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Final Year > Evolutionary Ecology > Flashcards

Evolutionary Ecology Flashcards

1
Q

What did this study find?
Compared EQ to mean group size across primate phylogenies

A

Cassien et al. 2017
Mean group size was not a good predictor of brain size
Diet seemed a stronger predictor
Some diets may need greater cognitive ability like frugivores
Higher energy turnover & higher quality diets may lead to larger brains.
It is an example of the comparative approach, and showed that ecology could be more of a predictor of brain size than sociality

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2
Q

Define the Comparative Approach

A

Studying patterns and processes across different species or populations to understand the evolution of traits, behaviors, and ecological interactions. By examining these variations, researchers can infer evolutionary relationships, adaptations, and the selective pressures that have shaped ecological strategies.

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3
Q

What did this study find out? What is it an example of?
Looked across the Americas at nest predation in different species
Predicted that where physical conditions are easy, interrelationships between species would become paramount adaptive problem. Thus tropics would have more predation

A

Freeman et al. 2020
An example of the comparative approach again
Found very little latitudinal trend in predation
HOWEVER found that predation rate was negatively correlated with nesting period - longer nesting, less daily predation rate
BUT for same nesting period length, tropical species would experience higher daily nest predation rates than temperate species - Concluded that adaptation is dampening geographic patterns in interaction rates

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4
Q

Define adaptive radiation theory

A

Predicts that niches are partitioned early in the clade history in the presence of ecological opportunity

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5
Q

Cetacean study found – evidence for declining diversification rates in cetaceans overtime, and instead found the rate to be quite s—-.
Study supported evidence for an early burst in d—— but NOT d——-

A

Slater et al. 2010
No evidence, cetaceans, steady.
Disparity within clades was lower than expected with a constant-rate model
disparity, diversity

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6
Q

What is correlated evolution?

A

Tries to answer if changes in one trait are correlated with changes in another
Use statistical analysis to see if the differences observed are down to chance or not
Regression or correlation analysis is the most common form of comparative analysis

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7
Q

Why may we begin to use comparative methods instead of intraspecific studies alone? Give a classic example of this

A
  • Including more species can create more variation in life history and ecology
    to better test a theory
  • A typical example of this would be Tinbergen’s gulls in 1962, although this was just 2 species.
  • Black-headed gulls were ground nesting, with cryptic nests & chicks, and removed egg shells. They had higher chick mortality
  • Kittiwakes were cliff nesting, didn’t remove shells, and had more obvious nests and chicks
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8
Q

Give an example of the comparative approach applied across mammal taxa

A

Harvey et al. 1991
Correlated BMR and size across many mammal taxa
Found positive correlation across family, genus and species levels

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9
Q

Give some general pros of the comparative approach? 4

A
  • Very general
  • Incorporates large amount of variation
  • Incorporates large amounts of data, which can be found in online databases
  • Can guide experimental / observational work
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10
Q

Give the 2 main problems of using phylogeny in the comparative approach

A
  1. Pattern vs process - black and polar bears are different colours, but we still don’t know what process drove that pattern (if we don’t know what the ancestor was like)
  2. Statistical Non-Independence - Could result from taking data from same place, same animal and same time. Species may show similar traits just due to relatedness
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11
Q

Give an example of pattern vs process in a real study

A

Pagel & Meade 2006,
Mating systems in old world primates.
Tried to see if female oestrous displays correlated with multiple partners
Looked at phylogeny to see what came first and come to a conclusion

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12
Q

What could cause statistical Non-independence in the comparative approach? How can you control for this?

A

Could result from taking data from same place, same animal and same time. Species may show similar traits just due to relatedness. This may show different correlations across different taxa even if individual taxa show different ones
ie. Passerine and non-passerine birds have significantly different levels of correlation between BMS and body size. - this is an example of the comparative approach MASKING patterns
Can control for this for accounting for phylogenetic relatedness in comparative analysis

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13
Q

Give 3 reasons for phylogenetic dependence

A
  1. Phylogenetic niche conservatism - the main one, species (such as Darwin’s finches) inheriting niches from their ancestors giving them similar ecologies
  2. Evolutionary lags such as vesitigal organs and evolutionary inertia. A situation in which a species or population fails to keep pace with changes in its environment through the process of evolution.
  3. Different adaptive responses: Macaw and Kea having similar beaks but for different purposes
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14
Q

