multiplication of species

8/3/2019 Multiplication of Species

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Multiplication of species

Aguilar, Veronica

Alonso, Alejandro

Angeles, VeronicaBaldoria, Avram

Bandales, Antonio


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Species

A group of interbreeding individual s of common

ancestry that are reproductively isolated from all

other such groups

Descent of all members from a common ancestral

population forming a lineage of ancestor-descendant

populations

Reproductive compatibility within and reproductive

incompatibility between species for sexually

reproducing animals

Maintenance within species of genotypic and

phenotypic cohesion


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Speciation

Formation of new species


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Reproductive barriers

Biological features that prevent different species

from interbreeding

If diverging populations reunite before

reproductive barriers have evolved, interbreeding

occurs between the population and they merge

Result from evolution and refer to various

behavioral, physical, physiological and ecologicalfactors

Behavioral barriers evolve faster than the others


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Premating barrier

Cause members of

divergent populations

either not to recognize eachother as potential mates or

not to complete the mating

ritual succesfully

Sibling species different

species that are

indistinguishable in

organismal appearance

Postmating barriers

Reproductive barrier that

impairs growth and

development, survival orreproduction of hybrid

individuals


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Geographical isolation followed by gradual

divergence most effective way for

reproductive barriers to evolve

Geographical separation prerequisite for

branching speciation


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Geographical barriers

Spatial separation of two populations

Prevent gene exchange

Usually a precondition for speciation


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Allopatric Speciation

Allopatric in another land population of

species that occupy separate geographical

areas

Resulting speciation if populations are

allopatric immediately preceding and during

evolution of reproductive barriers between

them


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Ernst Mayr

Contributed greatly to our knowledge of

allopatric speciation through his studies of

speciation in birds


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Vicariant speciation

Climatic or geological changes fragment a

speciess habitat, producing impenetrable

barriers that separate different populations

geographically


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Consequences of Vicariant speciation

Vicariant process does not induce genetic

change

Same vacariant events may fragment several

different species simultaneously


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Founder event

Dispersal of organisms from an ancestral

population across a geographic barrier to start

a new, allopatric population

New population has a very small size which

can cause its genetic structure to change

quickly


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Founder effect

Change in the genetic

constitution of a newly

founded populationbecause of a small number

of founders

Founder-induced speciation

Subset of founder eventsin

which a founder effect

hastens species-leveldivergence of the newly

founded population


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Hybridization

Occurrence of mating between divergent

population

Hybrids- offspring of these matings


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Nonallopatric speciation

Sympatric speciation

same land

Different individualswithin a

species becomespecialized

for occupying different

components of the

environment

Parapatric speciation

Geographically intermediate

between allopatric and

sympatric speciation


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Adaptive radiation

Production of ecologically diverse species

from a common ancestral species

multiplication of species

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