EVOLUTION Flashcards
Define Evolution
changes in the genetic composition of a population over time.
Darwin was trying to explain three key observations;
adaptation, unity and diversity.
Define adaptation
the fit between an organism and the environment or the striking way that organisms appear to be suited for living in their environment.
Explain the concept of unity and diversity
That is the organisms and species have many shared characteristics (unity) but at the same time there is rich diversity.
The Greek philosopher, Plato (427–347 BC) viewed species as
immutable ‘types’.
earthly forms were simply imperfect copies of a transcendental ideal.
Explain Essentialism
Essentialism saw natural variation as noise that had to be filtered out in order to describe the true form of a species.
What did Aristotle do?
made the first serious attempt to classify animals on the basis of their anatomy.
Aristotle thought that species could be arranged on a ladder of increasing complexity later called the Scala Naturae (scale of nature). Each species having an allotted run on the ladder.
What did Linnaeus do?
Linnaeus founded modern taxonomy by developing the system of Latin binomial nomenclature, e.g. Homo sapiens.`
Explain Gradualism
Gradualism argues that profound change is the cumulative result of slow, continuous processes.
What are The 4 principles of natural selection?
- Individuals within populations are variable, in terms of their morphology, physiology, and behaviour (variation).
- The variation among individuals are, at least in part, passed from parents to offspring (heritable).
- In every generation some individuals are more successful at surviving and reproducing than others (differential survival).
- The survival and reproduction of individuals are not random; instead they are tied to the variation among individuals. The individuals with the most favourable variation are selected (selection).
Of Darwins two claims, which is fact and which is a theory?
That species evolve is now an accepted fact (pattern). The mechanism (process) that Darwin proposed for adaptive evolution – natural selection – is a theory.
Define homologous structures
species that have structures that have underlying similarities yet quite different functions.
e.g. The mammalian forelimb preforms quite different functions but are constructed from the same elements.
Define vestigial structure
A vestigial structure is a functionless or rudimentary version of a body part that has an important function in other closely related species.
e.g. The North Island brown kiwi, Apteryx mantelli, is a flightless bird but still has a tiny stubby wing.
What is Biogeography?
Biogeography is the scientific study of the geographical distribution of species.
What are theories?
Theories are conceptual frameworks with explanatory power supported by many lines of evidence.
What is microevolution?
Change within a species
Is natural selection the only mechanism of evolution?
no
What is an example of artificial selection?
selective breeding
HOW DID S. aureus strains become resistant to methicillin
S. aureus strains exhibited variation and some strains could synthesise their cell wall with a different protein not affected by methicillin.
How did bacteria destroy penicillin?
By producing the enzyme penicillinase.
What is macroevolution?
Differences between different species.
homology can be seen in
morphological, genetic or behavioural characteristics.
Explain the 18th century theory of blending inheritance
Blending inheritance was the idea that features in the child resulted from combining or blending qualities of both parents, this was thought to occur in the blood.
This hypothesis predicts that over generations a freely mating population will give rise to a uniform population of individuals.
What did the blending hypothesis fail to explain?
The blending hypothesis fails to explain the reappearance of traits after skipping a generation.
Define Polygenic inheritance
– mode of inheritance in which the additive effect of two or more genes determines a single phenotypic character.
How many genes are speculated to control human skin colour?
at least three separate genes
Define population
A population is a group of individuals of the same species that live in the same area and interbreed.
Define the gene pool
the sum of all the alleles of all genes of all individuals in the population.
What is meant by the term fixed allele?
If only one allele exists at a particular locus or gene in a population, the allele is said to be fixed.
What is the Hardy-Weinberg equations?
p + q = 1
p^2 + 2pq + q^2 = 1
What are the Conditions for Hardy-Weinberg?
1. No mutations.
- Mating occurs at random.
- No natural selection.
- Extremely large population size.
- No gene flow
In the Galapagos Islands, what happened when there was a drought to the seeds available and also the beaks of the birds?
Seeds in abundance were large hard seeds, and only finches with large deep beaks could crack them open, therefore directional selection occurs for larger beaked finches.
Explain the Biological species concept
a group of organisms that actually (or potentially) interbreed in nature, producing other reproductively viable offspring, and are reproductively isolated from other groups.
What type of mutations are the most common?
silent mutations
What is Haemophilia?
Haemophilia A & B are X-linked recessive disorders caused by nonfunctional / absence of certain blood clotting proteins.
Define genetic drift
Genetic drift is the change in allele frequencies as a result of chance events.
The overall affect of drift is a loss of
genetic variation
What is the founder effect?
Founder effect results when a small population branches off from a larger one, by chance the small population may not have all the alleles present in the larger population.
What is a population bottle neck?
Population bottlenecks occur when a population is drastically reduced in numbers, consequently chance effects can result in the loss or fixation of alleles.
