evolution exam 3
Forward smearing
-Burrowing animals move fossilized remains up through the layers -Date an extinction later than it actually
Allopatric Speciation Vicariance-
-1 large population divided in 2 still large populations ex) snapping shrimp -Aggression between males and females used as an indicator of reproductive isolation
Parapatric Speciation
-Adjacent populations diverge into separate species in the absence of a geographic barrier -Often results in a hybrid zone ex) big stagebush
Haldane's Rule
-Among hybrid offspring, if one sex is absent, rare, or sterile, that sex is the heterogametic one -males suffer greater fitness consequences than females
Permian Mass Extinction
-Largest mass extinction -90% of species went extinct -Plankton hit hard -series of large volcanic eruption in Siberia
Asexual reproduction Apomixis
-Unfertilized eggs are produced by mitosis-like cell division -Daughter cells are genetically identical to mother
Itay Budin and Jack Szostak sought to understand how cell membranes composed of single-chain lipid molecules could possibly evolve to the more complex phospholipids seen in modern cell membranes (Budin and Szostak 2009). Which statement best summarizes their results?
Adding a small fraction of phospholipid molecules resulted in vesicles with higher phospholipid content; these cells tended to grow in size conferring a selective advantage.
stable peptide bonds
CO present
Reproductive Isolation via Change in Ploidy
Change in the number of complete sets of chromosomes -Common in plants
Dead Clades Walking
Clades that survive a period of mass extinction only to go extinct some time in the following geological time period
Which of the following statements regarding the Midas and Arrow cichlids in Lake Apoyo does NOT suggest that the speciation event responsible for forming these two species occurred in sympatry rather than allopatry?
Lake Apoyo is large, creating geographic isolation between the two species.
Abiotic Niche
Temperature, Salinity, Humidity, Acidity
Sexual reproduction amphimixis
alternating phases of meiosis and gamete fusion 1. Recombination (crossing over) 2. Gamete production 3. Gamete fusion
Cladogenesis
branching speciation events
Lipids
can spontaneously assemble into vesicles with a bilayer membrane
Reproductive Isolation via Chromosomal Rearrangement
occurs between individuals with original chromosome arrangement and those with the new chromosome arrangement
red queen hypothesis
parasite load ex) Sex more common in populations with high parasite load
Active Trend
tendency for entire distribution to increase/decrease
Minimal gene set
~ 206 genes
punctuated equilibrium
-Changes occurred quite rapidly (perhaps not even captured in the fossil record -A minor degree of change is always occurring but stasis, is the rule during the vast majority of a lineage's history
Phylogenetic Species Concept
-Draws species boundaries using shared derived characters -Those that are unique to one monophyletic group and absent from all other populations in the phylogeny
Issues with Biological Species Concept?
-Extinct organisms -Occasional hybridization events (reduced fertility) -Asexual species
How do Paleontologists choose sites?
-Focus on sites that best match geological and abiotic conditions in which fossilization is likely to have occurred -Begin near sites where other fossils have been found -Make predictions using phylogenetics, biogeography, and molecular genetics
phyletic gradualism
-Fossil record is hiding a series of small-scale changes -New species arise from slow constant change
The Cretaceous-Paleogene (K-PG) Mass Extinction
-Half of all genera died (including the dinosaurs -large asteroid- Chicxulub Crater -Found high levels of iridium in rock strata
Fossil snapshots
-Imagine finding evidence for a species from the fossil record 5 MYA -At 4 MYA you find evidence for 2 new species that descended from the prior species
Distinguishing Between Sexual and Asexual Reproduction
-Individuals mating -Courtship behavior -Sexual organs -Presence of males -Genome -Degree of phylogenetic incongruity between nuclear and mitochondrial DNA
Pleistocene Megafauna Extinction
-Intense human hunting -Fire -Habitat fragmentation -Exotic species -Dramatic temperature change -Human hunting (superior weapons compared to predecessors)
Cambrian Explosion
-New array of multicellular organisms with new body forms and shapes -Most of the animal groups that have ever lived appeared for the first time
Who might use phenetic species concept?
