Exam 1 Flashcards
What is the simple definition for evolution?
The change in organisms throughout earth’s history
We have descended from earlier life and are different today also known as “descent with modification”
What are the two periods of views on life before Darwin?
- Antiquity through the 1600s
- Age of reason (1700s - 1800s)
Describe the antiquity through 1600s period and the beliefs held at the time.
Aristotle: had an idea of fixed ideal species and the scala naturae (ladder of nature)
- humans at the top, plants at the bottom
Judeo-Christian Bible:
- similar to scala naturae but had god and the archangels on top instead
What’s the order of the guys for the Age of Enlightenment/reason?
Linnaeus
Cuvier
Hutton
Lyell
Erasmus Darwin
Lamarck
Charles Darwin
Mnemonic: Lord Cuffrey helps linger erectile dick loudly cocky and darwin.
What did Linnaeus (1707 - 1778) do?
Created an orderly, nesting system w binomial naming
- eukarya, animalia, etc,
The stuff w the phylum and domain and kingdom etc
What did Georges Cuvier (1769 - 1832) do?
Fossil dude
- Said that fossils are a record of change over time caused by catastrophic events
-Connected fossils with where they likely lived
-He figured out the rock strata (or layers) could tell you the relative ages
-Discovered that species likely changed because of local extinctions and then the area got recolonized by different species
What is gene flow?
Alleles moving in and out of populations.
This includes:
- Migration of adults
- dispersal of gametes, seeds, and larvae
What is the results of gene flow?
- add diversity to population
-reduce diffferences between populations - less differences in the same streams compared to different streams seperated by a mountain
What is relative fitness?
comparing individuals in a population to each other in terms of their reproductive fitness (how good is their ability to reproduce and have viable offspring)
What does “fittest” mean?
best reproductive success
What does fitness include?
survival, finding mates, and the # of healthy fertile offspring
Who has the greater relative fitness?
A mom with two kids or a single women who works out
The mom
What is directional selection?
A form of natural selection. It is a shift of a character’s mean value to one direction. The lab simulation with the beach/field mice is this concept. (Mice population becoming more darker as they evolved)
What is disruptive selection?
A form of natural selection. The intermediate is less fit than the two extremes which helps maintain the diversity. (White mouse and dark brown mouse are more fit than the beige mouse)
What is an example of disruptive selection?
Seedcracker finch with 2 size beaks. One with a super wide bill and one with super narrow. If you have one in the middle, then how will you pick up the tiny seeds (small bill) or pick up the giant seeds (big bill).
What is stablilizing selection?
A form of natural selection. Intermediate type is more fit than the extremes and so there is less variation
What is an example of stabilizing selection?
Human babies born at around 6 pounds have a significantly lower infant mortality than babies born at 10 pounds or 3 pounds. Babies with big weight need C-section to exit and have more issues that come w them.
What is sexual selection?
A form of natural selection. Basically now successful and fit you are based on certain traits that can help get mates. (not directly related to environment)
Can lead to dimorphism meaning that males and females look different. Examples include birds like cardinals and peacocks. Red-breasted birds that pound on their chest as well. Dancing male birds.
What is a gynandromorphic cardinal?
Bird that is both male and female. Has an ovary and a teste. This is due to error fertiliziation or early development. Occurs in birds, crustaceans, and insects but NOT mammals
How is genetic variation maintained?
1) Through diploidy
2) Through disruptive selection: l
3) Through heterozygote advantage:
4) Through frequency-dependent selection:
Describe the sickle cell-malaria connection with allele types
HbAHbA - normal red blood cells but more likely to die from malaria
HbAHbB - malaria resistant and no sickle cell disease just a carrier (not an intermediate phenotype)
^THIS IS THE MOST FITTER ONE^
HbBHbB - sickle cells disease
What are limitations of natural selection?
It acts on phenotype of entire individual - its adaptation may be a “compromise” in form due to competing needs. Ex: Deers have adaptations for standing super still but also for running super fast
It can only act on existing variation. Extinction happens when adaptation is impossible and form is constrained by ancestry.
What are the three things that play a role in natural selection?
