BM108 Block A Lecture 2 +3 + 4

  • Created by: amykane
  • Created on: 07-05-18 07:08
When did Ediacara biota take place?
600 millions years ago - first multicellular organisms (metazoans)
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When did the cambrian explosion take place and what happened?
540 million years ago.Hundreds of species in the world - suddenly went up to millions. Ediacaran biota largely lost.A massive burst of evolution over a very short geological time period.
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Why did this happen?
Sudden increase in oxygen concentration levels made predation feasible – prey also had to respond. Calcium concentrations increased: shells/skeletons.
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What does evolution explain?
(1) the diversity of life. (2) the relatedness of life. (3) the complexity of living organisms. (4) how life can change over time.
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What is taxonomy?
- the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups.
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What did alfred wallace discover?
The 'wallace line' - a boundary that separates the ecozone of Asia and the Australasian ecozone.
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What are the 3 theories of evolution?
(1) Genetic diversity. (2)selection pressure. (3)survival of the fittest.
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What are the 6 pieces of evidence that helped define the theory of evolution?
(1) the fossil record. (2_ comparative genetics, biochemistry and cell biology. (3) comparative anatomy. (4) speciation. (5) microevolution. (6) artificial selection.
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What is a Archaeopteryx?
reptile-like and bird-like characteristics, suggesting birds may have evolved from reptilian ancestors
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2 different types of evolution?
gradual and punctuated
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What are HOX genes?
are a group of related genes that control the body plan of an embryo along the head-tail axis
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How many HOX genes does a human have in a set compared to fruit flies?
fruit fly has 1 - we have 4.
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example of comparative anatomy?
bat and bird wings - look similar but different functions
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what is speciation?
the formation of new and distinct species in the course of evolution
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What are species?
Can interbreed to produce fertile offspring. Reproductively isolated from other species
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What is allopatric soeciation?
speciation that results when a population is separated by a physical barrier (also known as geographical)
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What is sympatric speciation?
occurs without physical separation of members of the population
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What is meant to be the most important type of isolation?
geographically isolation
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What is ecological isolation?
live in same area but different habitats
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What is temporal isolation?
breeding at different times
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What is behavourial isolation?
reproductive isolation based on the behavior of species in the context of mating rituals and signals.
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What is mechanical isolation?
anatomical differences prevent mating
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what is gametic isolation?
gametes cannot unite
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What is hybrid isolation?
offspring infertile (sympatric)
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What is the Lenski experiment?
12 identical bacteria strains set up. 25 years and 53,000 generations later… 100s of millions of mutations, only 20 have become ‘fixed’ in population. These must be advantageous for living in a ‘lab environment’.
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What is polymorphism?
the presence of genetic variation within a population, upon which natural selection can operate
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Selfish gene 3 is sexual selection. What can the struggle involve?
female choice (intersexual) male-male competition (intrasexual
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What is sexual dimorphism?
differences in appearance between males and females of the same species, such as in colour, shape, size, and structure, that are caused by the inheritance of one or the other sexual pattern in the genetic material
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What is paleontology?
scientific study of life that existed prior to, and sometimes including, the start of the Holecene Epoch (11.7k years before present)
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What is geochronology?
The science of determining the age of rocks, fossils and sediments using signatures inherent in the rocks themselves
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What is radiometric dating?
measuring the amount of radioactive decay of a radioactive isotope with a known half-life, the absolute age of the parent material can be established
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How is the method for paleogenetics?
Uses the methods of genetics to study early humans and other ancient populations. Extracting ancient DNA from bones (e.g. femur- thighbone which is longest and strongest bone in body)
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What is the human evolution timeline?
Homeininae - Sahelanthropus, aridithecus, and australopithecus. Homo - Homo habilis, homo erectus, homo heidelbergensis, neatherthal, denisovan, homo sapiens.
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What is bipedal?
animal using only 2 legs to walk
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Which group does the fossillucy belong to?
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Which group should first burial behaviour?
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What are the two hypotheses for migration?
(1) out of africa (2) alternative model
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Card 2


When did the cambrian explosion take place and what happened?


540 million years ago.Hundreds of species in the world - suddenly went up to millions. Ediacaran biota largely lost.A massive burst of evolution over a very short geological time period.

Card 3


Why did this happen?


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Card 4


What does evolution explain?


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Card 5


What is taxonomy?


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