Transcript 174-16-Winter_10_4-F..

Lecture 11:
Individual Variation
1
The biological importance of individual variation
has recently been reemphasized in the fields of
comparative physiology, functional morphology,
animal behavior, behavioral ecology, as well as
eco/evo physiology.
It is also coming into medicine, spurred by the
availability of genetic data (e.g., SNPs) that clearly
demonstrate differences among individuals (and
among "racial" groups, although that is a political
hot potato!):
Childs, B., C. Wiener, and D. Valle. 2005. A science of the
individual: Implications for a medical school curriculum.
Annual Review of Genomics and Human Genetics 6:313-330.
Sometimes these genetic variants correlate with
disease susceptibility, psychiatric conditions, etc.
2
However, an appreciation of the fundamental
importance of individual variation is not new to
these and related fields.
For example,
Tryon, R. C. 1942. Individual
differences. Pages 330-365 in
F. A. Moss, ed. Comparative
psychology. Prentice-Hall, New York.
outlined four main problems that
should be addressed when studying
individual variation.
He was talking about psychology,
but his points also apply to physiology,
morphology, etc.
https://mikemcclaughry.files.wordpress.com/2013/02/robert_choate_tryon_-_oss_r__a_division.png
3
Four main problems that should be addressed
when studying individual variation (Tryon 1942):
1. How consistently do individuals differ and
how large are those differences?
2. Does individual variation in one (behavioral)
domain correlate with variation in other
types of (behavior)?
4
Four main problems that should be addressed
when studying individual variation (Tryon 1942):
1. How consistently do individuals differ and
how large are those differences?
2. Does individual variation in one (behavioral)
domain correlate with variation in other
types of (behavior)?
This leads to the question of whether nonhuman animals have personalities?
This is a controversial topic …
5
It is now generally accepted that human
personality includes five primary factors:
extraversion
openness
conscientiousness
neuroticism
agreeableness
each of which includes a number of subordinate
facets.
Human personality is typically measured via
questionnaires, not specific tests of people in
various settings.
6
"In the introduction of his presidential address to the American Society
of Naturalists in 1938, the eminent primatologist, Robert Yerkes
underscored the idea that personality could be found in animals: "I am
assuming that personality is the correct and adequate term for what is
now known concerning the integrated behavior of the chimpanzee.
Indeed, in my present thinking there is no question about the reality of
chimpanzee mind, individuality, and personality" (Yerkes, 1939, p. 97).
Yet in 1954, Hebb and Thompson described receiving looks of "open
astonishment" (p. 532) when they presented the idea that animals
should be of interest to psychologists interested in social behavior.
Even today, the idea of "animal personality" is often treated with
skepticism or even ridicule. However, as this article documents, the
body of research on animal personality is growing. If properly
implemented and interpreted, this research may be able to provide
important insights into the genetic, biological, and environmental
determinants of personality that could not be achieved by relying on
human research alone."
Gosling, S.D., 2001. From mice to men: What can we learn about
personality from animal research? Psychological Bulletin 127:45-86.
7
Behavioral ecologists also recently became
interested in animal personality.
Different definitions of animal personality have
emerged in this field.
Under the broad definition of personality, any
repeatable behavior can technically be termed a
personality trait, as repeatability implies that
differences among individuals show at least some
statistical consistency.
8
More useful is a narrow-sense definition of
personality (Reale et al. 2007) which, as presently
construed, emphasizes:
general activity
exploration
boldness
aggressiveness
sociability
because these traits potentially underlie an
individual’s behavior in many different contexts
(e.g., mating, parental care, agonistic interactions,
foraging, dispersal).
9
Personality Factors
Human
Non-Human
extraversion
general activity
openness
exploration
conscientiousness boldness
neuroticism
aggressiveness
agreeableness
sociability
The five commonly recognized personality factors
are not the same in humans and other animals.
10
Personality Factors
Human
Non-Human
Non-Human Measure
extraversion
general activity
home-cage activity
openness
exploration
novel open-field test
conscientiousness boldness
reaction to a predator
neuroticism
aggressiveness
mirror test
agreeableness
sociability
reaction to conspecific
11
Four main problems that should be addressed
when studying individual variation (Tryon 1942):
1. How consistently do individuals differ and
how large are those differences?
