1.1: Darwin's Theory of Natural Selection Flashcards
Which biological fields does the theory of evolution through natural selection unify?
Human behavioural ecology Primatology Palaeoanthropology Genetics Evolutionary Psychology
Essentialism
God created all living things on the 13rd October 4004BC (Bishop Ussher -1668)
All species are unchanged and immutable
Transmutation
Species change through time
When were apes first discovered and fossils of the first human ancestors found?
17th Century
1800s
Evolution
Descent with modification
What did Count de Buffon propose in 1776 ?
Species originated form common ancestors
Evolution is positive and constant changes
Scriptures are unreliable
How do things evolve according to Lamarkism?
Inheritance of acquired characteristics
How do things evolve according to Darwin and Russel Wallace?
Individuals compete for survival
Resources are limited
Natural selection
Variation created
Conditions necessary for natural selection to occur (3)
Variation
Competition
Heredity
Two factors by which fitness is determined
Survival
Reproductive success
Define natural selection
The fittest individuals with the ‘fittest traits’ (variation) who out-compete others (competition) will survive and reproduce and pass their traits onto the net generation (heredity), leading to adaptations
Examples of adaptations (2)
Camouflage
Mimicry
Is natural selection about individual or group fitness?
Natural selection is about individual fitness, not the group, but evolution is revealed in the population
4 common misconceptions about evolution by natural selection. Give examples that prove they are misconceptions.
Natural selection produces perfect adaptations (babies heads vs. mother’s vagina)
Evolution means greater complexity (lizards lost legs to become snakes)
Some species are more evolved than others (all species are equally evolved to their environment)
Evolution means ‘progress’ (evolution is about diversifying, progress is circumstantial, you could be more evolved to one environment than another)
Which two mechanisms are debated to be most important for evolution?
Natural selection: plays a small roll in shaping diversity
Chance: plays a larger role in shaping diversity
Phylogeny
The tree of life that maps all existent and extinct organisms as genetically related through evolutionary history and speciation
Speciation
Different species arise from previous forms (ancestral species) via descent
What are evolutionary constraints
Evolution doesn’t have infinite possibilities; there are limits to design
Give an example of an evolutionary constraint
Phylogenetic constraint: phylogenetic history of a lineage may prevent an anticipated course of evolution in that lineage
What is contingency in evolution
Existence of each species is entirely dependent on the existence of our evolutionary ancestors, therefore entirely dependent on the CHANCE that that ancestor existed
Example of contingency in evolution
If Pikaia (a chordate ancestor) had not survived, minearalised skeletons, muscularised appendages, image-forming eyes, teeth, bipedalism, endothermy, placenta, social behaviours, etc. would not exist
Convergent evolution (Simon Conway Morris)
Different species evolve independently through natural selection to adopt the same anatomy/behaviour/physiology
Similar solutions to similar problems – it is not random, it maximises fitness
Example of convergent evolution
Jellyfish, octopus and mammal eyes evolved through natural selection independently across species
How common is convergent evolution?
Out of 78 traits, 70% evolved more than once through convergent evolution (Vermeji, 2006)
Four examples of complex human phenotypes
Bipedalism
Large brain
Sociality
Language
Did Wallace agree that humans’ complex phenotypes evolved through natural selection?
No, he argued that humans have unique organs of speech, calculation of numbers, ideas of symmetry and justice
Did Darwin agree that humans’ complex phenotypes evolved through natural selection?
Yes, he argued that humans are not unique
Three examples of how human phenotypes are not unique
Killer whales have specific calls for each individual (language and names)
Symmetry in humans is an indication of good genes and health for survival, it is found attractive in different cultures
Monkeys show sense of fairness
