Lecture 33: Principles of evolution Flashcards
Adaptive changes in organisms occur through natural selection, what can this lead to?
the formation of new species
How do organisms evolve?
- response to environmental change creating new niche
- occupying unoccupied niche
- migrating to new environment
humans shared a common ancestor with chimpanzees, how many years ago?
eight million years ago
humans shared a common ancestor with whales, how many years ago?
60 million years ago
All organisms are related far back in time to probably a single successful, DNA containing cell, true or false?
true
How do changes in species occure?
natural selection
what do variations involve?
body size, hair colour, facial markings, voice properties, or number of offspring
what traits show little or no variation?
number of eyes in vertebrates
what does the case of the pepper moth show us?
natural selection changing the frequency of a particular allele or gene.
what happened to the white pepper moth?
industrial pollution made trees darker, caused increase in black pepper moth, population chawed due to environmental change.
can taits be influenced by environmental conditions?
yes
what happens if theres a high rate of population growth?
local resources can’t support them all leading to a struggle for resource
Individuals who possess traits that are well suited for the struggle for resources will do what?
They will reproduce, contributing more offspring to the next generation.
Do certain characteristics lead to individuals being eliminated?
yes
what are the first 5 principles of evolution?
- Variating exists, through random mutations and recombination
- Evolutionary changes depend upon changes within populations. (proportion of genotypes)
- Allele frequencies remain constant unless forces change them.
- Natural selection can alter allele frequency.
5, Evolution proceeds at afferent rates
what factors alter allele frequency in a population?
mutation, genetic drift and gene flow
what is a mutation?
change in DNA, the genetic material
what does an organisms DNA affect?
looks, how it behaves, and its physiology
Are mutations random?
yes
Do all mutations matter to evolution?
Not all mutations matter to evolution
what is a point mutation?
a mutation affecting only one or very few nucleotides in a gene sequence.
what can point mutations cause?
These can cause miscoding that can result in changes to a protein or even its absence
what are examples of biological mutagens?
certain chemicals present in bacteria, plants and animals
what are examples of non-biological mutagens?
heavy metals, radiation, cooked food
what does the advantage of an allele or genotype depend upon ?
the enviroment
what does expiation general require?
barriers to gene flow
what are the principles of evolution, 6-10?
6) Mutations are advantageous in some ways and disadvantageous in others, or neutral. The advantage depends upon the environment.
7) The chance that a mutation will occur is not affected by the advantage or disadvantage it confers.
8) Organisms cannot evolve adaptations in anticipation of future events
9) Not all characteristics evolved because they were adaptive.
10) Speciation generally requires barriers to gene flow
what are the principles of evolution, 11-15?
11) If gene flow among local populations of a species is sufficiently restricted, the populations may so diverge that they will not or cannot interbreed. That is, speciation occurs.
12) If two populations have become different species, the genetic changes in one are usually not transmitted to the other.
13) The principles of intraspecific evolution apply to all genetically controlled characters.
14) Biodiversity can be defined in terms of genetic diversity, species diversity and ecosystem diversity.
15) Systematics is the study of biodiversity and the evolutionary relationships that exist among organisms.
Does evolution through natural selection always allow organisms to better survive?
No, it can can result in extinction as species fail to adapt to new conditions.
whats an Adaptive significance off the complex nervous system?
. increases behavioural repertoire – more able to cope with environmental pressures
. Animals to respond in more diverse ways to environmental conditions
what responsiveness do bacteria and plants show?
phototaxis (light)
chemotaxis (chemicals)
geotaxis (gravity)
How does a ciliate swim smoothly?
coordinated beating of its cilia controlled by electrical potentials
what fibres are associated with the sensory nervous system?
afferent fibres
what fibres are associated with the motor system?
efferent fibres
What helps us understand how the nervous system may have evolved?
Diverse range of living invertebrates offers clues to how the nervous system might have evolved
what is evolution?
a random process leading to changes in species, driven by variations and mutation.
