Bio 152 Exam #1

Bio 152

Explain the Scientific Process

1. Ask a question 

2. Do background research 

3. Construct Prediction

4. Test hypothesis 

5. Analyze your data 

6. Record your results

5 requirements for life

1. homeostasis

2. reproduction

3. metabolism

4. DNA/heredity

5. cells

Evolution

-theory supported by fossil record and observations of the environment 

-@ population level traits of organism has to be inheritable

-traits passed down from parent cell to offspring cell

Compare Lamarck and Darwin’s ideas on the mechanism behind evolution

Lamarck: said that evolution happened on individual level and if an doesn’t need that trait they lose it

Darwin: evolution is upon natural selection and the trait is given for an advantage to the environment

Observational Studies

-study patterns in nature to test ideas

-patterns can be predicted 

Quasi-Experimental Studies

-making use of natural difference to test ideas

-effects of wildfires on wildlife 

Manipulative Experiments

-changing the conditions to test ideas

Hypothesis

reasoned explanation or proposed relationship of a natural phenomenon that generates testable predictions(best guess)

Prediction

connected to hypothesis, outcome that would result if hypothesis true

Dependent Variable

variable that is being measured and is being affected

Independent Variable

is alone and doesn’t change through other variables

Treatment Group

receives treatment in experiment

Control Group

group in experiment where they don’t receive treatment

Theory

testable explanation supported by hypothesis, inferences, observations, facts

Fact

confirmed phenomenon

Hoe does evolution act on a population?

some populations are able to survive and reproduce in a certain environment

Why were Lamarck’s ideas rejected but Darwin’s were accepted?

Darwin’s theory had evidence to back it up whereas, Lamarck’s theory didn’t have any

Major components that define life

cellular organization, ability to reproduce, growth & development, energy use, homeostasis, response to environment, ability to adapt

Comparing genetic drift to other processes of evolution

doesn’t work to produce adaptations

Comparing genetic flow to other processes of evolution

can increase genetic variation in populations

Comparing mutation to other processes of evolution

genetic variation starts with mutation

Population genetics

-distribution of alleles in population & causes of allele frequency to change

Locus

location of a specific gene or sequence of DNA on a chromosome(ex. Location of gene for color of flower)

Allele

version of gene at a locus

Genotype

combination of alleles found in an individual

Homozygous

individual carries 2 copies of the same allele

Heterozygous

individual 2 carries different alleles

Phenotype

observable measurable characteristic of an organism(color of eyes, lactose, disease) 

Dominant

trait or allele whose phenotypic effect is observed when it is present in homozygous or heterozygous form(capital letter)

Recessive

trait or allele whose phenotypic effect is observed only in homozygous individuals(lowercase letter)

Null Hypothesis

there is not a difference between the observed results & the expected results

Fitness

overall reproductive success of individual w/ particular phenotype 

Relative Fitness

 fitness of a genotype standardized by comparison to other genotypes

Natural Selection

change in allele frequencies in a population caused by differential reproductive success of individuals b/c of phenotype

Gene Flow

movement of alleles between populations 

• Population allele frequencies become similar to one another

• Random w/ aspect to fitness

• Increases genetic diversity 

Genetic Drift

change in allele frequencies in a population that is due to chance

• random selective to fitness

• strongly impacts small pop.

• can lead to fixation

Genetic Bottleneck

sudden reduction in the diversity of alleles in a population

• Survivors of natural disasters

• Over hutning.fishing

• disease/famine 

Founder Effect

change in allele frequencies that occurs when a new population is established 

• Colonization of new locations 

Mutation

any permanent change in the hereditary material of an organism 

• Ultimate source of new genetic variation

Directional Selection

average phenotype of a population changes in one direction, normal distribution & after either drift left or right

• Positive directional selection: average trait value increases

• Negative directional selection: average trait value decreases 

• Alleles for traits can be lost

Stabilizing Selection

favors phenotypes near the middle range of phenotypic variation

• Reduced genetic variation

Disruptive Selection

favors extreme phenotypes at both ends of the range of phenotypic variation 

Intrasexual Selection

competition among individuals of the same sex for mates or resources (Ex.males fight for access to females,most die w/o mating)

Intersexual Selection

selection of an individual of one sex for mating by an individual of the other sex (one sex is choosy) 

5 assumptions of HWE

-no genetic drift (very large population)

-no natural selection (equal chance of survival and reproduction)

-random mating(no sexual selection)

-no mutation(no change in DNA at locus)

-no gene flow(no migration) 

3 requirements for natural selection to occur

-struggle for existence

-variation

-inheritance

What happens to genetic variation when a given mechanism acts on a population?

natural selection

Advantages and Disadvantages of different species concepts

Biological Species:

Advantages: two very different people can still reproduce

Disadvantages: reproductive isolation prevents genetic flow between species

Morphological Species:

Advantages: can be applied to asexual organisms and fossils and does not require information on possible interbreeding

Disadvantages: relies on subjective criteria and researches may disagree on which features distinguish a species

Phylogenetic Species Concept:

Advantages: history can be traced by comparing characteristics

Disadvantages: difficult to agree on the amount of difference required to establish separate species

Process of Allopatric Speciation

occurs when a species separates into 2 separate groups which are isolated from one another

Process of Sympatric Speciation

occurs when there are no physical barriers preventing any members of a species from mating w/ another & all members are in close proximity to one another

Compare the possible outcomes of secondary contact between populations that have been isolated

Fusion, extinction, reinforcement, hybridization, new species

Species

evolutionarily indep. pop. or group of pop.

