Biology Exam 2: #1 Flashcards
Genetic Isolation
barrier to gene flow that isolates populations; REQUIRES REPRODUCTIVE ISOLATION
Sexual Reproduction
Union of Sperm and Egg
Prezygotic Isolation
isolation occuring before the zygote forms more complex cellular structure
Prezygotic Isolation where mating cannot typically occur
Mechanical Isolation
Mechanical Isolation
physically impossible for breeding to occur
Examples of mechanical isolation
- snails having male/female reproductive parts(shells and bodies) that do not line up to let reproduction happen
- “lock and key” mismatch: Carabidae ground beetles, where each male has a copulatory(male reproductive piece) that only fits the opening of females of the same species
Prezygotic Isolation instances where mating can occur, but doesn’t for a range of reasons
Habitat(Ecological) Isolation, Behavioral Isolation, and Temporal Isolation
Habitat(Ecological) Isolation
organisms live in same location, but some ecological factor(habitat preferences for breeding and feeding) differs between them which prevents mating
Examples of Habitat(Ecological Isolation)
- Anole Lizards: Anolis sagrei(Tree) and Anolis homolechis(Ground)
- Toads: live in same habitat but breeding in stream/ditches(Woodhouse Toad) vs. in ponds(American Toad)
Behavioral Isolation
some aspect of behavior differs between groups of organisms that prevents mating; this could be differences in songs/calls, ritualized movements, and flying displays
Examples of Behavioral Isolation
- Lacewings: different species have different calls males make through vibrations
- Anole Lizards: difference in dulaps and species specific movements for males to attract females
- fireflies: individual light pusles and paths made by males to attract females on ground
(RISKS involved, like being taken out by a predator)
Temporal Isolation
breeding period of similar closely related species occurs at different times of the year; prevents interbreeding
Example of Temporal Isolation
Spring field cricket(spring breeder) and fall field cricket(fall breeder)
Mating occurs, but there is NO fertilization
Isolation by prevention of Gamete Fusion
Isolation by prevention of Gamete Fusion
sperm and egg cannot form, sperm cannot penetrate egg, toxic uterine environment(uterus kills sperms of wrong species)
Post Zygotic Isolation
after zygote forms, offspring don’t survive or are not capable of successful reproduction
Post Zygotic Isolation where mating and successful fertilization occurs, and zygote forms, but issues arise
Hybrid Inviability, and Hybrid Infertility and Sterility
Hybrid Inviability
accumulation of genetic issues resulting from mismatch sperm/egg; zygote offspring die before or soon after birth
Example of Hybrid Inviability
Ring-necked Dove and Rock Pigeon mating leads less than 6% of eggs to hatch and nearly all die
Hybrid Infertility/Sterility
offspring produced by breeding of closely related species survive to adulthood, but are sterile/infertile
Example of Hybrid Infertility/Sterility
Horse and Donkey create mules(infertile) and Tiger and Lion(typically occurring in zoos where offspring are sterile)
Partial Isolation
individuals that bred with members of other population have LOW offspring survival and fitness; not sustainable long term(since reproduction is energetically expensive; would be wasted energy and effort)
