1
Q
Phylogenetics
A
The study of ancestor descendent relationships (objective –> to construct phylogenies)
2
Q
Phylogeny
A
A hypothesis of ancestor-descendent relatrionships
3
Q
Phylogenetic tree
A
A graphical summary of a phylogeny
4
Q
Plesiomorphy
A
Ancestral character state
5
Q
Apomorphy
A
- A character state different than the ancestral state, aka a DERIVED state
- 2 types: synapomorphy and autapomorphy
6
Q
Synapomorphy
A
Derived character state that is shared by 2 or more taxa due to inheritance from a common ancestor
7
Q
Autapomorphy
A
A uniquely derived character state
8
Q
Monophyletic
A
- Group that includes ALL descendants of a common ancestor
- Aka clades
9
Q
Non-monophyletic
A
Any case that does not include ALL descendants of a common ancestor
- 2 types: paraphyletic and polyphyletic
10
Q
Paraphyletic + example
A
- Group that excludes some, but not all descendants of a common ancestor
- e.g. reptiles (excludes birds)
11
Q
Polyphyletic
A
Assemblages of taxa that have been erroneously grouped together based on homoplasious characters
12
Q
What character state is used to define monophyletic groups?
A
Synapomorphies
13
Q
Homology
A
Character state tat is shared b/w 2 DNA sequences or taxa due to common ancestry (more broadly)
14
Q
Homoplasy
A
Shared character that was evolved independent
15
Q
Types of homoplasy
A
Parallel evolution, convergent evolution, secondary loss
16
Q
Parallel evolution
A
Independent evolution of the same character state from the SAME ancestral condition
17
Q
Convergent evolution
A
Independent evolution of same character state from DIFFERENT ancestral condition
18
Q
Secondary loss
A
Reversion to ancestral condition
19
Q
Analogy (non-homology)
A
- Shared character state that is NOT due to shared ancestry, independently evolved
- May be similar in form/function but is NOT result of shared ancestry
20
Q
Principle of Parsimony
A
- Simple explanations are preferred over more complicated ones
- Less evol steps are better than more steps to explain relationships and hypotheses
21
Q
What character state is phylogenetically informative?
A
Synapomorphies
22
Q
Outgroup
A
- Not part of group of interest (ingroup) but not too distantly related to it
- Character state possessed by outgroup is a priori ancestral (plesiomorphic) –> allow identification of synapomorphies –> identify monophyletic groups
23
Q
Bootstrap method
A
- Computational technique for estimating confidence level of a phylogenetic hypothesis
- Computes number of times a particular grouping/branch appeared in the tree
24
Q
Cladistics
A
- Use of parsimony to construct evol relationships
- Goal of cladistic taxonomy: ONLY recognize monophyletic groups as valid taxa
- Cladistic taxonomy = evolutionary taxonomy
25
Biogeography
- Branch of science that seeks explanations for why organisms are found in some regions, but not others
- Use phylogenies to test hypotheses concerning geog origins of different species/groups of species
26
Coevolution
- Evol changes in traits of one species drives evol species in traits of another species
- Can involve predators + prey, hosts + parasites, and mutualism
- Can also result in co-speciation
27
Adaptation
- A trait that increases fitness of the individual relative to individuals that do not possess the trait
- Initially arise by mutation + subsequent selection, process may be aided/hindered by drift + migration
28
The 3 methods to study adaptions
1. Experimental studies (NEED CONTROL)
2. Observational studies
3. Comparative studies (NEED PHYLOGENY)
29
Examples of experimental studies
REQUIRE CONTROL
- Tephritid fly mimics spider to deter predator (spider)
- Snakes keep optimal temp by staying under medium rocks + moving position under rock
30
Comparative approaches
- Evaluate strength of hyp by testing for patterns across species/lineages
- REQUIRE PHYLOGENY (evol relationships)
- e.g. correlation b/w large groups of bats + large testes size (sperm competition)
31
Phenotypic plasticity
- Phenotypes arise b/c of genotypes + envtal interactions
- Identical genotypes can result in different phenotypes in different envts
- Phenotypic plasticity itself CAN evolve (e.g. phototactic behaviour in Daphnia)
32
Trade-off
- Compromise b/w one character + another (or 2 aspects of a single character) which cannot be avoided
- Prevent simultaneous optimization of 2 diff characters/aspects of single character
33
Constraint
Factor that tends to retard rate of adaptive evol/prevent pop from optimizing a trait
34
Obligate parthenogenesis
Entire species consists of females only --> reproduce by genetically identical cloning
35
Cyclical parthenogenesis
Pops consist of females that reproduce clonally for most of the year, but at certain times, males are produced + sexual reproduction occurs
36
Hermaphrodites
Orgs w/ both male + female sex organs (gonads) and are capable of self-fertilization
37
Self-fertilization
- Strongest form of inbreeding
- Still sexual reprod b/c gametes still formed via meiosis
- Offspring of selfing hermaphrodites are genetically less diverse than offspring of indivs that outcross
38
Maynard Smith's null model
- A female's reprod mode does not affect # of offspring she can make --> but in some species, males provide parental care --> violation
- A female's reprod mode does not affect probability that her offspring will survive --> do offspring of sexual repro have higher fitness?
