Chapter 14 Flashcards
Why do mutations proliferate more quickly in prokaryotes than eurkaryotes?
- Bacteria have much shorter lifespan and much quicker generations, so the effects of natural selection can happen faster, and allele frequencies in populations change much quicker
- Bacteria are haploid, having only one allele for each gene. New alleles have effects immediately.
In plants and animals, what factors serve as buffers against mutation?
- longer lifespan
- Diploid genomes
- Low mutation rate (1 mutation in 100,000 genes PER GENERATION!)
What is a mutation?
A R A N D O M change in DNA nucleotide sequence
Most mutations are ______
Harmful. But on some occasions they can actually improve reproductive success. Take for example the DDT-resistance flies.
What is a population?
A group of individuals of the same species that live in the same area and interbreed
What is a gene pool
Total collection of genes in a population at a given time
Evolution uses genetic variation!! What are the two different sources of genetic variation?
- Mutation
2. Sexual reproduction
What generates new allele assortments? (3 different processes)
- Crossing over during prophase 1 of meiosis
- Random arrangement of alleles during metaphase 1 of meiosis
- Random fertilization
2 scales of evolutiion:
Microevolution and macroevolution!
Microevolution is…
- Changes in allele frequencies within the gene pools of populations from one generation to the next
- Genetic variation as the raw material
Macroevolution is…
• Major changes recorded in the history of life
○ Eg. Evolution of flight
• Occurs above the species level, over long periods of time
• Encompasses origins of new taxonomic groups
What are the mechanisms of microevolution?
Natural selection
Genetic drift
Gene flow
What are the 3 main contributing factors of macroevolution?
- Continental drift
- Mass extinctions
- Adaptive radiations
Explain the 3 mechanisms of microevolution.
Natural Selection
Genetic drift
Gene flow
Natural selection: when certain alleles are favoured by environmental factors, and the organisms carrying those alleles have higher chances of surviving, changing the overall allele ratios in the gene pool.
Genetic drift: Alterations of allele frequency that happen due to random chance. Greater impact in smaller populations.
Gene flow: Alterations of allele frequency, occurs when alleles transfer from one population to another
Does genetic drift produce adaptations?
No, allele frequency changes happened due to random chance
What are the two different types of genetic drift?
- Bottleneck effect
2. Founder effect
The bottleneck effect is a mechanism of _______(micro/macroevolution), namely ______(which mechanism??). It occurs when…
microevolution, genetic drift
Occurs when a population is drastically reduced. Allele frequencies generally change during such an event.
The founder effect is a type of _______. It occurs when…
Genetic drift!
Occurs
How does gene flow happen?
When fertile organisms move from one population to another
Or whenever gametes transfer, eg. Pollen transfer
Gene flow affects more than one population. How does between-population variance, and within-population variance?
Decreases between-population variance.
Can increase within-population variance (of new population).
What causes mass extinction?
Natural disaster due to habitat loss, climate change.
Evolution of new predators
Evolution of new competitors.
5 big daddy mass extinctions killed _% of earth species.
50%+!!!!!!!
Why is the 6th “mass extinction” maybe currently happening???
- more than 1000 species extinct in the last 400 years!
- this is “between 100-1000” times the normal rate of extinction.
:’( W T F
Continental drift caused by
ViOLenT tEcTONiC activity!!!!!!!
Whacky plates! Earthquakes!
How long does it take for biodiversity to recover post-quake?
5,000,000-10,000,000 years!!
tf is adaptive radiation?
What causes it?
- rapid diversification; emergence of new unique organisms from ancestral species.
- occurs as a result of environmental change opening up new environmental niches. eg. Result of predator death, like when dinosaurs died and prey could flourish.
