Final Exam Flashcards
What is a phylogenetic tree?
A graphical description of evolutionary history. Focus on nodes when interpreting.
Define “phylogeny”
Evolutionary history meaning “kind or type of production
What are the different parts of a phylogenetic tree?
- Root: Base of the tree
- Branch: Horizontal lines represents a specific species as it changes through time
- Node: Branches splits into two or more descendant groups during a speciation event.
- Tips: Labeled name of the taxon represented at each tip
What is a taxon?
A taxon represents any named group.
What is a monophyletic group?
A group that consists of an ancestry and all of its descendants (also known as lineages). Natural evolution group due to shared ancestory.
What is homoplasty?
Similarity in traits that is due to independent evolution.
What is a synapomorphy?
Any characteristic or trait that is shared by other members of monophyletic group but is not found in other groups.
Arise once an ancestor has split into descendant groups.
What is homology?
Similarity in traits that is due to common ancestry. Like birds and humans being bipedal
On a phylogenetic tree, what is the outgroup?
Outgroups are linage that is not part of the monophyletic group that is focus of the tree. An outgroup can have no members associated with it (remebmer invertabrae question)
What is the single origin hypothesis and why do scientists like it?
Single origin states that we come from once common ancestor. They like it because of parsimony (simple = correct)
What is the difference between a clade and not a clade?
What are the ancient greeks four prevailing views about organisms?
- Species are static, meaning that they do not change through time
- Variation among individuals within species is extremely limited, and in its inconsequential.
- Species were created independently, meaning that they were not related to each other; and
- Species were created recently
What is the 19th century theory of evolution?
Species change over time because certain traits in populations lead to higher fitness.
Currently, life scientists update this claim by pointing out that natural selection and other evolutionary processes change allele frequencies in every species in every generation.
What is the evidence of change throughout time?
Fossil Record that has two types of data:
- Extinction: Species ceases to exist
- Transitional Forms: In addition to finding fossils from species that are no longer present, many species that are alive today have no representative in the fossil record.
Fossil record is the reason we know species are related.
If earth formed January first, when would we see life begin? When would we see photosynthesis begin? Plants on land?
Life: April
Photosynthesis: June
Plants on land: November
What is macroevolution?
Describes trends and changes that occur across different taxa
What are two important structures to understand macroevolution?
- Homology (Structural, Molecular)
- Fossil Record
What are the different forms of fossils?
- Actual Remains
- Indirect evidence - foot print in rock
- Molecular in nature - ancient DNA
- Very small fossilized spores
What are transitional fossils?
Fossils from an early version of an important adaptation. The estimated time of these fossils give us an idea of what the adaptations occured.
What is important about the African Rift Lake?
They house an enormous amount of varius chichlid species that demonstrate rapid adaptive radiation creating new species to occupy new niches.
What is adaptive radiation?
The rapid diversification of a single lineage into a large number of species, each adaptation allows them to exploit a different resource and habitat.
What are the three significant domains from the tree of life?
- Archea
- Bacteria
- Eukaryote
What are bacteria?
A monophyletic group that all share the common characteristics of:
- Almost all unicellular
- Almost all have a single circular chromosome, though many also have small, circular, auxiliary DNA molecules called plasmids.
- Some are able to perform photosynthesis and obtain energy from outside sources.
What is a key synapomorphy of bacteria?
Cell walls that feature a structural carbohydrate called peptidoglycan which is a lattice made of sugars lined with hlycosidic bonds, but also have short chains of peptide-bonded amino acids that:
- Protrude from them
- Line adjacent chains
What are ecological opportunities?
The availability of new an unexploited resources, habitats, or ecological roles that can be filled by a species or a group of species
What is a morphological innovation?
When a new adaptation arises that opens the door to rapid diversification.
What are mass extinctions?
Reset ecosystems and open ecological niches, providing the opportunity for surviving species to adapt and diversify. (50%-75% of species die out in a certain time)
What is a prokaryote?
A single cell organism that lack a nucleus (old definition for bacteria and archea)
What are archea?
A single cell organism that is a prokaryote that survives in extreme conditions (extremeophile)
What are synapomorphies of archea?
- All unicellular (similar to bacteria)
- Circular chromosomes and plasmids
- Do not have a nucleus
- Have histone like proteins like DNA (similar to eukaryotes)
- Distinct cell membrane
How does bacteria use respiration and fermentation?
In many bacteria, cellular respiration starts with glucose as the source of high-energy electrons and ends with oxygen as the electron acceptor BUT:
Some species can use other molecules as the source of high-energy electrons, including hydrogen gas, phosphite, methane, ammonia, hydrogen sulfide
What are tetrapods?
A common clade of four limbs - monophyletic (all one ancestor
Are fish paraphyletic?
Yes - they don’t come from one common ancestor.
What are the three defining synapomorphies for eukaryotes?
1) Meiosis (sexual reproduction)
- reductin division as ploidly level is halved
- Genetic recombination: crossing over of parental
2) The nucleus
- Enclosed by a double membrane with pores that regulate molecule transport
- Transcription occurs inside.
- Contains linear chromosomes
- Contributes to adapative radiation thorugh gene repair and replication + genetic complexity.
3) The mitochondira
- Mitochondria began from bacterial cells that were engulfed by a eukaryote. The relationship was mutualistic. This is called endosymbiosis
What traits do eukaryotes share with non-eukaryotes?
Both have:
- Membrane bound organelles: ER, Golgi, responsible for protein transport, manufacturing etc.
- Cytoskeletal elements: actin filaments, intermediate filaments, more diverse and numerous in eukarytoes.
How are eukaryotes similar to archeans?
