This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Nettie Stevens (1904)
Tenebrio larva (Meal worm) Inheritance
Bio 151 Investigations in Genetics and Evolution Prof. Kellar Autumn [email protected]
Credit: DNA From the Beginning; http://vector.cshl.org/dnaftb/asp/ Discovery of chromosomal sex determination Kellar's 2nd Child's Karyotype
Q: was it a boy or a girl? Sex is a Mendelian character determined by sex chromosomes! Nettie Stevens (1904)
Credit: DNA From the Beginning; http://vector.cshl.org/dnaftb/asp/ Homogametic Heterogametic Males have 1 X: how do females compensate for double dosage of X?
Barr Bodies are inactivated X chromosomes X Inactivation
Is this a Male or Female cat? Copyright The MGraw-Hill Companies, Inc. X Inactivation
Mammalian females are "mosaics". In some of her cells her father's X chromosome is inactivated. In other cells, her mother's X chromosome is. Temperature-dependent sex determination
Lang J. W. and H. V. Andrews. 1994. Temperature-dependent sex determination in crocodilians. J. Exp. Zool. 270:28-44. All male All female All female TSD patterns
Pond Turtle, Emys orbicularis All female Map Turtle, Graptemys ouachitensis All female T.H. Morgan and his Fly Lab All male All male Lizard, Agama agama Map Turtle Nests All female All male All male All female Pough F. H., J. B. Heiser and W. N. McFarland. 1989. Vertebrate life, 3rd ed. McMillan, New York. Inheritance of White Eye
Male w Female +
Father (Xw Y) Daughter (X+ Xw) All wild type
Hypothesis: 3 wild :1 white ... but all white eyed flies are male!
Test hypoth. with: Son (Xw Y) F2 F3
3:1 Unequal male/female ratio What if we reverse sexes in the cross?
P: Male wild-type X Female White eye? Reciprocal cross: white eye F X wild M
Chickens: ZW system Female = heterogametic sex
Female: Heterozygous for White eye (looks like recessive) Male: Hemizygous for White eye (demonstrates pseudodominance) 1:1 Equal male/female ratio Inheritance of Xlinked traits is not reciprocal between sexes 3:1 Unequal male/female ratio. Only females are Nonbarred Sex unknown What's the mode of inheritance? h+
Copy 1 Copy 2 Consanguineous
Sex-linked recessive Skips generations #affected M > #affected F No father to son Oops -Kissing Cousins! h+ h+
Autozygous for h hh hh hh Eugenics in America
All human traits -even behaviorobey the rules of Mendelian inheritance Charles Davenport (1932) Director Eugenics Record Office Author of Naval Officers: Their Heredity and Development
Credit: DNA From the Beginning; http://vector.cshl.org/dnaftb/asp/ Eugenics in America Naval Officers: Their Heredity & Development
Damn the torpedos! Full speed ahead. Inheritance of Thalassophilia Junior officers Fearless parents Admiral David Farragut A "Fitter Family Contest" Booth at the Kansas State Fair (1920)
Credit: DNA From the Beginning; http://vector.cshl.org/dnaftb/asp/ Fearless son Credit: DNA From the Beginning; http://vector.cshl.org/dnaftb/asp/ Nazi Eugenics and Euthanasia
http://www.holocaustresearchproject.org Evolution by Langdon Smith (1895) "Who would want to be responsible for this?" Feeble-mindedness in related families in four neighboring towns Hitler's order authorizing the T4 euthanasia program "Bad genes enter a village" "A genetically ill person costs the state 50,000 Marks over sixty years" http://germanpropaganda.blogspot.com/2009/06/nazi-eugenics-posters.html "The Judaizing of Berlin 1932" ...
View Full Document