Final

Evolutionary stable strategy (ESS) – A phenotype that cannot be replaced by any other
phenotype under specified conditions; “A strategy that, if all the members of a population adopt
it, then no mutant strategy could invade under the influence of natural selection.”
Game theory – A branch of mathematics concerned with the analysis of strategies for dealing
with competitive situations where the outcome of a participant's choice of action depends
critically on the actions of other participants; often explained using the hawks vs doves metaphor
Assessor strategy – Escalates a conflict if opponent is judged to be smaller or weaker; retreats if
opponent is larger or stronger
Honest signal – Information that is a true indicator of the underlying quality of the sender and is
useful to the receiver
Altruism – An activity that enhances the fitness of other individuals, but lowers the fitness of the
actor
Reciprocation – A behavior whereby an organism acts in a manner that temporarily reduces its
fitness while increasing another organism's fitness, with the expectation that the other organism
will act in a similar manner at a later time
Manipulation – Donor dispenses aid because the donor is being manipulated by the recipient
Individual advantage – Cooperative behavior may evolve because it is advantageous to the
individual
Reciprocal altruism – A behaviour whereby an organism acts in a manner that temporarily
reduces its fitness while increasing another organism's fitness, with the expectation that the other
organism will act in a similar manner at a later time
Prisoner’s dilemma – A thought experiment that challenges two completely rational agents to a
dilemma: they can cooperate with their partner for mutual benefit or betray their partner (i.e.,
defect) for individual reward
Direct fitness – The effect of fitness of an allele on the individual that has it
Indirect fitness – The effect of fitness of an allele on other individuals that share the allele
Inclusive fitness – The effect of fitness of an allele on both the individual that has it and the
fitness of other individuals that share the allele; includes both direct and indirect fitness
Hamilton’s Rule – An altruistic trait can increase in frequency if the benefit (b) received by the
donor’s relatives, weighted by their relationship (r) to the donor, exceeds the cost (c) of the trait
to the donor’s fitness; altruism spreads if rb > c

Eusociality – The highest level of organization of animal sociality, is defined by the following
characteristics: (1) Cooperative brood care, (2) overlapping generations within a colony of
adults, and (3) a division of labor into reproductive and non-reproductive groups
Coevolution – When two or more species reciprocally affect each other's evolution through the
process of natural selection
Red Queen hypothesis states that species must continually evolve and adapt in order to survive
because other associated species are also ever-evolving

Oparin-Haldane hypothesis – Life arose gradually from inorganic molecules, with “building
blocks” like amino acids forming first and then combining to make complex polymers
Miller-Urey experiment – Provided the first evidence that organic molecules needed for life
could be formed from inorganic components
RNA world hypothesis – State that the first life was self-replicating RNA
The six major evolutionary transitions:
1) Separate replicators (genes) and formation of cell membranes → genome within cell
2) Separate unicells → symbiotic unicells
3) Asexual unicells → sexual unicells
4) Unicells → multicellular organism
5) Multicellular organisms → eusocial societies
6) Separate species → interspecies mutualistic associations
Strata – Sedimentary layers; can be distinguished using distinctive fossil taxa
Radiometric dating – A method of dating ancient rock layers by measuring decay of certain
radioactive elements
Endosymbiosis theory – Some of the organelles found in eukaryotic cells (e.g., mitochondria)
were once free-living prokaryotic microbes
Cambrian explosion – A relatively short evolutionary event, beginning around 542 million
years ago in the Cambrian period, during which most major animal phyla appeared, as indicated
by the fossil record
Diapsids – Vertebrates with 2 temporal fenestrae (e.g., dinosaurs, birds, lizards, crocodilians)
Synapsids – Vertebrates with a single temporal fenestra (e.g., mammals)
Refugia – Areas with isolated populations that were formerly broadly distributed

Microevolution – Evolutionary processes that occur within species
Macroevolution – Evolution above the species level, including rates of evolution, origin of
novel features, evolutionary trends, and patterns of origination, extinction, and diversification of
higher taxa
Gradualism – The hypothesis that evolution proceeds gradually; this is the pace that Charles
Darwin believed predominated
Punctuated equilibrium – A pace of evolutionary change in which long periods of little change
(stasis) is followed by short periods of rapid change
Hypotheses that account for stasis:
1. Internal genetic or developmental constraints
2. Stabilizing selection for a constant optimum phenotype
3. Brief and local divergence that did not leave evidence
Habitat tracking – The shifting of the geographic distributions of species in concert with the
distributions of their typical habitat
Saltation – Sudden evolutionary changes that happen in a single generation, rather than
gradually
Living fossils – Organisms that have changed so little over millions of years that they closely
resemble ancestors from millions of years ago
Phylogenetic niche conservatism – Tendency of species to retain their ancestral traits and
maintain a long-continued dependence on much the same resources and environmental
conditions
The five mass extinctions (The Big Five)
1. End Ordovician (440 mya) – May have been proportionally the second largest
extinction
2. Late Devonian (365 mya) – May have been multiple extinction pulses of up to 15 my
in duration
3. End Permian (250 mya) – Most severe mass extinction event
4. End Triassic (215 mya) – One of the least intense mass extinctions
5. Cretaceous-Tertiary or K-T (65 mya) – About 50% of all species became extinct;
evidence for impact of a large meteor

BIO 265: Fundamentals of Evolution
Background extinction rate – The extinction rate occurring outside of mass extinction events;
roughly estimated to be ~1 extinction per million species years; encompasses about 96% of known
extinction events
Evolutionary trend – A persistent, directional change in the average value of a feature
(character state)
Passive trend – Lineages in the clade evolve in both directions with equal probability
Active (or driven) trend – Changes in one direction are more likely than changes in the other
Three possible causes for evolutionary trends:
1) Individual selection, across many related lineages, can favor one phenotype (e.g.,
large body size) over another
2) Smaller species have a higher extinction rate, so species selection causes a trend
towards larger size
3) Recent speciation events have been more frequent in the clades with larger body
size
Predictability of evolutionary paths– The evolutionary history of life was inevitable; states that
evolutionary parallelism and convergence are widespread and dictate evolutionary process at
small and large scales
Contingency of evolutionary paths – The path of evolution has been directed by chance events,
such that the outcome of history would be different if any of the antecedent events had been
different