Lesson 5

Question 1

What’s speciation?

Answer 1

Process by which new species arise ex. Formation. Of biodiversity

Question 2

What studies are combined in speciation

Answer 2

Ecology, evolution and genetics, links micro and macroevo processes

Question 3

What drives pop divergence?

Answer 3

Nat select or drift b/w envo

Question 4

What causes initial population divergence ?

Answer 4

Physical/geographcal barrier, ecological difference -new food source (like interbreeding w like), insects that specialize in one host plant

Question 5

How does repro isolation evolve?

Answer 5

Pre and post zygotes barriers, accumulation of genetic differences over time

Question 6

What can happen when hybridization occurs?

Answer 6

Increased fit-new species,
decreased fit/not viable ex liger

Question 7

When is”the process” of speciation completed?

Answer 7

When pop repro isolated

Question 8

What must happen /w two populations with the same common ancestor happens for you to know speciation has occurred?

Answer 8

So genetically divergent through accumulation of fixed differences that mating b/w indvs of diff pops fails to produce viable, fertile offspring

Question 9

Whats a deleterious mutation?

Answer 9

Lowers fitness

Question 10

What types of mutations can occur diring divergence from parent population and what gets fixated?

Answer 10

Deleterious-eliminated by natural selection
Neutral-drifts of fixation or drifts to extinction
Beneficial mutation- driven to fixation by natural selection

Question 11

What’s allopathic speciation?

Answer 11

Pop of same species become geographically isolated by physical barriers, preventing gene flow causing separate populations to evolve independently allowing over time for different alleles to become fixed due to mutation and drift or selection

Question 12

What’s sympatric speciation

Answer 12

Process by which new species evolve from single parent population while inhabiting same geographical area, more common in plants, disruptive selection results in two genetically distinct pops over time

Question 13

What’s spontaneous speciation?

Answer 13

Polyploidization, rapid and sudden formation of a new species, often driven by genetic mutations or behavioural shifts

Question 14

What’s polyploidization?

Answer 14

Genetic process by which org aquire 3 (+) complete sets of chromosomes bc meiosis failed and produces 2n which if fertilized w another 2n=autopolyploids(repro isolated, can only mate with themselves), can cause sudden speciation, very common in ferns and flowering plants

Question 15

Ex of allopathic speciation?

Answer 15

Uplift of the isthmus of pans separated sea causing subdivision of marine orgs meaning patterns of mutation nat selec and genetic drift differed on each side, two diff species on each side now

Question 16

What conditions need to occur for significant divergence in allopathic speciation to occur?

Answer 16

Sufficient time

Question 17

What happens if barrier is removed and pops are ack together in allopathic speciation?

Answer 17

May remain distinct bc interbreeding is prevented by pre/postzygotic mechanisms

Question 18

Ex of sympatric speciation?

Answer 18

Lord Howe island has volcanic soil, acidic and nutrient poor-preferred by belmore palms and Calvary’s soil, alkaline and calcium rich preferred by kentia palms,
Timing of flowering relates to soil type meaning diff flowing time b/w two wind pollentated species meaning no repro, no gen flow, disruptive sleection

Question 19

Whats autopolyploidy?

Answer 19

Org posses 3 (+) chromosome sets all derived from single parental species, can only mate w other autos-> repro isolated

Question 20

What mechanisms help maintain reproductive isolation by preventing the mixing of gene pools?

Answer 20

Prezygotic ad postzygotic isolating mechanisms

Question 21

What are prezygotic isolating mechanisms>

Answer 21

Before fertilization and production of a zygote, recent mating/fertilization

Question 22

What are the types of prezygotic Barrie’s?

Answer 22

Habitats, behavioural, temporal, mechanical, gametic

All prevent fertilization, no hybrids

Question 23

What’s habitat isolation?

Answer 23

Two species occupy different habitats in the same general area which prevents them from mating, rarely incounter eachother ex. Gall wasps

Question 24

What’s behavioural isolation?

Answer 24

Diff courtship rituals, mating calls, dances, signals prevent closely related species from interbreeding, ex birds of paradise

Question 25

What’s temporal isolation?

Answer 25

Reproduce at diff times, preventing gene flow (ex. Flowing at diff times0

Question 26

What’s mechanical isolation?

Answer 26

Structural differences in gentelia/fclowers prevent successful mating b/w diff species

Question 27

What’s gametic isolation?

Answer 27

Sperm cannot fertilize egg, don’t recognize eachother, chemically incompatible

Question 28

How are gall wasps an ex of habitat isolation?

