Ch 22.1-2 Darwin and Descent

Aristotle’s views

species are fixed. arranged on a scala naturae (humans on top, animals ranked)

Carolus Linnaeus ideas

Thought organismal adaptations showed that the Creator had designed each species for a specific purpose. Founder of taxonomy. 

James Hutton and Charles Lyell ideas

Hutton: The species that adapt when the environment changes are the ones who survive

Hutton and Lyell: uniformitarianism: the same natural laws and processes that are here today have been in action for all of time.

Thomas Malthus ideas

Population will outgrow food supplies and resources. Heritable traits that are advantageous will increase in frequency as offspring who have these traits survive and reproduce.

Jean-Baptiste de Lamarck

Hypothesized that species evolve through use and disuse.

Georges Cuvier ideas

Father of vertebrate paleontology. Established that species had gone extinct in the past

Why did Darwin consider the fossil record unreliable?

1. only some organisms form well preserved fossils

2. fossil record will be full of holes because it is a difficult process

Transitional fossils

fossils that appear to be transitional forms between two distinct large taxa. Ex: Archaepteryx siemensii transition species between birds and reptiles

Social Darwinism

Argued for eugenics. Was not actually a Darwin idea

Adaptations

inherited characteristics that enhance an organism’s survival and reproduction in specific environments.

New species arise through gradual accumulation of small adaptations

Natural selection

process in which individuals with certain inherited traits tend to survive and reproduce better

Key Features:

1. increases the frequency of adaptations that are favorable

2. If env. changes over time, natural selection may lead to adaptation which may lead to new species

Note:

1. individuals do not evolve, populations do

2. Natural selection can only increase or decrease heritable traits that are already present in pop.

3. adaptations vary with different env.

Ideas from The Origin of Species

1. The unity of life

2. the diversity of life

3. the ways organisms are suited to life in their env.