Lecture 2 Flashcards
Humans do not evolve….. what does
Populations
What can amplify or diminish only heritable traits
Natural selection
An individuals acquired traits can or cannot be passed onto its offspring?
Cannot
Will traits that maximize an individuals survival become more come? Why?
It can be detrimental to an individual but can be selected for if relatives carry the genes for the behaviour
Are humans the pinnacle of evolution? Why?
No, evolution hasn’t directed the production of species to some endpoint, evolution will continue
Did humans evolve from closely related primates?
Living things evolved from a common ancestor but not from eachother
Does the theory of evolution explain the beginning of life on earth?
Evolution by natural selection explains changes in life on earth but the idea of how life actually started is still in the hypothesis stages
How did complex structures evolve
By incremental change ( in increments, not all at once)
How come there are gaps in the fossil record?
Some transitional fossils are not preserved
Why does natural selection involve tradeoffs
An adaptation for one life process may conflict with another
How is malaria and sickle celled anemia an example for a ‘tradeoff’
Heterozygous individuals have an advantage because they are resistant to the malaria parasite because they have two different copies ( so only little symptoms show)
What is stabilizing selection?
When natural selection favours intermediate phenotypes
What is directional selection?
Natural selection favours one extreme of the distribution
What is disruptive selection?
When natural selection favours both extreme ends of the distribution
What are the 3 kinds of natural selection
- Stabilizing
- Directional
- Disruptive
What does natural selection do to a population?
Diversifies it
Which two types of natural selection could lead to the development of new species?
Directional and disruptive
What is sexual dimorphism?
When there is differences between the male and female in the same species
What are the positives and negatives of sexual dimorphism?
Can have a high fitness in the sense of reproduction (because it’ll attract a mate)
Low fitness eg. uses energy
What is sexual selection
Makes with sexually selected traits
What are 4 positives of sexual selection?
- Chosen more often than females
- Produce offspring
- Traits are passed onto the next generation
- Higher frequency of the gene in these traits
What is genetic drift?
Sudden changes in genetic makeup in a population
What are some examples of things that can cause genetic drift?
Earthquakes, flood and fires
What is the bottleneck effect?
When a large number of individuals are killed and only a small population is left. By chance the new population may not resemble the old one
The bottle neck effect causes…?
Genetic drift
What is the founder effect?
Displaced population can have a different genetic makeup
What are two types of geological events that can cause evolutionary change
- Continental drift
2. Mass extinction
How many mass extinctions have there been?
5 major extinctions
What is gene flow?
When individuals move in and out of populations
What 2 things does gene flow do to populations?
Reduce differences and increases variability
What leads to adaptive evolution?
Natural selection
What is a hybrid?
An offspring of parents of two different species
What is the biological species concept?
A group of populations whose members can interbreed in nature and produce fertile offspring
What is speciation?
Evolutionary process in which one species splits into two species
Selection on one population leaded to accumulated differences that prevent what?
Successful interbreeding
Barriers to successful interbreeding can lead to…?
Speciation
What are two main types of reproductive barriers?
Pre zygotic and Post zygotic
What are 5 types of pre zygotic barriers and what do each mean
- Habitat isolation- rarely meet
- Temporal isolation- different breeding times
- Behavioural isolation- don’t recognize each other
- Mechanical isolation
- Gametic isolation- gametes are incompatible
What are 3 post zygotic barriers? Explain each
- Reduced hybrid viability- don’t survive/ fully develop
- Reduced hybrid fertility- don’t produce functional gametes
- Hybrid breakdown- weak or infertile
What is allopatric speciation
Geography prevents interbreeding
Ex. land masses, bodies of water
What is adaptive radiation?
Evolution of many diverse species from a common ancestor
When does adaptive radiation especially occur?
When a few organisms colonize new unexploited habitat
When speciation is gradual but not recorded in fossil record, why is this?
Sedimentation is slower than diversification
What are the 7 major events in the history of life?
- Origin of earth
- Prokaryotes
- Atmospheric oxygen
- Single celled eukaryotes
- Multicellular eukaryotes
- Animals
- Colonization of land
What was the earlier evidence of life?
Stromatolites: Similar to present day photosynthetic prokaryotes
Who first tries to find evidence for abiotic synthesis of organic molecules?
Miller
What are photocells?
Created by adding lipids to water
