Life on Earth is incredibly diverse

What is Darwin's Hypothesis Called and when was it Published?

-On the Origin of Species by Means of Natural Selection

-November 24, 1859

Evolution

Broadly Defined- Descent with modification = species are descendants of ancestral species that were very different form those alive today

Narrowly Defined- Change in genetic composition(allele freq.) of a population over time

Theories have two components, What are they?

Pattern- statement that summarizes a series of observations about natural world

Process- mechanism that produces that pattern or set of observations

All species are independent (unrelated) 

Life on Earth is young (6000yrs)

Species are immutable (incapable of change)

What was Darwin's Ship called and When did it Leave?

The Beagle

December 1831

5 year mission

Collected specimens of S.American Plants and Animals

Observed that fossils resembled living spevies form same region, and living species resembled other species from nearby regions

Read Lyell's principles of Geology book

Process in which individuals with certain heritable traits survive and reproduce more than others in a population.

Over time favored trait increases in Frequency

If environment changes, N.S may result in adaptation to new conditions, sometimes giving rise to new species

Editing Mechanism

(act on existing variation)

Cannot create favorable traits

Env. Factors vary and traits that are useful in one place can be useless or detrimental in another place

In 1844, Darwin wrote an essay on Origin of Species and Natural Selection but was reluctant to publish it

Wallace, a naturalist, sent Darwin a manuscript containing a hypothesis of Natural Selection, identical to Darwins

Darwin finishes the paper and published it the next year

descent- all organisms come from a common ancestor in the remote past-unity of life

Modification- over evolutionary time scales organisms accumulate adaptations to their environment-diversity of life

Individuals in a population vary in many heritable traits

(traits can be passed to offspring)

Population has potential to produce more offspring than will survive to produce offspring of their own

With more individuals than environment can support, competition is inevitable because resources are limited

Individuals are unequal in their likelihood of surviving and reproducing

Those individuals with heritable traits best suited to the environment will produce more healthy, fertile offspring

(increased fitness)

Unequal reproductive success can adapt a population to its environment

Over Generations, heritable traits that enhance survial and reproductive success tend to increase in frequency among population's individuals.

(N.S acts on the individual, Evolution acts on the Population)

Ability of an organism to reproduce relative to others in the population

(Adaptations increase Fitness)

Capacity to overproduce seems to be a characteristic of all species

(Only a tiny fraction of offspring completely develop and reproduce)

Population Thinking

Scientific, could account for change through time and made predictions that could be tested through observ. and exper.

Anatomical structures that represent variations on a structural theme present in a common ancestor

(may be evident in embryonic development) similarity in genetic structure reveals common ancestors

As fossil records improved, many transitional forms have been discovered with traits that are intermediate between earlier and later species

(provide strong evidence for change through time)

Geographic distribution of species provides evidence of evolution

(pangea and continental drift)

Species that are not found anywhere else in the world(common on islands)

Most island species are closely related to nearest mainland species

not all traits are adaptive and evolution by natural selection does not lead to "perfection"

(vestigial traits)

Compromise between traits, in terms of howthose traits are adapted for environment

(size of eggs individual makes and # of offspring)

1. Evolution is not "goal directed"

2. Evolution is not "progessive"

3. No organism is self less (inclusive fitness)

4. Evolution is just a theory