Chapter 18: Evolution Origins Flashcards
Theory
an explanation of collected data and facts
Darwin & Wallace
Independently developed the idea of natural selection
immutability
Things not changing
Natural selection
the process by which a selective force causes individuals in a pop. to survive & reproduce to a greater degree than others,
Happens to individuals
Leads to adaptive evolution & evolutionary change.
Fitness
the level of ability to survive and reproduce
Evolution
A change in genotype frequencies in a population over time.
Happens to populations
Natural selection standards
- Genetic variation (mutation, sexual reproduction)
- Selective Force (alteration in background, parasite presence, etc.)
- This causes differential survival that leads to differential reproduction. That some individuals are more successful at reproduction for a reason.
- Leads to genotype frequency alterations in a population.
Adaptation
any trait that makes the organism more likely to survive/reproduce
Improves fitness
Fecundity
Helps measure reproductive success by counting the number of surviving offspring
Trait adaptiveness
Whether or not a trait is adaptive, depends on the environment the organism finds itself in.
Divergent evolution
When two species (or more) evolve from a common ancestor.
Convergent evolution
Similar conditions can cause the evolution of similar traits – even in unrelated organisms
Ex. Long mouths
Evidence of evolution
Fossils
Anatomy & Embryology
Biogeography
Molecular Biology
Misconceptions of evolution
Evolution is ‘just a theory’
Individuals evolve
Evolution explains the origins of life
Organisms evolve on purpose
Homologous structures
structures that have similar parts due to shared common ancestry, which may or may not have similar functions.
Ex. Arms in humans and birds
Vestigial structures
Structures that have no apparent function and are likely due to evolution from an ancestor that had a function for that structure.
Microevolution
Changes within a species
Ex. Pocket mouse coat evolution
Macroevolution
Formation of a new species from pre-existing species.
Ex: Modern dog species from ancestral wolf species
Biological species
Population whose members can interbreed in nature & produce fertile offspring.
Morphological species
defines species by physical traits; doesn’t require mating
Ecological species
defines species by their role within the environment
Phylogenetic species
any group of organisms that have shared common ancestry, also may use morphology (physical traits)
Medical/micro species
Designated by biochemical, other phenotypic criteria & DNA relatedness, which groups strains on the basis of their overall genetic similarity.
Speciation
When one group of organisms becomes isolated and evolves enough to become their own species.
Allopatric speciation
When two populations are physically separated
Form of geographic isolation
Happens gradually
Sympatric speciation
Organisms become species through adaptation to different parts of the geographic space
Despite same behavior/organism, different mating behaviors can develop bc of selective factors
Reproductive isolation
Happens when two populations are no longer able to reproduce with each other
Causes rapid speciation
Broken up into 2 barriers: prezygotic and postzygotic
Prezygotic barrier
Mating behavioral diff.
Breeding @ diff. times
Live in diff. habitats
Mechanical and gametic isolation
Mechanical isolation
Form of pre zygotic reproductive isolation
Ex. mating structures are not compatible
Gametic isolation
Gametes unable to join
Form of pre zygotic reproductive isolation
Post zygotic barriers
Hybrids occur: these offspring between populations cannot survive or are not able to reproduce
Hybrid zones
Regions in which two species have the opportunity to meet, mate, and produce some offspring Types: Reinforcement Fusion Stability
Reinforcement
When hybrids are less fit (don’t survive or reproduce well) than parental species – maintains species
Fusion
When hybrids are more fit than parental species causing two species to fuse into one
Stability
When hybrids continue to be produced and are maintained
Geographic isolation
Large geographic formations isolating populations, like a mountain
Includes allopathic speciation
May contribute to reproductive isolation
Abiotic factors
Can act as a selective factor in survival
Ex. Air, soil, temp
Biogeography
How living organisms are positioned in geological spaces
Molecular Biology
All living things have the same DNA molecule & undergo protein synthesis.
Anatomy & embryology
Shared and conserved embryological development