Answer 28

2 host species studied, indvs wanted to mate w pops from same host plant, strong asoratitive mating b/w 2 pops but not in same host plant pop, indicated prezygotic repro isolated w host use diff

Question 29

What’s an example of behavioural isolation?

Answer 29

Tree frogs morphologically similar but distinct mating calls and female only responses to specific one even though they look almost identical, Barbour isolation driven by species spec. Mating calls

Question 30

What’s an example of temporal isolation?

Answer 30

2 species of pine n cali that overlap geographically but one relies pollen in feb and other in April and both rely on wind. Bc repro timing doesn’t overlap, pollen unlikely to fertilize ova of other maintains species separation

Question 31

What’s an example of mechanical isolation?

Answer 31

2 species of monk,ey flower attract diff pollinator due to dif floral structure, one w yelllow colour attracts bumblebee and red colour (deeper inside) attracts humming birds

Question 32

What are postzygotic mechanism ?

Answer 32

Prevent zygote development or reproduction

Question 33

What are the possible outcomes of hybridization affected by postzygotic barriers?

Answer 33

Reduced hybrid viability-lower survival Reduced hybrid fertility-sterile but alive Hybrid breakdown offspring have reduced fitness

Question 34

What’s an example of hybrid viability in postzygotic barriers?

Answer 34

Leopard vs wood frog frequently breed on the same pond and males grab females indiscriminately, fertilization can occur and embryos may begin to develop bu they usually die early in development and fail to reach maturity, no viable or fertile adult hybrids produced

Question 35

What’s an advantage of morphological species concepts?

Answer 35

Partical, simple to use

Question 36

What’s an example of hybrid fitness in postzygotic barriers?

Answer 36

Pizzly bears, grizzly x polar, are fertile, have colour variation, patterns of gender flow strongly unidirectional (polar->grizzly) suggesting low fitness in sea-ice (polar bear) habitat as even though they are genetically viable and fertile

Question 37

What are the major categories of species concepts?

Answer 37

20 species concepts, morphological, reproductive and phylogenetic/evolutionary

Question 38

What’s the morphological species concepts?

Answer 38

Species are discreee types of organism defined by unique reliable morphological characters, most traditional species concepts

Question 39

What’s the disadvantage of morphological species concepts

Answer 39

No clear genetic/evolutionary justification, choice of characteristic may be arbitrary, some species can’t be diagnosed morphologically (convergent evolution)

Question 40

What’s the biological/reproductive species concepts?

Answer 40

Species r group of actually or potentially interbreeding natural population that are reproductively isolated from other such groups, most used concept

Question 41

Advantages of BSC?

Answer 41

Clear criteria, clear evolutionary justification

Question 42

Disadvantage of BSC?

Answer 42

may be difficult to distinguish in the field, doesn’t a—ly to may forms of life that reproduce asexually, species hybridized a lot more than we thought which doesn’t fully align with this

Question 43

What’s the phylogenetic species concepts?

Answer 43

Based on reconstruction of evolutionary tree of an organism using morphological and genetic sequence data

Question 44

What’s a phylogenetic species?

Answer 44

Cluster of populations that emerge from the same small branch on a phylogenetic tree

Question 45

Advantage of phylogenetic species concepts?

Answer 45

More useful when thinking about asexual species, can apply to any group of organism, doesn’t require knowledge of interbreeding

Question 46

Disadvantage of phylogenetic species concepts?

Answer 46

Detailed evolutionary histories have been described for relatively few groups of organisms, potential for splitting species into very small groups based on slight differences

Question 47

What’s a subspecies?

Answer 47

When geographically separated populations of a species exhibit dramatic, easily recognizable phenotypic variation, biologist may identify them as different subspecies, “local variants of the area”, interbreeding but have different selective pressures

Question 48

What are ring species?

Answer 48

Some plants and animal species that have a ring shaped distribution that surrounds uninhabitable terrain, adjacent populations of these ring species can exchange genetic material but gene flow b/w sitandt populations occurs only through interbreeding populations, ex. 6 subspecies of salamanders distributed in a ring around Central Valley

Question 49

What are clinal variations?

Answer 49

Usually result from gene flow b/w adjacent populations experiencing different conditions, colouring and pattering important adaptive traits in many taxable, pattern of variation of a trait across a geographic gradient (cline), ex. Plains zebra have clinal variations latitudinally in striping pattern

Question 50

What’s a cline?

Answer 50

Pattern of variation of a trait across geographic gradient

Question 51

Species concepts key point?

Answer 51

Species in nature hard to define, no one species concepts is correct for all groups, BSC proven extremely useful for study of speciation, think of species as a hypothesis we can test