33 terms

H Bio Rossi- Everything you need to know about Ch. 14- Origin of Species

- formulated by Darwin
- process by which one species splits into two or more species
- distinct form of life
latin for "kind" or "appearance"
branch of biology that deals with naming and classifying organisms
4 different species concepts
1. Biological Species concept
2. Morphological Species Concept
3. Ecological species concept
4. Phylogenic species concept
(BMEP) or (B-MEP)
Biological Species Concept
- most common
- a group of populations whose members have the potential to interbreed in nature and produce fertile offspring
Morphological species concept
- species classification is based mainly on physical traits
- can apply to asexual organisms and fossils
- disadvantage --> very subjective
Ecological Species Concept
- species is based on ecological needs
- focus on unique adaptions to particular roles in a biological community
Phylogenic Species Concept
- smallest group of individuals that share a common ancestor
reproductive isolation
- different species do not usually mate with each other
- if barriers overcome, then hybrid
Types of Reproductive Barriers
1. Prezygotic Barrier
2. Postzygotic Barrier
prezygotic barrier
- no zygote formation
- mating/fertilization prevented
5 types of prezygotic barriers
1. habitat isolation
2. temporal isolation
3. behavioral isolation
4. mechanical isolation
5. gametic isolation
habitat isolation - prezygotic barrier
2 species that live in the same area, but do not live in the same habitat
temporal isolation - prezygotic barrier
species breed at different times
behavioral isolation - prezygotic barrier
no mate recognition between males and females of different species
mechanical isolation - prezygotic barrier
when male and female sex organs are not compatible
gametic isolation - prezygotic barrier
sperm of 1 species cannot fertilize the egg
reduced hybrid viability - postzygotic barrier
the zygote dies (most hybrid zygotes die)
hybrid fertility - postzygotic barrier
hybrid born; reaches maturity but is sterile
hybrid breakdown - postzygotic barrier
1st gen is fertile but future gen's are not
Mechanisms of Speciation
1. allopatric speciation
2. sympatric speciation
3. adaptive speciation
allopatric speciation
- formation of a new species due to geographic separation
- geographic barriers
sympatric speciation
- a new species arises within the same geographic area as its parental species
- originate via polyploid--> cells have more than 2 complete sets of chromosomes
hybridization of 2 different species
adaptive radiation
- evolution of many diverse species form a common ancestor
e.g.: galapagos finches
- regions in which members of different species meet and mate producing at least some hybrid off spring
- barrier forms separating one population from the others
- 2 populations still intact
- 1 population isolated
Possible Hybrid Zone Outcomes
1. Reinforcement
2. Fusion
3. Stability
Reinforcement Hybrid Zone Outcome
- when the hybrid is less fir, reinforces the barrier to prevent hybrid production
Fusion Hybrid Zone Outcome
- when reproductive barriers between species are not strong and species come into contact in hybrid zone
Stability Hybrid Zone Outcome
- all species continue with no problems
2 rates of speciation
1. punctuated equilibria
2. gradual pattern
punctuated equilibria
long periods of little change, punctuated by abrupt speciation
gradual pattern