BIO013 EXAM 4

Steps of binary fission:

1. Cell growth 2. Duplicate genome 3. Segregate genome 4. Assemble proteins 5. Divide cytoplasm 6. Build cell wall

Applications of phylogenetic trees - Molecular clocks:

A molecular clock uses the average rate at which a given gene or protein accumulates changes to gauge the time of divergence

Radioisotopes:

Actual ages of rocks can be determined. Isotopes that decay in a predictable pattern (unstable)

Prokaryotes:

All are unicellular. Divide by binary fission, NOT mitosis. DNA is often circular, NOT in a nucleus; floats freely inside the cell. No membrane-enclosed organelles

How do descendant lineages get separated?

Allopatric speciation: occurs when biological populations of the same species become physically isolated from each other. Via dispersal or vicariance (A physical barrier)

Limitations of biological species concept:

Allopatrically distributed species. Does not work for many bacteria, asexual reproducers. Many plant species readily hybridize like the tangelo (a mix between a grapefruit and a lemon)

Lineage:

An ancestor and its descendants. The branches of the phylogenetic tree

What effects peptidoglycan?

Antibiotics; gram positive is less resistant to antibiotics while gram negative is more resistant to anitbiotics

Habitat:

Apple maggot flies

Ether linkages:

Archaea. Single bonds

Ester linkages:

Bacterial and eukarya. C=O bonds

Why is genetic drift often a factor influencing speciation after a founder event?

Because founder events typically involve small numbers of individuals

Constructing phylogenetic trees:

Begin with an outgroup (a root/base to differentiate between) and the ingroup (the taxons that fit into the description). Compare and contrast the derived traits

Radiometric dating PUS fossil analysis =

Best methods to determine geologic age

Prokaryote reproduction:

Binary fission

EX of convergent evolution:

Bird and bat wings. The bones are homologous but the wings are not because they were developed independently on two different lineages

Which is homologous to the bones in the wing of a bird?

Bones in the flipper of a whale

Which statement about monophyletic taxon is false? A. It is a clade B. It includes all descendants of the common ancestor of the members of the group C. At least two "cuts" are required to remove it from a phylogenetic tree D. It is a historical group of related species E. It is a complete branch on the tree life

C. At least two "cuts" are required to remove it from a phylogenetic tree

All life is connected because all organisms have:

Cell membranes and ribosomes. Common metabolic pathways like glycolysis. Semiconservative DNA replication. DNA that encodes proteins

Microevolution:

Change in allele frequencies that occurs over time within a population. May lead to speciation, but not all evolution results in speciation

Synapomorphies:

Characteristics present in an ancestral species and shared exclusively ( in more or less modified form) by its evolutionary descendants.

Autopolyploidy:

Chromosome duplication in a single species

Arachaen morphology??

Cocci, bacilli, triangular, and square-shaped. Many have never been seen and are known only from environmental samples of DNA

Monophyletic:

Containing an ancestor and all descendants of that ancestor, and no other organisms. A description of a clade

Continental drift: A. Wegener (1912):

Continents have shifted over time, plate tectonics. Vulcanism, mountain building: due to collisions, and alter ocean currents

O2 changes:

Decreases when first photosynthetic bacteria arrive. Increases when permian mass extinction occurs

Phylogenetic tree:

Diagrammatic reconstruction of that history

Mechanical:

Differences in sizes and shape of reproductive organs, may be mediated by another species. EX: orchid wasp

Morphological species concept:

Distinguishing between species based on phenotype: Linnaean classification, Fossil taxa, and asexual taxa

Domain Bacteria: prokaryotic

Domain of metabolically diverse, unicellular , prokaryotic organisms

Domain Archaea: prokaryotic

Domain of unicellular, prokaryotic organisms, often adapted to extreme conditions (such as very hot or very salty environments)

Sedimentary rock:

Due to formation, not able to date accurately

Membrane lipids in BACTERIA?

Ester-linked, unbranches

Membrane lipids in ARCHAEA?

