Biology Exam 2: #1

Question 1

Genetic Isolation

Answer 1

barrier to gene flow that isolates populations; REQUIRES REPRODUCTIVE ISOLATION

Question 2

Sexual Reproduction

Answer 2

Union of Sperm and Egg

Question 3

Prezygotic Isolation

Answer 3

isolation occuring before the zygote forms more complex cellular structure

Question 4

Prezygotic Isolation where mating cannot typically occur

Answer 4

Mechanical Isolation

Question 5

Mechanical Isolation

Answer 5

physically impossible for breeding to occur

Question 6

Examples of mechanical isolation

Answer 6

• 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

Question 7

Prezygotic Isolation instances where mating can occur, but doesn’t for a range of reasons

Answer 7

Habitat(Ecological) Isolation, Behavioral Isolation, and Temporal Isolation

Question 8

Habitat(Ecological) Isolation

Answer 8

organisms live in same location, but some ecological factor(habitat preferences for breeding and feeding) differs between them which prevents mating

Question 9

Examples of Habitat(Ecological Isolation)

Answer 9

• 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)

Question 10

Behavioral Isolation

Answer 10

some aspect of behavior differs between groups of organisms that prevents mating; this could be differences in songs/calls, ritualized movements, and flying displays

Question 11

Examples of Behavioral Isolation

Answer 11

• 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)

Question 12

Temporal Isolation

Answer 12

breeding period of similar closely related species occurs at different times of the year; prevents interbreeding

Question 13

Example of Temporal Isolation

Answer 13

Spring field cricket(spring breeder) and fall field cricket(fall breeder)

Question 14

Mating occurs, but there is NO fertilization

Answer 14

Isolation by prevention of Gamete Fusion

Question 15

Isolation by prevention of Gamete Fusion

Answer 15

sperm and egg cannot form, sperm cannot penetrate egg, toxic uterine environment(uterus kills sperms of wrong species)

Question 16

Post Zygotic Isolation

Answer 16

after zygote forms, offspring don’t survive or are not capable of successful reproduction

Question 17

Post Zygotic Isolation where mating and successful fertilization occurs, and zygote forms, but issues arise

Answer 17

Hybrid Inviability, and Hybrid Infertility and Sterility

Question 18

Hybrid Inviability

Answer 18

accumulation of genetic issues resulting from mismatch sperm/egg; zygote offspring die before or soon after birth

Question 19

Example of Hybrid Inviability

Answer 19

Ring-necked Dove and Rock Pigeon mating leads less than 6% of eggs to hatch and nearly all die

Question 20

Hybrid Infertility/Sterility

Answer 20

offspring produced by breeding of closely related species survive to adulthood, but are sterile/infertile

Question 21

Example of Hybrid Infertility/Sterility

Answer 21

Horse and Donkey create mules(infertile) and Tiger and Lion(typically occurring in zoos where offspring are sterile)

Question 22

Partial Isolation

Answer 22

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)