Chapter 16 | Speciation

Question 1

what are species?

Answer 1

groups of organisms that mate with one another

Question 2

what do each species represent?

Answer 2

an independent unit of biodiversity

Question 3

what’s a good analogy to compare species with?

Answer 3

puzzles–pieces that fit are related, others not so much

Question 4

how does Linnaeus describe species?

Answer 4

based on appearance

Question 5

define the morphological species concept

Answer 5

individuals with unique morphology in comparison with other groups are identified as distinct species

Question 6

why do members of species look alike?

Answer 6

they are genetically related through a common gene pool

Question 7

define cryptic species

Answer 7

organisms that look similar but do not interbreed

Question 8

what are some common examples of cryptic species?

Answer 8

species of frogs and fish

Question 9

define sexual dimorphism

Answer 9

organisms can be of the same species but may have differing physical characteristics

Question 10

define morphological differences

Answer 10

variations in the physical form, structure, or appearance of organisms within or between species

Question 11

define the lineage species concept

Answer 11

species are terminal monophyletic branches on the tree of life

Question 12

what is the lifeline of the history of a each species?

Answer 12

starts at a speciation event and ends at extinction or another specification event

Question 13

what is a speciation event?

Answer 13

one species splits into two or more daughter species, which thereafter evolve as distinct lineages

Question 14

a group of organisms that includes a common ancestor and all of its descendants

Answer 14

monophyletic or distinct clade

Question 15

define the biological species concept

Answer 15

groups of actually/potentially interbreeding populations which are reproductively isolated from other such groups are defined as species

Question 16

what are exceptions or constraints to the biological species concept?

Answer 16

it does not apply to asexually reproducing organisms and is limited to a single point in evolutionary time

Question 17

list the types of reproductive isolating mechanisms

Answer 17

(1) prezygotic reproductive barriers
(2) postzygotic reproductive barriers

Question 18

define prezygotic reproductive barriers

Answer 18

barriers that act before ferritization which prevent mating

Question 19

what are some examples of prezygotic reproductive barriers?

Answer 19

(1) habitat
(2) timing
(3) behavior (i.e songs)
(4) mechanics (structure compatability)
(5) gametes

Question 20

define postzygotic reproductive barriers

Answer 20

barriers that act after ferritization that prevent the development of viable offspring or lower their fertility

Question 21

what is an example of an animal that is infertile as a result of cross-organism mating?

Answer 21

mules/donkeys

Question 22

what is necessary for lineages to remain distinct through evolutionary time?

Answer 22

reproductive isolation

Question 23

what happens if reproductive isolation does not occur for lineages?

Answer 23

the exchange of genes maintain a common gene pool

Question 24

define the Dobzhansky-Muller model

Answer 24

(1) a single ancestral population is divided into two and they evolve independently
(2) in each lineage, new alleles become fixed at different loci. these new alleles at the two loci work fine with other alleles within their own gene pool

Question 25

if two separated populations come back together, what could they still be able to do?

Answer 25

hybridize/interbreed

Question 26

what are Dobzhansky-Muller genetic incompatibilities

Answer 26

new alleles of hybrid offspring are inferior or lethal, reducing viability and/or fertility

Question 27

as pairs of species diverge genetically, they become

Answer 27

increasingly reproductive isolated

Question 28

occurs when populations are separated by a physical barrier

Answer 28

allopatric or geographic speciation

Question 29

as populations accumulate genetic differences

Answer 29

they increasingly become incapable of successful reproduction

Question 30

for marine organisms that experienced allopatry, if a random species on both sides shared a gene pool, what would that imply?

Answer 30

the gene pool is air dispersed or organisms found a way to cross the barrier

Question 31

if marine organisms experienced divergence before a barrier was present, what does that suggest?

Answer 31

the barrier had no effect on their gene flow and was already in the process of splitting

Question 32

what are two main kinds of allopatric speciation?

Answer 32

organisms are separated by a barrier or organisms cross a barrier to form new isolated populations

Question 33

when a small group of individuals becomes isolated from the main population and establishes a new population in a different geographic area

Answer 33

founder event

Question 34

a partition of a gene pool without physical isolation

Answer 34

sympatric speciation

Question 35

what's an easy way to describe sympatric speciation?

Answer 35

populations aren't separated, but something occurred that made them split/evolve into separate species

Question 36

what are some concepts that could cause sympatric speciation?

Answer 36

(1) behavioral changes (2) genetic mutation (3) adaptation to ecological niches

Question 37

what's a real-life example of sympatric speciation?

Answer 37

fruit flies used to lay eggs on hawthorn fruits, but some flies now lay their eggs on apples when Europeans brought them over

Question 38

sympatric speciation most commonly occurs by

Answer 38

polyploidy

Question 39

duplication of whole sets of chromosomes

Answer 39

polyploidy

Question 40

chromosome duplication in a single species

Answer 40

autopolyploid

Question 41

combination of chromosomes from two species and duplicating them

Answer 41

allopolyploidy

Question 42

how does a tetraploid individual come about?

Answer 42

accidental autopolyploid of two diploid gametes combining

Question 43

polyploidy can result in ______ in two generations

Answer 43

complete reproductive isolation

Question 44

how can interbreeding occur?

Answer 44

if differentiated populations in sympatry do not completely discriminate in choice of mate

Question 45

how will gene pools be mixed and such that no speciation occurs?

Answer 45

if hybrid offspring are fit and interbreed with both parental populations

Question 46

strengthening of prezygotic barriers

Answer 46

reinformcement

Question 47

if hybrid offspring survive or reproduce poorly

Answer 47

natural selection may favor prezygotic barriers

Question 48

what are some characteristics that influence speciation rates?

Answer 48

(1) in plants, rates are higher in animal-pollinated than wind-pollinated plants (2) sexual selection (3) specialized diets (4) faster in species with poor dispersal abilities

Question 49

the proliferation of a large number of species from a single ancestor

Answer 49

evolutionary radiation

Question 50

resulting species live in a wide array of environments

Answer 50

adaptive radiation