Human Evolution & Microevolution Flashcards
What significant event occurred around -70,000 years related to human migration?
Humans left Africa and dispersed to the rest of the world
What does heterozygosity refer to in the context of human genetics?
Genetic variation
Where is the richest genetic variation found in human populations?
Ancestral areas in East Africa
What caused a bottleneck in the human population size?
Climate change
What species overlapped with modern humans for up to 5,000 years?
Homo neanderthalensis
How much Neanderthal DNA do non-Africans typically have?
Around 3%
What evidence suggests that Neanderthals lived in family groups?
Males appeared to stay in groups and females may have moved between groups
eDNA of 14 Neanderthals revealed father-daughter relationships
What type of artifacts did Neanderthals create?
Jewelry and cave art
True or False: Neanderthals are considered a separate species from modern humans.
False
What is the significance of the Denisovan tooth discovered in 2008?
It led to the identification of a previously unknown hominin group
What allele did Tibetans acquire from Denisovans?
EPAS1 allele
(Allows them to live in conditions of hypoxia)
Fill in the blank: The Denisovans are believed to have used _______ to disperse.
boats
What is Homo floresiensis commonly referred to as?
The Hobbit
What are key human behaviors mentioned in relation to what makes us human?
- Cooperation and how we run our societies
- Art
What is a major consequence of human tool use mentioned in the text?
Increased CO2 levels
What did the 2010 sequencing of the Neanderthal genome reveal?
Non-Africans interbred with Neanderthals
How many amino acid differences are there between humans and Neanderthals?
96
What is the estimated age range of the ‘Dragon man’ skull found in China?
138,000 - 309,000 years old
True or False: Denisovans were not sensitive to smells.
False
What is microevolution?
Microevolution is changes in the gene pool of a population of organisms over time.
Evolutionary events within a species or population
Microevolution plus chance events gives rise to macroevolution
What is the gene pool?
The gene pool is all alleles of all genes of all individuals in a population.
It represents all the genetic variation, the ‘raw material’ of evolution, in a population
Define macroevolution.
Macroevolution refers to evolution on a grand scale, including major evolutionary events above the level of the species, such as the evolution of major animal groups.
Examples include speciation and the emergence of new taxa.
What is the difference between microevolution and macroevolution?
Microevolution involves evolutionary events within a species or population, while macroevolution involves larger-scale evolutionary changes.
Microevolution plus chance events can lead to macroevolution.
What are the requirements for evolution by natural selection?
- Differential reproductive success
- Genetic differences between individuals (genetic variation)
Evolution changes the genetic structure of a population or species
What is population genetics?
Population genetics is the study of microevolution and involves a synthesis of Darwin’s theory of evolution by natural selection with Mendel’s theory of inheritance.
Who are the key figures associated with the modern synthesis of evolutionary biology?
- John (JBS) Haldane
- Sewall Wright
- Ronald Fisher
What can population genetics reveal about evolving human pathogens?
- Antibiotic resistance in bacteria (e.g., MRSA)
- Resistance to antiviral drugs in viruses (e.g., HIV)
- Emerging new pathogens (e.g., Ebola virus, influenza viruses, coronaviruses)
When did SARS-CoV-2 first infect humans?
The time to the most recent common ancestor (tMRCA) is 24 November 2019.
This is based on a 95% confidence interval from 6 October 2019 to 11 December 2019.
What is the most similar coronavirus to SARS-CoV-2?
The most similar coronavirus to SARS-CoV-2 is from horseshoe bats, with a 96% sequence identity.
What factors can lead to changes in allele and genotype frequencies?
- Genetic drift - low population size
- Non-random mating
- Migration/gene flow
- Selection
What is Hardy-Weinberg equilibrium?
Hardy-Weinberg equilibrium is when allele and genotype frequencies remain unchanged through generations under specific conditions.
Conditions include large population size, random mating, no migration, no selection, and no mutation.
What is the Hardy-Weinberg equation?
p² + 2pq + q² = 1
Where p^2 is the frequency of the dominant allele (homozygous) and q^2 is the frequency of the recessive allele (homozygous).
p (dominant) + q (recessive) = 1
What does f(R) represent in population genetics?
f(R) represents the frequency of allele R in a population.
How do you calculate allele frequency?
Allele frequency is calculated as the number of alleles of one type divided by the total number of alleles.
What is genetic drift?
Genetic drift is a mechanism of evolution that refers to random fluctuations in allele frequencies in a population, particularly impactful in small populations.
What is the paradox of variation?
The paradox of variation refers to the surprising amount of genetic variation found in natural populations despite phenotypic variation being easier to measure.
How is genetic variation preserved?
- Natural selection
- Balancing selection (maintains genetic variation)
- Heterozygote advantage e.g. sickle-cell anaemia (protects against malaria)
- Frequency dependent selection e.g. scale eating fish
- Clinal variation (different selective pressures across the geographic range of the population)
What is the role of neutral theory in population genetics?
Neutral theory posits that many alleles are selectively neutral and their frequencies will fluctuate randomly over time due to genetic drift.
Fill in the blank: The dominant allele is represented by _____ and the recessive allele is represented by _____.
[A] [a]
True or False: Alleles of a gene can be both dominant and recessive.
True
How did Neanderthals and Denisovans smell?
Differences in perception of androstenone are due to altered neuron activity caused by two single base changes in your DNA
Denisovans = sensitive to smells associated with honey
Neanderthals = sensitive to sulphurous smells
What does speciation do?
Forms a link between microevolution and macroevolution
What can population genetics tell us about the genetic structure of wild populations?
- How much genetic diversity is present in a population and how it is distributed
- The response of the population to change e.g. climate change (change in genes)
What are conservation genetics?
Low levels of genetic diversity
How is the gene pool studied?
A sample of the gene pool is studied = look at one gene at a time
What is measured in a gene pool?
Allelic frequency
Genotype frequency
How is allelic frequency calculated?
Number of allele of one type
——————————————
Total number of alleles
How is genotype frequency calculated?
Number of individuals of one genotype
——————————————————-
Total number of individuals
When does the Hardy-Weinberg equilibrium apply?
ONLY WHEN
- large population
- mating is random
- no migration from other populations
- no selection
- no mutation (at high frequency)
How is the genotype frequency calculated from the allele frequency?
- First do H-W equation
- Compare observed genotype frequency to expected frequency
- Do stats test (Chi squared) to ensure differences are significant
