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BIO 203 exam 1
Dr Reddy PSU
Terms in this set (88)
the change of allele frequencies within a population over time
Evolution is not about ___________ it's about species and the likelihood of a species survival
Where do traits come from?
In sexually reproducing organisms, half the genetic material originates from the mother and half from the father
How Are Populations, Genes, and Evolution Related?
Inheritance of genes provides the link between the lives of individual organisms and the evolution of populations
Genes (__________) and the environment interact to determine traits/ physical characteristics (____________)
what characteristic is beneficial in all environments?
no characteristic is beneficial in all environments, that's why genotypes are always changing and evolving to fit a changing and evolving environment
individuals with traits that help them survive and reproduce leave more offspring
- differential survival and reproduction of individuals within a population in response to environmental pressure
- Advantageous traits become more common and population becomes better suited, or adapted, to environment
individuals with traits that help them survive and reproduce leave more offspring
measure of likelihood for reproduction and therefore contribute their genes to the pool of genes that can be drawn from
Natural selection acts on _____________, the structures and behaviors displayed by the members of a population
The selection of phenotypes subsequently affects ___________ and alleles present in a population
There is no such thing as ___________________, fitness is context dependent and dependent on a changing environment
a group of interbreeding individuals (species) that live in the same place at the same time and have the capacity to produce fertile offspring
Collection of all of the genes that are available in a population
allele frequencies change from one generation to the next
allele frequencies do not change from generation to generation and the following conditions are met:
No gene flow (immigration/emigration)
The population must be very large
Mating must be random, with no tendency for certain genotypes to mate with specific other genotypes
No natural selection
what is an Equilibrium population susceptible to
decimation in a rapidly changing environment
Causes of evolution:
1. Mutations (DNA mutations can happen on their own, video example was about a badger developing extra hairy ears and if that's favorable, that mutated gene will pass down to more generations
2. Gene flow (immigration/emigration)
3. Small populations
4. Non-random mating, with tendency for certain genotypes to mate with specific other genotypes
5. Natural selection (environmental pressure)
It is believed it is more advantageous to have __________ genetic diversity in populations because it increases the populations chances of survival in a changing environment
The Punnett Square predicts genotypes of _______________.
Hardy Weinberg predicts genotypes of _________________.
The Hardy-Weinberg law:
1. Frequency of the alleles in the gene pool does not change over time
2. After one generation of random mating, frequencies for two alleles can be calculated as p2 + 2pq + q2 = 1
what are Mutations are the ultimate source of genetic variability?
- Inherited mutations are rare but important
- Mutations are spontaneous, not goal directed
- Bacteria are prone to rapid mutation, making this organism an excellent case study in evolution
- Chemicals that either kill bacteria or slow their growth
How do antibiotics work?
Interfere with function of essential bacterial cell structures
In the absence of an antibiotic
The cell wall is string and ridged, water flowing into the cell exerts pressure on the cell wall
In the presence of an antibiotic
Beta-lactam antibiotics interfere with the cell wall causing it to be weak, water flowing into the cell exerts pressure on the cell wall and the weak cell ruptures
what is Binary fusion
type of asexual reproduction in which an organism replicates its DNA and divides in half, producing two identical daughter cells
what does a Large number of mutations mean
-> highly diverse gene pool → increase in likelihood of and allele which allows bacteria emerge that survive antibiotics
Acquisition of new alleles in bacteria may result in antibiotic resistance acquired through random mutation
Drug resistant bacteria and disease example
Methicillin-resistant Staphylococcus aureus (MRSA):
Natural selection occurs in patterns (hint: 3)
- Directional selection
- Stabilizing selection
- Diversify selection
predominant phenotype shifts in a particular direction
phenotype of populations settles near middle of range
phenotype of population is at both extremes of range
Lamarckian evolution: An incorrect theory
Lamarck believed trails that acquired in one's lifetime could be passed to offspring
His paper "On the law which has regulated the Introduction of new species" was published in 1855
Three years before "The Origin of Species" was published
what did Wallace lack?
Wallace described the pattern of evolution, but not the process of natural selection
Was given a chance opportunity that laid the foundation for evolutionary theory
Observed correlation between beak size and food resources on the ground finch
Creating the idea of Speciation!
All species are related by ______________
common ancestry (pattern)
Descent with modification (process):
Characteristics of species can be modified from generation to generation
High fitness → more surviving offspring
acquisition of a trait that increases fitness of individual
A group of individuals of the same species living in the same area at the same time
Requirements for natural selection to occur in a population
1. Individuals must vary in characteristics that are heritable
2. In a particular environment, certain versions of these heritable traits help individuals reproduce more than do other versions
- Because "stronger" individuals are more likely to have "strong" children.