Biological Species

species as a pop. or group of pop. that are reproductively isolated from other groups 

Pre-zygotic Species

prevents individuals of diff. species from mating successfully 

Post-zygotic Species

hybrid offspring of a mating between species either don’t survive or don’t reproduce

Temporal Isolation

timing of availability to reproduce

Behavioral Isolation

reproductively isolated due to diff. behaviors

Habitat Isolation

no interacting b/c they live in diff. habitats

Mechanical Isolation

reproductive organs have to fit together(lock & key) 

Gametic Isolation

sperm and egg has to match up(cellular level), have to have right receptors

Hybrid Inviability

baby cannot survive, b/c of too many/not enough chromosomes

Hybrid Sterility

offspring of parents cannot have its own offspring

Morphological Species

pop. or group of pop. that have measurably diff. anatomical feature from other groups

Phylogenetic Species

smallest monophyletic group in a phylogenetic tree

Allopatric Speciation

speciation that occurs when pop. of the same species become geographically isolated

Vicariance

physical splitting of a habitat

Dispersal

movement of individuals from one place another

Sympatric Speciation

speciation that occurs even though pop. live within the same geographical area

Autopolyploidy

doubling of chromosomes # and the chromosome all come from same species

Allopolyploidy

parents of diff. Species mate & then an error in mitosis occurs resulting in viable, nonsterile offspring w. 2 full sets of chromosomes

Fusion

gene flow removes any differences between species resulting in one species(disruptive selection is no longer occurring)

Extinction

one species goes extinct

Reinforcement

natural selection for traits that prevent interbreeding among pop.

Hybridization

geographic area where interbreeding occurs & hybrid offspring are common

New Species via Hybridization

hybrids are viable and fertile

Strengths and Limitations to Fossil Record

Limitations: conditions to fossilize is very rare

Strengths: fossil record provides evidence for when organisms live in earth, evolved, have gone extinct

How does adaptive radiation occur?

• New habitat lacks competitors, predators, or herbivores 

• Must undergo a selection to get a trait

How did How Genes lead to diversification?

• Duplication of hox genes led to new body forms

• New body forms allowed for new niche exploitation

Root

most ancestral branch in the tree

Tip

endpoint of a branch represents a living or extinct species or other taxon(doesn’t have to be species)

Branch

line representing a population through time

Outgroup

taxon that diverged prior to the taxa that are the focus of the study

Node

point within the tree where a branch splits into 2 or more branches(isolation mechanisms leads to split)

-Most recent common ancestor of the descendent groups

Polytomy

node that depicts an ancestral branch dividing into 3 or more branches

-Relationship among taxa is not resolved

Sister Taxa

lineages that diverged from the same node

-Share a common ancestor

-Also known as a clade

Character

Any heritable genetic, morphological, physiological, developmental, or behavioral characteristic that varies among the taxa to be studied

Synapomorphy

Shared derived trait

-shows who shares trait (helpful)

Symplesiomorphy

shared ancestral trait(most helpful to creating tree)

-relation (not helpful)

Autapomorphy

unique derived trait 

-only 1 group has trait (not helpful)

Monophyletic

Includes the common ancestor & all the descendents

Paraphyletic

Includes the common ancestor but not all the descendents

Polyphyletic

includes the descendents but not the common ancestor

Homology

shared trait due to common ancestry

Homoplasy

shared trait due to convergent evolution (environmental pressure-natural selection)

Parsimony

most likely explanation/pattern is the one that requires the fewest steps

Adaptive radiation

rapid evolutionary diversification within one lineage 

• Many descendents adapted to side range of habitats

• Fossil record & phylogenetic evidence

Hox Gene

 determine body segment organization

Background Extinction

avg. rate of extinction observed when a mass extinction is not occuring 

• ~ 1 species/million yrs.

Precambrian(Most important event in that era)

(4500-451 mya)

• All life unicellular

• Cyanobacteria = oxygen, synthetic organism (released oxygen)

-2500 mya

• Couldn’t use oxygen as source = no oxygen

Phanerozoic Era

(541 mya - present)

• Paleozoic: land plants, some land animals, fungi aquatic animals

-all died 252 mya

• Mesozoic: dinos, mammals, land plants, aquatic plants & animals

-dinos & seed plants dominant species

-dinos & many others taxa extinct 66 mya

• Cenozoic: many modern lineages

-flowering plants & mammals dominant