Intro - First Chimp Fossil Flashcards
Anaximander (611-547 BCE)
- Didn’t think species were unchanging
- Thought some species of fish were intermediate
- Concluded: humans MUST be descended from another species
Plato (424-348 BCE)
- Species = type or kind of animals or plants
- Have essential nature (essence)
- Are unchanging
Medieval Europe
“Great Chain of Being” = unchanging nature of classes of humans and animals
- Fixed hierarchy (within nature - lower and higher (humans = top) forms of life)
- Elite at top (royalty & clergy)
- Ranked by degree of perfection
- Each is a product of special creation
- No intermediate forms = no mobility between classes
Ernest Mayr (1904-2005)
Biological Species Concept “BSC”
- Species is a reproductive community of individuals = find mates within own species & don’t usually mate outside own species
- Resemble each other = closely related to each other (heredity)
- No platonic essence
- Species CAN change over time
Denis Diderot (1713-1784)
“Enlightenment”
- Empiricism
- Obtain knowledge by observing nature
- Not by tradition, authority, or scripture
Carolus Linneus (1707-1778)
Swedish Naturalist
- Taxonomy & classification
- Binomial nomenclature = two names for individual species i.e. genus & species name
- Species NOT unchanging
Montesquieu (1689-1755)
- One species can give rise to another
- Number of species can increase over time
- Tree of Life = shows extinction & process of species over time
Erasmus Darwin (1731-1802)
Charles Darwin’s grandfather
- Wrote books about evolution in verse; “Zoonomia”, “Phyologia”, “The Temple of Nature”
- All vertebrae animals = similar body structure form due to descent from common ancestor
- Bilateral Symmetry = equal on both sides of body
- Pentadactyl = 5 digits -> fingers and toes for humans
Lamarck (1744-1829)
- True = one species can give rise to another species
- False = mechanism -> inheritance of acquired characteristics; characteristics acquired during animal’s lifetime passed on to offspring
Archbishop Ussher (1625-1636)
- Biblical Chronology = counted generations in books of Old Testament
- Concluded: world was created on the evening of Sunday October 23rd, 4004 BC (now know the earth = 4.5 billion years old)
Cuvier & “Catastrophism” (1769-1832)
- How to explain fossils = successive groups of fossils, periodic extinctions & creations (catastrophes), “antediluvian” = before the flood (not a divine creation)
Hutton & Uniformitarianism (1720-1790)
- Present is the key to the past
- Processes observed today
- Operating over long periods of time
- Can produce geological features observed in the modern world
Charles Lyell (1797-1875)
The Principles of Geology (1830) = systemized all fields of evolution
- Earth history
- Gradual change
- Long period of time
Charles Darwin (1831)
The Origin of Species
- The Beagle Voyage = looked at details of coastal South America -> fauna and marine life
- Observation #1: extinct animal fossils resemble living ones in the SAME region
- Observation #2: geographic variation = birds similar, but different types live on different islands; overall similarity = common ancestor; superficial differences = beaks/plumage: adaption to local conditions
Darwin’s Ideas of Evolution
1837: began notebooks kept on Transmutation of Species
1. Evolution = descent with modification (transmutation of species); takes place over generations; needs a LONG period of time; earth changes -> animal & plants change (adaption)
2. Natural selection (mechanism) = sexual reproduction produces variation among offspring (not all offspring are a like); some offspring are better suited to conditions than others -> produce more offspring than others (FITNESS = reproductive fitness); over many generations produce enough change to result in a new species -> “struggle for survival”, “elimination of unfit”, or “differential reproduction”
Adaption
“Goodness” of fit of an organism with its environment = result of natural selection
Thomas Malthus (1766-1834)
An Essay on the Principle of Population
- More offspring produced than resources can support
- Periodically eliminated by warfare, disease, & famine
Wallace (1823-1913)
Independently came up with the idea of evolution (1856)
- Checks on human population growth (war, disease, famine, etc.) also apply to animals
- Variety in nature is affected by this process
- Can account for change through time
Artificial Selection
Produces a variety of domestic animals
1. “Selective breeding” = people control which animals breed -> humans are the fate of offspring vs. “natural breeding” = nature controls which animals breed -> nature is the fate of offspring
Microevolution
