Similarities and Connections

Common Descent Theory that all living things come from common ancestors. Cladogram: diagram showing evolutionary relationships and the points where species appear to have diverged from common ancestors

Speciation 2 or more new species form from an existing species. Often occurs due to isolation. Individuals of a population cannot interbreed. Over time, the populations will become different (physically and/or behaviorally).

How Speciation Occurs Reproductive Isolation: Individuals are physically unable to interbreed. (ex: dogs can’t mate with fish) Geographical isolation: individuals are separated by a physical barrier. (ex: river, ocean, mountain) Behavioral isolation: individuals do not breed due to differences in courtship or mating behaviors. (ex: songs of frogs do not attract birds)

Analogous Structures Structures that have similar function but different structure. Demonstrate convergent evolution. Example: wings of insects, birds, and bats.

Homologous Structures Structures that have similar structure but different functions. Used as evidence of a common ancestor. Example: Bones of human hand, dolphin flipper, and dog foot are similar in structure, but serve different functions.

Vestigial Structures Structures that are reduced or altered from their original function. Used as evidence of common ancestry. Examples: Ostrich wings (can’t fly), whale pelvis, and human appendix.

Embryology Organisms develop similarly based on shared ancestry What are some differences between: Fish Salamander Tortoise Chicken Pig Sheep Human Organisms develop similarly based on shared ancestry

Embryology E C B D A Who is who? F G

Embryology Study of the formation, early growth, and development of living organisms. Similarities between organisms is used as evidence for a common ancestor.

DNA Blueprint for life Composed of nucleotides that have one of 4 bases – adenine, cytosine, guanine, thymine Sequence of nucleotides/bases determines amino acid sequence. Video: http://statedclearly.com/videos/what-is-dna/

GENES Portion of a DNA strand that codes for a specific trait Traits are determined by genes that are active (not all genes are active). Video: http://statedclearly.com/videos/what-is-a-gene/

Protein Shape The shape of the protein is determined by the sequence of amino acids. The shape of the protein determines its function. If the order of the amino acids is changed, the resulting protein is changed (may not be functional).

Mutations Change in the DNA, source of genetic diversity.

DNA Similarities Many organisms have similar DNA sequences. Similar DNA sequences will code for similar amino acids/proteins. Similar DNA is used to indicate organisms have a common ancestor. A greater number of similarities is assumed to indicate a closer relationship.

Convergent Evolution - fyi (not on test) Unrelated species develop similar traits, often due to similar environments. Example: Bill of duck and platypus. Both are similar in shape but are not made of the same material.

Coevolution – fyi (not on test) Organisms evolve in response to the changes in another species Plants and Pollinators Predator and Prey Parasite and Host