Lecture 1 - introduction of principles of evolution & lecture 2 - classifying life Flashcards
What are the 6 basic concepts of neo-Darwinian evolution?
- reproduction
- excess
- variation
- environmental selection (natural selection)
- divergence
- ancestry
What is the concept of reproduction?
species mate with the same species
What is the concept of excess?
lots of products of reproduction die
What is the concept of variation?
caused by mutation (in non-sexual reproduction)
What is the concept of environmental selection (natural selection)?
e.g. sea/land - some animals are more suited to their environments “survival of the fittest”
What is the concept of divergence?
animals adapt of their environment
What is the concept of ancestry?
we can be related through a series of individuals
What are causes of variation in sexual reproduction?
- independent assortment
- chromosomes
- crossing over - e.g. during meiosis
- mutations
What is biodiversity?
Biodiversity is the variety of life, in all its manifestations. It encompasses all forms, levels & combinations of natural variation.
What is taxonomy?
the science of classification of organisms (hierarchal system)
What is phylogeny?
the study of evolutionary relationships
How did chemists work out how old the world is?
Using isotopes?
What % of time on Earth (Pre-Cambrian Earth) were there only single-celled organisms?
88%
How old is Earth?
4.6 billion years old
What is the order of time periods in descending order?
Quaternary, Neogene, Paleogene, Cretaceous, Jurassic, Permian, Carboniferous, Devonian, Silurian, Ordovician, Cambrian
How can we study biodiversity?
- can study genome of living organisms
- however, only fossils available or extinct organism
- as a result, sequencing of evolution through deep time is aided by a fossil record
Why is the fossil record considered incomplete?
- very few organisms that lived will end up being fossilied
- species of a high taxa may not be preserved - including species that:
- with low preservation potential
- with small population
- that inhabit a small geographical area
- that lived only for only a short period of time
Why is the fossil record biased?
- some environments are more likely to be preserved - e.g. net deposition rather than net erosion.
- fossils of aquatic organisms, or organisms that find their way into aquatic environment are much more likely to be preserved.
- organisms with recalcitrant (resistant) - and therefore more readily preserved - tissues, are more likely to be preserved (e.g. bone, tooth, wood, shell vs sot-bodied organisms)
How has the environment changed through time?
- the environment of plant Earth is spatially variable today
- the environment of plant Earth is temporally variable (diurnal, seasonal)
- but the environment has also changed over longer periods of time (e.g. Milankovitch cycles) or even over vast periods of deep time
can be short, medium or long-term events
What are examples of long-term environmental change through time?
- solar luminosity
- distance between the Earth & its moon (tides) - moon moving away from Earth
- continental drift & plate tectonic events
- changing atmosphere & climate change - live evolved with no oxygen in the atmosphere
- milankovitch cycles
- the evolving biota - the biota available will change based on atmosphere
What the examples of short-medium term & rare events through time?
- large igneous provinces (LIPS)
- shorts-medium term atmospheric/climate change
- super eruptions
- meteorite impacts
- tsunamis
- mass extinctions - 5 times
What is the taxonomy established by Linnaeus?
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Why is it an advantage that evolution works via divergence (splitting system)?
this allows us to place all new species in the hierarchical system
What do we want phylogeny to represent?
taxonomy, as well as speciation events
Other than genetics, what else can help determine phylogeny?
physical characteristics - e.g. swirl of fossil
How do you carry out a phylogenetic (cladistic) analysis?
- create a data matrix of character states for the taxa under consideration.
- use a computer package to analyse the data & create a cladogram (using the principles of parsimony or Bayesian methods)
What does it mean if characters are homologous?
similarity due to common ancestry
What does it mean if characters are analogous?
similarity due to convergent evolution (homoplasy)
What are synapomorphies?
shared derived characters
What are synplesiomorphies?
shared ancestral characters
What are autopomorphies?
characters unique to a taxon
What is a monophyletic group?
contains the latest ancestor plus all, and only all, of its descendants
What is paraphyletic group?
diagnosed by plesiomorphies and not including all the descendants of a common ancestor. A paraphyletic group remains after one or more parts of a monophyletic group has been removed.
What is a polyphyletic group?
a group in which the most recent common ancestor is assigned to some other group and not the group itself. It is defined on the basis of convergence, or by non-homologous characters assumed to have been absent in the latest common ancestor
What is the 5 kingdom system?
- monera (bacteria)
- protista
- animalia
- fungi
- plantae
What is the 8 kingdom system?
- bacteria
- archaea
- Archaeozoic
- protista
- chromista
- animalia
- fungi
- plantae
What is the 3 domain system?
- domain bacteria
- domain archaea
- domain eukarya
What are examples of prokaryotes?
bacteria/eubacteria & archaea
What are examples of eukaryotes?
protists, fungi, plants, animals
How big are prokaryotes?
1 - 10um
How big are eukaryotes?
10 - 100um
What type of cells are prokaryotes?
unicellular
What type of cells are eukaryotes?
multicellular with tissues
What are cell walls made of in prokaryotes?
made of particular sugars & peptides
What are cell walls made of in eukaryotes?
made of cellulose or chitin (but lacking in animals)
Do have prokaryotes have flagella or cilia?
some flagella (made of flagellin protein)
Do have eukaryotes have flagella or cilia?
flagella or cilia with microtubules (flexible) - help with locomotion
What organelles are found in prokaryotes?
no membrane-bound organelles
What organelles are found in eukaryotes?
have membrane-bound organelles
What type of metabolism is found in prokaryotes?
anaerobic or facultative aerobic (switch between the 2)
What type of metabolism is found eukaryotes?
aerobic
What type of genetic organisation is found in prokaryotes?
loop of DNA in cytoplasm
What type of genetic organisation is found in eukaryotes?
DNA in chromosomes in membrane-bound nucleus
How do prokaryotes reproduce?
binary fission - dominantly asexual but some parasexual
How do eukaryotes reproduce?
by mitosis or meiosis - dominantly sexual
What are the 2 types of prokaryotes?
- eubacteria (bacteria)
- archaebacteria (archaea)
What is the difference between archaebacteria and eubacteria?
archaebacteria are less numerous & diverse than eubacteria & inhabit extreme environments - thermophiles (very hot) & halophiles (very salty)
What came first - bacteria or archaea?
archaea - before giving rise to eubacteria & eukaryotes
How many types of archaea are there thought to be?
2 - archaea 1 & archaea 2
