L8: Evolution Theory

What is Biological Evolution? Where does it happen?

inheritance of traits, passing on genes from one generation to the next

happens in the population, when specific processes cause organisms to be different from their ancestors

What are products of biological evolution?

• Heritable changes - permanent changes in DNA sequence (i.e. mutations)

• Phenotypic Modifications - temporary changes in organism’s appearance

Biogeography

the study of organisms in geographic locations and distributions
→ similar species, different locations

Name an example of an organism that demonstrates biogeography

3 Types of Ostriches: African ostrich, South American rhea, Australian emu
→ similar characteristics, eat similar diets, but live in different environments

What are 3 types of Evidence that Organisms seem to change over time?

1. biogeography - ostriches

2. comparative morphology/homology - bones

3. fossil evidence - different layers signify change over time (different time zone)

Homology

similar anatomical structure/genes but for different purposes (i.e. - bones)

Genetic similarity

genetic makeup/DNA sequence of an individual/species that matches another species/individual

How many S components are in the eukaryotic ribosomal small subunit vs the prokaryotic ribosomal small subunit?

eukaryotic - 18S
prokaryotic - 16S

Explain difference in extinct vs extant species

extinct = no longer exist

extant = still exist in the world

George-Louis Leclerc

• focused on anatomy, homologous traits

• believed species were created and separated into hierarchy “my life matters more than yours”

• suggested species could change over time due to environmental change → “internal mold” and believed species shared a common ancestor

Carolus Linnaeus

• came up with taxonomy (classifying organisms into groups in hierarchy)

  • also developed naming organisms in two parts (genus + species)

• did not embrace evolution, but did embrace idea of change

Hierarchy of Biological Classification

Species - seaweed
Genus - green
Family - fresh
Order - over
Class - candy
Phylum - pick
Kingdom - kids

Jean-Baptiste de Lamarck

• famous for proposing the first cohesive theory of evolution

• principle of disuse and use - if you use an organ often, it will grow stronger and larger

  • giraffes using their necks to get grass and it grows longer and longer

• inheritance of acquired characters (Lamarckism)

  • the physical structure an organism acquires by using it gets passed off to their offspring

Explain the difference between Adaptation vs Acclimation

Adaptation = gradual, slow process of genetic change in a population (across multiple generations)

Acclimation = fast, temporary change in an organism does to handle stress in an environment

Thomas Malthus

• concerned about the “decline of living conditions” in England

• argued that human populations grew exponentially while food production only increases linearly

  • because humans grow faster than food production, we are constantly struggling → “struggling for existence”

Charles Lyell

• looked at evolution geology and through Earth

• proposed that Earth changed slowly over time (gradualism)

• suggested that this happened through the same process today (uniformitarianism)

Charles Darwin

• traveled on The Beagle for 5 years

• Gathered fossils of extinct fossils (i.e. birds and barnacles)

• recognized layers of rock that gradually formed, weakened, or experienced in Chile

• Finch Collection - discovered differences in Galapagos bird beaks (seed crusher vs nectar vs eating cactus vs insectivores)

Why did Charles Darwin stand out from the rest of the naturalists?

He rejected mechanisms previous naturalists had proposed

He also published The Origin of Species 3 decades after Lamarck’s death

Who was Wallace and what significance does he have related to Darwin?

Wallace was a naturalist and he competed against Darwin for the development theory of natural selection

Story time w/ Wallace and Darwin

• had the same idea for Natural Selection - BOTH independently developed it

• they met up for a dual for the ownership of the idea

• Darwin won because he had more data while Wallace used more of his backyard observations

How did religion play a part in Darwin and Wallace’s theory development of Natural Selection?

Wallace was religious which led him to think that human growth required more force rather than just natural selection

Darwin was an atheist so he believed that evolution was a naturalistic evolution (and God had no part)

Sexual Selection

type of Natural Selection

animals develop traits that help them get more mates and reproduce, even if the traits don’t help them survive

Example: male birds attempting to attract female birds to mate (peacocks)

Artificial Selection

humans get to choose specific plants/animals to reproduce to get desired traits

• i.e. - dog breeding

How did Artificial Selection connect to Darwin?

Darwin argued that if human breeders could create different species by picking preferred traits, then natural selection could also produce varied species on Earth (in a slower time)

proved all domestic breeds of birds came from single ancestral rock pigeon

Natural Selection

specific traits that helps an organism survive (gives them an advantage)

organisms that are better suited to the environment are more likely to survive and pass those genetic traits to their offspring

What were Darwin’s Evolution Findings by Natural Selection?

1. common ancestry - came from same ancestors

2. struggle for existence - humans overpower the food production, always competing for resources

3. natural selection - organisms have specific and advantageous traits that are more likely to help them survive and pass off those traits to their offspring

4. descend with modification - over generations, these modification and advantageous traits build up and eventually will build whole new species with those traits