The Origin of Species

What is the source of biological diversity

The origin of species is the source of biological diversity

What is Speciation

Speciation, is the origin of new species

What is at the focal point of evolution

Speciation

How do new species originate from existing species?

Three populations of species are connected by gene flow

Then a barrier occurs to gene flow is establsish

• An example of a barrier is reproductive barrier (such as different habitats or mating behaviors)

• This barriers causes the popualtion to degin to divereg genetically from the other two populations.

• Gene flow continus between the other two population

• Eventually the population that began to diverage genetically is then reproductively isolated from the other two forming a new species. That can not interbreed with the other two populations.

Macroevolution

Earth’s incredible biological diversity is the result of macroevolution, which begins with the origin of new species.

What did Carolus Linnaues do to define species

Carolus Linnaeus, a Swedish physician and botanist

Used physical characteristics to distinguish species

What did Carolus Linnaues develop

Developed the binomial system of naming organisms

What did Linnaeus system established

It established the basis for taxonomy and is the branch of biology concerned with naming and classifying the diverse forms of life.

What can make defining species difficult

Similarities between some species and variation within a species

Example there is only one specie for humans homo sepians but humans look different with race, hair color, and eyes but still we are one specie while other aniamls look very much alike but are different species

Name all of the species concept

The biological species concept

The morphological species concept

The ecological species concept

The phylogenetic species concept

Biological species concept

Defines a species as a population or group of populations whose members can interbreed and produce fertile offspring

Morphological species concept

Classifies organisms based on observable phenotypic traits

The ecological species concept

Defines a species by its ecological role

The phylogenetic species concept

Defines a species as a set of organisms representing a specific evolutionary lineage

What do reproductvie barriers do

Reproductive barriers keep species separate and serve to isolate a species’ gene pool and prevent interbreeding

What are reproductive barriers cartoizged too

prezygotic and postzygotic

or prezygotic (before fertizlaition) and postzygotic (after fertilization)

Prezygotic barrier

prevent mating or fertitlization between species

In temporal isolation

Habitat Isolation( was not explain on a slide show but on the picutre)

Behavioral isolation

Mechanical isolation

Gametic isolation(was not explained on the slide show but is on the picture)

Temporal isolation

Two species breed at different times. Or Mating or flowering occurs at different seasons or times of day

Behavioral isolation

There is little or no sexual attraction between species, due to specific behaviors.

Mechanical isolation

Female and male sex organs or gametes are not compatible as ther is a sturcual differences in genitalia or flowers prevents copoulation or pollen transfer or mating.

Habitat isolation

Populations live in different habitats and do not meet

Gametic isolation

Male and/or female gametes die before uniting(mating) or fail to unite(mate)

Postzygotic Barriers

Operate after hybrid zygotes are formed and prevent the development of fertile adults(meaning prevent audlt offspring to be fertile to reproduce)

Hybrid inviability

Hybrid sterility

Hybrid breakdown

Hybrid sterility

One postzygotic barrier where hybrid offspring between two species are sterile and therefore cannot mate

An example is a donkey and horse mating to make a mule and a mule is infertile/sterile

Hybrid inviability

Hybrids fail to develop or to reach sexual maturity

Hybrid breakdown

Offspring of hybrids are weak or infertitle

Geographic isolation (allopatric)

Geographic isolation can lead to speciation where in allopatric speciation a population is geographically divided, and new species often evolve.

Also geographic isolation is a major pre-zygotic barrier that stops gene flow and acts as a facilitator for the ecolgocial species concept.

What can reproductive barrier elove to

Reproductive barriers may evolve as populations diverge

An example: is Laboratory studies of fruit flies

• Have shown that changes in food sources can cause speciation

Geographic isolation in Death Valley

Has led to the evolution of new species of pupfish

How can new species also arise

New species can also arise within the same geographic area as the parent species.

Sympatric speciation

New species mayarise without geographic isolation meaning that new species are formed in the same geographic area that is the same as the parent species(which the new speices branched away from). And is where, genetic, behavioral, or ecological barriers evolve without physical isolation. This happens when subpopulations exploit different resources (habitat differentiation), mate selectively (sexual selection), or undergo chromosome changes (polyploidy), preventing interbreeding.

Polyploidy

multiplication of the chromosme number due to errors in cell division and many plant species have evolved by polyplodiy.

The importance of polyploid plants

Polyploid plants clothe and feed us and many plants, inclduing food plants such as bread, wheat, are the result of hybridization and polyplodiy.

Adaptive radiation

Adaptive radiation occurs when mass extinctions or colonization provide organisms with new environments and causes the evolution of new species

An example of adaptive radiation is island chains

Also the occasional hybridzation of finch species may have been important in their adaptive radiation

Peter and Rosemary Grant

Study the evoltuion of Darwin’s finches

and have documented nautral selection acting on populations of Galapagos finches.

Gradualism model

New species evolve by the gradual accumulation of changes brought about by natural selection

Punctuated equilibrium model

Draws on the fossil record where species change the most as they arise from an ancestral species and then change relatively little for the rest of their existence

Macroevolution

Evolutionary novelties may arise in several ways

Many complex structure evolve in many stages

• From simpler versions having the same basic function

Example are the eyes

Exaptation

The gradual adaptation of existing structures to new functions. Other novel structures result from exaptation

“Evo-devo”

is a field that combines evolutionary and developmental biology. And Genes that control development are important in evolution

What are the results of evolutionary transformation

Many striking evolutionary transformation are the result of a change in the rate or timing of developmental changes

What has alo been important in human evolution

Changes in the timing and rate of growth has alo been important in human evoltuion

Evolutinoary trend

Evolutionary trends reflect species selection

The unequal speciation or unequal survival of species on a branching evnoltionary tree.

• Evolutionary trends do not mean that evolution is goal directed