Macroevolution

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Macroevolution

evolution over geologic time above the level of the species.

Speciation

The process by which a new species evolves

Allele

evolution within a species means a change in that population’s ______ frequency.

hurry up buddy

GO READ POWERPOINT FOR MORE THOUROGH EXPLANATION ON “HOW DO NEW SPECIES ARISE”

Allopatric speciation

when geographical barriers divide a population followed by the development of mechanisms in the separated populations that prevent interbreeding

Geographical

________________ isolation is the most important factor in starting speciation

Reproductive isolation

any factor in nature that prevents interbreeding between individuals of the same or closely related species

Extrinsic

________ isolating mechanism- outside of the organisms in question

Ex. Geographic isolation

Intrinsic

________ isolating mechanism - internal characteristics that prevent interbreeding

Ex. differences in anatomy, physiology and behaviour

Ecological Isolation

When 2 species have different habitats, they will rarely have contact

Ex. Lions and tigers prefer different habitats

Temporal Isolation

2 species that share the same habitat but do not mate within the same time frame

Ex. Plants that release their pollen at different times

Behavioral Isolation

Even if populations are in contact and breeding can occur, they must choose to mate

Ex. mating displays

Mechanical Isolation

reproductive organs differ in size or shape or another feature

Gametic Isolation

even if mating occurs, offspring may not result if there are incompatibilities between sperm and egg, or between sperm and the female reproductive tract

Infertility

Even if offspring develop, they are most often malformed or sterile

Sympatric speciation

occurs when there are no physical barriers preventing any members of a species from mating with another, and all members are in close proximity to one another.

New species can be based on a different food source or characteristic and seems to develop spontaneously

!_!

GO read powerpoint slide 19 for sympatric speciation

hybridization

where the egg and sperm come together to produce offspring

rarely a hybrid is produced

sometimes successful in plants

Polyploidy

a multiplication of the normal number of chromosomes in an organism

often happens in plants that self pollinate

Generalist

those with a diverse diet

Specialist

those with a very specific diet

Adaptive radiation

rapid emergence of species from a single species that has been introduced into a new environment

2 conditions that contribute to speciation

specialization of food source and environment

Migration to a new environment, especially if there is no competition

Phyletic gradualism

evolution occurs by the gradual accumulation of small changes.

The intermediate stages of evolution not represented by fossils merely testifies to the incompleteness of the fossil record

Punctuated Equilibrium

evolutionary history consists of geologically long periods of stasis with little or no evolution, interrupted by geologically short periods of rapid evolution

divergent evolution

occurs when two separate species **evolve** differently from a common ancestor

Convergent evolution

occurs when species have different ancestral origins but have developed similar features