Lecture 3: The tree of life Flashcards
DEF: a family tree of organisms that describes the
genealogical relationships among species with a single ancestral species at its base.
The tree of life
DEF: the actual genealogical relationships among all
organisms
Phylogeny
Biologists study RNA and DNA from different
organisms:
- Compare sequences of the building blocks (_, _, _, _,)
A, T, C, G
Fewer sequence variations between two species may
indicate a ______ ________
Closer relationship
DEF: Is used to show the relationships between species
Phylogenetic tree
- Branches that share a recent common ancestor
represent species that are ____ - Branches that do not share recent common ancestors
represent species that are more _____ related
Related, Distantly
A phylogenetic tree is constructed using
sophisticated _____ _____
Computer programs
Arrangement of _____ that is most consistent with the similarities and differences observed in the genetic data
Branches
The universal tree or ____ __ ____ includes a diverse array of species
Tree of life
Tree’s main ____ is the common ancestor of all living
species (aka Last Universal Common Ancestor or LUCA)
Node
The 3 major groups of organisms of the tree of life:
The eukaryotes
- Eukarya
Two groups of prokaryotes
- Bacteria and Archaea
A tree is a prediction, its validity is
based on current data. More robust
datasets could mean changes in the
tree’s shape or the position of its
branches. T or F
True
DEF: the effort to name and classify organisms
Taxonomy
DEF: a named group
Taxon
DEF: Woese created this new taxonomic level
Domain
Domain consists of 3 taxa:
- Bacteria
- Archaea
- Eukarya
DEF: a major lineage within a domain
Phylum
Who established the classification system still in use today (in 1735)?
Carolus Linnaeus
Each organism is given a unique two-part
scientific name consisting of the _____ and the
_____
Gensus, species
DEF: Made up of a closely related group of species
Genus
DEF: Made up of individuals that regularly breed together or have characteristics that are distinct from those of other species
Species
An organism’s genus and species designation is
called its _____ name or _____ name
Scientific, Latin
An organism’s genus and species designation is
called its _____ name or _____ name
Scientific, Latin
- Scientific names are always italicized.
– Genus names are always capitalized,
– Species names are not capitalized
T or F
True
Humans can select certain individuals to produce
the most offspring leading to _____ selection
Artifical
Adult male rams normally begin reproducing at six years of age. T or F
True
____ mating success is dependent upon body size
and horn length.
Male
Big horned sheep are hunted
for trophies, not for meat T or F
True
Large males with long horns are not surviving long
enough to reproduce:
- The overall weight and horn length of four-year-old
rams has steadily ____.
- ____ selection from hunting has allowed the smaller
rams to breed
Decrease, artificial
DEF: They allow researchers to test the effect of a single, well-defined factor on a particular phenomenon
Experiements
Hypothesis testing is a 2-step process:
1. State the hypothesis as precisely as possible and list
the predictions it makes.
2. Design an observational or experimental study that is
capable of testing those predictions.
T or F
True
The ______ hypothesis states:
- ____ always know how far they are from the nest
– Because they track the number of steps taken
– And they know length of their ____
Pedometer, Ants, Stride
Wittlinger’s group manipulated the ants into three
groups after walking from the nest to a feeder:
1. ____ – legs were cut to form shorter-than-normal
legs
2. ____ – individuals were left alone with normal legs
3. _____ – bristles glued on legs to form longer-than-
normal legs
Stumps, Normal, Stilts
Wittlinger’s groups also Measured the distance the ants travelled back to the nest via a different route T or F
True
DEF: Specifies what we should
observe if the hypothesis being tested does not
hold
A null hypothesis
Results:
– “Stumps” stopped short of the nest.
– “Normal” ants returned to the nest.
– “Stilts” walked beyond the nest
T or F
True
Does the conclusion support the pedometer hypothesis:
– Desert ants use information on stride length and
number to calculate how far they are from the nest
Yes
Well designed experiment needs what 3 things:
CET
- Controlled groups
- Experimental conditions controlled
- Test was repeated
We need control groups to:
To check for other factors that might influence the outcome
We need experimental conditions controlled to:
To eliminate other variables
We need to repeat tests to:
To reduce the effects of distortion due to small sample size
