Origin of species Flashcards
What is a species?
group of organisms whose members can breed and produce fertile offspring
What is speciation?
the emergence of a new species
What is micro evolution?
Changes on the small scale, frequency of individual alleles within species and populations.
differences between individuals
What is macro evolution?
Evolution on the grand scale, branching out of new species and larger groups
What are the two basic patterns of evolutionary change?
Anagenesis and Cladogenesis
What is anagenesis?
Phyletic evolution.
accumulation of changes that gradually transform a given species into a species with different characteristic
What is cladogenesis?
Branching evolution
one or more species arising from the original species ( a splitting of a lineage)
What is reproductive isolation?
Existence of biological factors that impede members of two species from producing viable, fertile hybrids
prezygotic barriers and postzygotic barriers
What are prezygotic barriers?
Impede mating between species or hinder the fertilization of ova if members of diff species attempt to mate
What are postzygotic barriers?
Prevent hybrid zygote from developing into a viable, fertile adult
What is temporal isolation? (Prezygotic)
Species breeding at different times ( different seasons or times of day)
What is habitat isolation?(Prezygotic)
Species found in different habitats but in same area that rarely come across each other even though there are no obvious physical barriers
What is beavioural isolation?(Prezygotic)
Every species has its own mating rituals and behaviours and because of this, different species will not attract each other which prevents them from mating
What is mechanical isolation?(Prezygotic)
When male and female sex organs are not compatible, fertilization cannot occur
What is Gametic isolation?(Prezygotic)
Gametes will not unite to form a zygote
What is hybrid inviability? (postzygotic)
zygote forms, but dies after a few series of cell divisions (genetic info from male and female parent were insufficient to carry the organism through morphogenesis)
What is hybrid sterility? (postzygotic)
When the offspring of two parents cant reproduce (offspring are sterile)
What is hybrid breakdown? (postzygotic)
When the first generation of hybrids can reproduce, but the next generation of hybrids is sterile or the individuals cannot survive
What are the two ways speciation can occur?
Allopatric speciation and sympatric speciation
What is allopatric speciation?
A population forms a new species while geographically isolated from its parent population
- one large pop split into two, separated by physical barrier (no gene flow)
- two populations diverge from eachother due to genetic drift, selection, mutation
What is sympatric speciation?
A population becomes a new species without geographic separation
- occurs in groups tat occupy the same geographic area (gene flow)
- groups diverge from each other through natural selection despite gene flow
- ex. apple maggot flies
What is dispersal?
Colonization of a new habitat different than original
-island biogeography
What is Vicariance?
one population is separated into two due to landscape changes ( change in river course)
What is Polyploidy?
species have more than two sets of chromosomes in cells due to accidents during cell division
- reproductively isolated from their non-polyploid parent species.
-rare in animals, common in plants
ex potato, seedless watermelon, kiwi, wheat, atlantic sturgeon, sugarcane
