Ch. 14 The Origin of Species Flashcards
Taxonomy
The branch of biology concerned with identifying, naming, and classifying diverse forms of life
Biological species concept
A species consists of organisms so smilier in structure/function that they can reproduce fertile offspring.
- sexual species
What does failure of sexual reproduction result in?
1) Prevention of Gene flow
2) Is the gap between species
In what situations does biological species concept not work? Why?
Extinct forms of life and asexual reproducers.
- no gene flow
Speciation
The evolution of a new species
Evolutionary species concept
The definition of a species as a cluster of recognizably distinct organisms that represent a lineage of descent
- may be recognized by genotypic/phenotypic features
- ex. DNA sequence and body structures
Evolutionary history rather than reproductive ability
- represent a genealogy
- applies to sexual, asexual, and extinct
What is classification based on?
Observable and measurable phenotypic traits and DNA analysis
What did Kar von Linne (Carolus Linnaeus) do?
Binomial nomenclature “two name system of naming”
- genus + species
What is a species?
Genetically distinct group of organisms that share a common gene pool
What are the 3 (plus 1) factors of a species?
1) Anatomy (Structure)
2) Physiology (Function)
3) Behavior (Acts)
Plus reproduction
What are the 3 criteria to classification?
1) Observable and measurable phenotypic traits
2) Ability to mate and produce fertile offspring
3) DNA & Protein analysis of genotype
What are 2 types of barriers that prevent inbreeding?
1) Geographical
- physically isolate
2) Reproductive
- biologically isolate
What are the two types of reproductive barriers?
1) Prezygotic
- occurs before fertilization
2) Postzygotic
- prevents the development of fertile adults
What are the 5 types of pre zygotic reproductive barriers?
1) Temporal Isolation
- same general area, different mating time
2) Habitat
- same area but not specific part
3) Behavioral
- little or no sexual attraction
4) Mechanical
- sex organs are not compatible
5) Gametic
- gametes do not unite to form a zygote
What are 3 types of post zygotic reproductive barriers?
1) Hybrid Inviability
- hybrid is too frail, fails to develop or reach sexual maturity
2) Hybrid Sterility
- sterile organisms
3) Hybrid Breakdown
- first generations are okay, but then their offsprings are infertile
What do reproductive barriers form?
Reproductive barriers form boundaries around closely related species to prevent species from losing their identities.
What is the key event of speciation?
Separation of a population from other populations of same species
- gene pool is isolated
Allopatric Speciation
The formation of a new species as a result of an ancestral population’s becoming isolated by a geographical barrier
- depends on the ability of organisms to move about
- creates opportunity for speciation (not guaranteed)
- reestablishes the reproductive barriers between the two populations
- small isolated populations
Adaptive radiation
The emergence of numerous species from a common ancestor introduced to new/diverse environments
Sympatric speciation
The formation of a new species as a result of a genetic change that produces a reproductive barrier between the changed population (mutants) and the parent population
- ex. plant evolution
- polyploid cells
Polyploid cells
A cell with more than 2 complete sets of chromosomes
- meiosis fails, mitosis occurs –> diploid gametes
What are the 2 events required of sympatric speciation?
1) Hybridization of 2 parent species
2) Failure of meiosis in resultant hybrid
Gradualist model
The view that evolution occurs as a result of populations becoming isolated from common ancestral stock and gradually becoming genetically unique as they are adapted by natural selection to their local environment
- Darwin’s view of origin of species
What are the 2 patterns of gradualist model?
1) Divergence of a new lineage
2) Evolutionary changes with unbranched linage
Punctuated Equilibrium
The idea that speciation occurs in spurts followed by long periods of little change
- abrupt divergence of new lineages
- no speciation within unbranched lineage
