Natural Selection
What is natural selection?
Individuals with more favourable variations are more likely to survive and pass these variations on.
This scientist thought the giraffes' long necks were inherited because their ancestors stretched to reach higher leaves.
Jean Baptiste Lamarck
The boundary called the ________________ exists because deep ocean channels prevented species from migrating between the Asian and Australian faunal zones.
The Wallace Line
What does comparing DNA between two species tell scientists about their evolutionary relationship?
The more similar the DNA, the more closely related the organism is
What is a species?
- A group of organisms capable of interbreeding and producing viable (fertile) offspring
During a hot summer day, you sweat to cool down. This is an example of a ____________ adaptation.
physiological
This scientist(s) thought that finches with beak shapes best suited to their food sources survived and reproduced.
Charles Darwin
Alfred Wallace
Why are transitional fossils considered important evidence for evolution?
- Fill gaps in the fossil record by showing intermediate forms between species
- Help scientists understand evolutionary processes and relationships
What do similarities of embryos in different suggest about their evolutionary relationships?
This suggest a common ancestor. The more closely related organisms are, the more their developmental stages will resemble each other.
____________ occurs when two populations are formed from one original population. Over time, enough change accumulates, and enough isolation occurs that one population can no longer interbreed with another.
Speciation
A mutation in fruit flies that shortens or damages wings makes it harder to escape predators and find mates. This is an example of a _________ mutation, so the organisms will likely ________, therefore it is a selective ________________.
harmful
die
disadvantage
What is a scientific theory?
A well-supported explanation that connects many observations and helps scientists predict what will happen in new situations or experiments
The wings of birds, bats, dragonflies are an example of ____________ structures.
Analogous
Homologous structures result from ________ evolution
Divergent
_____________ describes speciation as a periodic process where big changes occur suddenly, followed by long periods of no change)
Punctuated equilibrium
Explain how the changes in tree colours influence the fitness of each moth phenotype (light-coloured and dark-coloured), and describe why the shift in moth colouration is considered an adaptation instead of a random change in the population.
Light moths had higher fitness before the Industrial Revolution because they were camouflaged on the trees, dark moths were more visible to predators
Pollution darkened tree bark = selective pressure favouring dark-coloured moths because they could camouflage better
Dark moths were had higher survival and reproductive success, light moths were eaten more often
Over generations, dark moths became more common
The dark colouration is an adaptation because it is a heritable trait (gene passed down) that improves fitness in the changed local environment
Which experiment proved that Lamarck's theory of evolution was FALSE? Why?
August Weismann's mice experiment.
Cut off tails of the parent mice. If his theory was true, their offspring would be born without tails.
Draw a diagram that represents divergent evolution.
See slide 25 of EVO3
___________ evolution occurs when different species evolve similar traits but do not share a common ancestor, but share a common environment
Convergent
List all pre-zygotic and all post-zygotic isolating mechanisms:
Pre-zygotic: temporal, ecological, behavioural, mechanical
Post-zygotic: hybrid inviability, hybrid infertility, hybrid breakdown
Explain the process of natural selection using the mnemonic: ICE AGE
- Inherited variation exists within the population
- Competition results from an overproduction of offspring
- Environmental pressures lead to differential reproduction
- Adaptations which benefit survival are selected for
- Genotype frequency changes across generations
- Evolution occurs within the population
Both Lamarck and Darwin tried to explain how species change over time. What was Lamarck's theory? What was Darwin's?
Darwin: Species change over time because individuals with traits that help them survive and reproduce pass those traits (genetic material) to the next generation
Explain the difference between homologous and analogous structures?
Homologous: Common ancestor, similar bone structure, can have different function
Analogous: No common ancestor, different bone structure, face similar environmental pressures, similar function
Darwin's finches on the Galapagos Islands are an example of which type of evolution, where beak shapes change to fit different food sources?
Divergent evolution
Describe gradualism and punctuated equilibrium by drawing a diagram of each.
See slide 25 of EVO4.