Chapter 13: How Populations Evolve Flashcards
What is evolution
Descent with modification
Who is Charles Darwin
Famous for proposing that evolution occurs by natural selection and for writing “origin of species”
How did Darwin study evolution
Compared how their appearance, mating and eating habitats change with different locations and climate (water vs land) (cold vs warm) (wooded area vs beach)
What did Darwin observe
Blue footed booby, marine iguana, giant tortoise, finches
Who studies evolution
Paleontologist
Paleontologist
Study fossils, imprints of remains of organisms that lived in the past
Amber
Fossilized resin produced by pine trees
Ammonite cast
Replicas of ammoites which were shelled marine animals related to the present day nautilus
Fossils found in the ______ layer are older than those found in ______ layere
Lower, upper
Carbon dating
Estimates fossils age up to 50,000 years old
The longer the organism has been dead….
Less carbon and more nitrogen tend to be present in body
How does carbon dating work
Compares amount of carbon 14 in the air to the amount of c in the fossil (dead organism)
Homologous structures
Have different functions but are structurally similar because of common ancestry.
Veterbrae
Organism that Has backbone
Analogous structure
Have similar appearance and functions but they aren’t derived from a common ancestor (evolved independently)
Example of analogous structures
Wings of a bird and butterflies (which are insects) have the same function flying but they evolve separately
Biogeography
Compares organism and their traits between different locations geographies
Marsupials
Animals which carry their young in a pouch
Comparative anatomy
Compares body structures between organism
Molecular biology
Compares DNA sequences between different organism
What does each branch point represent in a evolutionary tree
Common ancestor of the lineages beginning there and to the right of it
A hatch mark represents what in a evolution tree
Homologous character shared by all the groups to the right of the mark
Ostriches, hawks, and others are considers what
Birds
Lizards, snakes and crocodiles are considered what
Reptiles
What are tetrapods
4 appendage
What is an evolutionary tree
Allows us to determine which traits are shared by different organisms and which ones are unique to a certain group of organisms
Tetrapods limbs are shared by…
Amphibians, mammals, reptiles, and birds but not lungfishes
Amnion
Fluid filled membrane that encloses an embryo is shared by mammals, reptiles, and birds but not by lungfishes and amphibians
What are unique to birds
Feathers
How does nature affects evolution
Natural selection
Natural selection
The process where nature selects traits that help organism survive and reproduce in a specific environment and over time increase in population
Example of natural selection
The surviving and increase of the bugs resistant to pesticides rather than the bug that is not.
3 rules of evolution by natural selection
1) populations evolve, not individuals
2) natural selection can only affect heritable (encoded in DNA) traits (not acquired traits
3) perfectly adapted organism are not created by natural selection
What forces affect evolution
Artificial selection
Artificial selection
Process by which humans select and breed organism with desired traits
What are the sources of variation within a population
Mutation and sexual reproduction
Mutation
Change in the nucleotide sequence of DNA and ultimate source of new alleles
The hardy-Weinberg equilibrium
Used to calculate the allele and genotype frequencies in population
What is the equation for hardy-Weinberg, us to calculate frequency or genotypes
P2 + 2pq + q2 = 1, P + q = 1
P represent in hardy Weinberg equation
Frequency of dominant allele
To be in a hardy weinberg equilibrium a population must
Be very large Keep all its members together, keep strangers away Not mutate Have random mating (no inbreeding) Not undergo natural selection
How do you find the frequency of a dominant phenotype
P2 + 2pq
Determines frequency of recessive phenotype
Q2
How can the gene pool of a population change
Natural selection, genetic drift, gene flow
What is an example of adaptive evolution
Natural selection
Natural selection
Alleles selected by nature, they are favorable for survival and reproduction of a population
What are examples of non-adaptive evolution
Genetic drift and gene flow
Genetic drift
A random change in allele freq; bottlenecking effect. Alleles are randomly selected; may be favorable for survival
Gene flow
When genes or alleles move in and out of population because of changes in mating locations
Bottlenecking effect
Lead to loss of genetic diversity when population is greatly reduced in size because sudden change in environment.
Examples of bottlenecking
Fire, earthquake, flood
Founder effect
Leads to loss of genetic diversity when a few individuals isolated from a large population creating new population(s)
What are the different effects of natural selection
Stabilizing selection, directional selection and disruptive selection
Disruptive selection
favors individual at both ends with phenotypic range allowing mice with light or dark fur colors to survive
Stabilizing selection
Favors individuals with intermediate fur colors selecting against individuals with light and dark fur colors
Directional selection
Acts against individuals at one end of phenotypic range
Sexual selection
Type of natural selection where members of the same species compete for access to mates
Primary structures
Are needed for reproduction to happen (viable sperm and penis)
Secondary sex structures
Are not involved into reproduction directly but the chance of reproduction occurring (ex; feathers of male peacocks)
Balancing selection
Occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population
Frequency dependent selection
Is a type of balancing selection that maintains two different phenotypic forms in a population acting against either form when becomes too common in a population