2. Does individual variation in one (behavioral)
domain correlate with variation in other
types of (behavior)?
3. Does individual variation in behavior relate
to underlying differences in physiology and
morphology?
4. Are individual differences caused by
genetic differences among individuals?
12
Remember that individual variation is the raw
material on which selection acts, so to those
four we can add the more field-oriented
question not mentioned by Tryon (1942):
5. Does individual variation in morphology,
physiology or behavior correlate with
Darwinian fitness in nature.
In other words, is selection acting on the
individual variation that presently exists for a
trait?
This is one direct way to study "adaptation" in
the genetic, evolutionary sense.
13
We will discuss all of these components in more
detail, and how they can actually be measured.
For now, we need to know how to quantify and
study individual variation.
Individual differences can be documented by
measuring each of a series of individuals multiple
times and testing for significant "repeatability" of
the differences among individuals.
14
"Repeatability" has a specific definition in
quantitative genetics, but for now just think of it
as any statistic that takes on a high value when
individuals are consistently different and a low
value when they are not.
For example, is the rank order of individual values
consistent across trial days?
15
The Western
Fence Lizard,
Sceloporus
occidentalis
16
The rank order of
sprint speed,
measured on a
photocell-timed
racetrack, is rather
consistent (and
statistically
significant) across 5
successive trial days.
Bennett, A. F. 1987. Inter-individual
variability: an underutilized
resource. Pages 147-169 in M. E.
Feder, A. F. Bennett, W. W.
Burggren, and R. B. Huey, eds.
New directions in ecological
physiology. Cambridge Univ. Press,
Cambridge, U.K.
17
How do
we treat
"outliers"
(unusual
observations)?
18
Was this a
measurement
error?
Having a
bad day?
How do
we treat
"outliers"
(unusual
observations)?
19
Resting
Figure 1. Mass-adjusted values of VO2rest and
VO2act in 10 males of Scinax sp. 1. Bars are
standard errors of three measurements. To
facilitate visual comparisons, we present
graphs of residuals of a regression
analysis of the logarithm of body mass that
have been adjusted to the overall mean body
mass (3.20 g) and then reconverted to the
original arithmetic scale.
10 Individual Frogs,
each measured 3 times:
Active
both resting and active
metabolic rate show
reproducible differences among
individuals, but resting and
active values do not appear to
be correlated.
Gomes, F. R., J. G. Chauí-Berlinck, J. E. P. W. Bicudo,
C. A. Navas. 2004. Intraspecific relationships between
resting and activity metabolism in anuran amphibians:
influence of ecology and behavior. Physiological and
Biochemical Zoology 77:197-208.
20
Daily blood pressure measurements taken on one human
subject at random times over 4 months (11/79-2/80).
Iberall, A. S. 1984. An illustration of the experimental range of variation of blood pressure.
Am. J. Physiol. 246 (Regulatory Integrative Comp. Physiol. 15):R516-R532. Fig. 1.
21
Problems with and/or Objections to
Studies of Individual Variation
1. Extreme values are atypical or abnormal and do
not reflect the true response of most individuals.
Essentially a restatement of the typological
species concept.
Real populations do have highly unusual
individuals!
These "abnormal" individuals do exist and hence
must be considered.
Selection and inheritance in the real world applies
to them.
22
Example:
Garland, T., Jr. 1988. Genetic basis of activity
metabolism. I. Inheritance of speed, stamina,
and antipredator displays in the garter snake
Thamnophis sirtalis. Evolution 42:335-350.
The 46 dams gave birth between 2 August and 6
September 1984. Litter size ranged from one to 26
(mean = 12.2, SD = 5.15). Of the 562 offspring produced,
23 were born dead (frequencies were 10, 5, 2, 2, 1, 1, 1, and
1 individuals born dead in each of eight different families);
another 13 were born with obvious deformities (eight with
kinked tails, bodies, or necks; one with deformed ventral
scales; four with one or both eyes small or absent); there
were no more than two deformed individuals in any one
family.
