Test 2 Flashcards
First hominids
6 mya Phanerozoic eon Cenozoic era Neogene period Age of mammals
First Homo sapiens
0.15 mya Phanerozoic Eon Cenozoic Era Quaternary period Age of mammals
First flowering plants
130 mya Phanerozoic eon Mesozoic era Cretaceous period Age of reptiles
First birds
150 mya Phanerozoic eon Mesozoic era Jurassic period Age of reptiles
First dinosaurs/mammals
200 mya Phanerozoic eon Mesozoic era Triassic period Age of reptiles
First reptiles
300 mya Phanerozoic eon Paleozoic era Carboniferous period Age of amphibians
First amphibians
400 mya Phanerozoic eon Paleozoic era Devonian period Age of amphibians
First fish
500 mya Phanerozoic eon Paleozoic era Cambrian period Age of invertebrates
Cambrian explosion
542 mya Phanerozoic eon Paleozoic era Cambrian period Age of invertebrates
First animals
635 mya
Proterozoic eon
Edicarian period
Age of invertebrates
First multicellular organisms
1000 mya
Proterozoic eon
First eukaryotic cell
2000 mya
Proterozoic eon
Increase in atmospheric O2
2500 mya
Proterozoic eon
First cell
4000 mya
Archaean period
Formation of the earth
4600 mya
Hadeon eon
The “great dying”
250 mya
90% species went extinct
Phanerozoic eon, Mesozoic era, Triassic period
Burgess Shale
Set of fossils found in Canada, indicates increase in diversity of life Occurred around Cambrian explosion
"Burgess beasts" include
Anomalocaris
Marella
Trilobite
Wiwaxia
Etc.Five mass extinctions— when did they occur?
Late Ordovician period Late Devonian Late Permian Late Triassic Late Cretaceous
Order of periods in Phanerozoic era (oldest to most recent)
Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Paleocene Neogene Quaternary
First groups of animals
Porifera (sponges)
Jellyfish (radial symmetry)
Proteosomes (insects, crustaceans,etc)
Deuterosomes (us!! Mammals(?))
Tikaalik roseae
- reps transition from fish to amphibians
Devonian period - has skull, neck, ribs, flat head like land animal
- has fins, scales, primitive jaws like a fish
When was the evolution of the jaw?
Silurian period
Originally jaw was meant to be supportive bone to help gills function
When did amniotic egg first arise?
Carboniferous period
We use fossil fuels from fossils during which period?
Carboniferous period
When was Pangea formed?
Permian period
Main point of Simmons article
Giraffe’s neck evolved due to sexual selection, not natural selection
Jared diamond article
Sexual selection applied to many of the traits that appeal to humans, and have no direct effect on survival
Bradt article
Talks about Tiktaalik roseae, features, that land animals originated from it
Nowack article
bc of repeated actions, evolved to cooperate; Prisoner’s dilemma
Neyfack article
Hamilton rule, E.o. Wilson says it doesn’t apply (supports group selection)
Sexual selection
If there is variation in a trait that affects the ability to obtain mates the variations conductive to success will become more common over time
Fitness
Ability to survive and reproduce in a particular environment INCLUDING the ability to find and attract mates
Sexual dimorphism
Distinct difference in size and/or appearance b/w sexes of animal in addition to difference b/w sexual organs
Anders Møller experiments
Artificially lengthened barn swallow tails—> determined that longer tail results in more offspring
Possible factors that affect female choice
- Display is indication of resources (direct benefit)
- Display correlates with genetic quality (indirect benefit)
- Display exploits a preexisting bias in female
- Display is arbitrary (runaway selection)
Kin selection
A form of natural selection that favors the spread of alleles that benefit close relatives (increase indirect component of fitness)
Possible explanations for altruism
Kin selection
Reciprocal altruism
Group selection
Direct fitness
Ability for Survival and reproduction
Ability to find and attract mates
Indirect fitness
Additional reproduction by relatives that is made possible through an individual’s actions
Inclusive fitness
= indirect fitness + direct fitness
Coefficient of relatedness
Probability that a gene in one individual is an identical copy, by descent, of a gene in another individual
R= (summation of)[0.5]^L
Where L is each generation
Hamilton’s rule
An allele for an altruistic behavior will spread if rB - C>0
Eusociality
- Castes of nonreproductive workers
- Cooperative brood care
- Overlap generations
Evolved from haplo-diploidity
Problems with Eusociality
- Multiple mating
- Multiple queens
- Haploid diploid species that are not eusocial
- Eusocial species that are not haplodiploid
Reciprocal altruism
Altruism in related and unrelated individuals where there is potential for reciprocity
Reciprocal altruism is most likely to evolve when…
- individuals repeatedly interact
- many opportunities for altruism
- individuals have good memories
Reciprocal altruism evolves in species that…
- Are Long lived, intelligent, social
- Have low rates of dispersal
- Have high degree of mutual dependence
Eg. Prisoner’s dilemma
Group selection
Alleles can spread in a population b/c of benefits they bestow upon groups, regardless of fitness w/in group (ie. natural selection that operates on groups)
Problem with group selection
Not an evolutionary stable strategy (ESS)
ie. This kind of behavior can be readily driven to extinction by alternative strategy.
