Unit 8: Evolution AP BIO

Diagram that shows the classification of a species into more and more specific group

• New branches have some significant differences

• same as Cladograms

group of organisms that includes an ancestor and all descendants of that ancestor on the phylogenetic tree (also known as monophyletic)

characteristics that are different from the ancestor

characteristics or features inherited from ancestors

Morphological

• Structure

Molecular

• Look at mitochondrial or nuclear DNA

• more accurate than morphological

• common ancestor and all the descendents

  • clade

organisms but not all descendents

do not include common ancestor and may be product of convergent evolution

distant relative to all other organisms being compared

• purpose

  • helps determine what traits are ancestral and which are derived

all other organisms being compared

• evolving independently after facing similar pressures

  • homoplasies

evolve back to an ancestral state from a derive state after facing similar pressures

• homoplasies

similarities in traits or characteristics between different organisms that are not due to shared ancestry but rather to convergent evolution, evolutionary reversals, or other factors

simplest explanation with the fewest assumptions

• using the fewest evolutionary changes to construct a phylogenetic tree

groups of individuals who can actually, or potentially, interbreed and produce fertile offspring

• genetic mixing is possible

Forming a new distinct species from a preexisting one

• how?

  • isolated by different environments

  • favorable adaptations accumulate

  • become so different that they don’t interbreed anymore

Parent species changes and transforms into one new species

• type of speciation

single ancestral species splits into two or more distinct lineages

• type of speciation

• promotes biological diversity

Evolution happens through many small changes

Evolution happens through short bursts of change

• supported by fossil record because its hard to find transitional fossils

geographical division

• the population is divided by a physical barrier

• each separated population accumulates variation due to

  • natural selection

  • mutations

  • genetic drift

New species without geographical division

• Change in ecological requirements

• Polyploidy

  • can only mate with other polyploidy

having multiple sets of chromosomes due to errors from meiosis (nondisjunction)

Chromosome number is accidently not reduced in gametes of parent (2N stays 2N)

• two times the amount of chromosomes so (4N)

  • usually happens in plants

• can only mate with other 4N

  • new species

mating between two different species

• interspecific hybrids are usually sterile

Individuals do NOT evolve; populations do

• Genetic makeup/allele frequency changes over time

a group of interbreeding organisms in a geographic area

How much(percent) of the gene pool is a specific allele

• from 0.0 to 1.0

Random changes in the DNA of an organism that could be neutral, harmful or beneficial depending on the environment

• increase variation

• affect phenotype because the DNA 🡪 genotype 🡪 phenotype

Random changes in the allele frequencies of a small population

• decrease variation

• Gene pool will remain the same when there is a large population size, when you decrease the size, genetic drift will occur

decrease in size caused by natural catastrophe- floods, volcanic eruptions, ice age; predation, disease

• decrease variation

• population undergoes dramatic decrease in size

migration and isolation of a small subset of the population

• forms a new population

• reproduce with each other

movement of individuals and alleles between populations

• not significant source of evolution in large populations, but substantial in small pops

• introduce alleles

• remove alleles

chooses for or against based on current abiotic(living) and biotic(nonliving) factors at a moment in time

• choosing against phenotype

null hypothesis to evolution

• calculates if there are significant changes in the gene pool/ number of alleles present

1. Random mating

   1. no choosing mates based on certain phenotypes

2. No mutation

3. No events

   1. no genetic drift/ migration

4. Large population size

   1. In small populations, allele frequency is more likely to change due to genetic drift

5. No natural selection

   1. Specific phenotypes/ alleles will not be favored

• Species reproduce

• If growth rate was unchecked,
  overpopulation would occur

• Resources become scarce

• Competition among and
  between species

• Individuals are different= VARIATION

• Only best suited to environment will survive to reproduce

• Those who reproduce/choose to reproduce pass on their genes

• Competition

• Natural Selection

  • Phenotypic Selection

  • Right Place, Right Time

  • Variation (is it beneficial to the gene pool)

• Reproduction/ Fitness

Competition within one species

• lose-lose situation

Competition between different species

measured by the ability to pass its genetics onto the next generation, compared to other organisms in the population

• how many children you have that survive to adulthood

Human driven selection

1. Humans can select traits to co-breed

   1. Many genes cross

   2. Not selective to just one trait- intended AND unintended traits cross

2. Humans can select specific genes for

   manipulation

   1. One gene to manipulate → GMOs

   2. Gene switches are not fully

      understood

Species with little genetic diversity (little variation) are at risk of extinction

• allows each individual in the population to respond differently to the same environmental change

Creates new combination of alleles

• Crossing Over

• Independent Assortment

  • random combinations of maternal and paternal chromosomes

• Random Fertilization

Eliminates individuals that have extreme or unusual traits

• Reduces variation in a population

• Most common type of natural selection

Individuals with an extreme phenotype contribute more offspring to the next generation

• Traits at opposite extreme are selected against

• Could lead to speciation

Both extreme phenotypes are favored over the intermediate phenotype

• divergent evolution

Acts on the characteristics that determine reproductive success, not survival

• females choose superior males based upon certain characteristics

• Females makes a greater energy investment in producing offspring than males, they can increase their fitness by increasing the quality of their offspring by choosing superior males

• Males contribute little energy to the production of offspring and therefore increase their fitness by maximizing quantity of offspring produced

Sexual Dimorphism

• female and male appearance is different

• Fossil record

• Anatomical similarities

• Embryological similarities

• Biochemical similarities

• Conserved core processes

• Homeostatic controls

• Biogeography

provide record of transitional forms

• Law of Superposition

• evidence of evolution

in an undisturbed sequence of rock layers

• youngest are at the top

• the oldest rocks are at the bottom

Similar structure but possibly different function 

• Evidence of common ancestry (divergent evolution)

One group develops into a new, distinct species

• two populations adapting to separate environmental needs

Extreme form of divergent evolution

• Ancestral species diverges into a wide variety of new species

  • ex

    • Galapagos finches

Similar function but different structure

• resemble each other due to similar selective pressures and not recent common ancestry

• evidence of convergent evolution

• ex.

  • wings

Remains of structures that are no longer needed

• evidence of evolution

Embryos of related species show similar patterns of development in early stages

All species use the same molecular building blocks

• Use the same genetic code and share amino acids

• Compare amino acid sequences between species

  • Similar the code the closer related

• product of convergent evolution

The things that cells do that are shared between all cells

• Transcription

• Translation

• organelles

• Central Dogma of Biology

control systems support common ancestry

• Ex. (excretory system)

  • Utilizing membranes in kidney to clean out keep concentration of particular things

  • Worms kinda have the same thing

  • Both uses membranes to maintain homeostasis

Geographic distribution of species

• Islands have many animal and plant species that are endemic (related to species from the nearest mainland)