Give 3 consequences of phylogenetic dependence

A
  1. Important patterns masked
  2. Spurious correlations generated
  3. Statistical tests compromised
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15
Q

Fill in the gaps: To account for phylogenetic dependence we rely on m———— models of trait evolution
This is a m———- or c———- representation of how species traits evolve through time.
This predicts how similar or dissimilar species are as a function of the evolutionary d——- between them

A

mathematical
mathematical, computational
distance

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16
Q

Give 3 pros of the Brownian model

A

Makes minimal assumptions
Mathematically easy to work with
Makes predictions which look a lot like real data

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17
Q

Give 4 assumptions of the Brownian model

A

Traits change all the time
Evolution is neutral - traits can increase or decrease in equal probability
Rate of evolution is constant - the accumulation of differences from ancestors always the same
Species independent of one another

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18
Q

Define the Brownian model

A

A theoretical framework used in evolutionary biology to describe the random, continuous change of quantitative traits over time. Can allow us to see if there may be a correlation between two traits - correlated evolution.
REVIEW LECTURE 3 when revising. This lecture does not especially lend itself to flashcards

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19
Q

What does this describe?
1. Use data to infer ancestral states of these traits
2. Calculate contrasts between different lineages by subtracting them from one another
3. Perform correlation analysis between the two traits having accounted for part of trait due to phylogenetic dependence

A

The Felenstein 1985 method for Brownian evolution and calculating phylogenetic contrast. Thus accounts for phylogenetic dependencies when looking for evidence of correlated evolution. Thus allows statistical control for non-independence

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20
Q

Give the four main limitations of the Brownian model

A
  1. Variance can increase forever
  2. No ecological basis
  3. Species are independent of one another once they have split
  4. Rate is constant - no punctuate equilibrium and such
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21
Q

Non-brownian evolution adds on some extra t— evolution that is i——– of the phylogeny to try and account for a species specific l—– adaptations

A

trait, independent, local.
Brownian + Non-Brownian evolution = net amount of evolution
Look at lecture 4 to review actual maths and that

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22
Q

How do you apply non-brownian methods to real-world data?

A

Try out different values and see which ones best fit patterns seen in real-world data
Uses a statistical model called ‘maximum likelihood’ to do this
You can then see if real data is alining best to Brownian or Non-Brownian patterns

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23
Q

What does lambda do in the Brownian model? What does it mean when lambda is closer to 1?

A

Tests for phylogenetic dependence
Looks for evidence of niche conservatism
Allows for differing levels of phylogenetic dependence in statistical models.
A lambda closer to 1 indicates higher levels of phylogenetic dependence

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24
Q

What does the adaptive constraints / the Ornstein-Uhlenbeck model do? What letter is used for this constraint?

A

Addresses the unrealistic Brownian assumption that trait variation can increase indefinitely by showing evolution selecting against traits when they become too big / too small.
Thus you don’t see so much splitting / diverging in traits between two species over time.
Alpha is used in reference to this constraint

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25
Q

We can measure the rates of evolution separately between two or more sets of branches and perform a statistical test -
Tested on pr——- / semipr——– and al——birds
T—- used in reference to this
Finds evidence that indeed p—– birds have higher level of evolution as less c——-

A

Thomas, Szeckeley & Freckleton 2006
Precocial, semiprococial, altricial - precocial are born quite independent, altricial more hopeless, featherless and blind
Theta
precocial, constrained

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26
Q

To address another Brownian assumption, how do you test for the influence of Geography upon a phylogeny? What letter measures the relative contribution of spatial distance to a phylogeny?

A
  • Species living together may be expected to be more similar in trait values
    -*Compute phylogenetic contrasts
    *Compare with phylogenetic & spatial distance
    *Compute index phi – measures relative contribution of spatial distance
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27
Q

What did Freckleton & Jetz, 2008 test the comparative influence of geography vs phylogeny on?

A

Applied to bodymass, temperature & range size in mammals
Asks whether these show phylogenetic, spatial signals, or both
Found strong relationship between spatial distance and trait variation NOT phylogeny for temperature
Found neither significantly influenced for range size
Found phylogeny stronger factor for bodymass

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28
Q

Does the comparative approach count as an observational, experimental or theoretical approach? Why?

A

Is observational as uses real-world data from nature. Fits models to data which are then used to make predictions

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29
Q

Jetz and Freckleton fitted an evolutionary model to body size in mammals and found that…

A

This could make very accurate predictions (about 65-95% accuracy) about unknown mass. Did this by removing known values and seeing what model predicted, then seeing how close to the true value this was.

