Lecture 3: Speciation Flashcards
Define macroevolution?
broad patterns of evolutionary change above the species level (ex: origin of new species)
Define what is speciation?
formation of a new and distinct species in the course of evolution. (*evolution of reproductive isolation)
What forms a conceptual bridge between Marco and micro evolution?
speciation
why does name species and identifying them are an issue?
-NO universal definition
-species concept
What are the two species concept?
-morphological species concept
-biological species concept
What is the principle of morphological species concept?
-distinguish by body shape
-structural features
-emphasize pattern or appearance
-convergent evolution
Why morphological species concept is an issue?
-subjective criteria
-not reliable
-some different species can look alike
What is the principle of biological species concept?
-group of members who have the potential to interbreed
What is the main problem with the biological species concept?
-Don’t apply to all situations
need to think about fossiles? asexual organism? hybridization?
What is the solution to identify species?
to use binomial nomenclature
What are two processes occurring during speciation?
-identical populations must diverge (genetic composition)
-Reproductive isolation must evolve to maintain these differences
What is a type of agent of evolution that erase any genetic differences?
gene flow
what is the goal of achieving genetic isolation?
so new species can arise
what are the two conditions for new species to arise?
-allopatric speciation
-sympatric speciation
What is the principle of allopatric speciation?
(3 points)
-population living in different locations
-physical barrier blocks gene flow
-population evolves differently
If the population where bring back together would they be able to interbreed?
no
if the population is small what agent of evolution will allow divergence?
genetic drift
What are examples of instances of allopatric speciation?
-geographical isolation
-continental drift
What is the main effect of geographical isolation?
-colonization of remote areas by one or few individuals
-barries to movement – split ancestral population
-Extinction of intermediate populations
What is the principle of sympatric speciation?
-speciation within the same area
-disruptive selection
-polyploidy creates new species
What is polyploidy?
-organism with an extra set of chromosomes
-chromosome can replicate but can’t seperate
In what kingdom polyploidy is common?
plants
Does different policy can reproduce?
no
What is reproductive isolation during speciation process?
gene flow must be restricted during that time
What are the two mechanisms of reproductive isolation?
-prezygotic
-postzygotic
What is prezygotic mechanisms?
mechanism that prevents formation of zygotes
What is postzygotic mechanisms?
mechanism that prevent the proper development of zygotes after they are formed
What are 5 examples of reproduction Barries for pre zygotic mechanisms?
-geographical isolation
-ecological isolation
-behavioural isolation
-mechanical isolation
-prevention of gamete fusion
What is geographical isolation?
separated by physical barriers – gene pool will remain separate
What is behavioural isolation?
-sympatric species avoid mating with wrong species
In behavioural isolation what are the 3 hints that they have found the wrong species?
-visuals signals
-sound production
-pheromones
What is ecological isolation?
occupying different habitat – will never encounter
What is temporal isolation?
reproduce in different seasons or different time of the day
What is mechanical isolation?
can’t reproduce due to structural differences
What is prevention of gamete fusion?
gametes function poorly with the gametes of other species
What are post zygotic mechanisms?
-hybrid inviability
-hybrid breakdown
-hybrid sterility
How does post zygotic prevent zygote from developing? (3 points)
-structures
-functions
-development abnormalities
What is hybrid inviability?
when fertilization can’t occur
when hybrid can’t reach maturity to breed
What is hybrid sterility?
if they develop they may be sterile
What is hybrid breakdown?
when the first generation is vigorous and can reproduce but the offspring’s are weak and often die
What is adaptive radiation?
when species find themselves in a new/sudden changed environment – evolution of new traits will allow individuals to use certain part of the environment that wasn’t used before
What is the role of natural selection and niche adaptation in reinforcing speciation?
they promote divergence between populations and they reduce gene flow – ensuring that emerging species remain distinct and they don’t merge back into a single population
