Zusammenfassung der Ressource
Biology 108: Lectures 1-6
- BIOLOGICAL DIVERSITY
Anmerkungen:
- * variability among living organisms from all sources; includes diversity within species, between species and of ecosystems
- Levels of Organization
- Biosphere
- Ecosystems
Anmerkungen:
- * community + physical environment
- Communities
Anmerkungen:
- * different species (populations) interacting with each other
- Populations
Anmerkungen:
- * group of individuals of same species in an area
- Organisms
- Organs/Organ systems
- Tissues
- Cells
- Organelles
- Molecules
- Atoms
- Methods of Organization
- Nomenclature
Anmerkungen:
- Taxonomy
Anmerkungen:
- practice (discipline) of naming and classifying organisms by similarities
- Systematics
Anmerkungen:
- theory and practice of classifying organisms based on their evolutionary history (phylogeny)
- Phylogenetic Trees/Cladogram
Anmerkungen:
- evolutionary trees/hypotheses that show the evolutionary relationship between organisms (past/present)/common ancestors and descendants
- In-group
Anmerkungen:
- *group of tree that we are interested in studying
- Out-group
Anmerkungen:
- * different than in group; distantly related
- character
Anmerkungen:
- * type of structure, behavior, DNA sequence
ex. eye colour
- state
Anmerkungen:
- *expression of character
ex. brown
- synapomorphy
Anmerkungen:
- symplesiomorphy
Anmerkungen:
- shared, ancestral state (acquired from ancestor)
- homologous
Anmerkungen:
- look the same and have the same evolutionary origin; result from divergent evolution
- divergent evolution
Anmerkungen:
- process by which members of a species become more and more different, resulting in 2 different species; usually due to different environments (unique selective pressures)
- analogous
Anmerkungen:
- structures in different species that look the same but actually developed independently; result of convergent evolution and usually due to similar envrionments
- convergent evolution
Anmerkungen:
- when unrelated organisms evolve similar characteristics due to similar environmental pressures (same selective pressure)
- vestigial (structures)
Anmerkungen:
- body structure that is reduced in form and function but may have been useful in ancestor
- principle of parsimony
Anmerkungen:
- * choose phylogenetic tree/relationships that has the least number of times the character changes states... b/c evolutionary change does not occur so frequently
- clade/monophyletic group
Anmerkungen:
- has common ancestor and ALL of its descendants and NO other unrelated taxa; use homologous traits
- polyphyletic group
Anmerkungen:
- more than one common ancestor or lacking common ancestor/taxa is grouped together although they do not share recent ancestors; or grouped by superficial similarities instead of common ancestory
- paraphyletic group
Anmerkungen:
- groups that do not contain ALL descendants of a common ancestor; usually happens when most divergent group (group that looks the most different) is removed
- sister taxa
Anmerkungen:
- two (or more) groups that are each others closest relatives
- Linnean System of Classification
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
- Domain
- Binomial nomenclature
Anmerkungen:
- 2 part name = genus + species
* genius = capital
* both = italicized
ex. Homo sapiens
- Why do we study it?
- Threats
Anmerkungen:
- - resource exploitation
- conversion of land
- pollution
- transport of species
-global climate change
* As human population increases, extinction increases.
- Direct value
Anmerkungen:
- * drugs (antibiotics)
* agricultural value
- Indirect value
Anmerkungen:
- allows us to have info to use for
* recycling biological and geochemical matter
* nutrient-cycling decomposers
* water cyclings (transpiration of trees)
* prevents soil erosions
* regulates climate-carbon cycle
* ecotourism ($)
- Scientific Method
- Observation
Anmerkungen:
- * asking and developing question
- Hypothesis
Anmerkungen:
- * prediction; purpose = answering question; cause/effect formate
* testable and falsifiable
* data can support or reject hypothesis but can't prove it
- Predictions
Anmerkungen:
- * follow the hypothesis
* must be testable
- Hypothesis testing/experimentation
Anmerkungen:
- * testing of predictions through observing and experimentation
- experiments agree with prediction =
process is repeated for more info
- results are not consistent with
the predictions = new hypothesis
- proximate questions
Anmerkungen:
- * questions that deal with mechanism and may not require evolutionary explanations
- ultimate questions
Anmerkungen:
- * questions having to do with evolutionary origins and functions
- Questions
Anmerkungen:
- * seek to explain observation
- Natural Selection
Anmerkungen:
- context dependent; increases fitness but does not work towards perfection
- Organisms produce many
more offspring than survive
to reproduce themselves.
