Evolution 🧫 Flashcards
(36 cards)
What is a gene pool?
All the alleles in a population of a specific species at a particular point in time.
Or the amount of genetic diversity within a population
What is an allele?
Alternative form (different version) of a gene
What is a population?
All the members of a species in a location at a specific time
What is a mutation?
Change to the DNA of an organism that is random and unpredictable
Therefore the gene and the change within the gene cannot be predicted.
What are the 2 types of mutations?
Spontaneous mutation: A mutation that happens for no particular reason.
Induced mutation: Caused by something such as ionising radiation or chemical mutagen.
All of these are unpredictable and random.
What is a fossil?
Evidence of life from the past
What is a mold?
Impression of a living thing left in a rock
What is a cast?
When a mold is filled with sediment or minerals
What is a petrified fossil?
When minerals move into and replace the space of organic material in an organism
What are trace fossils?
Geological records of activity of an organism such as footprints or burrows
What is a species?
Group of living organisms consisting of similar individuals that could potentially mate and produce viable and fertile offspring.
What is the morphological species concept?
If a group of organisms have similar morphology (physical form/characteristics) the same they are the same species (used by palaeontologists)
What is the phylogenetic species concept?
The smallest clade (group of organisms that all have a common ancestor) that can trace its evolutionary origins to a common ancestor
- contain unique characteristics from that ancestor that sets them apart from other groups.
What is speciation?
When one species separates into and forms seperate species
What is allopatric speciation?
- A parent population containing variation is divided by a geographic barrier
- There is no gene flow (immigration and emigration) between 2 daughter populations.
- Mutations (may) arise in populations randomly
- AND/OR different selection pressures act on the populations causing natural selection
As a result the 2 populations evolve via natural selection to become so different they can no longer produce viable and fertile offspring –> leading to different species.
Explain the case of the: Galapogas finches
- Group of 18 species of finches live on the Galapogas islands
- These islands have different habitats on them
- As a result, these different islands contain different environmental selection pressures
- Natural selection acts on the finches and they rapidly evolve to become distinct/different species in a process of adaptive radiation
Example of allopatric speciation
- Process of adaptive radiation: Rapid speciation of once species into many, adapting to different ecological niches.
What is sympatric speciation?
Evolution of a new species from original population of species while they inhabit the same geographical region.
What is disruptive selection?
- Cause of sympatric speciation
If sympatric speciation occurs in animals it is thought to be because of disruptive selection. - Type of natural selection that favours extreme traits over intermediate traits
Explain the case of the Lord Howe Island palms
- A palm tree that once occupied the Lord Howe Islands underwent sympatric speciation to give rise to 2 types of palm trees.
- The curly palm (howea belmoreana) and Kentia palm (howea forsteriana) both live on Lord Howe island.
They have developed physiological differences (due to soil types) which cause them to be reproductively isolated due to a difference in flowering times H. Belmoreana flowers 6-7 weeks later than H. Forsteriana (as a result of the different soils)
Though there is difference in elevations on the Lord Howea Islands as well
Where does the howea belmorana grow (curly palm)?
In nutrient rich volcanic soils that have low pH
Where does the howea forsteriana (kentia palm) grow?
In nutrient poor calcarenite soils which have high pH
What is the significance of the different soils the palms of Lord Howe Islands grow in?
That are believed to have caused the shift in their flowering times causing reproductive isolation hence different species –> speciation
Example of disruptive selection
What is relatedness?
Refers to how recently species split from common ancestor
If species are related y evolution, should show similarities in biochemical and genetic composition
Greater degree of similarity if species are more closely related due to being split from shared common ancestor more recently
What is molecular homology
Homology is the existence of a shared ancestry between a pair of DNA sequences, proteins or amino acid sequences (shows a common evolutionary origin)
The more mutations that accumulate in DNA sequence between species, the more time will have passed since the 2 species diverged from common ancestor
Sequences from different organisms are homologous if they follow the same basic pattern, implying that molecules have a shared evolutionary history.