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30
Q

phylogeny & s—– data can be used to predict species traits

A

spatial - based on their geographical closeness to one another

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31
Q

Jetz & Freckleton
Looked at mammals
Looked at range size, body mass, human encroachment, human impacts and interactions between range size and body mass
Used phylogenetic & spatial information to make predictions and fill in gaps such as body mass
What data were they using?
What did they find out?

A

Jetz & Freckleton, 2012.
Note: Study of the same citation also done on predicting unknown sizes in mammals.
To discern the threat level DD species were probably experiencing
The relationship between observed and predicted values was very good
Data deficient species predicted to have a HIGHER threat probability across many mammalian orders
NON-RANDOM probability of data-deficient species being more threatened - probably as these species have a low population size, live in remote areas

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32
Q

Compare the difference in findings about how widespread phylogenetic dependence was across ecological and behavioural data.
Why may there have been a difference?

A

So freckelton aimed to see how widespread phylogenetic dependence was across ecological data, and found it to be present in 88% of data sets
Bloomberg did the same thing with behavioural data and found a much weaker signal of dependence, potentially as behavioural adaptations are more labile, and can be taken on relatively quickly

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33
Q

Phylogenetic comparative methods can go beyond just measuring correlations and can make p———- too.
They can link e—– outcomes to e—— models

A

predictions,
ecological, evolutionary

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34
Q

What does an R-squared analysis tell you about the correlation between 2 (or more!) traits?

A

When R-Squared is higher, there is a stronger correlation between the 2 traits. Just like any other regression analysis. The slope value in this result in r can also tell you the gradient of this relationship

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35
Q

Define the incubation limitation hypothesis

A

*In bird species where males incubate but are smaller than females, egg size may be constrained by male body size, and hence ability to incubate the eggs.

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36
Q

What did Buckey & Jetz discover about the correlation between Anolis lizard density on islands and presence of competitors/predators?

A

Lizard density found to be higher on islands with fewer competitors and predators. This shows density compensation as a result of ecological release.

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37
Q

What would happen to intraspecies interactions as population density increases?

A

Intraspecies interactions could become more frequent and stronger
Increased intraspecific competition would favour niche expansion, and increased phenotypic diversity of the population

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38
Q

What did Svanback & Bolnick do to those sticklebacks? What did they find out about ecological release?

A

Svanback & Bolnick, 2007
They manipulated the population density of three-spine sticklebacks.
Used a paired experimental design
Control measures were taken outside of the enclosures
They found that:
Prey density declined at high biomass
Thus increased population density reduced prey availability
Individuals added alternative prey types to their diets
Diet variation among individuals INCREASED relative to low-density control enclosures
Niche breadth increased across the whole population
EVIDENCE FOR ECOLOGICAL RELEASE

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39
Q

Divergence in Pseudomonas fluoresces - a study into niche availability
Three morphs:
S—– spreader
W—— spready
F—– spreader

All 3 mediums grow in a h————– medium in distinct areas, suggesting distinct niches associated with each morph

They compared h————– to h———— environments, finding the range of morphs to increase initially dramatically in the h————– environment compared to the h———–.
NO morphological divergence found for the h——— microcosms showing that niche availability WAS favouring divergence

A

Pseudomonas fluoresces, Rainey & Travisano, 1998’
Three morphs:
Smooth spreader
Wrinkly spready
Fuzzy spreader

All 3 mediums grow in a heterogenous medium in distinct areas, suggesting distinct niches associated with each morph

They compared heterogeneous to homogeneous environments, finding the range of morphs to increase initially dramatically in the heterogeneous environment compared to the homogeneous.
NO morphological divergence found for the homogeneous microcosms showing that niche availability WAS favouring divergence

40
Q

Lab study on Pseudomonas found that niche availability c——- divergence in Pseudomonas m——— as the number of evolved m——– DECLINED as occupied niches INCREASED

A

Brockhurst et al., 2007
Constraints, Microcosms, morphotypes

41
Q

Define the Ecological Limits Hypothesis

A

Species richness at a biogeographic scale exists in a state of dynamic equilibrium
This equilibrium results from diversity dependence of speciation and / or extinction rates, much like population density dependent factors
That diversity dependence of evolutionary rates results from constraints of natural resource availability

42
Q

In the ELH:
———-rate declines as species richness increases
———- increases as species richness increases

A

Speciation,
Extinction

43
Q

Asymptotic diversity dependence:
There is a limit on the total of potential ——
- This constrains ——– diversity and ——— diversity/disparity

A

niches, species, phenotypic

44
Q

How does darwinian diversity dependence differ from asymptotic diversity dependence?

