Natural Selection Flashcards
Primary sources of evidence supporting evolution:
- The fossil record
- Comparative morphology
- Biogeography
Fossils and the fossil record
-Traces of past organisms that give a visual of evolutionary change over time
-Can be dated by examining of carbon 14 decay
Comparative morphology
Analysis of structures of living and extinct organisms
Homology
Characteristics in related species that have similarities even if the functions differ
Embryonic homology
Many species have similar embryonic development
Vestigial Structures
Structures that are conserved even though they no longer have a use
Molecular homology
Many species share similar genetic information
Homologous structures
Characteristics that are similar in two species because they share a common ancestor
ex. Arm bones of many species
Convergent evolution
Similar adaptations that have evolved in distantly related organisms due to similar environments
Analogous structures
Structures that are similar but have separate evolutionary origins
Ex. Wings in birds vs bats vs bees
Common ancestry evidence
- Membrane bound-organelles
- Linear chromosomes
- Introns in genes
Biogeography
The distribution of animals and plants geographically
Systematics
Classification of organisms and determining their evolutionary relationships
Taxonomy
Naming and classifying species
Phylogenetics
Hypothesis of evolutionary history
-Use phylogenetic trees to show evolution
To determine evolutionary relationships, scientists use
-Fossil records
-DNA, proteins
-Homologous structures
Phylogenetic trees
diagrams that represent the evolutionary history of a group of organisms, similar to cladograms except trees show the amount of time
Cladograms
-Each line represents a lineage
-Each branching point is a node
-Root is the common ancestor of all the species
Sister taxa
Two clades that emerge from the same node
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Basal Taxon
Lineage that evolved from the root and remains unbranched -
Synapomorphy
A derived character shared by clade members
Derived characteristics: similarly inherited from the most recent common ancestor of an entire group
Ancestral characteristics: Similarity that arose prior to the common ancestor
Monophyletic group
Includes the most recent common ancestor of the group and all of it’s descendants
Paraphyletic group
Includes the most recent common ancestor of the group, but not all of it’s descendants
Polyphyletic group
Doesn’t include the most recent common ancestor of all members of the group
Species
Group able to interbred and produce viable, fertile offspring
Speciation
Formation of a new species
Allopatric speciation
-Physical barrier divides pop. or a small pop. is separated from main pop.
-Populations are geographically isolated
*prevents gene flow
*Often caused by natural disasters
Sympatric
-New species evolves while still inhabiting the same geographic region as the ancestral species
*usually due to the exploitation of a new duty within the population
Speciation occurs due to
- Prezygotic
- Postzygotic
Prezygotic barriers
- Habitat isolation
- Temporal isolation
- Behavorial isolation
- Mechanical isolation
- Gametic isolation
Habitat isolation
Species live in different areas or they occupy different habitats within the same area
Temporal isolation
Species breed at different times
Behavioral isolation
Unique behavioral patterns and rituals separate species
Mechanical isolation
Reproductive anatomy of one species doesn’t work with the anatomy of another species
Genetic isolation
Proteins on the surface of the gametes don’t allow for sperm and egg to fuse
Postzygotic-reduced hybrid viability
genes of different parent species may interact that impair hybrids development or survival
Reduced hybrid fertility
Hybrid can develop into a healthy adult, but is sterile
Hybrid breakdown
The hybrid of the first generation may be fertile, but when they mate again or with another species offspring will be sterile
Microevolution
Change in allele frequencies within a single species or pop
Macroevolution
Large evolutionary patterns
Punctuated equilibrium
Rapid evolution
Gradualism
Slow evolution over hundreds, thousands of years
Divergent evolution
Groups with the same common ancestor evolve and accumulate differences resulting in the formation of a new species
Adaptive radiation
If a new habitat or niche becomes available, species diversifies rapidly
Convergent evolution
Two different species develop similar traits despite having different ancestors
Origins of life
-Earth formed 4.6 billion years ago
-Life suitable 3.9, fossils found 3.6
*cyanobacteria
How did life arise?
Early life contained inorganic molecules, these could have synthesized organic molecules due to free energy and abundant oxygen
Miller and Urey hypothesized
Organic molecules served as building blocks for macromolecules
RNA world hypothesis
Proposes that RNA could have been the earliest genetic material
