Natural Selection

What is evolution

A process of biological change where descendants come to differ from their ancestors

Biological Species

group of organisms that can reproduce and have fertile offspring

Why do we need to know different types of evolution?

To learn about the past and apply changes to the future

NATURAL SELECTION

a mechanism of evolution

Through natural selection we see

changes in species over time/ LEAD TO CHANGES IN ALLELE FREQUENCIES

Variation and Inheritance

variation within the population for a given trait

Variation COMES FROM WHAT

MEIOSIS (crossing over and random assortment) AND GERMLINE MUTATIONS (gametes can be inherited)

Example of variation

flower color/ hair color/ different shapes red blood cells

Variation can be

something we cant see that makes the body function differently

Variation Evidence comes from

direct observations from darwin and wallace and paleontologists like Buffon, Linnaeus, and Cuvier

Lamarck considered a mechanism for

how something might be passed from parent to offspring

COMPETITION

Resources for any organism within an ecosystem are limited/ organisms have to compete for resources

Factors that could be limited in competition

food, water territory

Example of competition

The purple flower of pea plants makes them more attractive to pollinators. outcompete white flowers/ dark hair protects from sun

Competition People help

Malthus' economic theories and the ideas of his grandfather Erasmus

ADAPTATION

inherited trait that benefits an organism in in CURRENT ENVIRONMENT

How Adaptation can become less beneficial

if the thing changes environments

Example of Adaptation

The purple pea plant is better adapted to its environment because it is better able to attract pollinators.

Adaptation influential people

His grandfather again and Lamarck (certain traits are favorable), Hutton (natural selection in dogs), Malthus (some will outcompete others), and Wallace (his own theory of natural selection)

Fitness

over time animals that are better adapted to compete will live to reproductive age/ higher fitness will pass on traits

Example of fitness

more purple pea flowers due to more pollinators making them have a higher fitness/ In areas with a lot of sunlight, we see strong selection for darker hair.

TIME

geologists mostly and this idea that we can trace past events in the Earth by what we have available to us today (Hutton and Lyell) (evidence for evolution)

DARWIN'S JOURNEY

Species in different environments globally showed differences and species similar environments globally showed similarities

Fossils

showed that the earth was very old

Benefits of a fossil

very old/ structurally okay

Disadvantage of fossil

fragmentary/ no DNA

Biogeography

How members of a species distributed across geography can tell us about evolutionary relationships

two observations involving biogeography that were important to Darwin's thinking

closely related species evolve diverse adaptations in slightly different environments. very distantly related species develop similar adaptations in similar environments.

Benefit of biogeography

variation

Disadvantage of biogeography

different animals/ not every animal is useful/ human action disturbed ability to see relationships

Comparative anatomy

Homologous structures (due to common ancestry) Analogous structures (due to convergent evolution) Vestigial structures (due to common ancestry but the trait is no longer used)

key to identifying homology is

common structure and origin during development

vestigial structure can have

a nonobvious function

vestigial structures often have a very low BLANK

fitness

Benefits of fitness

very obvious shared ancestry

disadvantage of fitness

difficult to assess without very particular technology/ Can't be done with extinct animals

Genetics and Molecular biology

Animals with closer evolutionary relationships have more similar genetic sequences for specific genes

which type of evidence for evolution is more informative fossil evidence or genetic evidence

Genetic because you have DNA which you can see genetic relationships

Benefits of genetic and molecular biology

same nucleotides=more related/ see time of common ancestor

Disadvantages of genetics and molecular biology

need DNA (not possible for things extinct)

Embryology and Development

how an animal develops as an embryo is the result of evolutionary relationships (for example, all vertebrates have a similar developmental body plan, thus they look very similar throughout early development

Benefit of embryology

very obvious shared ancestry

Disadvantage of embryology

difficult to access without specific technology