Living Organisms

Living Organisms

 1.

Embryology  2.Homologous and Analogous Features  3. Vestigial Features and Anatomical Oddities  4. Biochemical Evidence  5. Artificial Selection

 The

study of organism in the early stages of development  Von Baer (a German Scientist ) said he could not differentiate between the embryos of lizards, birds and mammals.  It was later suggested that similarities where do to their evolution from a common ancestor  Embryology helps identify homologous structures

~ 1-2 days

~ 41 days

~ 52 days

~ 120 days

 Homologous  

Features

Features with similar structures but different functions Example – flippers of a seal, forelimbs of a dog, wings of a bat, the human arm

 Homologous

structure are thought to have followed a process of divergent evolution.  Divergent Evolution – the process where to species with the same ancestor have developed different forms and functions as a result of adaptations to different environments

 Analogous 



Features

Features that are similar in appearance and function, but do not appear to have the same evolutionary origin Example: wings of a insect and wings of a bird

 Analogous

structures are thought to have evolved through a process of convergent evolution  Convergent Evolution – independent evolution of traits based on adaptation to similar environments

 Divergent

Evolution

Homologous Structures - same origin, different appearance and function

Convergent Evolution

Analogous Structures - different origin, similar appearance and function

 Vestigial

Features are rudimentary structures with no apparent useful function  This suggests that they once served some function in an ancient ancestor, but the organism evolved to function without the structure.

 Eg.

Whales and snakes have vestigial hip and leg bones!

 Based

on the theory that all life came from one original cell  Genetic material (DNA) is similar in all organisms  This is “tested” by comparing the number of differences in amino acid sequences. The fewer differences, the closer related the organisms are. The more differences, the further apart the organisms are from a common ancestor.

 Cow:

GAG GAAG G T T C G G T C



 Human:

G

AC GTAC GTAC GATC

 Monkey:

GAG G TAAG TAC C AT C



 Just

like biologists descovered vestigial anatomical features, geneticists are discovering vestigial genes!!!!

 Humans

have a set of (defective) genes that would allow us to make our own Vitamin C! Fortunately for Florida orange growers, we have lost both the ability and the need to make our own.

 The

process of humans selecting and breeding individuals with specific desired traits.

 Practice  Lab 

Questions page 145 # 1-2

Exercise 5.A on page 147

Do the evidence and analysis

 5.3

Questions page 149 # 1-3