Unit 4 Flashcards
What is ‘descent with modification’?
biological populations change over successive generations
life evolved from a common ancestor
What are the four propositions of evolutionary theory?
- More individuals are produced than can survive
- There is competition
- Individuals within a species show variation
- Those with advantageous traits survive and reproduce.
What is Natural selection?
a gradual, non random process by which biological traits become less or more common in a population through differential reproductive success.
What are the other two types of Selection?
Sexual selection (intrasexual & intersexual) Artificial Selection
What is the difference between intrasexual and intersexual selection?
intrasexual- intimidating rivals
intersexual- attractive to opposite sex.
What is endosymbiotic theory?
the theory that an ancestral prokaryote engulfed an aerobic and photosynthetic prokaryote.
What evidence is there for Endosymbiotic theory?
Prokaryotes, Mitochondria and Chloroplasts each have:
1 single. circular chromosome
70S ribosomes
Similiar size
Replication via Binary Fission (1 cell splits into 2)
What was the aim of the Miller- Urey experiment?
to replicate the speculated early atmosphere
What was Miller & Urey’s theory on the creation of life?
Early atmosphere was composed of ammonia, methane and lots of hydrogen- these with accumulated and created amino acids.
What is a hydrothermal vent?
mid oceanic ridge system where heat (energy) produces mineral rich water, reducing the oxygen environment.
What is special about the bacteria in Hydrothermal vents?
due to low oxygen environment, bacteria runs a reverse Krebs cycle- generating organic material (CO2 and hydrogen), the porous rocks act like a cell membrane.
What are prezygotic barriers of isolation? What are some examples?
Prezygotic- no chance to mate Geographical location Mechanical isolation e.g. size Temporal isolation (active at different times of the day) Behavioural isolation
What is a postzygotic barrier in isolation?
What are some examples of this?
Postzygotic- incomplete fertilisation or hybrids not fertile
Gamete incompatibility
Hybrid infertility (F1)
Hybrid mortality
What are the 6 features of Speciation?
Variation Isolation Decreased gene flow Selection Divergence Speciation
What is allopatric speciation?
seperation by geographic isolation, barriers prevent two or more populations from mating- leads to speciation
How are extinct organisms classified?
Phylogenetic species concept- all possess a combination of certain defining or derived traits.
Also uses cladogenesis (branching of species using morphological species).
How does Speciation occur on islands?
Founders effect- new population is created by a small amount of individuals from a larger population- leads to loss of genetic variation
What is sympatric speciation?
when a new species evolves from an ancestral species whilst inhabiting the same place.
What is the difference between Peripatric and Parapatric speciation?
Peripatric- formed from small isolated populations on the outskirts of a species’ range
Parapatric- reduced gene flow within the range of a species
What is an ecological niche?
the role the species plays in the ecosystem e.g. includes the food, where it reproduces, relationship with other species.
What is ‘Domestication Syndrome’?
Give examples
when animal is domesticated it loses specific traits
e.g. reduced size, horns are removed, coat colour varies, breeds are formed.
What forces of evolution are involved in domestication?
Mutations
Genetic drift
Selection
Migration
What is the difference between artificial and natural selection?
Artificial- quick, extreme performance of one trait with negative effect on the others, low genetic variation, organisms cannot adapt to changes in environment
Natural- long process, formation of balanced organisms that fit environment, high genome variation
What is Quantitative Trait Loci?
Traits associated with one or more gene/chromosome location- their loci is the QTL.
What are the genes called that control the expression of other genes?
Homeobox genes (Hox genes)
What happens if a Hox gene is mutated?
Transform one segment of DNA into another
Can result in different morphology and anatomy
What proteins are important for Development? What do they do? (4)
- Cell adhesion proteins- control migration
- Cell surface receptors- important in extracellular signals
- Secreted morphogens- stimulate local cell response
- Regulator of cell death
Early development is _______, late development is not.
Fill in the gap. What does this mean?
Constrained
changes in early development may provide catastrophic results
What are the role of genes in Development?
genes control rate, timing and spatial pattern of morphology
What are Transcription factors role in development?
regulate gene expression and hold potential for speciation