Small changes (gene frequencies) within populations over a short period of time (few generations)
Macroevolution
Large changes (appearance of new species & extinction) over a long period of time (many generations)
Mendel & Genetics (1822-1884)
1940s = Darwin + Mendel + Statistics = “New Synthesis” -> looking a populations rather than individuals
- “Particulate” nature of inheritance
- Gene (particles) in pairs
- One gene inherited from each parent
- Genes = alleles; & can be dominant or recessive
Allele
Different versions of genes; one inherited from each parent
Dominant
Expressed gene
Recessive
Gene not expressed
Homozygous
Same allele
Heterozygous
Different allele
Genotype
Genetic code
Phenotype
Expression of gene in an organism (physically)
Changes of Allele Frequencies (Microevolution)
- Mutation = changes in allele
- Natural Selection = positive selection -> “directive” selection & negative selection -> “purifying” selection
- Genetic drift = small population -> chance elimination of new alleles
- Population bottleneck or founder effect = small founding population -> may not resemble parent population (less variation than parent population & receive different alleles)
- Assortive mating = mate selection is NOT random -> share a common allele (allele resembles itself)
- Inbreeding = close relatives are MORE likely to share alleles (more likely to inherit double alleles -> if recessive they will be expressed)
- Gene flow = population movement; migration introduces new alleles (one population moves into an area of another population causing interbreeding)
4 Basic Kinds of Evolutionary Events (Macroevolution)
- Stasis = lineage shows no change
- Extinction = lineage terminates
- Anagenesis = gradual evolution within lineage (one species giving rise to the next)
- Cladogenesis = splitting of lineage (species 1 being split into 2 daughter species -> no relation between daughter species)
Cladogenesis: How does splitting occur?
- Allopathic Model = species isolated geographically
- Sympatric Model = species live in same area, use different resources (different adaptions occupy different niches or “niche partitioning”) -> do not compete for resources (separate species in same environment)
Isolating Mechanisms
- Morphological differences (i.e. hair color, body shape, etc.)
- Genetic incompatibility (mating would be a failure at fertilization or implantation)
- Behavioral differences (i.e. posture, vocalizations, etc.) -> important among primates
- Mates recognition = both morphological & behavioral traits (species mate recognition system “SMRS” = Hugh Paterson)
Tempo of Microevolution
- Gradual change (Darwin) = slow accumulation of changes creates new species
- Punctuated Equilibria = long periods of no change -> rapid evolutionary change in short period of time -> new species appears suddenly
Special Cases of Tempo (Microevolution)
- Adaptive radiation = sudden appearance -> many closely related species (species giving rise to another species)
- Mass extinction = global cause
Synapomorphy
Shared derived traits
Autapomorphy
Unique traits
Homoplasy
Similarities due to convergent evolution
Homology
Similarities due to common ancestor
Taxon (pl. Taxa)
Any named group in Linnaean classification (i.e. genus, species, family); classified by anatomical similarities; taxa grouped by hierarchy
Classification of Humans
Kingdom = Animalia Class = Mammalia Superfamily = Hominoidea Family = Hominidae Subfamily = Homininae Genus = Homo Species = sapiens Subspecies = sapiens
Systematics
Linnaean system = shows overall similarity
Charles Darwin = species are similar due to common descendent
Willi Hennig = classification should reflect phylogeny (evolutionary relationships); names matter
Cladistics
Goal = to reconstruct evolutionary relationships Methods = identify monophyletic groups (defined on basis of shared derived traits) and clades
Clade
Same group including common ancestor which may not be known
Monophyletic Group
Group of species that descend from a common ancestor; more closely related to each other than species outside the group
Primitive Traits
Evolved long ago; now found among groups only DISTANTLY related
-> derived traits
Evolved more recently, reflect closer evolutionary relationships -> polarity (which is primitive, which is derived)
Shared derived traits -> used to define monophyletic groups (clades)
Problems with using Overall Similarities to Determine Relationships
- Primitive Retentions = some characteristics retained from distant ancestor; not useful for establishing more recent evolutionary relationships
- Convergence = similar traits can evolve in distantly related species; reflect adaptions to similar conditions, not evolutionary relationships