Chance, environment, and history
(Ex: dinosaurs getting wiped out by a meteor)
Natural selections acts directly on the —————— but the fundamental unit of evolution is the —————-
Individual, population
What are paraphyletic taxons?
leaves out a common descendant
What are polyphyletic taxons?
What is a method of determining phylogeny?
Cladistics
How does cladistics work?
you must identify homologous characters in a group as ancestral or derived
What is plesiomorphy?
homologous characters shared with ancestor
What is synaptomorphy?
novel or evolved shared character different from ancestor
What is autapomorphy?
derived and unique
How are dichotomous trees created?
they are based on shared derived characters (synapomophies)
What principle do you use to choose the best tree?
maximum parsimony - fewest evolutionary events
What are clades?
All the species on a branch
- All the species in a clad share homologies
- the more shared characters, the closer the relationship
- the character shared by all = earliest things
- most unique things = latest stuff
We can infer the —— of evolutionary events from cladistic trees but not ———
sequence, absolute time
———— estimate divergence times. They assumes the constant rate of homologous DNA mutations over time.
Molecular clocks
What was the older five-kingdom system?
Bacteria/Archae/Monera, Animalia, Plantae, Fungi, Protista
What is LUCA?
Last Universal Common Ancestor. Likely was a prokarya and had ribsomes
What is the current 3-domain system?
bacteria, Archaea, eukarya
the “root” of the tree is complicated by ——-
horizontal gene transfer: prokaryotes just take in other genes and stuff all the time. DNA moving between species.
What is Hadean Eon?
Earth planet formed 4.6 billion years ago
- molten rock surface - no liquid water and unhospitable
What is Archean Eon?
Crust of the earth cooled off and solidified 3.8 billion years ago.
- Condensed water formed the global ocean
The crust that cooled began breaking and moving around - plate tectonics
- Volcanoes created the first land
What created the first land?
Volcanoes
What was the first type of life to emerge on earth?
prokaryotic cells (3.5 bya)
During the Archaon Eon, was the earth hospitable by humans?
No. The air was filled with volcanic gases and low O2 gas in the atmosphere. However, the first sign of life existed as prokarya.
What was the oxygen revolution?
Occured approximately 2.7-2.5 bya: Prokaryotes performing photosynthesis made the seas and atmosphere O2 rich
What is macroevolution?
Describe the Proterozoic Eon
Occured 2.5 bya
- Continents formed from the plates
-Had some shallow seas which are great for incubating life
-Eukaryotic life began 2.1 bya
How did new groups of life began?
Each new group began with 1 ancestral species and they arose by speciation.
What are classic examples of analagous structures?
Wings - birds and bats
Fins - Fish and dolphins
What is a pleisomorphic character?
An ancestral trait shared among all organisms on a phylogenetic tree
What is development & evolution (Evo-Devo)?
Devolpmental genes control development of multicelluslar organisms
Many developmental genes are ——— genes which control when, where, and which genes are expressed
regulatory
Many regulatory genes are ——– factors
transcription
A single mutation may affect expression of —- gnes during development
many
What can cause dramatic changes in the final body form of an organism?
a single mutation
What is heterochrony?
Other timing (think:kronos)
evolutionary change in form due to change in rate or timing of developmental events
baby chimpanzee and baby human look similar
adult chimpanzee and adult human look very different
^^^ “Small change in timing of developmental genes give dramatic change in jaw shape”
What is paedomorphosis?
a change of timing produces a sexually mature adult with juvenile features
- retain juvenile features as an adult
What are hox/homeotic genes?
the mutation of these genes affect the placement of body parts itself
Ex: fruit flies have legs on their head instead of where they should have antennas
Ex: can also have duplication of body parts: fruit fly with extra wings
What explains body plan changes in animals?
hox genes: can suppress limb formation or reduce legs.
Ex: snakes loosing their legs
What are fossils?
Remnants, casts, or traces of organisms
What do fossils tell us?
- anatomy and habitats
- diet, lifestyle, and activity
-genetic info (DNA)
Ex: from the teeth of the T-rex you can tell it was a carnivore with the big slashing teeth
What is relative dating?