-Plant taxonomists -Microorganisms -Paleontologists
Second wave of colonization
-Species that fed on insects and nectar were especially susceptible to extinction -Habitat destruction and introduced predators devastated lowland forests
Mass Extinction
-a sudden spike in the rate of extinction -Typically a 50%-75% loss of species in many major taxa over a broad geographic range
Background Extinction
-all other extinction -About 95% of extinction events
Process of Fossilization
-anoxic environment -sedimentary rocks
What Caused the Greatest Mass Extinction of All Time?
-lava spewed into air -greenhouse effect -Increased ocean acidification -Low levels of oxygen
Prebiotic Soup Hypothesis
-matter arriving from outer space (carry lipids, amino acids, and nucleobases) -Hydrothermal vents -alkaline vents
Asexual reproduction Automixis
-production of haploid gametes from meiosis which subsequently fuse to restore diploidy -Daughter cells are genetically distinct from mother and siblings
Fossil
-the remains or traces of a past-living organism -Typically more than 10,000 years old
Pleistocene megafauna extinction
10,000 years ago, 2/3 were extinct
The Biological Species Concept
A focus on populations (not individuals) and gene flow -use pattern if genes to assign species boundaries
Why is the higher fidelity of DNA proofreading and repair (compared to RNA) evolutionarily important?
A lower mutation rate allows for longer genes and more storage of information in the genome.
Lakes have changed less over time than streams
Asexual prediction
Which of the following statements regarding the benefit of making the switch from an RNA- to a DNA-based genetic system during the evolution of life is correct?
DNA is a more stable molecule because deoxyribose is less reactive than is ribose.
Signor-Lipps effect (backward smearing)
Date an extinction earlier than it actually occurred
In 1977, Sidney Fox tried a different approach to testing the prebiotic synthesis of biological molecules. He mixed a number of different amino acids together at a high temperature (120°C) in an environment lacking water. When he subsequently placed the mixture into water to investigate what the amino acids would form, what happened next?
He found some peptide-like structures, but the bonds between the amino acids were weak and unstable.
If horizontal gene transfer was predominant in early evolution, how would this affect our ability to reconstruct the tree of life?
Horizontal gene transfer blurs the concept of species, making it difficult to delineate ancestral species.
Which of the following statements best explains secondary reinforcement?
If the reproductive isolating mechanisms that developed during the geographic isolation are somewhat weak but the hybrids between two populations have lower fitness, then the speciation process may continue.
Backward smearing
Lag time between last known species and extinction
Ring Species
Mixtures of both parapatry and allopatry ex) Ensatina eschscholtzii
How can complex organic molecules assemble into more elaborate structures?
More likely on a solid surface such as minerals and clay
The origin of cell structures might be hypothesized to have involved a hypercycle, based on mutualism at the molecular level. Which of the following is correct regarding the hypercycle model?
Natural selection will favor a hypercycle that is enclosed in a membrane.
Sympatric Speciation
No geographic barrier separates diverging populations ex) Cichlids -Genetics reveal these 2 species form a monophyletic group
Which gas was most likely the LEAST abundant in early Earth's atmosphere?
O2
Why do species go extinct?
Predation Competition Disease Climate Change
Biotic Niche
Predation, Competition, Parasitism, Life history
The first genetic material on Earth was most likely __________.
RNA
Allopatric Speciation
Reproductive isolation due to geographic separation ex) Mountain range, river, ocean, desert, etc.
During first wave of colonization
Species that were large, flightless, and nested on the ground suffered much higher rates of extinction
Which of the following statements about the Lincoln and Joyce experiment on self-replicating ribozymes is most likely correct?
