Exam 1 Flashcards
Evolution
change over time
Theory
a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence and that generates testable and falsifiable predictions and hypotheses
Fact
some form of evidence that has been tested and confirmed so many times that there is no compelling reason to keep confirming it
Is evolution a fact or a theory?
both
Hypothesis
a proposed explanation for an observation or phenomenon that can be tested
Working hypothesis
a provisionally accepted hypothesis proposed for further testing, consideration, and research
Alternative hypothesis approach
a hypothesis created that debates the original hypothesis
-it is essential to avoid trap of the incorrect “pet hypothesis”
Pet hypothesis
the hypothesis you want to believe versus the once based on observations and predictions
Darwin’s Theories of Evolution
-evolution as such
-gradualism
-descent with modification
-multiplication of species
-natural selection
-sexual selection
Non-Darwinian Theories of Evolution
-genetic recombination (flu)
-genetic drift
Mechanisms of Evolution
-natural selection
-sexual selection
Patterns of Evolution
-evolution as such
-gradualism
-descent with modification
-multiplication of species
Evidence for Evolution
-paleontological record
-vestigial organs
-extinction
-transitional forms
-evidence of descent with modification
-homologous structures
-molecular homology and fossil genes
-age of earth and geological time
Law of Succession
fossil types are succeeded, in the same geographic area, by similar fossils or living species (ex: south american armadillos)
Fossil genes (pseudogenes)
a gene that once produced a protein, but because of accumulation of mutations no longer does (not a switch gene that turns other genes on and off)
Examples of Vestigial Organs
-appendix
-tails in humans
-vestigial legs in snakes
-wisdom teeth in humans
-vestigial wings in New Zealand Kiwi
-vestigial hip and leg bones in whales
Examples of Extinction
-mammoths and mastadons
-titanotheres (large herbivore)
-glyptodont (large armadillo like)
Examples of Transitional forms
-bats with claws
-snails to slugs (snails have a shell, slugs do not)
Evidence of Descent with Modification
-phylogenic trees
-titanothere
Homology
similar characteristics among species
-structural homology
-developmental homology
Structural Homology
-all mammals have the same or very similar bone structure in the arm/wing/flipper
-indicates descent with modification from a common ancestor
Carolus Linnaeus
father of modern taxonomy
Taxonomy
the science of describing, naming, and classifying species of living or fossil organisms (family, class, group, etc.)
Nicolaus Steno
discovered strata layers in rock (stratigraphy)
-discovered fossils
Stratigraphy
the study of layering in rock (stratification)
Taxonomy Order (largest to smallest)
-kingdom
-phylum
-class
-order
-family
-genus
-species
Robert Hooke
came up with natural theology - God furnished each plant and animal with contrivances necessary for their own existence
William Paley
believed anatomy was evidence of design by a Divine Creator
-wrote the Natural Theology book
George-Louis LeClerc Buffon
proposed Earth was formed according to the law of physics (comet struck the sun)
Paleontology
the study of prehistoric life
Georges Cuvier
proposed the idea of extinction
Extinction
refers to the permanent loss of species; marked by death or failure to breed of the last individual
Mary Anning
studied marine fossils which furthered evidence of extinction
James Hutton
rocks form very slowly and changed landscapes in drastic ways
William Smith
realized older layers of rock had different fossils than younger layers
Jean-Baptiste Lamarck
the diversity of life was the product of evolution still based off the Great Chain of Being
-primitive life was spontaneously generated all the time
-plants and animals could adapt to their environment
Uniformitarianism
the idea that the natural laws observable around us now are also responsible for events in the past (earth was shaped by gradual processes like erosion)
Homologous characteristics
similar in 2 or more species because they are inherited from a common ancestor
Archetype
a fundamental plan to which some variation could be added
Thomas Malthus
claimed only those who could adapt to society’s needs to produce useful work would be able to survive and reproduce
-gave Darwin and Wallace the idea of natural selection
Adaptations
inherited aspects of an individual that allow it to outcompete other members of the same population that lack the trait (or have a different version)
-traits that have evolved through the mechanism of natural selection
Genetic Drift
evolution arising from random changes in the genetic composition of a population from one generation to the next
Artificial Selection
breeders select a desirable trait in their plants and animals and then increase that trait’s frequency in the stock
What species did Darwin breed himself?
pigeons
-common ancestor = Common Rock Dove
What island did Darwin study on?
Galapagos Islands
What specific species did Darwin study on the Galopagos?
finches
The Modern Synthesis
when evolution came together with genetics
-gradual evolution results from small genetic changes acted upon by natural selection
Macroevolution
the evolution of new species from existing species
-can be explained by microevolution
Microevolution
natural selection acting on individuals
How many inferences did Darwin’s theory of natural selection consist of?
