1. Pedigrees and Adaptations
Genetics and Diversity II
Pedigrees and Adaptations

2. S1-1-14 Explain the inheritance of sex-linked traits in humans and use a pedigree.
S Investigate adaptations of plant and animal species which enhance reproductive success.
Vocabulary & People 
Sex-linked Pedigree
Natural Selection Adaptation

3. Sex chromosome X carries genes that code for traits other than gender.
Traits determined by genes on the X chromosome are called sex-linked traits.
Hemophilia, colour-blindness, and baldness are three common examples

4. Sex-linked traits are more common in malesy x
Inherits trait from mother
(give the X)
Phenotype always shows gene
(no other allele to mask it)
Will pass to ALL daughters
Inherited from either parent
Needs two alleles to show
recessive trait
One recessive allele: will not
show the trait - but is a
“carrier”
Sex-linked traits are more common in males

5. X Y X X X X Y X X X Y X Father = XY Mother = XX
Mother is a carrier X X
¼ color-blind male – 25% X X Y X
½ disorder free – 50%
¼ female carrier – 25% X X Y X

6. Genotypes can be determined by analyzing the trends of the pedigree
Pedigree: diagram representing the phenotype
history of a family.
Genotypes can be determined by analyzing the trends of the pedigree
Symbols:
Male – square
Female – circle
Dominant trait – blank
Recessive trait – filled

7. What are the genotypes for each person in this family?
A widow's peak hairline (W) is dominant over a straight hairline (w):
What are the genotypes for each person in this family? W w W ww w W w ww ww W ? W w W w ww ww W ?

8. Natural selection is the gradual process of traits becoming more common in a population because the traits may improve reproductive success of organisms in an environment.
(It is a key mechanism of evolution)
Luck and timing has something to do with it too…

9. disadvantage : no offspring
Anything that gives you an advantage will help you pass that positive trait on to offspring
disadvantage : no offspring

10. “Only The Strong Survive”
Adaptation: a naturally selected trait that enhances reproductive success.
Can be physical or behavioural
How would big tail feathers make him more successful? How would they make him less successful?

11. Examples of Adaptations
Behavioural
caring for young
mating calls
dances
fighting
Physical
colours / camouflage
size / shape
pheromones
multiple offspring
Those best able to modify their behavior or those with positive mutations that improve their survival and reproductive success pass on these traits to future offspring

12. Think of adaptations that have evolved to help an organism (including humans) survive its environment and reproduce.

13. CAN YOU ANSWER THESE QUESTIONS? S1-1-14:
What is a pedigree and how is it used to track inheritance of a trait?
S1-1-08:
What are some ways plants and animals improve their chance to reproduce?
Vocabulary & People 
Sex-linked Pedigree
Natural Selection Adaptation