Pedigrees and Adaptations Genetics and Diversity II Pedigrees and Adaptations

S1-1-14 Explain the inheritance of sex-linked traits in humans and use a pedigree. S1-1-08 Investigate adaptations of plant and animal species which enhance reproductive success. Vocabulary & People  Sex-linked Pedigree Natural Selection Adaptation

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

Sex-linked traits are more common in males y 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

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

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

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 ?

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…

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

“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?

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

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

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