EvolutionChapter 15 & 16

Lecture # 18

change over time, A theory that describes the process by which modern organisms descended from ancient organisms

Scientific Theory

• a well-supported, testable explanation of phenomena that have occurred in the natural world.

• (e.g. Evolution and the idea of “Pangea”)

Pangea

A theory that all land mass was once connected together. So the animals that were in existence were able to travel over all of the land.

Charles Darwin

• took a trip around the world on the ship, the M.S. Beagle,

• collected evidence that led him to propose his famousTheory of Evolution.

• His observations showed Organisms are adapted to the environment where they live

• most important was on the Galapagos Islands

The Galapagos Islands

• The islands had different climates, and therefore, had different varieties of animals

• He studied:– Giant Tortoises– Iguanas– Finches

Galapagos Turtles Finches

Isabela IslandDome-shaped shell

Pinta IslandIntermediate shell

Hood IslandSaddle-backed shell

Beak shapes in the finches indicated their type of diet, what they ate, and this told him where they lived

The shape of each turtle’s shell is different and the different shapes depend on the turtle’s habitat.

Lamarck

– Living things have changed over time

– Living things respond to their environments

– Through either use or disuse, organisms acquired or lose certain traits during their lifetime, and these traits could be passed on to the next generation (“If you want it you can have it, and if you don’t use it you will loose it”)

• His theory was wrong!

NATURAL SELECTION• Darwin said that the

“STRUGGLE for ExistenceSTRUGGLE for Existence” was a major driving force for why organisms evolve

• He also stated that organisms that are well suited to their environment will compete out others. This is known as ““Survival Survival of the Fittestof the Fittest””

Reasons WHY we compete to Struggle

To Obtain:• Food• Living Space• Other Necessities in Life

Fitness

• The ability of an organism to survive and produce FERTILE offspring

• Darwin said that organisms that are better adapted to their surroundings are the “FITTEST”

adaptation

Can you find me? any inherited characteristicthat increases an organismschance of survival(e.g. human’s opposablethumbs, porcupine’s quills, theway in which a plant performsphotosynthesis)

Today’s assignment• Read the article “Lucy in the Earth”• On your own sheet of paper answer

the questions in complete sentences.• #4 on the back says, “How does a

human transmit weight when walking?”

***Lucy is being shown at the Museum of Natural Science if you bring me a ticket stub And a pamphlet I will add 10 points to your lowest major grade.***

Proof for Evolution

• 1. Fossil record– provided evidence

that living things have been evolving for millions of years

2. Geographic Distribution of living species

– similar species in similar environments but in different locations, were products of different evolution paths

Beaver

Muskrat

Beaver andMuskrat

Coypu

Capybara

Coypu andCapybara

Development during the early stages of animals with backbones are very similar .These common cells growing in similar ways leads to homologous structures

• Homolgous structures all develop from the same embryo tissues but have different functions in the adult organism.

3.Homologous Body Structures

4. Vestigial organs

organ with little or no function, left over from the past (e.g. Wisdom teeth, tail bone, and appendix)

Artificial Selection

the intentional breeding for certain traits, orcombinations of traits, over others… this canlead to speciation

Adaptive Radiation

• the evolutionary process through which a single lineage gives rise to many new species

• models how geographical separation leads to evolutionary divergence (diversity of species form).

Gradualism vs. Punctuated Equilibrium

Gradualismslow, steady process in whichthe species accumulatesadaptations over time slowlydiverging from a common ancestor

Punctuated Equilibrium a new species changes most as itbuds from a parent species andthen changes little

Tempo of Speciation

Speciation

• Formation of a new Species

• when natural selection and isolation mechanisms lead to the creation of a new species

Types of ISOLATION that lead to Speciation

All are forms of Reproductive isolation:• Behavioral Isolation• Geographic Isolation• Temporal Isolation

Reproductive Isolation

populations become reproductively isolated from each other, so it leads to evolution of a new species

Behavioral Isolationwhen two populationscan interbreed, but donot because theirbehaviors don’t match(e.g. courting rituals/ mating calls)

Geographic Isolation two populations are separated by geographic barriers, like mountains or oceans and can’t interbreed

(e.g. tucans found in every rainforest and the blue throated tucanet)

Temporal Isolation

two populations are separated by different

reproductive times