Ether-linked, branched

Lateral gene transfer:

Even distantly related prokaryotes sometimes exchange genetic material

Macroevolution:

Evolution above the species level. E.g. Radiation of flowering plants

Speciation:

Evolutionary process by which populations evolve to become distinct species i.e. splitting of lineages. Interruption of gene flow. As species diverge genetically, reproductive isolation increases

Transformation, conjugation, and transduction =

Exchange of genetic info between prokaryotes

The nodes are key to

Figuring out a phylogenetic tree

Nicholas Steno:

First to recognize fossils were remains of organisms. We can use order of layers to determine relative age of rocks/fossils

Evolution is the...

Framework for how life is connected

Population subdivision:

Gene incompabilities develop in discrete populations

What describes the most likely order of events in allopatric speciation?

Genetic isolation, genetic drift, divergence

Taxa:

Group or level of organization into which organisms are classified on a phylogenetic tree

Biological species concept:

Groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.

Evolutionary interactions:

Habitat change leads to behavior change, cascading effects on predator

Historical changes in earth's environment:

Hot-cold climate shifts: glaciation = sea level change. Volcanic eruptions: Permian "great dying". Meteors. Oxygen concentrations increase and decrease depending on the environment = 2.5 billion years ago = photosynthesis = origin of eukaryotes and multicellular organisms

Scientific classification:

How organisms are related to one another. Evolutionary relationships

EX: Synapomorphy:

Humans, cats, whales, and bats share similar bone structure because of homology.

Isolating mechanisms: Post-zygotic:

Hybrids often less fit: selection works against them, BUT not always. E.g: Hybrid sunflower- ecological shift (drier environment than parents); new selection pressures.. speciation

What is the goal of the phylogenetic tree?

Identifying monophyletic groups

Stratigraphy:

In sedimentary rock layers (strata), the oldest layers are at the bottom, and successively higher strata are progressively younger. Certain fossils are always found in in younger rocks, others are found in older rocks. Fossils in more recent strata are more similar to modern organisms.STILL only tells us the relative age of sedimentary rocks and fossils they containA

Applications of phylogenetic trees- Reconstructing past events:

In zoonotic diseases (infections transmitted to humans from another animal), it is important to understand when, where, and how the disease first entered a human population. HIV entered twice into the population because it came from two different taxa.

Domain Eukarya:

Includes all eukaryotic organisms: protists, fungi, plants, and animals. Alveolates, stramenopiles, rhizarians, excavates, and amoebozoans

Hierarchical ranks in classification: Largest to smallest

Kingdom, Divison/Phylum, Class, Order, Family (generally start here for ID), Genus (clearest taxon to see), Species, and Subspecies (geographic variants of a species; contains viable offspring)

Biggest pattern of macroevolution?

Life on earth

Behavioral:

Mating calls of male frogs

Isolating mechanisms: Prezygotic:

Mechanical, temporal, behavioral, habitat, and gametic

Limitations of morphological species concept:

Members of the same species do not always look alike (e.g. male and female hooded mergansers). Cryptic species- species that are morphologically indistinguishable but DO NOT interbreed

Parsimony:

Minimizing the number of evolutionary changes. The simplest form

Folk classification:

More utilitarian. Influenced by culture, BUT based on extensive empirical observations. Evolutionary relationships often visible in morphology

Differences in temperature and other environmental conditions can cause individuals of certain snail species to look different despite lack of genetic divergence. This observation illustrates a limitation of using a strict ______ species concept.

Morphological

How do we study ancient life?

Much of Earth's history is recorded in rocks... geologic inference

Limitations of lineage species concept:

Must know the phylogeny and cumbersome

Founder Effect:

New population established by a small number of the original population. Reduced genetic variation form the original population, a non-random sample of the genes in the original population

How primitive are modern day Bacteria and Archaea?

Not very much

Why so few fossils?

Only about 300k fossil species because fossils in oxygen-rich environments rapidly decompose. In addition, fossils are hard to find and can be destroyed by geologic processes

How to date an event:

Original concentration of the isotope must be known or estimated. Half-life of the isotope must be known. This results in the amount of isotope remaining indicated how much time has passed

Gram negative:

Outer membrane cell membrane and inner membrane cell membrane with a single layer of petidoglycan in the middle

If there is no lava flow intrusions, what do we use?