3 inferences
How many facts were Darwin’s inferences (for his theory of natural selection) based off of?
5 facts
What are Darwin’s inferences for his theory of natural selection?
1.) since more individuals are produced than can be supported by the available resources but population size remains stable, it means that there must be fierce struggle for existence among the individuals of a populations resulting in the survival of only a part of the progeny of each generations
2.) survival in the struggle for existence is not random but depends in part on the hereditary constitution of the surviving individuals. This unequal survival constitutes the process of natural selection
3.) over the generations this process of natural selection will lead to a continuing gradual change of populations, that is, to evolution and to the production of new species
What are Darwin’s facts for his inferences of the theory of natural selection?
1.) all species have great potential fertility that their population size would increase exponentially if all individuals that were born reproduced successfully
2.) except for minor annual fluctuations and occasional major fluctuations, populations normally display stability in size
3.) natural resources are limited. In a stable environment they remain relatively constant
4.) no two individuals are exactly the same; rather every population displays enormous variability
5.) much of the variation is heritable
What are the 3 patterns of selection?
-directional selection
-stabilizing selection
-disruptive selection
Directional selection
when the population or trait as a whole shifts left or right over generations
Stabilizing selection
when the population or trait as a whole gets narrower or wider over generations
Disruptive selection
when the population or trait splits into two different directions over generations
What do prevailing environmental conditions influence?
which individuals with a given genetic phenotype will best survive and compete, and thus will leave the most offspring in the next generation
Darwinian Fitness
the ability of an individual to survive and reproduce in nature
-easy to understand but not easy to define or measure
How can fitness be measured?
-as a number of offspring produced by an individual
-as a number of grand-offspring produced
-as number of great, great, great grand-children produced
Reproductive success
the relative production of fertile offspring by a genotype
-a measure of fitness
Inclusive fitness
the number of viable offspring you produce plus the number of viable offspring produced by those related to you
-the most complete measure of reproductive success
Direct fitness
the number of viable offspring you produce
Indirect fitness
the number of viable offspring produced by those related to you
Examples of evolution acting on pre-existing characteristics of an individual
-evolution of the eye
-mammalian sesamoid bones
Evolutionary trade-off
-species with a big gut cannot have a large brain
-species with a large brain have small guts
Phylogeny
a visual representation of the evolutionary history of populations, genes, or species
Phylogenetics
the study of the evolutionary history, development and relationships among groups of organisms
Clade
an organism and all of its descendants
Where does variation occur?
in the population (not the individual)
Richard Lenski
studied E.Coli
Peter and Rosemary Grant
studied evolution and natural selection on the island of the Galapagos, Daphne Major
-studied the medium ground finch
Daphne Major
volcanic island that is ecologically simple and has had no species go extinct (due to hard to get to for humans)
-finches rarely come or go
Finch eating habits
-beak size is heritable
-only when the environment changed did finches food become specialized
-after drought = deeper larger beaks
-after wet rainy season = smaller beaks
3 lessons from the Grants research:
1.) natural selection may vary in intensity
2.) evolution can happen surprisingly fast
3.) the pattern of selection can change over time (strength and direction of selection fluctuate)
Ecological character displacement
refers to evolution driven by competition between species for a shared resource
-traits evolve in opposing directions minimizing overlap between species
Hopi Hoekstra
studied mice in Southeastern US
Requirements for natural selection to lead to evolution:
1.) phenotypic variation
2.) a genetic basis that can be passed down from parents to offspring
3.) variation in the trait leads to differential reproductive success among individuals in the population
Gene flow
the movement, or migration, of alleles from one population to another
-controlled by many variables
Harper and Pfennig
studied scarlet kingsnakes color pattern and found that variation between the northern and southern populations of kingsnakes is not a result of genetic isolation, there was gene flow
Aposematism
an antipredator strategy used by a potential prey item to signal danger or a lack of palatability
How many agents of selection can act on a trait?
more than one
-sometimes they can drive populations in 2 different directions at once
ex.) gallfly
Extended phenotypes
structures constructed by organisms that can influence their performance or success
-they are not apart of the organism itself but the properties reflect the genotype of each individual
Gallflies
-inherited differences of the flies not the plants
-flies induced galls to form their host plant
-gallsize influenced fitness
Three-spined sticklebacks
-isolated sticklebacks experienced a new set of selected pressures
-marine sticklebacks have armor (Eda gene)
-lake sticklebacks have less armor
Where is the frequency of lactase persistence the highest?
