Speciation

Question 1

speciation preserves

Answer 1

differences because specialized populations no longer interbreed

Question 2

environment determines local conditions which influences

Answer 2

adaptive evolution and degree of isolation

Question 3

environment cahnges over space and time so that

Answer 3

populations may experience different selection pressures (which change) and population isolation (which may change)

Question 4

population isolation leads to

Answer 4

population divergence

Question 5

population divergence leads to

Answer 5

speciation

Question 6

within a collection of populations each population is influenced by

Answer 6

local conditions

Question 7

populations can diverge, but what overcomes small differences between populations

Answer 7

gene flow

Question 8

what happens if populations become isolated

Answer 8

gene flow stops (genetic isolation), divergence of populations, and speciation - genetically independent

Question 9

allopatric speciation

Answer 9

speciation that begins with geographic isolation

Question 10

two types of allopatric speciation

Answer 10

dispersal or vicariance

Question 11

dispersal

Answer 11

Founder effect - members of population colonize a new space, which may change allele frequencies and course of natural selection

Question 12

vicariance

Answer 12

a physical barrier divides the original population into two separated populations

Question 13

speciation of shrimp - Isthmus of Panama

Answer 13

Caribbean shrimp more closely related to sister species in Pacific than to other species in Caribbean due to common ancestor from population before the separation

Question 14

sympatric speciation

Answer 14

speciation that occurs even though species live in same geographic region

Question 15

two modes of sympatric speciation

Answer 15

disruptive selection and polyploidy

Question 16

disruptive selection

Answer 16

leads to reproductive isolation, resulting in divergence and speciation

Question 17

apple hawthorne fly case study

Answer 17

related, but have genetically based different scent receptors - hybrids aren’t attracted well to either fruit resulting in reduced fitness of hybrids

Question 18

speciation can lead to

Answer 18

speciation

Question 19

example of speciation leading to speciation

Answer 19

speciation of apple/hawthorne flies lead to speciation of parasitic wasps that feed on larvae

Question 20

how do plants protect against herbivory by caterpillars

Answer 20

in response to leaf wounds and caterpillar regurgitate, signal pathway leads to release of chemical that recruits parasitic wasps

Question 21

two main mecahnisms of reproductive isolation

Answer 21

prezygotic and postzygotic

Question 22

pre-zygotic mechanisms fo reproductive isolation

Answer 22

temporal, habitat, behavioral, gametic barrier, mechanical barrier

Question 23

temporal reproductive isolation

Answer 23

populations isolated because they breed at different times

Question 24

habitat reproductive isolation

Answer 24

populations isolated because they breed in different habitats

Question 25

behavioral reproductive isolation

Answer 25

populations do not interbreed because courtship displays differ

Question 26

gametic barrier reproductive isolation

Answer 26

matings fail because egg and sperm incompatible

Question 27

mechanical barrier reproductive isolation

Answer 27

matings fail because male and female reproductive structures incompatible

Question 28

post-zygotic reproductive isolation

Answer 28

hybrid viability and hybrid sterility

Question 29

hybrid viability

Answer 29

hybrid offspring do not develop normally and die as embryos

Question 30

hybrid sterility

Answer 30

hybrid offspring mature but are sterile as adults

Question 31

frog mating calls in allopatry

Answer 31

two species calls are closer in pitch and have a wider pitch range for each species

Question 32

frog mating calls in sympatry

Answer 32

two species calls are more distinct in pitch and have a smaller pitch range for each species

Question 33

frog mating call disctinctiveness in sympatry example of

Answer 33

behavioral isolation

Question 34

mimicry of plants orchids

Answer 34

reproductive isolation - only males of specific species of insect will pollinate the flower, prevents pollination by other species or orchids

Question 35

possible outcomes of bringing two isolated populations together

Answer 35

interbreeding, independence, hybrid zones, new species

Question 36

interbreeding when isolated populations come together

Answer 36

interbreeding allows sufficient gene flow to re-distribute genetic variability - become one population

Question 37

independence when isolated populations come together

Answer 37

if sufficient reproductive isolation has developed, populations continue to diverge into separate species

Question 38

hybrid zone

Answer 38

geographic area where two species interbreed and hybrid offspring are common

Question 39

over time hybrid zones can

Answer 39

shift or stabilize

Question 40

how can hybrid zones stabilize over time

Answer 40

hybrids half as fit as non-hybrids - hybrid zone narrows - hybrid zone still exists as pure species continue to move into space and interbreed to produce more hybrids

Question 41

how might hybrids develop a new species

Answer 41

hybrids may have adaptive trait

Question 42

allopolyploidy

Answer 42

two species hybridize and the hybrid offspring undergo genetic doubling (one species is n=3 one species is n=2 so that hybrid is n=5)

Question 43

allopolyploidy hybrids are sterile unless

Answer 43

chromosome doubling occurs (n=5 fails during meiosis, doubling has 2n=10 so meiosis can happen)

Question 44

autoployploidy

Answer 44

one species has genetic doubling that results in new species

Question 45

autopolyploidy occurs when nondisjunction results in

Answer 45

diploid egg and diploid sperm that self fertilize to produce tetraploid offspring that is new species

Question 46

biological species concept

Answer 46

species is members of populations that actually or potentially interbreed in nature

Question 47

pros of biological species concept

Answer 47

works with sexually reproducing organisms

Question 48

cons of biological species concept

Answer 48

doesnt apply to asexual reproduction or fossils; grey area with "potentially" interbreeding

Question 49

morphological species concept

Answer 49

species are defined by size, shape, or other morphological features

Question 50

pros of morphological species concept

Answer 50

works with fossil and living species

Question 51

cons of morphological species concept

Answer 51

misidentifies polymorphs as diff. species; identitifes cryptic species as same species; morphology is subjective

Question 52

phylogenetic species concept

Answer 52

species defined by evolutionary history

Question 53

pros of phylogenetic species concept

Answer 53

widely applicable

Question 54

cons of phylogenetic species concept

Answer 54

not many well-estimated phylogenies are available

Question 55

diet speciation

Answer 55

populations with more specialized diets are more likely to diverge than populations with general diet (diet specilization leads to isolation)

Question 56

pollination affects speciation rates

Answer 56

speciation rates faster in animal pollinated cs. wind pollinated

Question 57

speciation rates correllated with pollinator _____

Answer 57

specialization

Question 58

dispersal affects speciation rates

Answer 58

decreased dispersal leads to isolation leads to increased speciation

Question 59

sexual selection affects speciation rates

Answer 59

organisms with increased sexual dimorphism have higher rates of speciation