CH.5-Speciation/Macroevolution Flashcards
What’s microevolution?
Changes in allele/genotype frequencies over generations
What’s macroevolution?
Broad patterns of evolution over long time spans (1000 yrs)
What is speciation?
Origin of new species (Stepping stone between micro and macro)
What is a species according to Ernst Mayr?
Population/Group of populations whose individuals can interbreed and produce viable, fertile offspring (Not w/ other species)
What keeps species together when populations are spread out?
1) Gene flow (active between pops of same species)
2) Reproductive isolation (from dif species)
How does gene flow help keep species tgt when populations are spread out?
When individuals from 1 population of species move ==> produce more offspring that help maintain species’ gene pool
Gene pool tends to change due to dif env but gene flow causes gene pool to remain more cte
How does reproductive isolation keep species tgt when populations are spread out?
Prevents mating with other species or production of viable/fertile offspring ==> Prevents mixing w other species’ gene pool
Choose the right answer:
Reproductive isolation that arises between populations of the (same/different) species may lead to the formation of (old/new) species.
same - new
Reproductive isolation is due to barriers preventing mating: What are they?
1) Prezygotic barriers (prior to fertilization)
2) Postzygotic barriers (after fertilization)
What are the types of prezygotic barriers?
1) HABITANT ISOLATION
(EX: Garter snakes live in same geographic area but one lives in water and other on land)
2) TEMPORAL ISOLATION
(EX: Skunks in same geo area but mate in different seasons)
3) BEHAVIOURAL ISOLATION
(EX: Mating calls in frogs unique to ch/ species, unique sequence of lights of fireflies)
4) MECHANICAL ISOLATION
(EX: Genital opening of dif snails are opposite sides)
5) GAMETIC ISOLATION
(EX: Release gametes into water, other species cannot fertilize other species’ eggs)
What are types of postzygotic barriers?
1) REDUCED HYBRID VIABILITY
(EX: Able to have hybrid of 2 species, but frail and can’t reproduce)
2) REDUCED HYBRID FERTILITY
(EX: Mules (donkey+horse) are infertile)
3) HYBRID BREAKDOWN
(EX: First gen is viable but later gens become more sterile)
Species concept cannot be applied to what?
1) Fossils (Can’t tell which groups mate successfully)
2) Asexually reproducing organisms
What are the other definitions of species?
1) Morphological species concept
2) Ecological species concept
3) Phylogenetic species concept
Morphological species concept:
1. Species defined by ——
2. Can be used for ——- and ——-
3. —— criteria
- physical features
- all living organisms and fossil remains
- subjective
Ecological species concept:
1. Defined by its ——. How it —– with other living organisms and the ———-
2. Can be applied to —– but not —-
- ecological niche — interacts —– physical environment
- all living organism —- fossil remains
Phylogenetic species concept:
1. Species defined by —— in —– and physical ——
2. Can be applied to —–, DNA not usually available for —–
- similarity in DNA — morphology
- all living organisms — fossil remains
How do new species arise?
Gene flow must stop between populations of existing species ==> Separated pops must be exposed to dif pressures
What are the modes of speciation?
1) Allopatric speciation
2) Sympatric speciation
What does allopatric mean?
Different country
What’s allopatric speciation?
Reproductive isolation due to physical environmental barrier ==> New species due to physical barrier separating pops of existing species
What’s sympatric speciation?
Reproductive isolation between individuals in same area ==> New species in same geo area due to formation of reproductive barriers
What does sympatric mean?
In same country
For sympatric speciation, reproductive isolation between 2 pops in same geo area can arise due to:
1) Chromosomal changes
2) Habitat differentiation
3) Sexual selection
What is chromosomal changes is sympatric speciation?
New species formed when viable/fertile polyploid offspring is created ==> Isolated form parent kind reproductivelyW
What is habitat differentiation in sympatric speciation?
Genetic variation within a pop allows individuals to exploit a habitat/resource not used by rest of pop
What is sexual selection?
Select mate by characteristic, certain features
What is speed of speciation?
Species appear to remain relatively the same over long periods then new species arise
What is Punctured Equilibrium?
Speciation occurs rapidly during moments when environmental pressures change
What are the 2 types of patterns that can happen in time course of speciation?
1) Punctuated pattern (drastic change)
2) Gradual pattern (gradual change)
