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