Characteristics of complex traits
- influence by environment is often present
- more common than simple traits
- continuous (not discrete, not just one or other)
- measurable (quantitative)
- described by bell curve (normal distribution) —–> regression to the mean (b/c you have many factors that influence outcome)
Quantitive Trait Loci
Genes that influence complex traits
Can be determined via mapping –> can answer: What are genes that contribute? How much do they influence them?
Genome wide association study
SNPs –> QTL mapping, association with region of difference with trait
Vp =
Vg + Ve
Phenotypic variation equals genetic variation and environmental variation
Heritability (&eq)
h^2 = Vg/Vp
Proportion of phenotypic variation that is due to genetic differences
Studies via twin studies and parent-offspring studies
Heritability tells us nothing about the role of genes in determining traits that are shared by all members of a population, but allows us to predict whether selection on a trait will cause a population to evolve
Response to selection
R = h^2 * S
R refers to directional, stabilizing, diversifying
S is selection strength
Barriers to gene flow result in…
Genetic divergence & reproductive isolation over time
Speciation is a byproduct of genetic divergence between isolated populations!!!
Biological species concept
Groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups (Ernst Mayr’s definition)
Difficulties with the biological species concept
- practical shortcomings (test of hybridity cannot occur very often, according to Wallace)
- asexual organisms
- extinct organisms
- ring species (eg. Green warbler—> gene flow around geo features separating groups of organisms and animals)
- hybridization
Phylogenetic species concept
A species in a single lineage (ancestor- descendent) of populations or organisms that maintains its identity from other such lineages, which has its own evolutionary tendencies and historical fate
Ecological species concept
A species is a lineage (or closely related set of lineages) that occupy an adaptive zone minimally different from that of any other lineage in its range, and which evolves separately from all lineages outside its range
Morphospecies concept
Members of a species that look alike
BUT.. Problem b/c there are many organisms that look alike but are separate species
Prezygotic barriers to reproduction
(Before formation of zygote)
- Ecological/geographical – separate in space
- temporal – sep in time
- sexual/behavioral – sep by preference
- mechanical — mating cannot occur
- gamete incompatibility (sperm can’t fertilize egg; esp in plants and marine animals)
Postzygotic barriers to reproduction
- Hybrid inviability (zygote can’t develop)
- hybrid sterility (zygote/offspring is not sterile)
Allopatry
Speciation occurs b/c of literal geological barrier that separates the populations
Two types:
Vicariance
Dispersal
Sympatry
Speciation on same plot of land (w/out geological barrier)
Vicariance
Allopatric speciation that occurs when something physical divides the populations (eg. A mountain)
Dispersal
Allopatric speciation when parts of population leave (involuntarily; eg. freak storm)
Most emblematic vicariant effects
Supercontinent formation/breakup
Mechanisms of allopatric separation
Natural selection
Genetic drift
Sexual selection
Mechanisms of Sympatry
(Unsure if Sympatry even exists)
- Natural selection (diversifying/disruptive selection)
- Sexual selection
Speciation rates
Depend on change in environment
Slow: Horseshoe crab
Fast: Darwin’s finches
Instantaneous: Hybridization (plants)
Difficulties with natural selection (according to class and Darwin)
Class: Sexual dimorphism Altruism Complex traits Speciation/ defining species
Darwin: Absence of transitional forms (living and fossils) Perfection Instinct/behaviors Sterility of hybrids
Rhynie chert
Early Devonian sediment/fossil, shows variety of plant life, indicating early stages of plant colonization on land
