Evidence for Evolution

FOSSIL EVIDENCE-Provides TRANSITIONAL LINKS

Archaeopteryx- links reptiles and birds

Anatomical EvidenceHOMOLOGOUS STRUCTURES

structures that are similar because they were inherited from a COMMON ANCESTOR

ANALOGOUS STRUCTURES

similar in function, but NOT inherited from a

common ancestor

NOTE: similar structure, but NOT always function!

NOTE: similar FUNCTION, but not STRUCTURE

More Anatomical Evidence:Vestigial Structures

Vestigial Structures are undeveloped structures that were functional in some ancestor, but are no longer needed in that organism.

EMBRYOLOGY- suggests common ancestors

BIOGEOGRAPHICAL EVIDENCEWhen we study the distribution of plants and

animals on the planet, we notice:Animals evolved differently in each of the

biogeographical regionsWe see evidence that as the continents drifted,

organisms were separated and evolved.

BIOCHEMICAL EVIDENCEAlmost all living things use the same

biochemical moleculesDNA, Protein, ATP

Vast diversity came about by only slight differences in the same genes

The more closely “related” the organisms are, the more similar their DNA

Patterns of EvolutionMacroevolution refers to large-scale

evolutionary patterns and processes that occur over long periods of time.

Six important topics in macroevolution are:

extinction adaptive radiation (divergent evolution) convergent evolution coevolution punctuated equilibrium changes in developmental genes

Gradualism Punctuated Equilibrium

GradualismOrganisms go through gradual and continuous

change

Punctuated EquilibriumOrganisms go through fast periods of change,

followed by long periods of no change (according to fossil record)

More than 99% of all species that have ever lived are now extinct.

Mass extinctions:provide ecological opportunities for

organisms that survived result in bursts of evolution that

produced many new species

Patterns of Evolution: 1. Convergent EvolutionConvergent Evolution: When 2 or more

unrelated species become more similar due to similar adaptations to their environment.

Divergent Evolution: when related species become more different as they adapt to different environments

Divergent evolution leads to Adaptive Radiation

Patterns of Evolution: 2. Divergent Evolution-Adaptive Radiation

Sometimes organisms that are closely connected to one another by ecological interactions evolve together.

The process by which two species evolve in response to changes in each other over time is called coevolution.

Ancestral Mammals

Adaptive Radiation of Mammals

This diagram shows part of the adaptive radiation of mammals, emphasizing current hypotheses about how a group of ancestral mammals diversified over millions of years into several related living orders. Note that the dotted lines and question marks in this diagram indicate a combination of gaps in the fossil record and uncertainties about the timing of evolutionary branching.