The self-replicating ribozymes that had more efficient catalytic activities would soon began to dominate their populations
Horizontal Gene Transfer (HGT)
The transfer of genetic material from one organism to another that is not its offspring
Ecological Species Concept
a cluster of individuals that occupy the same niche -Members of the same species compete with one another more directly than individuals of different species
Evolutionary Species Concept
a lineage of ... populations which maintains its identity from other such lineages and which has its own evolutionary tendencies and historical fate
6th Mass Extinction
a. The number of species that have already gone extinct b. The number of species seriously endangered c. We know very little about species that may be in danger of extinction d. The massive amount of deforestation/habitat fragmentation e. Climate change f. Species interactions (food webs)
In a study of red spruce trees and black spruce trees, scientists found that the red spruce was living in a smaller geographic area and had much less genetic variation than the black spruce. They proposed that the red spruce might have arisen from a southern population of black spruce, which became geographically isolated from other black spruce populations at some point during the Pleistocene glaciations. What is this an example of?
allopatric speciation with the peripheral isolate model
In a hypothetical scenario, imagine that you have discovered a rare species of bird on a remote Pacific island. You spend some time studying their ecology and habitation and discover that although these birds look alike, they are indeed two distinct populations with very different mating calls. You propose that these two populations must be two species since they are no longer able to mate with one another. Which of the following species concepts would you use to defend your statement?
biological species concept
Passive Trend
direction of diversification is limited due to some constraint on evolution (e.g. ancestor already minimal viable size)
Peripheral Isolate
divided populations differ in size ex) black spruce -Progenitor-derivative Species Pair
Phenetic species concept
draws species boundaries around clusters of phenotypically similar individuals or populations ex) a lot like lions a lot like tigers but few in between
"A species is a lineage of populations which maintains its identity from other such lineages and which has its own evolutionary tendencies and historical fate." This definition best represents the __________.
evolutionary species concept
Which of the following molecules involved in membrane structure was likely favored by natural selection in the evolution of early cells?
fatty acids
Law of Superposition (relative)
fossils found lower down in the sediment at a particular locality are older than those closer to the surface
Exonuclease
goes in an fixes DNA
Anagenesis
gradual modification of form without branching speciation
sexual reproduction favor
high environmental unpredictability, parasite load, number of niches
Parapatric Speciation Ecologically neutral dynamic equilibrium model
hybrids always inferior to non-hybrids
Parapatric Speciation Ecologically dependent bounded hybrid superiority model
hybrids may have superior fitness in the hybrid zone
Pseudoextinction
lineage has not died out but changed so much that now classified as a new species
endemic species
localized to a specific area
asexual reproduction favor
low environmental unpredictability, parasite load, number of niches
A log-odds ratio of zero for Species Geographic Range
no association between geographic range and extinction
multiple niche hypothesis
number of niches ex) Sex more common in lakes
What is a niche?
organism's role in an ecosystem
Carbonization:
organisms fossilize as layers of thin carbon spread on sandstone and shale
A researcher is trying to determine if populations of a butterfly seen on the eastern slope of the Rocky Mountains in Colorado are actually separate species. The researcher and her graduate students spent a summer capturing the butterflies at several locations, carefully documenting traits such as color, wing span, antennae length, proboscis length, etc. Which species concept could be applied using these data?
phenetic species concept
Which of the following was NOT identified as a basic function of genes included in a minimal gene set of Bacillus subtilis in Koonin's 2003 study?
photosynthesis
In a hypothetical flowering plant species, one population evolves a different response to environmental stimuli and begins to bloom significantly later in the season than nearby populations. What type of reproductive isolating mechanism would this be?
prezygotic
Lakes have a greater number of distinct ecological niches
sexual prediction
A positive value for Species Geographic Range
that species with broad ranges show reduced extinction rates
Sexual reproduction
the joining together of genetic material from two parents
Asexual reproduction
the production of offspring from unfertilized gametes
All of the following are true regarding Sol Spiegelman's experiment on the origins of life, except that __________.
there was no selection for any of the variations in length
Molecular mutualism
two or more molecular substrates each contribute in a positive way to the replication of the other
Dissolution:
water seeps into fossils breaking them down but the shape of the fossil is preserved
