Evolution and genetics Flashcards
(28 cards)
State the Hardy-Weinburg Equilibrium
The allele frequencies of a population does not change from generation to generation unless evolution takes place
What are the conditions for the Hardy Weinburg Equilibrium?
No mutations
No selection
No gene flow
No genetic drift
Random mating
Explain the difference between Gregor Mendel’ and pre-Mendel breeders’ ideas and theories on inheritance
The blending theory of Inheritance : Both parents contribute equally to the phenotype of the offspring and it falls somewhere in between (like mixing paint). The particulate theory of Inheritance : The original characteristics controlling the phenotype are not destroyed during breeding, genes remain distinct.
Differentiate between allele and gene
Gene : a segment of DNA that codes for a certain trait. It determines an individual’s genotype
Allele: different forms of a gene. It determines an individual’s phenotype
Define microevolution
Microevolution : The change in pool frequencies, small scale
What are the factors causing microevolution, explained?
Gene flow : This increases variation, it is when species are devided into 2
Genetic drift : This decreases variation, examples could be :
- the bottleneck effect: when a species undergoes extreme population reduction followed by an increase (e.g cheetahs)
- the founder effect : when a group of individuals of the same species colonise a habitat, thus interbreeding and increasing the chances of recessive diseases.
Mutations : create new allele - these are changes in the DNA sequence of an individual
Natural Selection : increases frequency of allele
Non random mating : when individuals don’t mate because of chance but by phenotype
Name and explain the types on non-random mating strategies
Inbreeding : when closely related individuals breed
Sexual selection : when females prefer males with certain characteristics
Assortive mating : When individuals mate with similar characteristics
Name the types of natural selection
- Directional : favours one extreme phenotype over the others
- Stabilising : favours the intermediate phenotype over the extreme ones
- Disruptive : favours both extreme phenotypes over the intermediate one
Define speciation
When a single species divides into two
Define a species
Individuals of a population that :
Can interbreed
Are reproductively isolated from others
Produce fertile offspring
Have a common gene pool
Have similar characteristics
Explain the pre-zygotic reproductive isolating mechanisms
Geographical isolation : populations separated by an impassible barrier
Habitat/ ecological isolation: when populations occur in different areas so they don’t meet to mate
Seasonal / Temporal isolation : When populations are active in different seasons
Behavioural isolation: when animals have different mating calls / dances / pheromones
Mechanical isolation : when the genitilia of the individuals don’t match
Gamete isolation : even if the individuals mate, the sperms don’t find the eggs or get destroyed in the female’s reproductive system
Discuss the post-zygotic reproductive isolation mechanisms
Zygote mortality : Zygote doesn’t develop any further
Hybrid sterility : the hybrid survives but doesn’t reproduce (infertile)
F2 fitness: the hybrid survives, fertile, reproduces but the offspring (F2 generation) is too weak to survive / out compete others
What is the difference between the Pre- and Post - zygote reproductive isolating mechanisms
The Pre- zygote mechanisms prevent mating, or successful fertilisation should mating occur
The post - zygote mechanisms it prevents the hybrid from surviving or reproducing if they survive
Explain the 3 types of speciation
Allopatric speciation : when the population is widely geographically from other populations and gene flow stops
Sympatric :when a population divides into 2 without any prior geographical separation
Parapratic : populations are exposed to different environmental conditions which they adapt to, because they are widely distributed geologically
Who discovered the microscope?
Antoni van Leeuwenhoek
Who suggested natural selection first?
Alfred Wallace
What were Thomas Malthus’ contributions to Charles Darwin’s theory?
Thomas explained how there were more humans than there was resources, leading to competition and the survival of only those who were well adapted. This influenced Charles Darwin’s survival of the fittest.
Charles Lyell’s uniformitarianism lead to the theory of gradualism
What did Empedocles contribute to the history of evolution?
He said that:
higher forms were from lower forms
Plants preceded animals
More well-adapted organisms outcompeted the less well-adapted ones
What was Aristotle’s contribution to the history of evolution?
He suggested the ladder of nature and believed that living matter could form spontaneously from non-living matter
Who suggested the biblical account for evolution?
St. Augustine
What were Carolous Linnaeous’ contributions to the history of evolution?
He suggested the scale of nature (with humans at the top) and never believed in spontaneous generation
He also came up with Fixity of species - which suggested that animals were created suited to their habitats
He came up with the Binomial Classification System
What was George Cuvier’s contribution to the history of evolution?
He disagreed with Linnaeous’ idea of Fixity of species, and explained Catastrophism
Define catastrophism
The periodic local extinction, followed by repopulation by a closely related species from surrounding areas
What were Charles Lyell’s contribution to the history of evolution?
He explain uniformitarianism - which suggests that the same processes that occur in the present times also occurred long ago.
He proves that Earth was old
