Bio352 lecture 4 exam 3
According to the endosymbiotic theory, early eukaryotes acquired the mitochondrion from a symbiotic bacterium. What happened to the bacterial genes?
Some bacterial genes were transferred to the nucleus, some were lost, and some comprise the mitochondrial genome.
In what way are single-celled slime mold amoebas and individual honeybees (social insects that live in colonies) alike?
Some individuals give up independent replication in the larger group.
In the phylogeny shown, which of the following hypotheses provides the most parsimonious explanation for the distribution of beak ("bill") color among the five species of magpie? The yellow-billed magpie has a yellow beak and the rest have black beaks.
The ancestral state was black-billed.
Which statement regarding the evolution of multicellularity is FALSE?
Most plants and animals are thought to have evolved through the coming together route.
Which of the following statements about multicellularity is true?
Multicellularity has evolved many times in eukaryotes.
Describe Lynn Margulis' endosymbiotic theory on the evolution of mitochondria and chloroplasts.
- hypothesized that mitochondria and chloroplasts did not evolve de novo as internal components of a eukaryotic ancestor - but rather through a long-term symbiotic, or mutually beneficial, relationship. -proposed that an independent bacterial species capable of energy production and photosynthesis began to reside within cells of another species, resulting in endosymbiosis, or symbiosis within a cell. - turned into an obligate relationship: the endosymbionts, which evolved into organelles of the host cells, were no longer able to live on their own.
From where do the "extra" membranes arise in mitochondria, chloroplasts, and apicoplasts?
-In a primary endosymbiosis event the endosymbiont ends up with its own cell membrane and the cell membrane of the host that wraps around it as it is engulfed. now enclosed in a double membrane, as seen in mitochondria and chloroplasts. -In secondary symbiosis, the engulfed cell already has a two-membrane organelle. Just like primary endosymbiosis, two more are added to the endosymbiont as it becomes engulfed, resulting in four membranes, as in apicoplasts.
What are three commonalities to John Maynard Smith and Eörs Szathmary's major transitions?
1) Individuals give up the ability to reproduce independently, and they join together to form a larger grouping that shares reproduction. 2) Once individuals aggregate into higher-level groupings, they can take advantage of economies of scale and efficiencies of specialization. 3) Aggregation and specialization facilitate changes in information technologies. Organisms develop new and increasingly efficient ways to acquire, process, transmit, and store information.
If the tree shown in the figure were rooted at the point labeled B, which of the following would be true?
3, 4, and 5 form a monophyletic group.
On Figure B, number each of the seven hash marks on the branches (indicating synapomorphy) with the corresponding numbered sequence change indicated in Figure A.
?
Which of the following statements regarding complexity is true?
Complexity, once gained, can be lost.
What is different between a rooted and unrooted tree?
Direction on a rooted tree indicates the passage of time.
The maximum likelihood tree (the tree with the clades numbered) constructed for the mammals in the figures shown supports which of the following hypotheses for the evolutionary relationships among mammalian groups?
The maximum likelihood tree supports the Theria hypothesis.
unites the organisms shown in the figure?
They are all eukaryotes
Which of the following is a benefit of multicellularity for slime mold amoebas?
ability to move quickly
Do the five trees shown in the figure represent the same or different relationships among the taxa numbered 1-4? Explain your answer.
all the same evolutionary relationships among the taxa. - any node can be rotated without altering the depicted relationships. - relative position from left to right don't matter - what matters is the distance to the most recent common ancestor
The eukaryotic nucleus likely originated from a(n)
archaea cell
What is the chemical signal for slime mold amoebas to aggregate?
cAMP
Which of the following is an advantage of the economy of scale?
division of labor
Which of the following is NOT an organelle that is thought to be the result of endosymbiosis?
endoplasmic reticulum
The figure shown is a phylogeny created with DNA sequence data and has high bootstrap support values. The tree also includes observed phenotypes (in varying shades of gray) for the five taxa. The character states are indicated by "B" or "b," "G" or "g," and "P" or "p." Evaluate the hypothetical phylogenetic tree using a parsimony approach. What is the minimum total number of state changes necessary to describe the observed distribution of characters in the taxa?
five
Which of the following is seen when a multicellular organism has many specialized cell types, resulting in a division of labor between reproductive functions and growth and maintenance functions?
germ-soma distinction
Economies of scale occur in major transitions when
groups can perform tasks more efficiently than individuals
A trait that is similar in one or more species even though it was not present in their common ancestor is called a
homoplasy
Based on the figure, multicellularity in plants and opisthokonts
is independently derived in each lineage
Transfer of genes between organelles and the nucleus
is ongoing
Why do groups offer protection in foraging?
many eyes detect predators more quickly
Eukaryotes share
more transcription- and translation-associated genes with archaea and more metabolic genes with bacteria.
The transition from unicellularity to multicellularity
must convey a selective advantage to individuals if it is to occur.
If the two sister species on the phylogenetic tree shown differ from the other two species in a single character state (e.g., dark or light fur), how many character state changes (evolutionary events) are needed to explain this pattern?
one
Which process was responsible for evolution of apicoplasts?
secondary endosymbiosis
Analogous traits are found in two or more species because
some evolutionary process (usually natural selection) has independently fashioned similar traits in each species.
The basic conceptual approach to phylogenetic tree building assumes that
species with many character states in common are more closely related than those with few character states in common.
As shown in the figure, suppose a population splits into two descendant populations prior to the evolution of dark coloration, then splits again after the evolution of dark coloration found in Taxa 1 and 2. Which of the following terms best describes the dark coloration trait in this situation?
synapomorphy
What is the fundamental idea behind parsimony?
the best phylogeny is the one that both explains the observed character data and posits the fewest evolutionary changes for a group of taxa
The experimental setup shown in the figure was designed to test which of the following?
the economy of scale of slime mold slugs and amoebas regarding efficiency of travel
Which of the following major transitions proposed by John Maynard Smith and Eörs Szathmary (1997) most likely occurred first?
the origin of the first cells
Homologous traits are found in two or more species because
those traits have been inherited from a common ancestor
Based on the figure, if a plant and nonplant mitochondrial genome contain the same gene, did they inherit the gene from a common ancestor? Explain your reasoning.
yes shared gene came from common ancestor. all mitochondrial genes originated form one acquisition of mitochondria all mitochondrial genes have one ancestral origin
What are apicoplasts, and what is the advantage of using them as a drug target for the treatment of malaria?
Apicoplasts are organelles found in a phylum of eukaryotic pathogens that includes Plasmodium falciparum, the organism that causes malaria. -probably arose from endosymbiotic events and thus have their own distinct genomes separate from the nuclear genome. Because the genes of an apicoplast are different from those of the host organism (another eukaryote), drugs that directly target apicoplast gene pathways should affect only the pathogen and not the host's cells.