Comparing the positions of the strata (rock layers)
Fossils at the top died more recent than those at the bottom - can figure out the dates and timings
How else can we figure out the dates of fossils?
Carbon isotopes - using radioactive carbon-14 which will decay eventually to nitrogen-14.
Can figure out by looking at how much carbon-14 is left in an organisms bones.
What is absolute dating?
age in years before the present
What is radiometric dating?
Uses the decay rate of radioactive isotopes to figure out the age of fossils. Checks the half-life.
What is half-life?
Amount of time it takes for 1/2 of the isotope to decay
What are some misconceptions regarding evolution?
1) Evolution is goal-oriented toward the more complex
2) Evolution creates new forms of life by dramatic mutations
3) An organism can evolve during its lifetime
4) An organism can influence the evolution of its own structures in response to the environment
5) Evolution is a completely random process
What did Hutton do? (1726 - 1797)
- Saw the slow, continuous processes of geological features
- Figured out gradualism: large morphological changes in organisms occur via a number of smaller steps over a long period of time
What did charles lyell do? (1797 - 1875)
- Father of Modern Geology
- Expanded on Hutton’s ideas with uniformitarianism: the same stuff that’s been there in the past are still there and are going at the same rate so the earth is extremely old.
- was good friends w Darwin
What did Erasmus Darwin do?
- Darwin’s grandpapa
- Was a physician and natural philosopher
- “natural philosophy” on evolution
- wrote ideas that “forms minute” slowly acquired complexity over time
What did Lamarck do (1744 - 1829)?
- linked evolution to adaptation
- basically said that extinct species have been replaced by descendants with new features
- these adaptations helped them survived in the environment (Darwin agreed with this)
He was the first to propose a mechanism for evolution:
- “use and disuse” was his idea which is basically that if you use a body part a lot it’ll develop more and if you don’t use a certain part of the body it’ll be diminish/go away.
Lamarckism: inheritance of acquired characteristics. Giraffe stretched neck to eat leaves and then passed on that trait. Human muscle example. If you plant the seeds of a really fancy bonsai bush and expecting the resulting shrub to look like the original
Darwin did not agree with these ideas and they are wrong
How does diploidy help maintain genetic variation?
less successful recessive alleles are hidden in heterozygotes - not obvious/visible
What is
How does disruptive selection help maintain genetic variation?
surviving extreme phenotypes will carry different alleles.
How does the concept of heterozygote advantage help maintain genetic diversity?
where selection favors heterozygotes over either homozygote maintaing both alleles. Ex: sickle cell allele when malaria is present.
How does frequency-dependent selection help maintain genetic diversity?
the fitness of a given phenotype decreases as its frequency increases in a population.
Ex: so the more you have of a certain trait the less likely it is to reproduce.
Rare forms are less likely to be identified by visual predators.
Over time, this will balance out with the rare phenotypes as the common ones are gonna get eaten so the rare ones populate more and then they are eaten so then the common ones produce more
In Alaska, you uncoer some mammoth bones sticking out of the melting permafrost. You radiocarbon date the bones and find out that 1/8 of the C14 remains. The half-life of C14 is 5,730 years. Approxyimately how old are the mammoth bones?
(1/2)(1/2)(1/2) = 1/8
3 x 5,730= 17,190
When did the first multicellular life (algae and animals) occur?
~600 million years ago
Hard to make fossils - these species are super squishy
Describe the phanerozoic era/paleozoic era
- emergence of sponges/isopods
- rise of fish
- invasion of land by seedless plants, fungi, and arthropods
- first land vertabreates: amphibians
first vertebrates with shelled eggs: amniotes
Continental drift is occuring throughout this - Pangaea
Era ends with the permian mass extinction
- massive volcanic activity
- lost 96% of marine species lost
- 70% land species
Describe the mesozoic era
- age of dinosaurs and reptiles
- cone-bearing seed plants dominate
- arrival of the first mammals and birds
Breakup of pangaea and continent drift
Era ends with cretaceous mass extinction - 50% marine species and many terrestrial familes (loss of the dinosaurs)
Describe the Cenozoic era (65 mya)
Major diversifcation of mammals, flowering plants, insects, and birds
First humans (~200,000 years ago)