39
Two-fold cost of sexual reprod
Asexual females can reproduce much faster than sexual reproduction --> there must be benefits to sex
40
2 most important components of sexual reproduction
1. Recombination (since matings b/w diff individuals = new combos of genes (may be more fit than existing ones)
2. Recomb + crossing over in meiosis during gametogenesis
Together --> create genetically diverse offspring + allow purging of deleterious alleles
41
Linkage disequillibrium
- Linked genes --> located close together on same chromosome
- Do not segregate independently --> can be inherited as a single unit
- Genotypes at 2 different linked loci will not be randomly associated w/ each other
- Results in less genetic diversity among offspring for genes in linkage diseqmb
42
How is linkage disequilibrium fixed?
Recombination during meiosis breaks up linked genes
43
Muller's Ratchet
- Over gens, oblig asexual orgs accumulate deleterious mutations --> lower fitness
- Total # of deleterious mutations + corresponding reduction in avg pop fitness = genetic load
- Genetic load will eventually become so high that the pop goes extinct (mutational meltdown)
- Evol dead end --> don't see ancient species that are oblig asexual (but ROTAFERS exist)
44
The Red Queen Hypothesis
- Species must continuously evolve new adaptations in response to changes within other organisms
- If species fails --> it will go extinct
- E.g. pathogen + host arms race
45
Advantage of asexual reproduction
Tend to have strong colonization abilities b/c entire pop can be founded by a single indiv
46
Sexual dimophism
Phenotypic diffs b/w males + females
47
Sexual selection
Differential reproductive success resulting from differential success to find a mate
48
Fundamental driving force of sexual selection
Asymmetric limits in reprod potential b/w the sexes
49
Asymmetric limits on reprod potential
- Usually (NOT ALWAYS) females --> greater parental investment --> reprod success limited by # of eggs they can produce + rear --> females choosy (can be arbitrary in terms of viability)
- Males --> infinite sperm --> reprod success limited by # of mates they can obtain --> males competative
50
Intra vs intersexual selection
- Intrasexual selection: interactions b/w members of same sex (competition, combat)
- Intersexual selection: b/w members of opp sexes (mating displays/rituals by males + females choose)
51
The Bruce Effect
Pregnancy termination (by females) in presence of unfamiliar males ("doomed" offspring since new males will kill them)
52
Runaway selection
- Female choice --> pop moves off eqmb line, it may never return
- Male is too extreme --> female pref increases --> makes male displays even more extreme, etc.
53
Polygyny
Males mating w/ 2 or more females
54
Polyandry
Females mating w/ 2 or more males
- e.g. Prairie dogs
55
Great apes
Hominidae: gorilla, chimp, bonobo, human
56
Closest living relatives of humans
Bonobo and chimps
57
Visual differences b/w chimps and bonobos
- Chimp: square jaw + snout
- Bonobo: hair part (bald spot)
58
How were chimps and bonobos separated?
Congo river separated bonobo from common chimp geographically
59
Fission/fusion of societies of chimps vs bonobos
- Chimps: Bump societies + exchange males; lots of warfare b/w them; sex ratio skewed towards females
- Bonobos: males + females move b/w communities (must impress dominant female w/ sexual activity); equal sex ratios
60
Social structures in primates
- Bonobo: females bond w/ each other, males bonded w/ mother for whole life
- Chimp: males bond w/ each other for hunting + protecting shared territory
- Gorilla: polygyny, females don't bond w/ each other
- Orangutan: males intolerant of other males; males + females meet only for copulation
BIOL 359
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