Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL 1111 > Chapter 18 pt 2 ppt flashcards only just in case > Flashcards

Chapter 18 pt 2 ppt flashcards only just in case

1
Q

stopping gene flow promotes

A

isolation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

reproductive isolating mechanisms

A
  • prevent individuals of different species from mating and producing viable offspring
  • by reducing the chances of INTERSPECIFIC mating and production of hybrid offspring-these isolating mechanisms,s prevent the gene pools of distinct species from mixing
  • isolating mechanisms operate at different times
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

interspecific

A

btwn species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

prezygotic isolating mechanisms

A
  • before fertilization and production of zygote
  • prevent the production of hybrid offspring
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

postzygotic isolating mechanisms

A
  • after fertilization and zygote formation
  • reduce the success of hybrid individuals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

these mechanisms are not …..

A

mutually exclusive
- two or. more of them may affect the outcome of between species interaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

prezygotic isolations

= premating

A

ecological isolation=species live in different habitats

temporal isolation=species breed at different times

behavioural isolation=species can’t communicate

mechanical isolation=species can’t physically mate

gametic isolation=species have non matching receptors on gametes

= 5 mechanisms that can prevent the production of hybrid offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

postzygotic mechanisms

= postmating

A

hybrid inviability- hybrid offspring do not complete development

hybrid sterility- hybrid offspring cannot produce gametes

hybrid breakdown- hybrid offspring have reduced survival or fertility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

N=4; prezygotic

A

N=4
- mechanisms limit the frequency of interspecific matings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

N=1;prezygotic

A

N=1
- blocks interspecific fertilizations
- gametic isolating mechanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

ECOLOGICAL ISOLATION

A
  • occurs when species in the same geographic region live in different habitats
    = might live in the same country but different habitats
  • example: lions live in open grasslands typically, versus tigers that live in dense forests
  • 2 species don’t encounter one another and do no interbreed in wild
  • in captivity, lion-tiger hybrids occur sometimes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

LIGER

A

ecological isolation

  • Liger (lion-tiger hybrid)
  • male lion and female tiger
    = this disruption doesn’t turn off or lower the growth gene because usually the mom will block it to prevent the baby from growing too big/fast but here the mom is the TIGER
  • 750-1000 lbs
  • lion dad passes on growth-promoting gene but antagonistic gene from female is absent
  • not seen in nature
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

TEMPORAL ISOLATION

A
  • species living in the same habitat can experience temporal isolation–if they mate at different times of the day or different times of the year

-will never hybridize or breed because they leave seeds at different times

  • e.g. : pinus radiata and pinus muricarta
  • p. radiata releases pollen February whereas P. murticat release spleen in April
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

overlap in geographic distribution

A
  • but don’t interbreed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

BEHVAIOURAL ISOALTION

A
  • many animals rely-on specific-specific signals
  • many recognized by other species to identify mates
  • behavioural isolation happens whrene signals uses by one species are not egagered

e.g. feel birds rely on song, colour, and disables to recognize eachother,

e.g. similar to foreign language another species doede understand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

hooded warblers

A

In hooded warblers, behavioral isolation occurs when individuals from different species or populations do not recognize or respond to each other’s courtship songs and displays, preventing interbreeding. This ensures mating only occurs within the same species.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

firefly flashing pattern xample

A
  • bioluminescent\ent signals
  • used to attract males
  • diff flashing patterns in 9 species
  • females Only respond to display given the males of their species
18
Q

Behavioural Choice-mate choice

A

-mate choice by females and sexual selection drive evolution of mate recognition signals

  • females invest a lot of energy into reproduction
  • strong selection against choosing wrong species
  • genes for wrong choice of species would be weeded out of population quickly (would not pass on their genes, assuming hybrids not fertile)
19
Q

Mechanical Isolation

A
  • differences in structure of reproductive organs (or other body parts) may prevent individuals of different species from interbreeding
  • e.g. plants have morphological traits that only allow certain pollinators (bird/insect) to collect and distribute pollen
  • case study: purple monkey flower (Limulus Lewisii) and scarlet monkey flower (Mimulus Cardinalis)
  • Overlap in distribution in state of California
20
Q

Purple monkey flower vs Scarlet monkey flower

A

Purple Monkey Flower
- pollinated by bumblebees
- landing petals for bees
- yellow stripes=nectar guides
- drink nectar and pick up pollen

Scarlet Monkey Flower
- pollinated by hummingbirds
- reproductive parts extend beyond petals
- red attracts hummingbirds (but outside of range for bees)

21
Q

GAMETIC ISOLATION

A
  • even when different species do mate–incompatibility of the sperm of one species and the eggs of another which may prevent fertilization
  • e.g. broadcast spawning marine invertebrates
  • release gametes into the open ocean for external fertilization
  • sperm and eggs of different species recognize each other via their respective surface proteins (e.g. JUNO is the egg cell that recognizes its sperm counterparts (IZUMOI) in mammals)

this allows for the egg to establish recognition for correct sperm ONLY

22
Q

Postzygotic Isolating Mechanisms

A
  • if pre-zygotic mechanisms are ineffective, sperm from one species sometimes fertilizes an egg from another species
  • 2 species will be reproductively isolated if their offspring (interspecific hybrids) have lower fitness than offspring from intraspecific matings
  • 2 post-zygotic isolating mechanisms exist

fully-formed fetus in embryo

23
Q

Postzygotic Isolating Mechanisms

A

1) hybrid invariability: species hybrids not surviving

2) hybrid sterility: species hybrids not producing functional gametes

3) hybrid breakdown: reduced fitness of F2
= usually due to inbreeding depression

