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94 Cards in this Set
- Front
- Back
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What is a phylogeny?
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the evolutionary history of a species or group of species.
p. 536 |
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What is systematics?
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a discipline focused on classifying organisms and determining their evolutionary relationships.
p. 536 |
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What is taxonomy?
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How organisms are named and classified.
p. 537 |
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What is a binomial?
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The two part format of scientific names.
ex: Homo sapiens. p. 537 |
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The first park of a binomial is the name of the:
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Genus.
p. 537 |
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Is the genus usually capitalized or in lower-case?
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capitalized
p. 537 |
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TRUE OR FALSE: Only the genus is italisized in a binomial.
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FALSE. The entire binomial is italisized.
p. 537 |
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TRUE OR FALSE: The first letter of the specific epithet is capitalized.
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FALSE. Only the first letter of the genus is capitalized.
p. 537 |
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What is the specific epithet?
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The second part of the binomial and is the unique name of the species in a genus.
p. 537 |
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What is the name of the common taxonomic system?
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Linnaean system
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From broad to specific, which is correct:
Domain -> Kingdom -> Phylum -> Class -> Order -> Family -> Genus -> Species Or Species -> Genus -> Family -> Order -> Class -> Phylum -> Kingdon -> Domain |
Domain -> Kingdom -> Phylum -> Class -> Order -> Family -> Genus -> Species
p. 537 |
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What is a taxon?
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the named taxonomic unit at any level of the hierarchy.
p. 537 |
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TRUE OR FALSE: In the Linnaean system, taxa broader than the genus are not italicized and not capitalized.
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FALSE. They are capitalized but not italicized.
p. 537 |
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What is a phylogenetic tree?
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The evolutionary history of a group of organisms can be represented in a branching diagram called the phylogenetic tree.
p. 538 |
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TRUE OR FALSE: The branching pattern in some cases matches the hierarchical classification of groups nested within more inclusive groups in phylogenetic trees.
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True.
p. 538 |
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Does the Linnaean classification system provide information about phylogeny?
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only a small amount.
EX: We may distinguish between 17 families of lizards, but that doesn't say anything about their evolutionary relationships to one another. p. 538 |
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What is PhyloCode?
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Only the names of groups that include a common ancestor and all of its descendents.
p. 538 |
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What are branch points?
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Relationships often depicted as a series of dichotomies, or branch points where each branch point represents the divergence of two evolutionary lineages from a common ancestor in a phylogenetic tree.
p. 538 |
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TRUE OR FALSE: In a phylogenetic tree, if you rotate a tree branch around a branch point, that changes their evolutionary relationship.
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FALSE.
p. 538 |
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What are sister taxa?
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Groups of organisms that share an immediate common ancestor.
p. 538 |
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What does it mean to be rooted?
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A branch point within the tree (typically, the one farthest to the left) represents the last common ancestor of all taxa in the tree.
p. 538 |
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What is a polytomy?
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a branch point in a phylogenetic tree from which more than two descendant groups emerge.
p. 539 |
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TRUE OR FALSE: A polytomy indicates a clear relationship between the descendants.
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FALSE. A polytomy indicates that evolutionary relationships among the descendant taxa are not yet clear.
p. 539 |
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TRUE OR FALSE: The sequence of branching in a tree helps indicate the actual (absolute) ages of a particular species.
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FALSE. They do not indicate that one species evolved more recently than another, it merely shows the most recent common ancestor.
p. 539 |
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TRUE OR FALSE: we cannot assume that a taxon on a phylogenetic tree evolved from the taxon next to it.
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TRUE. We can only infer the lineage leading to or from a common ancestor.
p. 539 EX. Wolves did not evolve from coyotes or vice cersa. |
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What are homologies?
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similarities due to shared ancestry.
p. 540 |
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What is a morphological homology?
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Genes or other DNA sequences are homologous if they are descended from sequences carried by a common ancestor.
p. 540 |
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What is analogy?
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convergent evolution.
p. 540 |
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What is convergent evolution?
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When similar environmental pressures and natural selection produce similar (analogous) adaptions in organisms from different evolutionary lineages.
p. 540 |
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TRUE OR FALSE: marsupials have their young complete their embryonic development in a pouch on the outside of their mother's body.
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TRUE.
p. 540 |
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TRUE OR FALSE: Eutherians have their young complete their embryonic development in the uterus within the mother's body.
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TRUE.
p. 541 |
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What are homoplasies?
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Analogous structures that arose independently.
p. 541 |
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TRUE OR FALSE: It doesn't matter how many points of resemblance two complex structures have; it says nothing about whether they evolved from a common ancestor.
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FALSE. the complexity of the characters being compared helps distinguish between homology and analogy.
p. 541 |
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TRUE OR FALSE: If genes in two organisms share many portions of their nucleotide sequences, it is highly likely that the genes are analogous.
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FALSE. The genes are probably homologous.
p. 541 |
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Why do comparable nucleic acid sequences in distantly related species usually have different bases at many sites and may have different lengths.
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Because of insertions and deletions accumulate over long periods of time.
p. 541 |
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TRUE OR FALSE: Two sequences that resemble each other at many points along their length most likely are homologous.
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TRUE. But in organisms that do not appear to be closely related, the bases that their otherwise very different sequences happen to share may simply be coincidental matches (homoplasies)
p. 542 |
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What is molecular systematics?
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The discipline that uses DNA and other molecular data to determine evolutionary relationships.
p. 542 |
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What is cladistics?
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An approach to systematics in which a common ancestry is the primary criterion used to classify organisms.
p. 542 |
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What are clades?
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groups that includes an ancestral species and all of its descendents.
p. 542. |
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What is monophyletic?
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"single tribe"
Consists of an ancestral species and all of its descendents. p. 543 |
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TRUE OR FALSE: A taxon is always equivalent to a clade.
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FALSE. Only if the taxon is monophyletic.
p. 543 |
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What is paraphyletic?
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"beside the tribe"
A group which consists of an ancestral species and some, but not all of its descendants. p. 543 |
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What is polyphyletic?
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"many tribes"
a group which includes taxa with different ancestors. p. 543 |
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TRUE OR FALSE: A taxa is polyphyletic.
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TRUE.
p. 543 |
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What is a shared ancestral character?
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a character that originated in an ancestor of the taxon.
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What is a shared derived character?
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an evolutionary novelty unique to a particular clade.
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What is an outgroup?
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a species or group of species from an evolutionary lineage that is known to have diverged before the lineage that includes the species studying (the ingroup).
p. 543 |
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What 4 things determine if an outgroup is suitable?
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morphology, paleontology, embryonic development, and gene sequences.
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TRUE OR FALSE: Some tree diagrams have branch lengths that are proportional to the amount of evolutionary change or the times at which particular events occurred.
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TRUE.
p. 544 |
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What is the principle of maximum parsimony?
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We should first investigate the simplest explanation that is consistent with the facts.
p. 544 |
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TRUE OR FALSE: For phylogenies based on DNA, the most parsimonious tree requires the fewest base changes.
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TRUE.
p. 544 |
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What is the principle of maximum likelihood?
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Given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events.
p. 545 |
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TRUE OR FALSE: Phylogenetic trees represents facts about how the various organisms in the tree are related to one another.
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FALSE. Phylogenetic trees represents only a hypothesis on how organisms are related.
p. 547 |
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What is phylogenetic bracketing?
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We can predict (by parsimony) that features shared by two groups of closely related organisms are present in their common ancestor and all of its descendants, unless independent data indicates otherwise.
p. 547 |
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What is parsimony?
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the concept that "less is better"
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TRUE OR FALSE: Generally, different genes evolve at the same rate, especially in the same evolutionary lineage.
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FALSE.
Different genes evolve at different rates, even in the same evolutionary lineage. p. 548 |
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the DNA that codes for _______ changes relatively slowly, and so comparisons of DNA sequences in these genes are useful for investigating relationships between taxa that diverged hundreds of millions of years ago.
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ribosomal RNA. rRNA.
p. 548 |
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_______ evolves relatively rapidly and can be used to explore recent evolutionary events.
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mitochondrial DNA (mtDNA)
p. 548 |
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TRUE OR FALSE: Molecular techniques now allow us to trace the phylogenies of gene duplications and the influence of these duplication on genome evolution.