Paleomagnetic dating which relates age of rock to predictable pattern of earth's magnetic field

What characteristics do ONLY bacteria have?

Peptidoglycan in the cell wall

Second radioisotope we use:

Potassium-40

First radioisotope we use:

Ratio of carbon-14 to carbon-12, but only has a half-life of about 60k years

Reproduction isolation:

Required for lineages to REMAIN distinct; responsible for morphological distinctiveness of species (LIMITS GENE FLOW). In end... evolution of reproductive isolation important for understanding origin of species

Applications of phylogenetic trees - Identify convergent evolution events:

Self-compatibility in flowering plants (3 times). Most flowering plants produce both male and female gametes on the same individual (in pollen and ovules) "perfect flower". Usually, evolved to prevent self-fertilization. BUT various groups have evolved self-compatibility

Homoplasy:

Shared character between two or more animals that did not arise from a common ancestor . AKA analogous structures (ex: bird, bat, and insect wings)

Results of binary fission:

Short generation time

Homology:

Similar structures in different species due to shared ancestry. Each character of an organism evolves from one condition (the ancestral trait) to another condition (the derived trait)

Gram positive:

Single cell membrane inside the cell and multiple layers of peptidoglycan outside the cell

Sympatric speciation:

Speciation without physical isolation because of polyploidy. Disruptive selection; micro-environmental differences lead to niche differentiation

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

Species X and Y share a greater number of homologies with each other than either does with Species Z

Lineage species concept:

Species are lineages or branches on the tree of life. Each species has a history that starts with a speciation event - one lineage is split into two and ends either at extinction or at another speciation event. Works for sexual and asexual reproduction. Based on evolutionary changes and the clearest model; reproduction isolation

Temporal:

Species may breed at different time of year or different times of day

Gametic:

Sperm/egg incompatible; important in marine spawners like the sea urchin

Bacterial morphology:

Spirillum, bacillus, and coccus

Genetic diversity in Prokaryotes =

Success

Never read a phylogenetic tree by the:

TIPS

Clade:

Taxon that consists of all the evolutionary descendants of a common ancestor

Who is Carolus Linnaeus?

The father of taxonomy. Developed binomial nomenclature. Classification framework to classify new and old species = hierarchy. Developed a system of ranking plants into 'taxa' based on morphological characters

The principle of parsimony:

The fewest possible changes. Minimizing the number of evolutionary changes necessary to build the phylogeny. Each clade supported by at least one synapomorphy. Any genetically determined trait can be used in a phylogenetic analysis. Morphology, development, fossil record, behavioral traits, and molecular traits

Morphology:

The form and structure of organisms

The root of the phylogenetic tree:

The most common ancestor

Applications of phylogenetic trees-Evolution of complex traits:

The sensory exploitation hypothesis suggests that female swordtails had a preference for males with long tails even before the tails evolved. Phylogenetic analysis identified the closest relatives, which do not have swords, but if a sword was attached artificially, females preferred that male

Half-life:

Time during which one half of atoms in a radioisotope sample decay, like changing into another element

Since sedimentary rock cannot accurately date fossils, we look for...

Volcanic ash or lava flow intrusions, like Igneous rocks.

Convergent evolution:

When superficially similar traits evolve independently in different lineages. Usually, due to similar environmental pressure

Node:

Where a branching even occurs, defined by a common characteristic/trait

Phylogeny:

evolutionary history of biotic relationships. All life is related through a common ancestor. Explains why the general principles of biology apply to all organisms. A snip-it of life relationships and connections.

Sequencing of ribosomal RNA (rRNA) genes:

rRNA was present in the common ancestor of all life. All free-living organisms have rRNA. Can track through tree of life. Lateral gene transfer of rRNA genes among distantly related species is unlikely; critical role in DNA translation. rRNA has evolved slowly

Prokaryotes: first life on earth:

~3.8 bya: Chemotrophic anaerobes existed where little to no O2 was available meaning it would have been toxic to these organisms. ~2.6 bya: photosynthesis occured producing cyanobacteria (orange). The orange color means it was younger the anaerobes, results in diversity