BI111 Study Guide - Parapatric Speciation, Sympatric Speciation, Allopatric Speciation

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Published on 20 Apr 2013
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WLU
Department
Biology
Course
BI111
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Chapter 19 13-03-03 1:59 PM
Biological species concept: the definition of species based on the ability of
populations to interbreed and produce fertile offspring.
Problems: some species reproduce asexually.. so are these not species…?
What about androdioecous organisms (all males) and gynogenetic organisms
(all female)
What about hybridization? Is the hybrid a new species? Are the two species
one?
Phylogenetic Species concept: defines a species as a group of organisms
bound by a unique ancestry.
Ecological species concept: defines a species as group of organisms that
share a distinct ecological niche (occupy the same location with the same
resources)
Morphological species concept: is the idea that all individuals of a species
share measureable traits that distinguish them from individuals of other
species.
There are total of 12 concepts
Ring species: some plants and animals have ring shaped geographic
distribution that surround uninhabitable terrain. Adjacent species of these
ring species can exchange genetic material directly, but gene flow between
distant populations occurs only through intermediary populations.
Clinal (cline) variation: a pattern of smooth variation along the
geographic gradient
Usually results from gene flow between populations… you can “see” the
evolution along a line…. Can be very different at the ends.
Allopatry (allopatric speciation): the evolution of reproductive isolating
mechanisms between two populations that are geographically separated.
Parapatry (parapatric speciation): speciation between populations with
adjacent geographical distributions.
Sympatry (sympatric speciation): speciation that occurs without the
geographic isolation of populations
Sympatric: occupying the same spaces at the same time
Species cluster: a group of closely related species recently descended from
a common ancestor.
Hybrid zone: a geographic area where the hybrid offspring of two
divergent populations or species are common
Autopolyploidy: the genetic condition of having more than two sets of
chromosomes from the same parent species. P 458
Allopolyploidy: the genetic condition of having two or more complete sets
of chromosomes from different parent species. P 458
Cohesiveness of species:
(biological species concept) a species is kept together by is gene flow (like
glue)
(morphological species concept) species share the same visible traits
distinctiveness of species:
(bio species concept) species are differentiated by the inability to breed
between species.
(morphological species concept) different traits are visible and determine
different species… is used in the identification of fossils.
Gene flow 1: many organisms are widely but sparsely distributed.. is gene
flow a cohesive force?
Gene flow 2: with the ability to measure gene flow and relatedness, we can
better appreciate geographic distribution.
Gene flow 3: social behavior of mice(ie) causes mice not to interbreed,
even though they can and live in the same niche
Gene flow 4: changes in the environment cause gene flow/ adaptive
radiation/ distribution
Reproductive isolating mechanisms:
Prezygotic (premating) mechanisms:
Ecological isolation>>species live in different habitats
Temporal isolation>> species breed at different times
Behavioural isolation >> species cannot communicate
Mechanical isolation>> species cannot physically mate
Gametic isolation>> species have non-matching receptors on gamaes (they
can try but the sperm and egg don’t recognize ech other)
Postzygotic (postmating) mechanisms:
Hybrid inviability>>hybrid offspring do not complete development
Hybrid sterility>> hybrid offspring cannot reproduce
Hybrid breakdown>> have reduced survival or fertility

Document Summary

Biological species concept: the definition of species based on the ability of populations to interbreed and produce fertile offspring. What about androdioecous organisms (all males) and gynogenetic organisms (all female) Phylogenetic species concept: defines a species as a group of organisms bound by a unique ancestry. Ecological species concept: defines a species as group of organisms that share a distinct ecological niche (occupy the same location with the same resources) Morphological species concept: is the idea that all individuals of a species share measureable traits that distinguish them from individuals of other species. Ring species: some plants and animals have ring shaped geographic distribution that surround uninhabitable terrain. Adjacent species of these ring species can exchange genetic material directly, but gene flow between distant populations occurs only through intermediary populations. Clinal (cline) variation: a pattern of smooth variation along the geographic gradient. Usually results from gene flow between populations you can see the evolution along a line .