Lecture 9: Species + Lecture 10: Phylogenetics

Question 1

Why did early researchers doubt evolution?

Answer 1

natural selection, genetic drift, mutation, and migration were seen as sources of microevolution not macroevolution (speciation)

Question 2

main definitions of species

Answer 2

taxonomic and biological

Question 3

sympatric

Answer 3

same area

Question 4

allopatric

Answer 4

different area

Question 5

taxonomic/morphological species concept

Answer 5

based on distinct morphological differences

Question 6

Is there a universal species concept?

Answer 6

No, nothing encompasses all species.

Question 7

What did Darwin think of species?

Answer 7

Darwin was not clear on what he thought species were. He talked about species and “varieties”. Thought that species were arbitrary labels humans gave animals and plants to satisfy our own need to categorize and we based it off how they looked (taxonomic).

Question 8

Who was Ernst Mayr? (1904-2005)

Answer 8

approached the “species problem”. Said that a species was not only a group of organisms that are morphologically similar, but a group that can exclusively interbreed.

Question 9

What happens on islands?

Answer 9

rapid genetic reorganization due to geographic isolation

Question 10

Biological Species Concept

Answer 10

Based on the inter fertility of populations, focuses on the process of speciation and how it occurs. Says that a species is a group of individuals that exclusively interbreed in the WILD. States that geographic isolation alone is not enough.

Question 11

What does the BSC not apply to?

Answer 11

Bacteria, asexuals (would identify each individual as their own species), highly self-fertilizing species, or fossils.

Question 12

Where can reproductive isolation occur?

Answer 12

Pre-mating isolation (finding a compatible mating, mating and fertilization) and post-mating isolation (development or zygote, adult growth and survival, reproduction and fertility of offspring).

Question 13

Example of pre mating isolation

Answer 13

• Change in host plant. Any number of things could cause pre mating isolation as soon as one small change occurs, it causes a cascade of reinforcements for speciation.
• Changes in behaviour leads to changes in sexual preference of even determine whether members of a species interact.

Question 14

What factors can prevent zygote formation?

Answer 14

geographical, ecological, temporal, behavioural, mechanical, prevention of gamete fusion

Question 15

Apple Maggot flies

Answer 15

Arrival of domesticated apples in 19th century led to host plant shift from hawthorn to apple. Change in host plant resulted in speciation (sympatric) because mating occurred at different times and on different part of the plant. Hawthorns and apples fruit at different times so there is temporal separation. Apple and hawthorn maggot flies are physically indistinguishable but have different genetic profiles. Gene flow is approx. 6% (they can hybridize fine).

Question 16

Abalone

Answer 16

Binding of sperm lysin to egg vitelline envelope receptor (VERL) required for fertilization. Lysin/VERL interaction has coevolved in different directions in different species causing reproductive isolation.

Question 17

What factors can prevent the proper functioning of zygotes once they are formed?

Answer 17

Inviability, sterility, or abnormal development of hybrids. Genes don’t work well together. Cannot be favoured by natural selection because the gene combo can’t be passed on.

Question 18

intrinsic post mating isolation

Answer 18

Sterility or lethality ex. mules cannot self sustain a population

Question 19

extrinsic post mating isolation

Answer 19

Poorly adapted hybrids ex. two butterflies A and B mate and hybrid has aberrant colour patterns making it more likely to get eaten (predation risk lowers mating success).

Question 20

What causes adaptive radiations?

Answer 20

• origin of a key innovation (a novel trait)
• ecological opportunity (abundant resources and few competitors often on oceanic islands or aquatic counterparts like African rift lakes)
• high rate of speciation characterize the clade (some species are more likely to radiate ex. Darwin’s finches and the honeycreepers radiated on mainland also whereas Galapagos mockingbirds radiated neither on islands or continents )

Question 21

polyploidy

Answer 21

an organism, tissue, or cell with more than two complete sets of homologous chromosomes (includes autopolyploidy and allopolyploidy)

Question 22

Are humans haploid or diploid?

Answer 22

Trick question—we have both. Our somatic cells are diploid and gametes are haploid. The sex cells only contain 1 copy of an allele, while the body cells have two copies (maternal and paternal). If we got a full set from both parents we would be polyploids.

