1. The Spandrels of San Marco
Adaptation or Drift?

2. Gould and Lewontin (1979)
The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme.
Do not assume that every trait is an adaptation
Cited more than 4000X

3. The Cathedral of San Marco

5. Organisms are more than collections of traits.
Are spandrels necessary architectural elements or byproducts of having adjacent arches?
How many traits of living organisms are spandrels rather than adaptations?
Organisms are more than collections of traits.
Stephen Jay Gould, , USA
Richard Charles Lewontin, 1929-present, USA

6. Evolution of Adaptation
Empedocles (Agrigentum, BCE): adaptation does not require a purpose (final cause)
Aristotle (Stagira, BCE): adaptation requires a purpose
Paley (Natural Theology, UK, ): organisms perfectly adapted through design toward a purpose
Lamarck (France, ): adaptation through increased complexity and influence of circumstances
Darwin (UK, ) and Wallace (UK, ): adaptation is ‘good enough’ outcome of natural selection

7. Addressing Adaptationism
Dr. Pangloss
(Voltaire’s Candide)
“Things cannot be other than they are… Everything is made for the best purpose. Our noses were made to carry spectacles, so we have spectacles. Legs were clearly intended for breeches, and so we wear them.”

8. Adaptation
Genetic change in response to changes in habitat (Red Queen Hypothesis)
Co-adaptations (diversification between insects and flowering plants in Cretaceous)
Compromise (e.g. sexual selection)

9. Classic Research on Adaptation
Peter and Rosemary Grant (1973-present) Darwin’s finches
John Arthur Endler (1980) Guppies

10. Sources of Genetic Drift
Stochastic drift of alleles in a reduced breeding population
Genetic Bottleneck: reduction of population, usually by some catastrophic or random event
Founder Effect: a small subpopulation becomes reproductively isolated from the larger population

11. Genetic Drift: Importance of Population SizeB O AB
 United States 
   42%   
   10%   
   45%   
   3%   
Chinese
31%
28%
34% 7%
Blackfoot
76%
-----
24%
Navajo

12. Genetic Bottleneck

13. Bottleneck in Prairie Chickens

14. Human Bottleneck

15. Founder Effect

16. Polydactyly in Amish Populations

17. Genetic Drift in Mice
Genetic drift in inbred mouse colonies happens slowly, subtly, and is difficult to detect and control. It is caused by the same factors (Bailey 1977; Bailey DW  Immunology Today 3:210-14) that lead to substrain divergence.

18. Developmental Allometry: Size Matters

19. Developmental Allometry of Humans

20. Developmental Allometry of Humans

21. Khrameeva et al Neanderthal ancestry drives evolution of lipid catabolism in contemporary Europeans. Nature Communications. 5:3584 DOI: /ncomms4584
NLS= Neanderthal-like sites
GW= Genome wide
LCP= Lipid Catabolism Protein

22. Importance of Gould and Lewontin (1979)
Cited ~4,000X
Functioned as a heuristic
When we examine traits should we assume that they are adaptations or drift?
G&L (1979) helped to make evolutionary biology more rigorous.