23
Example:
249 of the offspring were tested for maximal sprint speed on a
photocell-lined racetrack and for endurance on a motorized
treadmill moving at 0.4 km/h. Both tests were done twice, on
consecutive days. This is a histogram for the higher endurance:
40
40
Range =
1-23 min
30
But this
does not 30
account for
the
individuals 20
born dead
or severely
deformed!
20
10
10
Std. Dev = 3.52
Std. Dev
Mean = 6.0
Mean = .7
N = 249.00
0
.0
.0
.0
.0
38
1.
25
1.
13
1.
00
1.
8
.8
5
.7
3
.6
0
.5
8
.3
5
.2
3
.1
00
0.
23
21
19
.0
0
17
0
.0
9.
0
15
7.
0
.0
5.
0
13
3.
11
1.
Endurance (min)
HENDMIN
N = 249.0
0
log10 Endurance (min)
LHENDMIN
24
2. Extreme points are attributable to
instrumentation or procedural error;
do not result from real biological differences.
Typical physiological procedure might be to do
5-10 preparations (e.g., isolated muscles in
ergometer), then throw out the 1 or 2 that were
fairly different from the rest.
Unusual points assumed to represent preparation
errors, e.g., a damaged muscle.
Difficult to know if the measure cannot be
repeated on a single individual.
If the "preparation" can be repeated, e.g., most
measures of whole-animal physiological traits,
then we can rule out this possibility.
25
3. The variation is real (errors of measurement
apparatus are not very large) but reflects random
and unrepeatable responses of individuals;
intra-individual variability is so high that there is
no significant inter-individual component to total
variance.
Significant repeatability across trials answers this.
26
Most typically, repeatability is quantified by
measuring individuals on each of two days.
A scatterplot is made.
The Pearson product-moment correlation
coefficient, r, indicates repeatability.
27
No Repeatability
3
N = 50
2
1
R = 0.066
0
-1
looks like a shotgun
blast, random scatter
-2
-3
-3
-2
-1
0
1
2
3
28
High Repeatability
3
N = 50
2
1
R = 0.894
0
-1
often found for morphometric
traits, e.g., relative leg length
-2
-3
-3
-2
-1
0
1
2
3
29
Typical Repeatability
3
N = 50
2
1
R = 0.517
0
-1
fairly typical for
behavioral and
physiological traits
-2
-3
-3
-2
-1
0
1
2
3
30
Example:
Harris, M. A., and K. Steudel. 2002.
The relationship between maximum
jumping performance and hind limb
morphology/physiology in domestic
cats (Felis silvestris catus). J. Exp.
Biol. 205:3877-3889.
31
Example:
N = 231,
r = 0.696
log10 Endurance (min) Day 2
Garland, T., Jr. 1988. Genetic basis of activity
metabolism. I. Inheritance of speed, stamina,
and antipredator displays in the garter snake
Thamnophis sirtalis. Evolution 42:335-350.
log10 Endurance (min) Day 1
32
Lacerta vivipara from southern France
This species gives
birth, rather than
laying eggs, and
the newborns are
ready to run!
Sorci et al. 1995. Physiological Zoology 68:698-720.
33
Newborn Lacerta vivipara
Note double log
transform!
Raw data are
highly rightskewed. A few
individuals are
exceptional.
Treadmill endurance is more repeatable than sprint
speed, possibly because the latter is determined more
by inherent physiological capacities for exercise,
whereas the former is more determined by motivation?
Sorci et al. 1995. Physiological Zoology 68:698-720.
34
Long-term Field Repeatability
not
measured
* indicates P < 0.05
*
Hatchling body size
does not predict
yearling body size.
van Berkum et al. 1989. Functional Ecology 3:97-105.
*
*
*
35
Long-term Field Repeatability
*
* indicates P < 0.05
*
Hatchling sprint
speed does not
significantly predict
yearling sprint speed.
van Berkum et al. 1989. Functional Ecology 3:97-105.
*
*
36
Long-term Field Repeatability
*
*
*
Hatchling endurance does
predict yearling endurance.
*
*
van Berkum et al. 1989. Functional Ecology 3:97-105.
37
Angilletta, M. J., Jr., P. H. Niewiarowski, and C. A.
