Lecture 9

Question 1

what is microevolution

Answer 1

• NS
• migration
• mutation
• genetic drift
  it is the little issues to the population

Question 2

what is macroevolution

Answer 2

the process of microevolution explain macroevolution
- speciation, extinction, history, evolution of species

Question 3

why is there a problem with defining the definition of a species

Answer 3

there are many species concepts and there is different ways to express
- genetic, biological, Darwinian, evolutionary, phylogenetic, ecological
the two MAIN species concepts are taxonomic (morphological) and biological

Question 4

define taxonomic/morphological species concept

Answer 4

based primarily on distinct measurable differences
- species defined as a group of organisms that are sufficiently similar in phenotype (darwin also approved)

Question 5

define the biological species concept

Answer 5

a group of interbreeding natural populations that are reproductively isolated from each other’s groups
(when 2 different species stop sharing alleles and become isolated within reproduction)
- focuses on the process of divergence
- DOES NOT apply well for bacteria, asexuals, self-fertilizing species, fossils

Question 6

T/F reproduction is key to distinguishing species

Answer 6

true

Question 7

what are the 2 types of speciation

Answer 7

1. allopatric
2. sympatric

Question 8

explain allopatric speciation

Answer 8

• occurs when a population is geographically separated (mountain, river, etc) into 2 or more groups
• no gene flow
• overtime the genetic differences = too much = speciation

Question 9

what is sympatric speciation

Answer 9

• not physically separated
• reproductive isolation arises from behavioural, ecological, or genetic differences within the same environment.
  
  • this can begin to occur within an environment thru disruptive selection, behavioural selection (mate preference), different feeding habits

Question 10

at what stages can reproductive isolation occur

Answer 10

finding a mate
fertilization
development and growth of F1 generation
adult survival
reproduction of F2 generation

Question 11

what is included in pre-zygotic barriers

Answer 11

• finding a mate
• fertilization
  geographic, temporal, behavioural, mechanical, gametic - also known as cellular (prevents the formation of a zygote - prevention of mating)

Question 12

what is included in post-zygotic barriers

Answer 12

• development of zygote - F1
• adult reproduction - F1
• survival/growth/reproduction - F2
• Prevention of the offspring to become a viable fertile adult
• inevitability, sterility, hybrid breakdown

Question 13

what is an example of pre-zygotic temporal isolation (from lesson 9)

Answer 13

apple maggot flies
- there are different timings of fly mating on the preferred host plant
the apple’s reproductive time is earlier than the flies
- different flies have different mating times - meaning that they cannot = gene flow

Question 14

what is an example of pre-zygotic mechanical isolation from the lesson

Answer 14

the binding of the protein in the lysin sperm could not fertilize the egg because there was different evolutionary changes in different species

Question 15

what are the 2 types of post-zygotic barriers

Answer 15

1. intrinsic
2. extrinsic

Question 16

what do intrinsic post-zygotic barriers mean

Answer 16

• barriers that are due to internal factors that are not related to the environmental factors
  inviability, sterility, or abnormal development of hybrids after fertilization
• F1 generation has these problems

Question 17

what do extrinsic post-zygotic barriers mean

Answer 17

barriers due to the external/environmental factors that affect the survival/reproduction ability of the hybrid
- hybrids may survive but lack the adaptions that are needed to survive (this can occur behaviorally/ecologically)
- makes them less successful than the parental generation

Question 18

what is an example of intrinsic post-zygotic isolation

Answer 18

the mule
- it is a sterile hybrid that cannot create offspring
(male donkey x female horse)

the hinny
female donkey x male horse
sterile hybrid

• these examples affect the F1 generation (F2 not possible)

Question 19

what is genetic distance

Answer 19

it is the measure of the degree of genetic differentiation between samples
- as genetic distance increases, post-zygotic isolation increases (more differentiation between F1 and parental = less fit = intrinsic isolation)

Question 20

what is an example of extrinsic post-zygotic isolation

Answer 20

• poorly adapted butterflies
• the offspring was created with very bright wings = high risk of predation = higher mortality and lower mating success = very unfit
• there is a strong selection of lighter-coloured wing patterns - so the hybrids having bright colours is not favoured = extrinsic

Question 21

what is adaptive radiation

Answer 21

• a single ancestral species rapidly diversifies phenotypically and ecologically into multiple new species, each adapted to a different ecological niche or environment
• driven by NS
• originates from a single common ancestor
• the species differ a lot in traits - ie. Galapagos finches

Question 22

what is adaptive EVOLUTION

Answer 22

changes to the gene pool of a population which continuously improves the survival and reproduction of the organism as it becomes more popular among the population

Question 23

is local adaptation needed for speciation

Answer 23

it is not necessary but it accelerates population divergence and the evolution of reproductive isolation
- sometimes divergence can occur from genetic drift, founders effect, behavioural isolation
- BI: cichlid fish = different mate preferences - sympatric speciation - new species can evolve in the same habitat because of selective mating

Question 24

explain the example of the 3-spined stickleback fish in freshwater vs marine and how it relates to local adaptations

Answer 24

in freshwater, there are fewer predators meaning that they don’t need their armour
in marine, lots of predators = bony armour needed
this local adaptation is created because of the fitness of the environment - this can generate selection for reproductive isolating mechanisms

Question 25

why do organisms diverge and become distinct species

Answer 25

when pops genetically diverge it is because of evolutionary forces - microevolution (genetic drift, mutation, NS, barriers) - becoming reproductively isolation is a by-product of the evolutionary changes within a population

Question 26

what 4 features commonly identify an adaptive radiation

Answer 26

1. recent common ancestry of a single species 2. phenotype-environment correlation (adaptions based on different environments) 3. trait utility - actively using the new trait 4. rapid speciation

Question 27

what causes adaptive radiation

Answer 27

1. Ecological opportunity is the absence of competition for resources. When new or previously unavailable ecological niches open up, species can exploit them and diversify rapidly. - what triggers the exploitation is major changes such as colonization (new regions to explore and adapt to), extinction (eliminates big competitors from the prey to thrive in), climate change/natural disasters, the evolution of a trait that provides access to new resources (increase fitness in lizards after evolving toepads) 2. high potential/tendency for speciation - reproductive isolation is more readily common in some clades than others (finches and mockingbirds)

Question 28

what is hybridization

Answer 28

when 2 different species = offspring = hybrid - common in plants and fish - can result in complex patterns of variation - can be evolutionary significant for speciation

Question 29

what is polyploidy

Answer 29

when an organism, tissue or cell has more than 2 complete sets of homologous chromosomes (humans have 3, others may have 3,4,5...)

Question 30

what is allopolyploidy

Answer 30

- the most common type of polyploidy is allopolyploidy --> a duplicated complete set of chromosomes after hybridization between species (2 or more species) - often fertile - wheat is an allopolyploidy because it contains chromosomes from 3 different types of grass

Question 31

what is autoploidy

Answer 31

arises from a duplicated complete set of chromosomes (karyotype) WITHIN a species (more than 2 sets of chromosomes from one single species)

Question 32

how does hybridization form an allopolyploid

Answer 32

1. two species mate = F1 hybrid (AA) 2. F1 hybrid produces diploid gametes (meiotic nondisjunction - error that doesn't separate the pairs of chromosomes) 3. diploid gametes produce tetraploid F2 4. tetraploid zygote is fertile but is reproductively isolated from parental species (a form of sympatric speciation)

Question 33

what is the evolutionary significance of polyploids

Answer 33

- their inability to reproduce with parental generation - they allow the exploitation of new habitats - have improved growth and development than parents because of heterozygosity - a lot of the flowering plants = polyploids