Biology Unit 10 Evolution IHS Skavaril

(Clock terms) Earth’s history

Earth forms at

00:00

(Clock terms) Earth’s history

1st single celled life emerges

04:00

(Clock terms) Earth’s history

Multicellular life emerges

20:00

(Clock terms) Earth’s history

Land plants appear

22:24

(Clock terms) Earth’s history

Mammals appear

23:39

(Clock terms) Earth’s history

Modern humans appear

23:58:43

What did Darwin find out about fossils on his voyage

• Fossils of sea animals high in the Andes Mountains

• Fossils of extinct animals that resemble modern animals

Geologic Processes

• Geologic processes can add up to great changes over a long period of time

Variation

• Differences in a physical trait among organisms in the same species

• Basis for natural selection

• E.g. = variation in jaguar jaws/teeth sizes

What is variation caused by

Sexual reproduction and mutations

Adaptation

• A variation/characteristic that allows an organism to better survive in its environment for longer and produce more offspring

• Can lead to a genetic change in a population over time

• E.g. = larger jaws/teeth in jaguars → ones can eat shelled reptiles → new source of food → survives longer

• Is a TRAIT an organism has, NOT an action an organism does

Artificial Selection

• Humans change a species by breeding it for certain traits

Intrasexual Selection

• Male competition

• Males battle for a female/mate

  • Males tend to have bright color → attracts females

  • Females are more muted so they won’t attract predators

Intersexual Selection

• Female choice

• Between male & female

Heritability

• The ability of a trait to be passed down

Natural Selection

• Organisms better adapt to their environment tend to survive and produce more offspring

4 main principles to natural selection

1. Variation

2. Overproduction

3. Adaptation

4. Descent with modification

Overproduction

• More offspring are produced than survive

• Those best fit would survive

• E.g. = not enough resources to support overpopulation → jaguars who have an extra food source (see adaptation) would be the best to survive as they have an additional source of resources

Descent with modification

• Adaptations become more common characteristics in the population

• E.g. = long jaws/teeth jaguars survive better → long jaws/teeth are heritable traits → said characteristics become more common in population

Fitness

• Measure of survival

• Ability to produce more offspring

Selective Pressures

• Anything that changes the behavior and fitness of living organisms within a given environment

  • Competition

  • Predation

  • Disease

  • Climate

  • Humans

• DRIVING FORCE OF EVOLUTION AND NATURAL SELECTION; limits the amount of organisms that can survive and reproduce

  • Biotic & abiotic pressures

Fossils

• Preserved remains of a living thing

• Shows how species change over time

• E.g. aminite

Biogeography

• Geographical distribution of organism

• Shows how species change over time

• E.g. camels

Embryology

• Study embryos and development

• Similarities indicate a common ancestor

• E.g. = humans (gill slits, like fishes, in very early stages as an embryo)

Homologous Structures (Anatomy)

• Body parts that have different function but same structure

• Similarities indicate a common ancestor

• E.g. = bat wing & human arm → same bone structure but one used to fly, etc.

Analogous Structures (Anatomy)

• Body parts that have same function but different structure

• Similar selective pressures → same functions to be beneficial

• Different in structure → distant common ancestor

• E.g. = bat vs butterfly vs bird wing → all wings to fly but different bone structure

Vestigial Structures (Anatomy)

• Body part with little or no function

• Shows how species change over time

• E.g. = appendix

DNA Sequencing

• Comparing DNA sequence of different species

• Similarities indicate a common ancestor

• Less differences = closer the common ancestor

Protein Sequencing

• Comparing amino acids of different species

• Similarities indicate a common ancestor

• Less differences = closer the common ancestor

Divergent Evolution

• Different selective pressures acting on similar organisms

Convergent Evolution

• Similar selective pressures acting on different organisms

Gene Pool

• Collection of every allele for every gene in a population

Allele Frequency

• Measures how often an allele shows up in a population

Direction Selection

• Some kind of pressure made ___ trait unfavorable

• Graph can shift forward or backward depending on situation

• Variation in species did not change

Stabilizing Selection

• Selections are against extremes of ___ traits

• Being one end of the extreme is bad

• Being in the middle ground is good

Disruptive Selection

• Selections are against the mean/middle

• Middle ground is bad

• Being an extreme is good

• The most likely selective pressure to lead to a new species

Gene Flow

• Random movement from one population to

  another

• No big change in population

Genetic Drift

• Shift in genetic variation from random change

Bottleneck Effect

• Reduction in genetic variation due to a random event

• E.g. humans, natural disasters

Founder Effect

• A few individuals (often isolated & small groups) from a larger population start a new population with a different allele frequency than the original population

• Reduces genetic variation

Species

• A way to organize organisms based on characteristic

• Most specialized form of division

Speciation

• Formation of a new species

The 2 conditions needed for speciation to occur

• Open niche

• Isolation

Open Niche

• Niche = spot/job in an ecosystem

Isolation

• Population must become isolated to speciate; takes time

Reproductive Isolation

• Members of different populations cannot have fertile offspring

Behavorial Isolation

• Organisms adapted different mating behaviors

Geographic Isolation

• Different species are separated by a physical barrier

Temporal Isolation

• Different population have different mating seasons

4 outcomes of speciation

1. Common ancestors

2. Extinction

3. Divergent evolution

4. Convergent evolution

L.U.C.A

• Last Universal Common Ancestor

• First speciation event to take place

• L.U.C.A was a single celled organism

Carcinisation

• Everything is turning into a crab

Cladogram

• Model of the relationship between species

3 parts of a cladogram

1. Branches

2. Derived characters

3. Nodes

Branches

• Represents unique evolution/history of one species

• The longer the branch, the further back in the past the common ancestor occured

Derived characters

• Indicates adaptation used to separate species

• Often labelled with specific characeristics

Nodes

• Intersection of the lines on a cladogram

• Represents common ancestors

Contributions of Charles Darwin to science

• Wrote out and supported the Theory of Evolution by Natural Selection

• Traveled the world on the HMS Beagle, collecting specimens and making observations

Co-evolution

• When two species affect the phenotypes of each other

• Can lead to symbiosis (ecological relationship between organisms) with both species benefitting or an evolutionary arms race