exam 1 Flashcards
Natural Selection
The tendency for organisms to have subtle (or dramatic) differences within a population
Variation
Natural Selection
The ability of an organism to pass characteristics on to its offspring
Heredity
Natural Selection
Throughout an organisms life, the traits that are used frequently grow and develop, while those that are used infrequently wither (Lamarck).
Use and Disuse
Natural Selection
1.) Variation within a population2.) Some organisms must have traits that allow them to leave more offspring than those that don’t have those traits3.) The above traits must be passed
Criteria for evolution by natural selection
Natural Selection
Spontaneous changes in DNA, not understood by Darwin when formulating the principles of natural selection
Mutations
Evidence of Evolution
When two organisms possess structural similarities due to a presumed shared ancestry
Homologous traits
Evidence of Evolution
When two organisms share structural similarities despite not sharing an ancestor with those traits (usually a result of occupying a similar niche)
Convergent evolution (analogous traits, homoplasy)
Evidence of Evolution
Domestication of plants and animals that results in dramatic changes in those species.
Artificial Selection
Evidence of Evolution
Examining different species of organisms during fetal development to identify patterns/similarities/differences.
Comparative Embryology
Evidence of Evolution
The idea that most significant changes are ‘instantaenous’ and bookended by long periods of stasis.
Punctuated Equilibrium
Evo Misc.
Random changes in allele frequencies of small populations
Genetic Drift
Evo Misc.
When natural selections favors the extremes of a given trait – causes population to contain individuals exhibiting opposite phenotypes, but very little in-between.
Disruptive Selection
Evo Misc.
An organism’s cells have twice the number of chromosomes when compared to their parents
Autoploid
(example found in plants. Could result in defects of offsprings if chromosomes don’t match up)
Evo Misc.
Two plants (members of different species) hybridize to produce offspring
Allopolyploid
Evo Misc.
When two reproductively isolated, but ecologically similar species come into contact, and natural selection favors individuals that use resources not used by the other species
Character Displacement
Phylogenetics
Which organisms possess the ancestral trait for hair
Lizards, Salamanders, Sharks, Lamprey
all 0 for hair so it is not a derived trait but an ancestral trait
Phylogenetics
includes the most recent common ancestor of the group, but not all descendants
paraphyletic group
Phylogenetics
Includes the most recent common ancestor of the group and all of its descendants
monophyletic
Phylogenetics
does not include the most recent common ancestor of all members in the group
polyphyletic
Phylogenetics
The level of classification that falls between Class and Family
Order
Phylogenetics
A group of species that contains an ancestor, and all of their descendants
Monophyletic
Phylogenetics
If you were to remove lamprey from the character table, what would be the state for jaws in humans?
0 - ancestral
Removing outlier changes the ancestral trait bc the most recent ancestor
Reproductive Isolation
Barriers to reproduction occuring BEFORE fertilization
Prezygotic
Reproductive Isolation
Speciation that occurs when two populations are geographically isolated.
Allopatric
Reproductive Isolation
Speciation that occurs when two populations are not geographically isolated.
Sympatric
Reproductive Isolation
The exchange of genetic material between populations of the same species
Gene Flow
Reproductive Isolation
Two species of flies are unable to mate because they each have different courtship rituals. Females of species 1 will not respond to the courtship of species 2. (more specific than pre-zygotic)
Behavioral Isolation
Misc
Provide 3 reasons for the incomplete fossil record
Lack of hard parts, conditions required for fossilization, availability (surface), distribution
of organisms…..
Misc
Although horses and donkeys are capable of producing hybrid offspring, the mule is sterile, and therefore cannot reproduce.
Infertility (hybrid)
Misc
The amount of time it takes for ½ of a parent isotope to decay into its daughter isotope.
Half Life (3?)
Misc
Organisms are members of the same species when they can interbreed to produce fertile, viable offspring.
Biological Species Concept
Misc
The most significant mass extinction (in terms of % species lost) that we’re aware of.
Permian
Evidence for Evolution
the study of the similarities and differences in the embryos of different Species. Similarities in embryos are likely to be evidence of common ancestry. All vertebrate embryos, for example, have gill slits and tails
Comparative embryology
Evidence for Evolution
unused structures without function.Some structures exist in organisms that have no apparent function at all, and appear to be residual parts from a past common ancestor.
Vestigial structures
Evidence for Evolution
process in which two distinct lineages evolve a similar characteristic independently of one another
Convergent evolution
Evidence for Evolution
accumulation of differences between groups leading to the formation of new species
divergent evolution
Evidence for Evolution
process that measures the radioactive decay of certain elements.
Radiometric dating
Evidence for Evolution
any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group
Transitional fossils
Speciation
If natural selection favors an average phenotype, selecting against extreme variation, the population will undergo
stabilizing selection
Speciation
When the environment changes, populations will often undergo
directional selection
Speciation
Species occur in the same area, but they occupy
different habitats and rarely encounter each other.(i.e. tigers and lions in nature)
Ecological isolation
Speciation
Species differ in their mating rituals.(i.e. birds mating dance vs no dance)
Behavioral isolation
Speciation
Species reproduce in different seasons or at different
times of the day.(i.e. flowers blooming during different seasons)
Temporal isolation
Speciation
Structural differences between species prevent mating
Mechanical isolation
speciation
a rapid increase in the number of species with a common ancestor, characterized by great ecological and morphological diversity
Adaptive Radiation
Speciation
a species is a group of organisms that can potentially interbreed, or mate, with one another to produce viable, fertile offspring.
Biological species concept
Speciation
frequently applied in such cases(fossils), as it relies entirely on morphology (the physical structures or traits of an organism).
Morphological species concept
Speciation
Each species adapted to its environment.
Distinctions among species are maintained by natural selection.
Stabilizing selection maintains the species’ adaptations.
Hybrids are quickly eliminated from gene pool.
In some cases, strong selection overwhelms gene flow.
Ecological species concept
Speciation
defines species as groups of organisms that share a pattern of ancestry and descent and which form a single branch on the tree of life
Phylogenetic species concept
Mass Extinction
around 500 million yrs ago and around 400 families remained
Devonian
Mass Extinction
around 560 million yrs ago and around 325 families remained
Silurian- (ordovican)
Mass Extinction
around 250 million yrs ago and around 200 families remained (largest)
Permian
Mass Extinction
around 200 million yrs ago and around 300 families remained
Triassic
Mass Extinction
around 50 million yrs ago and around 625 families remained
Cretaceous
Mass Extinction
number of species decreasing at an alarming rate due to human activity (current)
6th – Anthropocene