A

So, in Darwinian, Interspecific competition influences the dynamics of evolution above the species level (trait evolution, speciation and extinction)
So, unlike in asymptotic dependence, this doesn’t EXPLICITLY model an upper limit for diversity, but this can still emerge anyways

45
Q

Which one is the process and which one is the pattern of diversity dependence?
1. Macroevolutionary diversity trajectory that shows evidence of diversity regulation similar to logistic growth in population ecology
2. : Effect of interspecific competition on macroevolutionary rates of speciation and / or extinction

A
  1. Is the pattern and 2 is the process
46
Q

Give some assumptions of diversity-dependent diversification (3)

A
  1. Assumes each lineage has the same rates of speciation and extinction
  2. Assumes that there is a theoretical maximum number of species a clade can support
  3. Assumes that that speciation and extinction rates are linear functions of the number of extant species
    SEE LECTURE 9 for equations
47
Q

E——- and s——- dynamics in a model adaptive r——- of island lizards (A—-) -
What did they do?

A

Equilibrium & Speciation dynamics in a model adaptive radiation of island Lizards (Anolis) - Rabosky & Glor, 2010
- They modelled different equilibrium & speciation dynamics, and saw which model seemed to fit best
- This was the one which assumed diversification rates were the same initial between islands, with island-specific linear changes in rate then occuring through time
- Model IMPERFECT but quite good
- Rate of decline correlated with island area, which is a proxy for ecological opportunity

48
Q

What is a phenomenological model?

A

Describes a statistical pattern, instead of describing a mechanism for thiat pattrn. This is problematic for diversity dependence as same patterns can emerge from distinct evolutionary processes. The Brownian Model is an example of a phenomenological model

49
Q

What is the adaptive landscape? What does it show us?

A

It shows us a theoretical environment in which species can evolve. There are multiple phenotypes leading to a fitness peak.
As time elapses, peaks are filled up.
This could model how some phenologies appear to have an early burst of diversification before niches are filled up

50
Q

Define limiting similarity and give an example

A

The principle that two species which are too ecologically similar to one another cannot co exist due to competitive exclusion. Examples:
- Macarthur’s warblers, 1967
- Georgy Gause’s yeast
- Hutchinson’s ratios, 1959 - different size amongst sympatric species often consisten across the taxa (a 1.3 ratio)

51
Q

What were Jared Diamons community assembly ‘rules’?

A

Relative to all the possibilites of species combinations, only a limited number co occur - Species exist in a “checkerboard” and there are “forbidden” species combinations dictated by principles around limiting similarity

52
Q

Explain the difference between a hypothetical habitat filtered, and competition structured community.

A

In habitat filtering, similar species would be attracted to similar habitats, ie. similar size class of fish
In competition structuring, fish communities would be divided up by size due to competitive exclusion principles.
Therefore,habitat filtering may have more similar distributions of species across the tree of life, and competition structured ones may have more dispersed ones.

53
Q

Define phylogenetic community structure

A

The phylogenetic community structure provides insights into how closely related species are distributed within a community and whether there are patterns of clustering or dispersion based on their evolutionary history. Relates to phylogenetic niche conservatism wherin closely related species may be expected to be more similar in traits to one another

54
Q

Phylogenetic o——–: The sum of branch lengths connecting species in a community is high (they are spread out) indicating potentially high competition

A

Overdispersal

55
Q

Phylogenetic c———-: Sum of branch lengths connecting species in a community is low indicating perhaps habitat filtering

A

clustering

56
Q

Compare randomisation and simulation null models used in understanding phylogenetic community structure

A

So randomisation would compare observed with expected patterns of species presence in a community based on chance alone. Simulation would generate emergent patterns based on plausible processes like colonization, extinction and speciation.
Both sum the resultant branch lengths of the species generated

57
Q

A study looked at at 142 communities across 3 m—— clades and found a COMMON tendency for phylogenetic o——– across overall communities suggesting c———- is at play. Used the r——— null model

A

Cooper et al. 2008
Mammal,
Overdispersal
Competition
Randomisation

58
Q

What are the limitations of randomization based models in testing for phylogenetic overdispersal?