Question 23

Why are polyploids reproductively isolated from parents?

Answer 23

They have more chromosomes than diploid parents and this cannot interbreed.

Question 24

Even though polyploidism is a relatively low probability event…

Answer 24

approximately half of flowering plants are of polyploid origin (including many crops and invasive species).

Question 25

Few characteristics of polyploids

Answer 25

• Permanent heterozygosity = fit hybrid, meaning they survive (in allopolyploids)
• exhibit new phenotypes thus can exploit new environments and niches

Question 26

Carolus Linnaeus (1707-1778)

Answer 26

father of taxonomy, binomial nomenclature (genus species), predictive hierarchal pattern of classification

Question 27

Linnaeus’ system

Answer 27

kingdom, phyla, classes, order, family, genera, species

king Philip came over for good soup

Question 28

monophyletic group

Answer 28

also called clade, a complete set of species that evolved from a common ancestor

Question 29

paraphyletic group

Answer 29

group that contains some but not all species derived from common ancestor (ingroup) the other species are part of outgroup

Question 30

outgroup

Answer 30

A less closely related species in a monophyletic group used as a reference point to determine evolutionary relationship between an in group (a group of more closely related species in the clade)

Question 31

Nodes in a evolutionary tree

Answer 31

represent speciation event

Question 32

taxon

Answer 32

taxonomic group of any rank (species, family, class, etc)

Question 33

ancestral trait

Answer 33

trait shared with common ancestor

Question 34

derived trait

Answer 34

trait that differs from ancestral trait in lineage

Question 35

homology

Answer 35

similarity of traits due to shared ancestry (fish and human skeletons are homologous structures, bird and bat wings are analogous)

Question 36

homoplasy

Answer 36

similarity of traits as a result of convergent evolution. Can trick biologists when just examining morphological structure. We must also look to molecular biology to differentiate

Question 37

features associated with greater diversification

Answer 37

• herbivory (as plants evolve, so do animals because od coevolution)
• species with more sexual selection (showy displays can make pre mating barriers emerge as different females have different preferences)
• animal pollination
• increased dispersal
• increased size range

Question 38

ecological speciation

Answer 38

evolution of local adaptation (where organism adapts tp their environment) as a result of divergent selection can lead to reproductive isolation and eventually maybe speciation

Question 39

“Speciation genes”

Answer 39

mechanism of selection, a lot of research focused in this area to try to understand mechanism of selection.

Question 40

Eda

Answer 40

Key gene in understanding adaptation and speciation during colonization of freshwater lakes from marine environment

• in marine fish bony armour (lateral plates) are favoured to protect against large fish predation
• freshwater fish do not have the plates and this increases growth rate and helps fish survive winter and breed earlier.

Question 41

What four traits identify adaptive radiation

Answer 41

1. Recent ancestry from a single species
2. phenotype environment correlation
3. trait utility
4. rapid speciation

Question 42

hybridization

Answer 42

exchange of genes between species as a result of occasional inter-specific mating. Common in plants and fish, rare in mammals. The result can be complex variation which could have evolutionary significance.

Question 43

How does polyploidism occur?

Answer 43

Either the duplication of a diploid genome (autopolyloidy AAAA) or fusion of diploid genomes from two species (allopolyploidy AABB)

Question 44

Which is more common allopolyploidy or autopolyploidy?

Answer 44

Allopolyploidy — occasional hybridization between species

Question 45

Polyploidism is…

Answer 45

immediate sympatric speciation

Question 46

systematics

Answer 46

the study of biodiversity and the evolutionary relationships among organisms

Question 47

Why is there really no such thing as reptiles?

Answer 47

What we call reptiles is a paraphyletic group. We should include birds or not have this grouping at all.

Question 48

What is the tree of life project and who is responsible for it?

Answer 48

Purpose is to provide information on tree of life. The web project provides 10 000 webpages about biodiversity and phylogenetic relationships. Wayne Maddison (UBC) and Dave Maddison (university of Arizona) started it but it is collaborative effort.

Question 49

Sister species

Answer 49

Either of the two species formed when an ancestral species split. Use of replicate sister group comparisons can help identify a key trait is involved in extensive diversification.