Ch. 14 The Origin of Species Flashcards Preview

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Flashcards in Ch. 14 The Origin of Species Deck (25):


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



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