A

They do NOT test for any ecological or evolutionary processes

59
Q

Using a dynamic null model to test for phylogenetic overdispersal, what do we find?

A

Low extinction can result in communities which would appear overdispersed under the random model. Thus extinction, not competition could result in overdispersal relative to the random null.
Look at lecture 10 for the actual method if u want

60
Q

A study using the random AND null model on communities of mammals and birds in Peru national park found that phylogenetic community structure is consistent with the combined effects of al——– speciation, ex——– and c———– NOT competition

A

Phylogenetic community structure is consistent with the combined effects of allopatric speciation, extinction and colonisation

61
Q

Define ecological communities

A

Collections of potentially interacting organisms

62
Q

Evolutionary allometry definition

A

how the proportions of different body parts or functions change as the size of an organism evolves amongst species.

63
Q

The theory of lines of l—- evolutionary resistance centres on investigating if quantitative g—— variation is useful for predicting long-term a——– evolution

A

least, genetic, adaptive

64
Q

A study into the Evolutionary paths of least resistance:
Looked at b— b— size allometry in v——-
Found that s—– and e—— allometries alined across several major taxa. In other words, within species and amongst species variation aligned.

HOWEVER, slope was LESS steep at higher taxa level, probably as
1. Within species r——– was constantly evolving
2. S——- is strong enough to drive species away from the evolutionary path of least resistance

A

Talbot et al. 2018
brain-body, vertrbrates
static, evolutionary

relationships
selection

65
Q

What is covariance?

A

Describes the degree in which two variable change together - the assosciation between them

66
Q

Define static allometry

A

The within species body-size correlations

67
Q

Vp= Vg + Ve
What does this mean?

A

Phenotypic variation is made up from the sum of genetic and environmental variation

68
Q

What is this? A symmetrical matrix that describes the additive variance and covariance of a set of quantitative traits
Look at lecture 12 for more details

A

The G matrix, used to quantify genetic variation

69
Q

If genetic variation is —- relative to phenotypic, then a trait is highly heritabl

A

High

70
Q

In the evolutionary line of least resistance, most p——- variance is expected to fall within the bounds of the g—— variation

A

Phenotypic, genetic

71
Q

PART ONE:
Another study into evolutionary lines of least resistance. Looks at traits in sticklebacks, bird species and mice to see if measurements of quantitative genetic variation are useful for predicting long-term adaptive variation . What did they predict? 3 predictions

A

Schilter 1996
1. Gmax should aline less with trait evolution over time (because environment plays more of a role?
2. Evolution should be relatively slow if selection favours divergence in directions away from Gmax
3. Recently diverged populations should diverge according to gmax

72
Q

PART TWO of the Stickleback/ birds / mice study into evolutionary lines of least resistance
Found support than evolution ———- from gmax overtime
Found support that morphological divergence was ——– correlated with deviations from gmax
Found morphological differentiation between species WAS biased in the direction of gmax for atleast 4 million years `

A

diverged - prediction one
Negatively - prediction two, evolution slower when away from gmax
Prediction 3 - recently diverged populations differ defined by gmax

73
Q

Gmax in Anolis lizards.
Addressed assumption as to if s—— in genetic correlations only persisted over relatively s—- timescales.
Looked at how variation in gmax could change in s—, s—- and o——-.
Looked at 9 traits in 7 species of Anolis
Findings:
gmax had d——- significantly but had similar orientations
This is likely as the evolution of g was proportional to both within-species g—– v—– and d—– between species.
Suggested l—t— relationship between within and without species variation DESPITE them being in different environments. This is possibly because there is a lot of c——– amongst the islands, perhaps constrained by their individual traits

A

Stability, short
size, shape and oreientation
Size - total genetic variation
Shape - % variation explained by gmax
Orientation - relationship between g max and phenotypic divergence

Findings:
Gmax had diverged
Genetic variation, divergence
Long-term
Convergence

74
Q

Define this according to Simpson: Transformation of whole lineages by slow and progressive evolution, including stasis

A

Phyletic evolution

75
Q

Define this according to Simpson: The rapid transition from one adaptive zone to another

A

Quantum evolution

76
Q

Define this according to simpson: Population differentiation and formation of a species without significant change in ecological niche

A

Speciation

77
Q

Why is is challenging to observe mega and macro evolution?