- Resources are limited.
(not enough food for all
offspring of all
individuals)
- Most populations =
relatively stable
- Organisms must compete for limited
resources, and not all succeed.
- Variation among individuals within
species; for natural selection to act on
variation, must be seen by environment
(expressed in phenotype) and be heritable
(caused by genotype)
- Some variation is heritable.
- Some heritable variations are may
provide individuals with a
competitive advantage.
- Individuals with advantageous variations are
likely to have more offspring than those
without these variations.
- Next generation will have more individuals with that
variation than were present in previous generation =
adaptive changes over generation = "descent with
modification"; refer to lecture 4 pg 7
- Types of Variation
- Phenotypic
Anmerkungen:
- Genotypic
Anmerkungen:
- Genes
Anmerkungen:
- combo. of 2 alleles in diploid (2 copies) individuals; one allele per chromosomes
- allele
Anmerkungen:
- one of two or + alt. forms of a gene; arise by mutation; found at same place on a chromosome
- allele frequency
Anmerkungen:
- how often an alternative form of a gene occurs
- Evolution
Anmerkungen:
- change in allele frequency in gene pool between generations
- caused by
- natural selection
Anmerkungen:
- can affect distribution of allele frequencies via different types of selection
- directional selection
Anmerkungen:
- 1 extreme phenotype is favored (highest fitness); shift in the mean of population; variance (degree of difference) = same
- disruptive selection
Anmerkungen:
- both extreme phenotypes are favoured; result = polymorphism (2 or more divergent phenotypes); maintains variation
- stabilizing selection
Anmerkungen:
- average/common phenotype(s) favored/ selection against extremes; mean of pop. stays the same = variance (degree of difference) decreases; little or no evolutionary change
- gene flow
Anmerkungen:
- transfer of genes (alleles) between pop.s; ex. interbreeding, migration; variation = increases within pop but decreases between pop.s b/c allele frequency between pop.s = more similar
- genetic drift
Anmerkungen:
- change in allele frequency due to *chance*; impact = greater in small pop.; rare alleles are more likely to be lost
- bottleneck effect
Anmerkungen:
- only few individuals survive; only they reproduce in next generation; allele frequency in next generation is diff. than previous
- founder effect
Anmerkungen:
- new pop. established by a few colonizers which have diff. allele frequencies than ancestors
- mutations
Anmerkungen:
- change in DNA caused by error in DNA replication or by structural damage to DNA; random process; can be good, bad, or neutral depending on environment
- fitness
Anmerkungen:
- extent to which an individuals's genotype is represented in the next generation; highest reproductive success
- gene pool
Anmerkungen:
- total # of genes of every individual in an interbreeding pop.; large = high genetic diversity; small = low genetic diversity
- Sources of Variation
Anmerkungen:
- - mutation (random changes in DNA)
- during meiosis
* recombination (crossing-over)
* independent assortment (of chromosomes)
- fertilization (sexual reproduction; 2 combine to make 1 new genotypes)
- Some heritable variations may
provide individuals with a
competitive advantage.
- acts on the individuals (causing differential survival
and reproduction), but outcome (evolution( is seen
at the population level).
- Selective Agent
Anmerkungen:
- something in environment (biotic/abiotic) that is always acting on/applying pressure on organisms/population over generations (ex. climate change, starvation)
- selection pressure
Anmerkungen:
- intensity with which selective agent acts on a population to evolve
- Adaptation
Anmerkungen:
- * heritable variation; individuals vary in their characteristics (phenotype) due to varied genetic makeup (genotype)
* limited resources = pop. produces more offspring than environment can sustain
* phenotypes with favorable traits = better suited to survive and reproduce; genetic contribution to next gen. = greater = increased fitness
* characteristics (and genes coding for them) of fit individuals = increase in pop.