- Example of strength: disease resistance
What Is a Species?
potentially interbreeding natural populations which are reproductively isolated from other groups
The biological species concept
reproductive isolation of group ensures evolutionary independence
Each species follows a separate evolutionary path because......
alleles rarely move between the gene pools of different species
Isolation of gene pools leads to _____________
prevents interbreeding between populations that do not come into contact
a group of organisms forms new species, whose adaptations allow them to fill new habitats or roles in their communities
The history of life can be represented by an ____________ ______
- Study of the genetic makeup of populations and how genetic composition changes
- Understand how a group of organisms is coping with environmental changes
movement of alleles from one population to another
- Movement of individuals between populations is a common cause of gene flow
- Alleles can move between populations even if organisms do not: Pollen (sperm) and seeds from flowering plants can move and distribute alleles
The evolutionary effect of gene flow
- Is to increase the genetic similarity of different populations of a species
- If gene flow between populations of a species is blocked, the resulting genetic differences may grow so large that one of the populations becomes a new species
Urbanization can prevent ___________, can lead to inbreeding
Non Random Mating
Mating within a population is almost never random
- assertive breeding
(sexual reproduction among relatives) is more likely if species lack mobility and tend to stay near their birthplace
mate choice bias.
- Chance events change allele frequencies. occurs more in small populations, where chance may dictate which in the gene pool are passed on
- Examples of chance events which prevent inheritance:
- Any organism killed by a flood prior to reproducing
type of genetic drift, occurs when population size is suddenly reduced
Population is drastically reduced by a natural catastrophe or overhunting
only a few individuals are available to contribute genes to the next generation, thus changing allele frequency
A type of genetic drift in which a small number of individuals leaves one population and establishes a new one
Isolated populations founded by small number of individuals
Why is genetic diversity important?
- Diverse gene pool gives a population more flexibility to survive in a changing environment
- The more genetically diverse a population, the more ways it has to adapt
Biological species concept
A population of individuals whose members can interbreed and produce fertile offspring
Different species cannot mate because they are reproductively isolated
types of Reproductive Isolation
- Ecological isolation
- Temporal isolation
- Behavioral isolation
- Mechanical isolation
- Gametic isolation
- Hybrid inviability
- Hybrid infertility
Key events in life's history
1. Prokaryotes lived alone on and transformed the atmosphere.
2. Photosynthesis by some prokaryotes produced oxygen that enriched the water and atmosphere of Earth.
3. Eukaryotes are about 1.8 billion years old.
4. The first multicellular plants and fungi began to colonize land about 500 million years ago.
- The fossil record tells us that land was colonized 400-350 million years ago
- Living on the land requires
o sturdier structure
o prevention of water loss
o a different way to take in oxygen
Reading the fossil record
- Shows an ordered succession of evolution
- Reveals changes over time in family of organisms
- Not all organisms are preserved
- The fossil record is not a complete record of past life
- Extensive enough to show arc of life
is the fossil record a complete record of past life?
scientists who study ancient life by means of the fossil record
- the preserved remains or impressions of once-living organisms
have to have a quick death and quick preservation
an assemblage of fossils arranged in order of age, which provides evidence of changes in species over time
How are fossils dated?
relative dating and radiometric dating
determining the age of a fossil from its position relative to layers of rock or fossils of known age
use of radioactive isotopes as a measure for determining the age of a rock or fossil
- carbon dating
compare c12 to c14
Higher the ratio, older it is
A famous fossil
Fossils reveal that the first tetrapod was a.....
four-limbed fish that lived in shallow water and could breathe air
Vertebrate with four true limbs
Jointed, bony appendages with digits
o Possessed many features of a lobe-finned fish
o Also had a jointed elbow, wrist, and fingerlike bones
Evolution is random, natural selection is not random
Proof of common ancestry
All tetrapods share the same forelimb bones, arranged in the same order
similarity due to common ancestry
are those that are similar because they are inherited from the same ancestor
Inherited from an ancestor and no longer serves a clear function in the organism that possesses it
Related organisms share ___________ ______________
- Closely related species have fewer DNA sequence differences than species more distantly related
An organisms evolutionary history is encoded on its __________
DNA coding for important sequences (like rRNA genes) is useful for......
investigating relationships between taxa that diverged hundreds of millions of years ago
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