cycle 8

Question 1

Homo sapiens (identify parts of species name)

Answer 1

Homo- genus, sapiens- species epithet

Question 2

how many species concepts have been proposed?

Answer 2

over 50 (no universal one)

Question 3

ecological species concept

Answer 3

species= a group of organisms that are adapted to a particular set of resources (niche) in the environment

Question 4

morphological species concept

Answer 4

species=a distinct cluster of individuals in phenotypic space; no intermediates or overlap with other clusters

Question 5

how are species organized by the morphological concept?

Answer 5

based on measurable, observable traits (can compare traits with fossils)

Question 6

issues with the morphological species concept

Answer 6

• phenotypic variability is not consistent for different species
• difficult to distinguish species that look very similar
• can identify differences, but no information on how these differences evolved

Question 7

biological species concept

Answer 7

species= group of interbreeding populations that are reproductively isolated from other groups

Question 8

criteria typically used to define a species

Answer 8

all individuals can successfully mate and produce viable, fertile offspring (biological concept)

Question 9

advantages of the biological species concept

Answer 9

testable, provides a means to explain how species have evolved (investigate heritable traits, behaviour, physiology that lead to reproductive isolation)

Question 10

issues with the biological species concept

Answer 10

• cant be used for asexually reproducing organisms
• may not be possible to test if individuals can reproduce sexually successfully
• cannot be determined for extinct organisms

Question 11

phylogenetic species concept

Answer 11

species= group of populations with a recent evolutionary history
(more closely related to each other than to anything else)

Question 12

construction of evolutionary trees (phylogenetic)

Answer 12

• use morphological info

- use genetic info (molecular phylogenetics)

Question 13

monophyletic group

Answer 13

all descendants from a common ancestor

Question 14

advantages of the phylogenetic concept

Answer 14

• can be applied to all organisms
• molecular data can be collected from preserved remains
• can determine how traits have evolved to give rise to new species

Question 15

issues with the phylogenetic species concept

Answer 15

• molecular data cannot be obtained from most fossils
• arbitrary to decide how much evolutionary change defines a species
• implies reproductive isolation for sexually reproducing organisms but does not prove it

Question 16

what information is needed to compare between populations?

Answer 16

• need to use info that matches the true evolution of the organisms (shared traits reflect common ancestry- homologous traits)
• sometimes info is misleading (homoplasies- traits that evolved independently through diff paths due to convergent evolution)

Question 17

comparing species concepts

Answer 17

lumpers vs splitters

Question 18

how are species ideally defined?

Answer 18

with multiple lines of evidence (e.g. morphology, behaviour, physiology, etc)

Question 19

as gene flow is restricted…

Answer 19

differences may evolve between populations to the point where they can no longer interbreed (speciation)

Question 20

clinal variation

Answer 20

species that lives at different inclines, vary morphologically and genetically as populations adapt to different conditions (still one species)

Question 21

ring species

Answer 21

e.g. recognize mating calls of different populations, considered one species with several subspecies (ends of ring cannot interbreed)

Question 22

reproductive barrier

Answer 22

prevents gene flow between populations (physical/behavioural)

Question 23

reproductive isolating mechanisms

Answer 23

barrier to gene flow (prezygotic or postzygotic)

Question 24

ecological isolation

Answer 24

prezygotic, occupy the same region but live in different habitats

Question 25

behavioural isolation

Answer 25

prezygotic, signals not recognized by another

Question 26

temporal isolation

Answer 26

prezygotic, mate at different times

Question 27

mechanical isolation

Answer 27

prezygotic, differences in structure prevent interbreeding

Question 28

gametic isolation

Answer 28

prezygotic, gametes not compatible (e.g. coral spawning)

Question 29

hybrid inviability

Answer 29

postzygotic, embryo is not viable

Question 30

hybrid sterility

Answer 30

postzygotic, offspring survive but are sterile

Question 31

hybrid breakdown

Answer 31

postzygotic, 1st generation hybrids can produce viable gametes and offspring, 2nd generation have low fitness, are sterile, or are inviable

Question 32

allopatric speciation

Answer 32

two populations are geographically separated (physical barrier individuals cannot cross)

Question 33

secondary contact

Answer 33

populations interact again after being geographically separated (barrier is removed)

Question 34

the outcome of secondary contact

Answer 34

- may resume interbreeding (fusion-when secondary contact occurs quickly and there are not many differences) - maybe have become partly/fully reproductively isolated (cannot interbreed- more time has passed)

Question 35

hybrid zone

Answer 35

where individuals of previously separated populations interbreed

Question 36

hybrids

Answer 36

often not well adapted to environments outside hybrid zone, low fitness (risk of extinction), fitness depends on how many differences accumulated towards reproductive isolation

Question 37

reinforcement

Answer 37

accelerates isolation after secondary contact (postzygotic isolation has occurred, individuals who don't hybridize are favoured, promotes the evolution of prezygotic isolation)

Question 38

sympatric speciation

Answer 38

populations are not geographically or environmentally separated (not common)

Question 39

examples of sympatric speciation

Answer 39

- polyploidy in plants (changes in the number of sets of chromosomes) - allopolyploidy in plants (gametes of 2 species fuse and can't undergo meiosis bc they're too different so it doubles the number of chromosomes)

Question 40

what traits are involved in reproductive isolation?

Answer 40

anything that makes a difference in reproduction between individuals

Question 41

speciation

Answer 41

populations do not immediately diverge into separate species