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TRUE.
p. 548 |
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What are gene families?
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groups of related genes within an organism's genome.
p. 548 |
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What are the two different types of homologous genes?
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orthologous genes and paralogous genes. p. 548
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What are orthologous genes?
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homologous genes that are found in different species because of speciation.
p. 548 |
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What are paralogous genes?
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A result from gene duplication, so they are found in more than one copy of the same genome.
p. 548 |
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TRUE OR FALSE: orthologous genes are usually centralized in a limited number of species.
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FALSE. Orthologous genes are widespread and can extend over huge evolutionary distances.
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TRUE OR FALSE: The number of genes seem to increase through duplication and at the same rate as the perceived phenotypic complexity.
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FALSE. Ex: Humans have only about four times as many genes as yeast.
p. 549 |
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What is a molecular clock?
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a yardstick for measuring the absolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates.
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What is the main assumption underlying the molecular clock for orthologous genes?
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The number of nucleotide substitutions in orthologous genes is proportional to the time that has elapsed since the species branched from their common ancestor (divergence time.)
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What is the main assumption underlying the molecular clock for paralogous genes?
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The number of substitutions is proportional to the time since the genes became duplicated.
p. 549 |
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TRUE OR FALSE: some portions of the genome appear to have evolved in irregular fits and starts that are not all clocklike.
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TRUE. The same gene may evolve at different rates in different groups of organisms, making it necessary to calibrate and use molecular clocks with care. Even among genes that are clocklike, the rate of the clock may vary greatly from one gene to another; some genes evolve a million times faster than others.
p. 550 p. 550 |
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What is the neutral theory?
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That much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian selection.
p. 550 |
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TRUE OR FALSE: Differences in the clock rate for different genes are a function of how important a gene is.
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TRUE. IF the exact sequence of amino acids that a gene specifies is essential to survival, most of the mutational changes will be harmful and only a few will be neutral. As a result, such genes change only slowly.
BUT, if the exact sequence of amino acids is less critical, fewer of the new mutations will be harmful and more will be neutral. These genes change more quickly. p. 550 |
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What are the 3 domains?
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Bacteria, Archaea, and Eukarya
p. 551 |
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Which domain contains most of the currently known prokaryotes?
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Bacteria. This includes bacteria that is closely related to chloroplasts and mitochondria.
p. 551 |
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Which domain consists of a diverse group of prokaryotic organisms that inhabit a wide variety of environments.
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Archaea. Some archaea can use hydrogen as an energy source, and others were the chief source of the natural gas deposits that are found throughout the Earth's crust.
p. 551 |
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Which domain consists of all the organisms that have cells containing true nuclei?
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Eukarya.
p. 552 |
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What is horizontal gene transfer?
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A process in which genes are transferred from one genome to another through mechanisms such as exchange of transposable elements and plasmids, viral infection and fusion or organisms.
p. 553 |
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CONCEPT CHECK 26.1
1) Which levels of the classification do humans share with leopards? |
Down to class. Leopards belong to the Order Carnivora whereas humans don't.
p. 540 |
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CONCEPT CHECK 26.2
1) a. Is a porcupine's quills and a cactus's spine analogy or homology? |
Analogy, since porcupines and cacti are not closely related and since most other animals and plants do not have similar structures.
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CONCEPT CHECK 26.2
1) b. Is a cat's paw and a human's hand analogy or homology? |
Homology, since cats and humans are both mammals and have homologous forelimbs, of which the hand and paw are the lower part.
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CONCEPT CHECK 26.2
1) c. Is an owl's wing and a hornet's wing analogy or homology? |
Analogy, since owls and hornets are not closely related and since the structure of their wings is very different.
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CONCEPT CHECK 26.3
1) To distinguish a particular clade of mammals within the larger clade that corresponds to class Mammalia, would hair be a useful character? Why or why not? |
NO. Hair is a shared ancestral character common to all mammals and thus is not helpful in distinguishing different mammalian subgroups.
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CONCEPT CHECK 26.3
2) Why might the most parsimonious tree not necessarily be the most accurate in representing evolutionary relationships for a particular group of species? |
The principle of maximum parsimony states that the hypothesis about nature we investigase first should be the simplest explanation found to be consistent with the facts. Actual evolutionary relationships may differ from those inferred by parsimony owing to complicating factors such as convergent evolution.
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CONCEPT CHECK 26.4
1) Exlain how comparisons between the proteins of two species can yield data about their evolutionary relationship. |
Proteins are gene products. Their amino acid sequences are determined by the nucleotide sequences of the DNA that codes for them. Thus, differences between comparable proteins in two species relfect underlying genetic differences.
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CONCEPT CHECK 26.5
1) What is a molecular clock? What assumption underlies the use of a molecular clock? |
A molecular clock is a method of estimating the actual time of evolutionary events based on numbers of base changes in orthologous genes. It is based on the assumption that the regions of genomes being compared evolve at constant rate.
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CONCEPT CHECK 26.5
2) Explain how numerous base changes could occur in DNA, yet have no effect on an organism's fitness. |
There are many portions of the genome that do not code for genes; many base changes in these regions could accumulate through drift without affecting an organism's fitness. Even in coding regions of the genome, some mutaions may not have a critical effet on genes or proteins.
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CONCEPT CHECK 26.6
1) Why is the kingdom Monera no longer considered a valid taxon? |
The kingdom Monera included bacteria and archaea, but we now know that these organisms are in separate domains. Kingdoms are subsets of domains, so a single kindom (like Monera) that includes taxa from different domains is not valid (it is polyphyletic)
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CONCEPT CHECK 26.6
2) Explain why phylogenies based on different genes can yield different branching patterns for the universal tree of life. |
Because of horizontal gene transfer, some genes in eukaryotes are more closely related to bacteria, while others are more closely related to archaea; thus, depending on which genes are used, phylogenetic trees constructed from DNA data can yield conflicting results.
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SELF QUIZ
In Figure 26.4, which similarly inclusive taxon descended from the same common ancestor as Canidae? a. Felidae b. Mustelidae c. Carnivora d. Canis e. Lutra |
b. Mustelidae
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SELF QUIZ
Three living species X, Y, and Z share a common ancestor T, as do extinct species U and V. A grouping that includes species T, X, Y and Z makes up a. a valid taxon. b. a monophyletic clade. c. an ingroup, with species U as the outgroup. d. aparaphyletic group. e. a polyphyletic group. |
d. a polyphyletic group
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SELF QUIZ
In a comparison of birds and mammals, having frou appendages is a. a shared ancestral character b. a shared derived character c. a character useful for distinguishing birds from mammals. d. an example of analogy rather than homology. e. a character useful for sorting bird species. |
a. a shared ancestral character
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SELF QUIZ
If you were using cladistics to build a phylogenetic tree of cats, which of the following would be the best outgroup? a. lion b. domestic cat c. wolf d. leopard e. tiger |
c. wolf
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SELF QUIZ
The relative lengths of the amphibian and mouse brances in the phylogeny in Figure 26.12 indicate that a. amphibians evolved before mice. b. mice evolved before amphibians. c. the genes of amphibians and mice have only coincidental homoplasies. d. the homologous gene has evolved more slowly in mice. e. the homologous gene has evolved more rapidly in mice. |
d. the homologous gene has evolved more slowly in mice.
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SELF QUIZ
To apply parsimony to constructing a phylogenetic tree, a. choose the tree that ssumes 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. base phylogenetic trees only on the fossil record, as this provides the simplest explanation for evolution. d. choose the tree that represents the fewest evolutionary changes, either in DNA sequences or morphology. e. choose the tree with the fewest branch points. |
d. choose the tree that represents the fewest evolutionary changes, either in DNA sequences or morphology
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SELF QUIZ
Based on the tree in question 7 p. 555, which statement is NOT correct? a. The lineage leading to salamanders was the first to diverge from the other lienages. b. Salamanders are a sister group to the group containing lizards, goats, and humans. c. Salamanders are as closely related to goats as humans. d. Lizards are more closely related to salamanders than to humans. e. The group highlighted by shading is paraphyletic. |
d. Lizards are more closely related to salamanders than to humans.
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