Evidence of Evolution

Shared ancestral character

a character on a phylogenetic branch that is shared by every clade

Cladistics

a method used to organize homologous traits to describe phylogenies using common descendent as the primary criterion used to classify organisms

Shared derived character

A character on a phylogenetic tree that is shared only by a certain clade of organisms

Clade

A group of species that includes an ancestral species and all its descendants.

Clade

A monophyletic group is a ________.

Vestigal structure

A physical structure present in an organism that has no apparent function and appears to be from a functional structure in a distant ancestor

Maximum parismony

Applying the simplest, most obvious way with the least number of steps

Analogous structures

Body parts that share a common function, but not a common ancestor

Analogous because a dolphin is a mammal and a fish is not - meaning they are not likely to share a common ancestor. Rather they have similar body shapes because of the similar environments they live in.

Dolphins and fish have similar body shapes. Is this feature more likely a homologous or analogous trait?

Phylogeny

Evolutionary history of a species

Biogeography

Geographical distribution of organisms on planet follows patterns that are best explained by evolution in conjunction w/ movement of tectonic plates over geological time

Molecular biology

Modern biochemical and genetic(DNA) analyses reveal

Homologous structures

Structures in different species that are similar because of common ancestry. Ex. appendage structure of humans and dogs

Descent with modification

The fact that DNA sequences are more similar in more closely related organisms is evidence of what?

Molecular systematics

The methods of using molecular evidence to identify phylogenetic relationships

Homologous structures

The wing of a bird and the arm of a human are examples of ________.

- Oldest human fossil dates back 2.8 million years. - An example of an embryological similarity is found when all vertebrates embryos develop tails and gill slits. - 88% of Earth's history occured during the Precambrian era - Igneous rocks are reliable to test for age because they are made from melted rock that has been cooled from a solid state and are typically unchanged from the moment they cooled.

WOW points

Periods

What are eras divided into?

Epochs

What are periods divided into?

Precambrian, Paleozoic, Mesozoic, Cenozoic

What are the four eras of the geological time scale in order?

Fossils, anatomy and embryology, biogeography, molecular biology

What are the four main bodies of evidence for evolution?

Cenozoic

What era are we in now?

A branching diagram showing the cladistic relationship between a # of species

What is a cladogram?

Age of the trilobites

What is the Cambrian period known as?

Record of time - life forms and geological events - through using rocks

What is the geological time scale?

Shared derived traits

What kind of trait is important to cladistics?

The vestigial structure is an ex of a homologous structure that has apparently been reduced through evolution to a non-function state because its function is no longer utilized by the species exhibiting it, therefore any mutations which might reduce its structure are not selected against.

Why do scientists consider vestigial structures evidence for evolution?

Monophyletic group

organisms that share a single ancestor (also, clade)