-northwestern europe
-western Africa
-southern Asia
Who cannot digest milk?
-Austrailia
-South Africa
-Asia
-southeast Europe
Hitchhiking
a new allele arises through a mutation passed down from one generation to the next with some surrounding DNA
Genetic linkage
refers to the physical proximity of alleles at different loci
Selective sweep
describes the situation in which strong selection can “sweep” a favorable allele to fixation within a population so fast that there is little opportunity for recombination
What did all modern corn/maize descend from?
a southern Mexico plant Teosinte
What is loss of variation an indication of?
strong selection and a genetic bottleneck
What 3 genes contributed to the evolution of maize?
1.) teosinte branched I
2.) prolamin box binding factor
3.) sugary I
What species has the most phenotypic variation today?
dogs
What was first used on crops to ward off insects?
sulfur and lime sulfur
Glysophate
chemical herbicide the kills weeds by blocking the construction of amino acids (attacks the EPSP enzyme)
Palmer amaranth
a type of weed that became resistant to glysophate because of gene duplication
Bt
a pesticide that evolution can be managed effectively by if used effectively
-produces toxic crystals in the insects gut and makes them sick
Bruce Tabashnik
proposed Bt-free “refuge” fields on farms to prevent resistance
Invasive species
often experience strong directional selection within their new habitat
ex.) cane frogs in austrailia
How did cane frogs adapt to their new environment?
their bodies and gland sizes got smaller
-legs got longer
-austrailian snakes became larger in response
Traits that experience selection due to human hunting and fishing:
-age and size at sexual maturity
-body size or morphology, sexual dimorphism
-sexually selected weapons
-timing of reproduction
-behavior
-dispersal/migration
Monophyletic
a term used to describe a group of organisms that form a clade
Synapomorphy
a shared derived character
-this is a character that evolved in an immediate common ancestor
What is determined by synapomorphies?
clades
Homoplasy
character state similarity NOT due to common descent (=analogous structures)
Convergent evolution
independent evolution of similar trait
-causes homoplasy
Evolutionary reversals
reversion back to an ancestral character state
-causes homoplasy
Parsimony
a criterion for selecting among alternative patterns or explanations based on minimizing the total amount of change or complexity
Paraphyletic
there are members of a clade left off on one of the sides/clades (not correct!)
Polyphyletic
there are members of multiple clades being left off (not correct!)
Ear bones
-ontogeny recapitulates phylogeny
-ear bones used to be on the jaw (example of exapation)
Exapation
characteristics evolved in the past, benefit in the future
Branches
lineages evolving through time that connect successive speciation or other branching events
Node
points in a phylogeny where lineage splits
Tips
the terminal ends of an evolutionary tree, representing species, molecules, or populations being compared
Internal nodes
nodes that occur within a phylogeny and represent ancestral populations or species
Cladogram
a phylogenetic tree that shows only the relationships among species
Characters (of the taxa)
heritable aspects of organisms that can be compared across taxa
Taxa
groups of organisms that a taxonomist judges to be cohesive taxonomist units such as a species or order
Carnassials
large side teeth that allow carnivores to shear meat off their pray (evidence that mammals descend from a common ancestor)
Outgroups
groups of organisms that are outside of the monophyletic group being considered
What is a tree that is most parsimonious?
the tree topology with the least number of character-state changes
Consensus tree
combining hypotheses into one tree-represents the resolved and unresolved portions of the phylogeny
Polytomy
describes an internal node of a phylogeny with more than 2 branches (represents unsolved relationships)
Independent contrasts
a method to minimize error
Neil Shubin
studied tetrapod fossils
-discovered Tiktaalik
What is the name of the clade with coelancanths, lungfishes, and tetrapods?
lobe-fins
-have fishy lobes with stout bones instead of webbed pectoral fins
Horizontal gene transfer
describes the transfer of genetic material other than from parent to offspring - to another organism sometimes distantly related one, without reproduction
Synapsids
mammals and their ancestors
What are the 3 branches of living mammals?
-Monotremes
-Therians = marsupials and eutherians
Monotremes
-produce milk but through a loose network of glands not a nipple
-lay eggs
-platypus and echnida
Marsupials (therians)
-bear live young
-young crawl into pouch after they’re born
-opossums, kangaroos, koalas
Eutherian (therians)
-develop a placenta to feed embryos in the uterus
-humans and mammals
-not higher up than monotremes
Archaeopteryx
an extinct bird that fossils show had teeth in its beak, claws on its wings, and a long reptillian tail
-led to the study of birds descending from dinosaurs