Navas. 2002. The evolution of thermal physiology in
ectotherms. Journal of Thermal Biology 27:249-268.
38
Why is repeatability important?
If a trait is not consistent, but varies wildly from
day-to-day, then selection has no clear "target."
Teleologically and anthropomorphically, selection
cannot penalize the bad individuals and reward
the good ones, because these get mixed up every
time selection "looks."
Similarly, if the "quality" of parents varies wildly
from day-to-day, then they cannot pass it on to
their offspring.
In general, repeatability sets an upper limit
to heritability.
39
Analytical Uses of Individual Variation:
1. Testing or generating hypotheses
about functional relationships
2. Measurement of selective importance:
Field studies - later lectures
correlational
experimental
Lab studies - useful because ...
correlational
experimental
3. Determining heritabilities of organismal
or physiological characters
40
Natural
& Sexual
Selection
Act
On
Behavior
This is the general model we usually have in
mind in ecological/evolutionary physiology.
Garland, Jr., T., and P. A. Carter. 1994. Evolutionary physiology.
Annual Review of Physiology 56:579-621.
http://en.wikipedia.org/wiki/Evolutionary_physiology
Morphology, DeterPhysiology,
Biochemistry mine
Organismal
Performance
Abilities
41
Natural
& Sexual
Selection
Act
On
Behavior
After some background, let's look at
some examples in which individual
variation was used to address this
part of the overall model.
Morphology, DeterPhysiology,
Biochemistry mine
Organismal
Performance
Abilities
42
Comparative physiologists have routinely looked
at differences among species.
Example: urine concentrating ability and length of
loops of Henle in kidneys:
a significant correlation among species
(or among populations) suggests that the
latter causes the former.
But interspecific comparisons are fraught with
difficulties:
Garland, Jr., T., and S. C. Adolph. 1994. Why not to do two-species comparative studies:
limitations on inferring adaptation. Physiological Zoology 67:797-828.
Garland, Jr., T., A. F. Bennett, and E. L. Rezende. 2005. Phylogenetic approaches in comparative
physiology. Journal of Experimental Biology 208:3015-3035.
Rezende, E. L., and J. A. F. Diniz-Filho. 2012. Phylogenetic analyses: comparing species to infer
adaptations and physiological mechanisms. Comprehensive Physiology 2:639-674.
http://en.wikipedia.org/wiki/Phylogenetic_comparative_methods
43
For example, we may be comparing apples and
oranges (e.g., burrowing owl vs. bobwhite quail have
been compared physiologically because both are
birds of about the same body size).
Also, species do not represent independent data
points, and so we need independent phylogenetic
information to perform proper statistical analyses:
this may not be available for the organisms
that we study.
One way to avoid such problems is to stick within
a single species.
If relationships really do exist, then we should be
able to demonstrate them.
44
... assuming that the "signal" is large enough to be
detected over the "noise" of short-term variability
within individuals!
Hence the importance of first demonstrating that a
physiological or behavioral measurement is
repeatable.
45
Example:
Harris, M. A., and K. Steudel. 2002.
The relationship between maximum
jumping performance and hind limb
morphology/physiology in domestic
cats (Felis silvestris catus). J. Exp.
Biol. 205:3877-3889.
Conclusions
We found that cats with longer hind limbs and
lower fat mass relative to their lean body mass
achieved higher TOVs. These two variables
explained significant variation in maximum
TOV in a manner consistent with predictions
based on the work done by extensor muscles to
increase both kinetic and potential energy
during takeoff. This study is the first to confirm
the limb length–jump performance relationship
in an endothermic vertebrate. Contrary to
predictions, however, extensor muscle mass
relative to lean body mass and percentage
composition of MHC IIx were not found to
significantly predict TOV.
Fig. 8. (B) Significant positive relationship
between maximum takeoff velocity (TOV)
and the ratio of extensor muscle mass/body
mass (r=0.647, P=0.004, y=7571x+220.9).
This is an ordinary least-squares linear regression
predicting organismal performance from the lower-level
(subordinate) trait of relative muscle mass. It would be
more appropriate to report r 2 rather than r.
46
Example:
Hammond, K. A., M. A. Chappell, R. A.
Cardullo, R.-S. