Chap. 26 - Book Flashcards
What is a phylogeny?
Evolutionary history of a species OR group of species
A phylogeny is the ___ history of a ___ or a group of ___
evolutionary, species, species
How do biologists reconstruct and interpret phylogenies?
Systematics
What do phylogenies show?
Evolutionary relationships
Taxonomy is the study of how _____ are named and classified
organisms
What is the first part of a binomial?
name of the genus to which a species belongs
What is the second part of a binomial?
epithet - (species)
Name Linneaus’s classification orders:
domains kingdom phylum class order family genus species
Does the Linnean system tell us about the evolutionary relationship between groups (amphibians, mammals, reptiles, etc.)?
No
Is the Linnean system based entirely on evolutionary relationships between organisms?
No, it is not (which is why a new system of classification is needed = cladistics)
Does a phylogenetic tree represent a hypothesis or certain evolutionary relationships?
a phylogenetic tree represents a hypothesis about evolutionary relationships
PHYLOGENETIC TREE
Groups of organisms that share an immediate common ancestor
sister taxa
PHYLOGENETIC TREE
2 organisms that are each other’s most close relatives
sister taxa
What is the term for a lineage that diverges early in the history of a group and originates near the common ancestor of the group?
basal taxon
To be ______ means that a branch point within the tree presents the most recent common ancestor of ALL taxa in the tree
rooted
What is a polytomy?
a branch point from which more than two descendants emerge
What does a polytomy signify?
evolutionary relationship is not clear
Are phylogenetic trees to show phenotypic similarity? What are they to show?
No, patterns of descent
extant
living
the similarity in the number and arrangement of bones int he forelimbs of mammals is due to their descent form a common ancestor with the same bone structure. This is an example of what?
Morphological homology
analogous structures that arose independently
homoplasies
With respect to flight, a bat’s wing is ______, not _____ to a bird’s wing
analogous, homologous
T/F the more elements that are similar in two complex structures, the more likely it is that they evolved form a common ancestor
True
SYSTEMATICS
in cladistics, what is the primary criterion used to classify organisms?
Common ancestry
What is a clade?
an ancestral species and all of its descendants
When is a taxon equivalent to a clade?
When the taxon is monophyletic
Taxon
a taxonomic group of any rank (species, genus, etc.)
What is the difference between monophyletic, paraphyletic and polyphyletic?
monophyletic: an ancestral species and ALL its descendants
paraphyletic: an ancestral species and some, but NOT ALL of its descendants
polyphyletic: distantly related species but not a recent common ancestor
For mammals, a shared backbone is what type of character and why?
shared ancestral character, character that originated in an ancestor of the taxon
Hair is a character shared by all mammals but NOT found in their ancestors. What type of character is hair?
shared derived character
a character that originated in an ancestor of the taxon
shared ancestral character
an evolutionary novelty unique to a clade
shared derived character
Is it a relative matter whether a character is considered ancestral or derived?
Yes
outgroup: a ____ or group of ___ from an _____ lineage that is known to have diverged ___ the lineage that includes the species that we are studying (in-group)
species, species, evolutionary, before
By comparing members of the in-group with each other and the outgroup, what can we determine?
which characters were derived at the various branch points of vertebrate evolution
What principles states that systematists should first investigate the simplest explanation consistent with the facts?
maximum parsimony
This approach identified the tree most likely to have produced a given set of DNA data, based on certain probability rules about how DNA sequences change over time.
maximum likelihood
T/F Phylogenetic tree represents a hypothesis about how the organisms int he tree are related to one another
True
The most parsimonious tree of evolutionary relationships can be inaccurate. Why?
Perhaps all nucleotide substations are not equally likely.
What can help us reconstruct phylogenies among groups of present-day organisms for which the fossil record is poor or lacking?
Molecular methods/systematics
Name two types of homologous genes
orthologous genes, paralogous genes
Although the cytochrome c genes in humans and dogs serve the same function, the gene’s sequence in humans has diverged from that in dogs in the time since these species last shared a common ancestor. This is an example of what?
Orthologous genes
Can paralogous species diverge within a species?
Yes, because they are located in more than one copy in the genome
What is the approach for measuring the absolute time of evolutionary change based not he observations that some genes and other regions of genomes appear toevolve at constant rates?
Molecular clock
An assumption underlying the molecular clock:
a) the number of ______ substitutions in _____ genes is proportional to the time that has elapsed since the genes
nucleotide, orthologous
In the past, phylogenies have shown that some prokaryotes differ as much from each other as they do from eukaryotes. What did this lead biologists to create?
A 3-domain system (Bacteria, Archaea, Eukarya)
The domain which contains most of the currently known prokaryotes:
Bacteria
Which domain consists of a diverse group of prokaryotic organisms that inhabit a wide variety of environments? What is the nickname for this domain?
Archaea, “extremophiles”
T/F (correct it): the domain Eukarya consists of only multi-cellular organisms.
False. Eukarya includes all organisms that have cells containing true nuclei: single-celled organisms and multicellular organisms.
Which two domains consist entirely of single-celled organisms?
Archaea
Bacteria
80% of genes in prokaryotic genomes have moved between species at some point during the course of evolution. What is this an example of?
Horizontal gene transfer
How does substantial movement of genes between organisms in the different domains occur?
Horizontal gene transfer
Why should the base of a “tree of life” be portrayed as a tangled web?
Horizontal gene transfer
What can a phylogenetic tree only represent?
patterns of descent
Explain the difference between homology and analogy
Similarity due to shared ancestry vs. similarity due ot convergent evolution
A monophyletic grouping that includes an ancestral species and all its descendants
clade
How can clades be distinguishes?
their shared derived characters
Some regions of _____ change at a rate consistent enough to serve as a molecular clock
DNA
In a comparison of birds and mammals, the condition of having four limbs is a
a. shared ancestral character
b. shared derived character
c. character useful for distinguishing birds from mammals
d. an example of analogy vs. homology
a. shared ancestral character
To apply parsimony to a phylogenetic tree’s construction,
a. Choose the tree that assumes all evolutionary changes are equally probable
b. choose the tree in which the branch points are based on as many shared derived characters as possible.
c. choose the tree that represents the few evolutionary changes in DNA seq. or morphology
c. choose the tree that represents the fewest evolutionary changes in DNA sequences or morphology
Three living species X, Y, and Z share a common ancestor T, as do extinct species U and V. A grouping that consists of species T, X, Y, and Z (but not U or V) makes up:
a. monophyletic taxon
b. in-group, with species U as the outgroup
c. paraphyletic group
d. polyphyletic group
c. paraphyletic group
If you were using cladistics to build a phylogenetic tree of cats, which of the following would be the best out-group?
a. wolf
b. domestic cat
c. lion
d. leopard
a. wolf
Can branch lengths represent genetic change?
Yes! (remember problem: mice have more slowly evolved the homolog than the frog)
How has molecular biology revolutionized the study of systematics?
Molecular data can help distinguish homologous organisms from analogous organisms, in regards to a character, etc. Statistical tools can show if two DNA sequences from distantly related organisms, although they share 25% of their bases, do so because they are homologous.
What was the permian mass extinction likely caused by? (defines the barrier between the Mesozoic and Paleozoic)?
an extreme episode of volcanism (rise in CO2 levels, etc.)
What are mass extinctions caused by?
a. continental drift
b. climate change
c. allopatric speciation
d. destroyed habitat
e. unfavorable environment change
f. an origin of an unrelated species
continental drift, climate change, destroyed habitat, unfavorable environment change, origin of unrelated species
How is continental drift implicated in the biogeography that we see today?
- promotes allopatric speciation
- organisms become extinct
- explains strange fossil patterns (same species-did. land)
- current distribution of organisms
Fossils of the same species of Permian freshwater reptiles have been discovered in both Brazila nd the West African country of Ghana. What may this be caused by? Specifically?
Continental drift, Pangea breaking apart
Why Australian fauna and flora contrast so sharply with those of the rest of the world?
Continental drift (Australia was set “afloat)
Know the names of the four geologic eras in earth’s history, the time span of each, and the notable events that define them
Phanerozoic - origin of humans, dinosaurs, gymnosperms
Proterozoic - oldest fossils of eukaryotic cells appear
Archaean - concentration of atmospheric oxygen increases, prokaryotes appear (fossils)
Hadean - origin of earth
heritable traits that can be compared across organisms, such as physical characteristics (morphology), genetic sequences, and behavioral traits.
Characters
