Homology/AnalogyHomolog structure: Similar structure and position, but different functionHomologySlide 4Wells’ Critique: Circular definitionHow would you test common ancestry?Slide 7Slide 8Slide 9Wells’ Critique: GeneticsSlide 11Slide 12Wells’ Critique: Developmental PathwaysSlide 14Slide 15AnalogyCounterargumentsConvergence = directionality?Slide 19Design or Mere Accident?Slide 21What is the PURPOSE of this seminar??Slide 23Slide 24Evolution vs. ID: Does it matter? If so, why?Homology/AnalogyNatalia AlvarezKevin Coleman2006Botany 940Evidence for evolutionHomolog structure: Similar structure and position, but different function Courtesy of Prof. Ken Sytsmahttp://evolution.berkeley.eduAnalog structure: Similar function, but different originHomologyHow can we explain this?Hypotheses??Courtesy of Prof. Ken SytsmaHomology•Archetypal explanation“The same organ in different animals under every variety of form and function.” (Owen,1843)•Common ancestry“A structure is similar among related organisms because those organisms have all descended from a common ancestor that had an equivalent trait. “ (Darwin,1859)Homology in character evolution. Staton, July 2000Wells’ Critique: Circular definitionHomology/Common ancestor“Features are homologous because they are inherited from a common ancestor”Common ancestry is inferred using homologous features.•Features can be tested by “Multiple ad hoc hypothesis of homology” (Kluge 1997)Origin of arthropod compound eye. Oakley,2002.How would you test common ancestry?How would you test common ancestry?•Fossil record–Structure and position–behavioral patterns•Fossil record -Fossil intermediates–Behavioral patternsDinosaurBirdAlligatorHow would you test common ancestry?•Fossil record–Structure and position–behavioral patterns•GeneticsWells’ Critique: Genetics•Assumption: homologous features are programmed by similar genes•Problems1. Similar genes determine radically different structures.2. Organisms with different genes produce similar structures.Example: Pax6 in fruit flies, mice and humans•Genetics: Homolog structures and genesIs there a correlation between genotype and phenotype?Pax6 in fruit flies, mice and humans:"master regulator of eye development“ (qtd. in Displan,1997). Downstream genes are not the same, thus determines different structures.http://big.big.or.jp/~mastakeu/pax6.htmlhttp://www.umich.edu/~mmgmed/faculty/glaser/glaser2-resprojects.htmlHow would you test common ancestry?•Fossil record–Structure and position–behavioral patterns•Genetics •Developmental pathwaysWells’ Critique: Developmental Pathways•Assumption: homologous features should develop in similar ways•Problems1. Similar pathways may produce very dissimilar features. 2. Similar features are often produced via very different pathways.Haeckel’s drawingsGilbert, S. F. 1997. http://7e.devbio.com/about.php•Developmental pathways: shared features, shared early developmental features ,presence and sequence of development stages.http://www.natcenscied.org/icons/icon4haeckel.htmlHow would you test common ancestry?•Fossil record–Structure and position–behavioral patterns•Genetics •Developmental pathways•others?Analogy•Different structures which perform the same function (Owen, 1843)•Convergence: Similarities between organisms that evolved independently. Tasmanian wolf Mexican wolfFoquieria – FoquieriaceaeNorth AmericaAllauidia – DidieriaceaeMadagascarCounterarguments•“Convergent evolution is used by evolutionists to explain homologies that do not line up with the evolutionary tree.”•The probability of a beneficial mutation is very low. In addition, the probability of two different organisms with the same configuration from the same mutation is astronomically low.Convergence = directionality?•Oakley and Cunningham 2002-“When you examine the tapestry of evolution you see the same patterns emerging over and over again. Gould's idea of rerunning the tape of life is not hypothetical; it's happening all around us. And the result is well known to biologists — evolutionary convergence. When convergence is the rule, you can rerun the tape of life as often as you like and the outcome will be much the same. Convergence means that life is not only predictable at a basic level; it also has a direction.” (Simon Conway Morris 2002)Design or Mere Accident?•“The mechanism of Darwinism is at last securely founded” and as a consequence “man has to understand that he is a mere accident.” - Jaques Monod, 1970•Two questions:Design or Mere Accident?•“The mechanism of Darwinism is at last securely founded” and as a consequence “man has to understand that he is a mere accident.” - Jaques Monod, 1970•Two questions:1. Why does a naturalistic mechanism preclude a divine scheme? 2. Are just men an accident, or are women merely accidental as well?What is the PURPOSE of this seminar??What is the PURPOSE of this seminar??•Understand evidence for evolution•Allow scientists in different fields the opportunity to discuss their perspectives•Circle the wagons against ID•Critically discuss how we can best communicate “evolution” to a non-technical audienceWhat is the PURPOSE of this seminar??•Awareness of the limits of science: the full range of the human experience cannot be explain by science alone•Openness to questioning and inquiry, and accepting the possibility of being wrong.•Reverence for life: life is amazing, should we not all be in awe of biodiversity?Evolution vs. ID: Does it matter? If so, why?•How do we stop the current loss of biodiversity? •Is this debate sucking energy away from the crisis at hand?•Can we find common ground and work together toward protecting the
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