Evolutionary medicine Flashcards
(30 cards)
definition of microevolution
(evolution on a small scale) refers to changes in allele frequency within a single population
Allele frequencies may change within a single population due to (4)
- Natural selection
- Genetic drift
- Mutations
- Gene flow
what is the ultimate source of new alleles in a gene pool
Mutations
how does natural selection affect the frequencies of alleles in a population
Some individuals with certain traits in a population have a higher survival and reproductive rate than others and pass on these inheritable genetic features to their offspring.
Evolution acts through natural selection whereby reproductive and genetic qualities that prove advantageous to survival prevail into future generations.
The cumulative effects of natural selection give rise to populations that have evolved to succeed in specific environments.
Natural selection operates by differential reproductive success (fitness) of individuals.
what is genetic drift
Genetic drift consists of random fluctuations in the frequency of appearance of a gene, usually, in a small population
The process may cause gene variants to disappear completely, thereby reducing genetic variability, even if they are beneficial traits that conduct to evolutionary and reproductive success.
In contrast to natural selection, environmental or adaptive pressures do not drive changes due to genetic drift and the effects of GD is larger in small populations and smaller in large populations.
Genetic drift is a stochastic process, a random event that happens by chance in nature that influences or changes allele frequency within a population as a result of sampling error from generation to generation
what is an allele
Allele is defined as any one of two or more genes that may occur alternatively at a given site (locus) on a chromosome……Alleles are responsible for variations in a trait
what are population bottlenecks and the founder effect examples of?
genetic drift
what is the bottleneck effect
Occurs when there is a sudden sharp decline in a populations size, typically due to environmental factors (natural disasters normally). It is a random event in which some genes at random are extinguished from the population. Drastic reduction in genetic diversity compared to the original gene pool.
what is the founder effect
Founder effect is the loss of genetic variation that occurs when a new population is established by a small number of individuals that are cleaved from a larger population.
what is a germline and somatic mutation?
Germline mutation- occurs in the gametes so are passed on.
Somatic mutations- occur in non-reproductive cells so are not passed on to the next generation.
According to their magnitude, mutations can occur at different levels and divided into 3 groups:
Gene mutations; any change in the sequence of nucleotides of the genetic material of an organism
Chromosome mutations; a change in the structure or arrangement of the chromosomes
- Duplications or deletions of chromosome segments
- Inversions of sections of DNA (reversed positions)
- Translocation
c) genome mutations; alterations in the number of chromosomes in the genome.
genome mutations can be split into 2 groups
Aneuploidy- the losses and/or gains of individual chromosomes from the normal chromosome set arising from errors in chromosome segregation
Euploidy: refers to variations in complete sets of chromosomes
what is gene flow
In population genetics, Gene Flow (also known as gene migration) refers to the transfer of genes from the gene pool of one population to another.
Gene flow may change the frequency and/or the range of alleles in the populations due to the migration of individuals or gametes that can reproduce in a different population
what is horizontal gene transfer
Process by which an organism (recipient) acquires genetic material from another one (donor) by asexual means.
relevence of evolutionary science to medicine
- Allows us to think more critically about why individuals suffer in different ways and broader reasons behind disease other than the “proximate causes”.
- Allows us to predict which therapies are more likely to work.
- Evolutionary medicine looks at how an organism trades off one component of tis biology against others to optimize its fitness (being its success at reproducing).
- Gives us a better understanding of immediate disciplines like anatomy, biochemistry and physiology to name a few.
what is the delphi method related to evo med
The Delphi method was used to elicit and validate a list of core principles for evolutionary medicine.
Fourteen core principles elicited at least 80% of the panelists to agree or strongly agree that they were important core principles for evolutionary medicine.
1- Types of analyses (100% agreement)
Both proximate (mechanistic) and ultimate (evolutionary) explanations are needed to provide a full biological understanding of traits, including those that increase vulnerability to disease.
2 Evolutionary processes 100%
All evolutionary processes, including natural selection, genetic drift, mutation, migration and non-random mating, are important for understanding traits and disease
reproductive success
Natural selection maximizes reproductive success, sometimes at the expense of health and longevity
sexual selection
Understanding how sexual selection shapes differences in male and female physiology and behavior is important for understanding differences in health risks.
Constraints on natural selection
Several constraints inhibit the capacity of natural selection to shape traits that are hypothetically optimal for health. They include path dependence, the inevitability of mutations, trade-offs such those seen in antagonistic pleiotropy and others
trade-offs
The role of evolutionary trade-offs in explaining disease vulnerability is a central and important core principle forevolutionary medicine.
life history theory
Life history traits, such as age at first reproduction, reproductive lifespan and rate of senescence, are shaped by evolution, and have implications for health and disease
multiple levels of selection
Vulnerabilities to disease can result when selection has opposing effects at different levels (e.g. genetic elements, cells, organisms, kin and other levels).
