Evolution and Ecology Flashcards
Georges Cuvier
Came before Darwin
Discovered extinction in 1813
Extinction was a wild notion
Carl: father of taxonomy
Made thousands of species
Responsible for the taxonomy system we use today
Coined the term homo-sapiens ( in italics because it is Latin)
Christian
Believed he was doing God’s work
Charles Darwin
The Origin of Species
1859
Used the phrase “descent with modification”
Natural selection (examples in book- hunting of big horn sheep and cod fisheries)
Went on a voyage : voyage of the beagle
What is Evolution:
Descent with Modification
Fossils: show descent with modification
In terms of teeth and limbs
Sticklebacks have lost their pelvic girdle over time
Often penetrate into fresh water, get trapped in lakes
The environment does not support their heavy armours
One of the trade-offs is: if you expend energy using these trade-offs, they will loose fertility
Species do change!!!!
Ex. stickleback fish and horses
Ex, dinosaurs being extinct is a type of descent with modification
What is Evolution
Allele Frequency Change
How fast does this happen?
Ecology: is the interaction between organisms
We do have allele frequency changes within a population
Populations of organisms we do see variation within them
If there is strong selection on a population, we will see genotype changes
Arizona desert white sand mostly certain mice want to be cryptic from their predators so they are less visible than other mice within the population
What is Evolution:
Populations evolve individuals do not
Important that populations evolve, NOT the individuals
Evolution never follows over evolutionary time
What are the mechanisms of evolution?
1. Mutation
Elephants utilize their tusks for manipulating their ecology
Recently, poaching has been very popular in places where they live
Poaching: harvest tusks
To get their tusks they just slaughter the elephants, take off their faces, and leave the body to rot
Mutation produces tuskless elephants
This mutation is increasing its frequency in a population
Individuals in populations differ in their phenotypes
Different alleles arise by mutation
Mutation: a change in DNA
Can result from copying errors during cell division, mechanical damage, exposure to chemicals (mutagens) or high-energy radiation
Very rare
In a generation, one mutation would occur in every 10,000 to 1,000,000 copies of a gene
Provides the raw material on which evolution is based, while recombination and independent assortment rearrange the raw material into new combinations
What are the mechanisms of evolution?
2. Natural Selection
Beaks of birds
Finches have massive bills used for cracking seeds
3 type of natural selection
Directional Selection
Individuals at one phenotypic extreme (e.g., large size) are favored ex; the finches
Stabilizing Selection
individuals with an intermediate phenotype are favored ex; 2 predators and the gall
Occurs if there is 2 selective agents operating on both sides of the curve
Disruptive Selection
individuals at both phenotypic extremes are favored
What are the mechanisms of evolution?
3. Genetic Drift
Occurs when chance events determine which alleles are passed to the next generation
Significant only for small populations
What are the mechanisms of evolution?
4. Gene Flow
Alleles move between populations via the movement of individuals or gametes
This causes:
1. Populations become more similar
2. New alleles can be introduced into a population
Ex. gene flow introducing alleles for insecticide resistance
Adaptations result from natural selection
Selects of traits that confer advantages
alleles increase in frequency over time
Adaptive evolution can occur rapidly
Male bighorn sheep that are bigger with a bigger horn will win the battle
Have been losing land (habitat has been deteriorating)
They will continue to be hunted- even tho hunters must pay $100,000
Adaptations are not perfect
Natural selection does not result in a perfect match between organisms and their environments
Environments are constantly changing, and there are constraints on evolution
WHY Evolution isn’t Perfect:
Lack of genetic variation
Spraying with DDT killed populations of mosquitoes carrying malaria
Killed off any form of mutations
WHY Evolution isn’t Perfect:
Evolutionary history
Whales perfect example of evolutionary history
Evolutionary Constraint: Whales always need to return to the surface to breathe
WHY Evolution isn’t Perfect:
Ecological trade-offs
Crab: Decreased mobility due to size
Snow Crabs - claws are small but legs are long trying to get away from predators
Adaptive Evolution is Driven by Ecological Interactions
Organisms interact with one another and with their environment
For every fox that caught a bunny, one fox went hungry
Evolution is constantly in motion, and the ecological context is under constant change
Patterns
Long-term patterns of evolution are shaped by large-scale processes
Speciation
Adaptive radiation
Extinction
Mass extinction
What drives speciation in a single population
Change in gene frequency
There is gene flow between white mice and dark mice
But overtime a river continues to grow between the two
At this particular point, no gene flow would be able to occur
This would cause the formation of 2 separate daughter species (since gene flow isn’t occurring)
Species Concept
Those individuals in the population must be able to have offspring, and those offspring should be fertile
Reproductive barrier between canis lupus and canis lupus familiaris
Wolves would eventually take over
Gene flow is limited by their mutualistic relation
Physical Barriers that Result in Reproductive Isolation and Speciation
Physical Barrier
Mutualism (behaviour)
Ecological Barrier
George Cuvier discovered of extinction
Excision is just a part of speciation
Over evolutionary time we have rates of extinction and speciation
Adaptive Radiation: Repeated speciation events increase the number of speciation in a group
Extinction: species are also lost
An Evolutionary Tree: a branching diagram that represents the evolutionary history of a group
Extant: is the opposite of extinct (means they are alive today)
Carl Lanius had binomial names but thought they were pinnipeds
Quite often, gaps occur between very distinct species due to species going extinct
Which can be seen in an evolutionary tree
The global ice age disappeared
Evolution of mammals
Cambrian Explosion: Adaptive radiation in animals
There were 5 mass extinction events
Some branches end while others are growing
Extinction is a natural process