A
  • Based on observations of a patchy fossil record
  • Absence of transitional forms in the fossil record as these would be faster, and punctuating long periods of stasis
  • Counter Darwin’s theory of gradualism
78
Q

Explain the difference between the tempo and mode of evolution

A

Tempo: Rate of phenotypic change within lineages / expressed as averages within major taxonomic groups
Mode: The pattern of evolution, whether it is continuous or episodic, whether it is primarily phyletic or proceeds mostly by lineage splitting
We often infer MODE by seeing how TEMPO varies

79
Q

These were the two hypothesise of tempo changing of Venditti et al. 2011 study on Body-size evolution in mammals across the tree of life:
1. Bursts of evolution on s—– branches
2. Bursts of evolution across whole c—–

What was found? Did it support these hypothesis

A

Venditti
1. species
2. clades

Lots of variation in rate of evolution across tree of life
Rates through time are generally stable after the major mammal orders have arisen
Gradualism is not supported as a theory

80
Q

Did Pagel et al. 2022 find support for Darwinian gradualism or not in the mammalian tree of life>

A

Pagel et al. 2022
They looked at directional changes (direction & magnitude of a change in single branches) and evolvability (shifts in rate across whole clades) in their model
They found widespread support for darwinian gradualism

81
Q

Across vertebrate clades, models showing ——— bursts of evolution are well supported

A

intermittent - ie. not supporting gradualism

82
Q

B—- et al. —-:
Phenotypic evolution along a phylogeny has 2 main components
The first is change attributable to the background rate of a clade
The second is change attributable to departures from the background rate

A

Baker et al. 2016

83
Q

Baker et al. 2016 tries to detect c——- rates, c—–wide shifts (wherin direction is the same) and b—– shifts (wherin direction changes)

A

constant, clade-wide, branch

84
Q

B—- et al. 2016 finds support for positive phenotypic selection (consistent directional change in a trait overtime) in…..

A

Mammalian eye shape and visual acuity

85
Q

What pattern of evolution does Goswami et al. 2022 find in 3d scans of mammal skulls?

A
  • A rapid burst in early clade history
  • Multiple rapid bursts in Cetacea
  • “Attenuated” evolution - an initial rapid increase, dropping off overtime
86
Q

Generally, m——– change amongst species and clades is consistent with Simpsoms hypothesis of q——- evolution (jumps between adaptive zones powering evolutionary change).
However, rates are HIGHLY variable across the tree of life, and give incomplete insight into the t—- and m— of evolution

A

morphological, quantum,
tempo,
mode

87
Q

Explain the term trait disparity

A

Range of Variation: This involves examining the diversity of traits within a group. For example, in a population of animals, the range of body sizes, shapes, or colors may be considered when assessing trait disparity.

Distribution of Traits: This involves examining how traits are distributed among different species or individuals within a group. A group with high trait disparity may have members with a wide variety of unique features.

Trait disparity is often contrasted with taxonomic diversity. While taxonomic diversity refers to the number of different species or taxa in a group, trait disparity focuses on the variation in the traits or characteristics themselves.

88
Q

In a study of dinosaurs recovery from the KPG extinction event, what do they look at?

A
  • Traits - whether or not species have them
  • Can then see different speciation in relation to their traits
89
Q

What is their brief method in that dinosaur study?

A
  • Look at phylogeny & trait data
  • Measure disparity overtime in this
  • Test the effect of the KPG to see if a constant or explosive rate emerges in morphological disparity
90
Q

Define
Volume
Density
Position
in terms of trait space (for dino study)

A

Volume - Product of all the ‘distance’ between the ranges
Density - pairwise distances between the trait space data points
Position - distance of species from the average / some other chosen centre

91
Q

Volume, density and position of points in dino study can be r—— changed to create a n— model

A

randomly, null

92
Q

In the dino study, an incomplete fossil record hindered getting a continuous idea of morphological disparity. How did they get round this?

A

Can estimate what is happening at certain time points in the fossil record.
Do this by estimating trait values of ancestors of species.
Can estimate it by asserting any combination of two diverged species traits

93
Q

In the dino study, they see if results look like the Brownian model, OU model or a Trend. What was found?

A

There was some support for explosive model and never for constant, but model imperfect. Also must consider that changes in trait space for mammasl

94
Q

A high rate of phenotypic evolution on one branch suggests which 3 things?

A
  1. directional change in trait values
  2. POsitive selection
  3. Quantum evolution
95
Q

Brownian model is a c—— and n—— model of evolution

A

constant, neutral

96
Q
A

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