They both have information processing machinery (e.g. RNA polymerase) similar to archea
How are eukaryotes similar to bacteria?
They both have cell membrane structure and metabolism similar to archea
What are the two forms of endosymbiosis?
Primary Endosymbiosis: A eukarytic cell engulfs a free-living prokaryote, which over time evolves into an organelle within the host cell.
Secondary endosymbiosis: A eukaryotic cell containing organelles from primary endosymbiosis is engulfed by another eukaryote, leading to more complex cells with inherited organelles.
What are the six major lineages for eukaryotes?
- Archaeplastids
- Metamonads
- Discobids
- Amoebozoans
- Opisthokonts
- SAR supergroup
What are algae classified as?
Algae are not a monophyletic group. They are classified as photosynthetic eukaryotes.
In contrast, land plants form a monophyletic group
What are protists?
A eukaryotic group that are not a fungus, animal, or land plant.
They are unicellular but do not have a monophyletic group.
What is multicellularity?
An adaptation that originated from common ancestors. All animals have this and it involves cell coordination, communication, and specialization. Allows different cell types to exist to differential gene expression. Allows animals to grow larger and access more food.
How are animals defines as a monophyletic group?
1) Movement: Under their own power during some life stage. Can be motile (capable of movement) or sessile (moves but eventually stationary)
2) Ingestion of food packets as their feeding method.
What are the three forms of animal body plans?
Asymmetry (No symmetry e.g. sponge)
Radial symmetry (many planes of symmetry e.g. starfish)
Bilateral symmetry (one plane of symmetry e.g. beetle)
What is cephalization?
When bilaterally symmetrical animals show distinc head regions, tail ragions, body regions. Indicated centralized nervous system enabling advanced information processing
All animals aside from sponges have 2 unique tissues, what are they?
Muscle tissue
Nerve tissue
What are the big themes in regards to animal diversification?
- Body plan
- Reproduction
- Sensory Systems
- Feeding strategies
What are archeaplastida?
A group of eukaryotes (red algae, green algae, land plants). They have chloroplasts acquired by primary endosymbiosis.
What are defining features of archeaplastida?
- They have chloroplasts
- House molecular machinery for photosynthesis
- Have cell walls that vary in composition (in land plants the cell wall is comprised of cellulose)
What are the key adaptations required for plants to transition to land?
- The development of cellulose cell walls. This allowed plans to grow upright.
- The cuticle - prevents dehydration and water loss
- Stomata - openings that can open and close so that water can go out and CO2 can go in
- Embryo retention - evolved to retain embryos
What are the two major groups of land plants?
- Bryophytes (non-vascular plants) - mosses
- Vascular plants - include sophisticated vascular tissue
What are the key innovations in vascular plants?
Pollen:
- The male gameteophyte. Haploid and multicellular
- Surrounded by a tough, waterproof coat
Seeds:
- Contains an embryo, a food supply and protective coat
- Enable reproduction in a dry enviornment.
What are plants called when they are diploid versus haploid?
Diploid: Sporophyte
Haploid: Gametophye - also the dominant phase
What are the key features of angiosperms?
1) Flowers:
- Contain reproductive structures
- Specializes in facilitating pollen
2) Fruits:
- Develop from ovaries and enclosed seeds
- Specialized in seed dispersal
What is a fungi?
A monophyletic group that is more closely related to animals than plants.
Two significant groups are:
Mushrooms: Edible with reproductive structures
Yeasts: Informal, bread and beer.
What are characteristics of fungi?
1) They have cell walls containing chitin, found in both fungal cell walls and insect exoskeleton
2) Acquire nutrients by absorbing them from the outside
3) Extracellular digestion - secretes digestive enzymes into the enviornment.
What do multicellular fungi form?
A mycelium which are branching filaments called hyphae. Individual hyphae are very thin tubes. Nutrient absorption depends on surface area of these.
What are the roles of fungi in the enviornement?
1) Decomposers: They decompose dead plant biomass
- Fungi produce enzymes that break down cellulose
- Some fungi also breakdown lignin, a complex and rigid macromolecule found in wood
2) Nutrient Providers: Mycorrhizae
- The associateion between the hyphae of the fungi and the roots of a plant. Plant photosynthesis and passes sugars to fungus and fungus gets soil from nutrients and pass to plants.
3) Parasites
What do viruses do?
They replicate and respond to the environment
What are key features of viruses?
They have genetic material packaged inside of a capsid (some with a lipid bylayer)
They replicate inside a host cell by hijacking the host cells machinery
When they are not in a cell they don’t do anything lifelike
How are viruses classified?
Type of nucleis acid:
- DNA vs RNA
- Double stranded versus single stranded
Presence or absence of an enveloped
- non-enveloped only have a capsid
- enveloped have a capsid surrounded by a lipid bylayer (primarily infect animals: HIV, Covid-19, Flu)
(Capsid is a protein shell surrounding the genome)
What is the life cycle of a virus?
- Entering through attachment to some form of protein thats on a cell membrane
- Replication involves making a new viron. Hijacks machinery to replicate copies of the viral genome and viral proteins. Localizes all of the ingredients in the host cell
- Exits the cell using lysing (lytic cycle). Viruses that use the lytic cycle will destroy the cell. Commonly used by non-enveloped viruses
- Enveloped cells will use budding. This means that viral envelopes come from the host cell. Can be from an outer cell membrane or membrane organelle.
What are the modes of transmission for a virus?
- Vertical (Mother to offspring)
- Horizontal (Between two individuals)
- Direct contact: Sexually transmitted, droplet (sneezing), open lesions
- Indirect contact: Airborne, Fomites (sits on desk), fecal oral, through a vector
