Quiz 1 Flashcards
Great Chain of Being
- Recasting of Aristotle’s Scala Naturae in Judeo-Christian themes
- Hierarchical organization of all life forms
- Organisms fixed in position on the chain
Carl Linnaeus
- Swedish botanist; developed comprehensive classification system for all known plants and animals
- Binomial Nomenclature
Linnaean System
Classification system based on similarities among physical characteristics of species
Taxonomy
The science of classification
Taxon (plural: taxa)
group of organisms in a taxonomy
Linnaean Hierarchy
Kingdom
Phylum
Class
Order
Georges-Louis Leclerc (1707-1788)
French naturalist who proposed species are created via modifications of their original form by environmental factors after creation
Georges Cuvier (1769-1832)
- French naturalist who discovered extinction
- Proposed catastrophism
Catastrophism
Fossils represented species that had gone extinct in cataclysms
Jean-Baptiste Lamarck (1744-1829)
Proposed that ‘use and disuse’ of traits is what drove changes in organismal characteristics through time, ultimately resulting in new species
Principles of Natural Selection
- Traits vary within a population
- Traits are heritable
- Individuals with traits that allow them to survive and reproduce pass those traits on to the next generation
James Hutton (1726-1797)
- Argued that features of ancient rocks could be explained by processes that were operating today, but happen very slowly
- Discoveries supported Deep Time (Earth was very old)
Charles Lyell (1797-1875)
- Proposed uniformitarianism; geological processes have always occurred at uniform rates
- Discoveries supported Deep Time (Earth was very old)
Thomas Malthus (1766-1834)
- Wrote ‘Population’ that emphasized a struggle for existence; populations expand faster than their resources
- Inspired Darwin’s theory of natural selection
Natural Selection
The differential survival and reproduction of individuals due to differences in phenotypes (physical traits)
‘On the Origin of Species’
- Published in 1859; presented evidence that evolution had occurred
- Explained evolutionary change occurs via natural selection
Evolution
Change in the allele frequencies (old: heritable characteristics) of biological populations over successive generations
Blending Inheritance
- 19th century model of inheritance
- Physical characteristics of offspring were a uniform blend of parents
- Refuted: After all traits have been ‘blended’ all variation disappears
Gregor Mendel (1822-1884)
- Augustinian monk who worked out the rules governing the inheritance of traits
- Each trait controlled by single gene
Genotype
Genetic signal
Phenotype
Physical expression (morphology) of the genotype
Gene
Unit of heredity passed from parent to offspring that codes for a particular trait
Allele
One or more alternative forms of a gene
Modern Evolutionary Synthesis
1) Genes are the units of inheritance
2) Phenotype is distinct from genotype. Phenotypes are outcomes of genetic/environmental factors.
3) Evolution is a change in the genetic structure of populations due to mutation, gene flow, genetic drift, and natural selection. Individuals do not evolve, populations do.
4) Speciation results from a gradual accumulation of small genetic changes
5) All organisms form a phylogeny that emerged by the branching of common ancestors into diverse lineages via speciation.
Four forces of evolution
1) Mutation
2) Gene Flow
3) Genetic Drift
4) Natural Selection
All are stochastic except for natural selection which is deterministic
Mutation
Appearance of new alleles
Point Mutation
Change in single base pair
Substitution
Codon swapped for another codon
Inversion
Codon inverted
Insertion
Insertion of a single base pair that shifts the entire sequence (frameshift)
Deletion
Remove of a single base pair that shifts the entire sequence (frameshift)
Genetic Drift
- Random changes in alllele frequencies
- Small population sizes
- Founder effect & bottleneck effect
Directional Selection
Selection for one phenotypes over the others causing phenotype frequencies to shift in one direction
Stabilizing Selection
Selection against the extremes of the phenotypic distribution
Sexual Selection
- Female choice
- Male-male competition
Systematics
The study and classification of organisms to reconstruct their evolutionary relationships with one another
Linnaean Taxonomy
Reflects phylogeny
Clade
A group of organisms that is monophyletic (composed of a common ancestor and all its descendants)
Monophyletic Taxon
Includes all the descendants of a particular common ancestor
Polyphyletic Taxon
Includes species that do not exclusively share a common ancestor
Paraphyletic Taxon
Includes some (but not all) of the descendants from a particular ancestor
Analogous Traits
Similar structures that evolved independently (convergent evolution)
Convergent Evolution
Distantly related species evolve similar features to serve the same function (E.g. bird and bat wings)
Homologous Traits
Shared traits that were inherited from a common ancestor
Primitive traits
Uninformative for sorting out relationships
Derived traits
Evolved in the lineage leading up to a clade and sets members of that clade apart from others
Synapomorphy
A derived trait shared among taxa
Autapomorphy
A derived trait unique to a single taxon
Cladograms
Arrange taxa by relatedness, not ancestry-descent
Anagenetic Speciation
Unbranching lineage of species through geological time
Cladogenetic Speciation
Branching of different species through geological time
Molecular Clock
A systematic accumulation of genetic change (E.g. mutations) that can be used to estimate the time of divergence between two taxa
Sexual Dichromatism
Sex differences in coloration
Sexual Dimorphism
Sex differences in body size or weaponry
Biological Species Concept
Reproductively isolated breeding populations
Morphological Species Concept
Phenotypically distinct evolutionary lineages
Ecological Species Concept
Populations occupying unique ecological niches
Lineage splitting over time
Ecological > Morphological > Biological
Allopatric Speciation
Speciation through geographic isolation
Sympatric Speciation
Speciation in the same geographic location