Random
What do mutations create?
New alleles
What is the best definition of a fossil
Any trace of an organism that lived in the past
What are the 4 mechanisms of evolution?
Natural selection, mutation, gene flow, and genetic drift
A population or group of populations that is evolving independently of other populations.
What is the name of the event in which the radiation of animals began?
The Cambrian explosion
They store energy
What is mass extinction?
When at least 60% of a species present are wiped out within 1 million years
What is stabilizing selection?
A mode of natural selection that reduces overall genetic variation in a population
What is the phylogenetic species concept?
It identifies species based on the evolutionary history of populations
What is one of the defining characteristics of vertebrates?
A segmented backbone
What is a point mutation?
A mutation that alters the sequence of one or a small number of base pairs.
Give your best characterization of an adaptive radiation
A single lineage diversifies rapidly, and descendant species occupy many habitats and ecological roles.
What is a genetic bottleneck?
A sudden reduction in the diversity of alleles in a population
What is a weakness of the morphological species concept?
Experts can disagree about whether differences between forms are consistent with normal within-species variation
or represent synapomorphies (traits that arose independently)
What are the 2 major subgroups within the bilaterian coelomates?
Protostomes and Deuterostomes
What does it mean to be benthic?
Lives at the bottom of aquatic enviornments
Recent fossils are much more common than ancient fossils. The older the fossil is, the longer it has been exposed to potentially destructive forces in deep layers of rock, and the less likely to be exposed to the surface by erosion.
Why isn't inbreeding considered an evolutionary process?
It does not change allele frequencies
What is a monophyletic group?
An ancestral population, and all of its descendants, and only those descendants.
What is an animal?
Something that eats and moves
Why is the following mutation considered random?
A change from a G to C, when DNA is copied during chromosome replication.
It just happens
Any change in base sequence is equally possible
Undirected with respect to fitness
Any change in chromosome number is equally possible
In what Eon is the first evidence of oxygenic photosynthesis present?
The Archaean Eon
True or False: Gene flow can either increase or decrease the average fitness of a population? Explain
True.
If gene flow into a population introduces a beneficial allele, fitness will go up; but if gene flow introduces a deleterious allele, fitness will go down
Why do phylogenies have to be estimated via an analysis of homologous traits?
Otherwise, species might be grouped on the basis of traits that appear similar but are not derived from a common ancestor.
Name one of the themes that occur in the diversification of the animal phyla
1. Higher oxygen levels
2. Rise of higher-quality food sources
3. The evolution of predation
4. New niches beget more new niches
5. Modified genes, modified bodies