24
Q

Hybrid Inviability

A
  • hybrids have 2 sets of developmental instructions
  • one from each parent species– which may not interact properly in relation to embryonic development
  • hybrids often die as embryos because of incompatible developmental pathways at an early age (known as hybrid inviability)
  • e.g. sheep and goats can mate and fertilize one another’s ova BUT the embryo always die before coming to term (incompatible developmental pathways)
25
Hybrid Sterility
- some hybrids may develop into healthy adults but may not produce functional gametes (HYBRID STERILTIY) - due to parent species having a different number of chromosomes which cannot pair properly during meiosis - these hybrids have 0 fitness because they leave no offspring (also called evolutionarily dead because they cant produce more offspring) - e.g. mule=female horse (2n=64) and male donkey (2n=62)
26
hybrid breakdown
- some f1 (first-generation) hybrids are healthy and fully fertile - can breed with other hybrids and with both parental species - BUT F2s produced via matings between F1 hybrids (or F1 and either parental species) may exhibit reduced survival or fertility (=hybrid breakdown) HYBRID BREAKDOWN: - genetic stand - functionally non-existent - hard to survive and find a mate is impaired
27
the geography of speciation
- Ernest Mayr recognized that geography hade a huge impact on whether gene pools had the chance to mix 2 MODES OF SPECIATION: - allopatric (physically separated): evolution of reproductive isolating mechanisms between 2 populations that are geographically separated - sympatric: speciation that occurs without the geographical isolation of populations (live on the same area, but are separated with a barrier) (main drivers: sexual selection, w/ enough sexual selection 2 species can co-exist but remain separate)
28
allopatric speciation
takes place when a physical barrier subdivides a large population or when a small population becomes separated from a species' main geographical distribution (2 main steps) - STEP 1: populations become geographically separated, preventing gene flow between them - STEP 2: as popns experience mutations and different patterns of NS and genetic drift, they may accumulate genetic differences that isolate them reproductively = unique and different environments produce different forms of natural selections which produces genetic differences
29
4 steps of allopatric speciation
1) at first a population is distributed over a large geographical area 2) a geographical change separates the original population (i.e. tectonic plates), creating a barrier to gene flow 3) in the absence of gene flow, the separated populations evolve independently and diverge into different species over time 4) when another geographical change allows individuals of the two species to come into secondary contact, they do not interbreed (test to see if they're reproductively isolated and separate species)
30
if during secondary contact, species breed and produce babies, then this is representative of what phenomenon
species fusion
31
geographical separation case study
2 SPECIES: CORTEZ RAINBOW WRASSE AND BLUE-HEADED WRASSE - genetically different with a common ancestor ------------------------------------------------------ - 5 MYA uplift of the Isthmus of Panama - seperated once continuous shallow sea into eastern tropical Pacific Ocean and western tropical Atlantic Ocean = became a separation for marine animals between atlantic and pacific oceans - mutation, NS, and drift differed on each side - populations diverged genetically and pairs of closely related species lie on either side now
32
Archipelago Spices Cluster
1) a few individuals of a species from the mainland arrive on isolated islands A and B 2) over time, they differentiate into new species on these islands. the purple species then colonizes islands C and D 3) over time, the populations on islands C and D differentiate into 2 new species - develop unique adaptations to their environment...NS 4) some time later, the blue species colonizes island A, and the orange species colonizes island B, establishing secondary contact
33
why do we use islands
- seperated so its easier to measure features - easy to date: carbon dating
34
secondary contact- test of allopatric speciation
- allopatric populations can reestablish contact when barrier is eliminated or breached (step 4 last slide) SECONDARY CONTACT: contact after a period of geographical isolation provides a test of whether the genes in a population have diverged enough to make them reproductively isolated = this is the only test to determine if they've changed - if not very different, species will interbreed and merge into one= species fusion
35
hybrid zones
hybrid zones: geographic area where the hybrid offspring of two divergent species are common
36
reinforcement
- evolution of prezygotic barriers to reproduction after post zygotic barriers exist
37
Sympatric Speciation
within a population - reproductive isolation evolves between subgroups that arise within a population - does not require population be separated geographically - HOST RACE: arises from mutations favouring genetically distinct host of parasite (apple maggot case study)
38
HOST RACE
arises from mutations favouring genetically distinct host of parasite (apple maggot case study) - species on an insect sticks to 1 host i.e. apple maggot to apple tree
39
POLYPLOIDY
species have multiple sets of chromosomes (plants), can't breed with parent species
40
sympatric speciation case study
apple maggot case study: - host plant in eastern NA is hawthorn - 2 host species have appeared in last 150 years - reside on apples and cherries - controlled by just a few genes [therefore, passed on easily and keep offspring separate]
41
genetic mechanisms of speciation
- genetic divergence in allopatric populations can lead to speciation - polyploidy is a common mechanism of sympatric speciation in plants - chromosome alterations can foster speciation

BIOL 1111 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions