lead to new functions•Novel traits can arise when existing genes are expressed in new developmental contexts–Recruitment or co-option1/12/13 Key Concepts•Duplicated genes accumulate mutations rapidly because they are released from purifying selection•Novel traits can evolve from duplication and co-option of proteins involved in other functions1/12/13 Hox genes are part of a conserved “genetic toolkit”1/12/13 Terminology1/12/13 Dorsal ventral-patterning is conserved1/12/13 Fly legs and mouse legs patterned by same genetic cascade1/12/13 Expression differences in a single gene give rise to limb elongationChange in expression of DppChange in expression of BMP2These genes are orthologs1/12/13 Changes in limb patterning pathway result in limb loss1/12/13 Disruptions in Shh expression1/12/13 Gene expression changes in adaptive radiation1/12/13 Key Concepts•Ancient regulatory networks determine body patterning in bilaterans•Blocking or interrupting a patterning pathway can result in complete loss of a structure•Subtle expression changes can dramatically alter phenotypes1/12/13 Mutations to gene networks can produce additional appendages1/12/131/12/13 Evolution of feathers1/12/13 Evolution of feathers1/12/13 Key Concepts•Changes in the timing and location of expression of developmental genes can alter the shape or properties of a structure1/12/13 Complex eyes have evolved in several lineages1/12/13 Opsins evolved from serpentine proteins1/12/13 Opsins evolved at least ~650 million years ago1/12/13 Crystallins evolved through gene recruitment1/12/13 Hypothesis for evolution of the vertebrate eye1/12/13 Key Concepts•Vertebrate eye the result of long history of gradual evolution–Gene recruitment important1/12/13 Constraints on adaptation•Laws of physics•Pleiotropy–Single gene affects expression of many traits1/12/13 Antagonistic pleiotropy: number of cervical vertebrae1/12/13 Key Concepts•Constraints on evolution arise when one evolutionary trajectory is more likely than any other•Antagonistic pleiotropy can constrain evolution–Some phenotypes unsuccesful1/12/13 Complex adaptations are not perfect1/12/13 Convergent evolution•Independent evolution of similar traits in different lineages–Result of similar selection pressures1/12/13 Convergent evolution in mammals1/12/13 Convergent evolution in mammals1/12/13 Parallelism•Convergent evolution that arises through mutation of the same genes•Deep homology: traits in different lineages arise from same inherited regulatory networks1/12/13 Key Concepts•Deep homology may help to explain cases of parallel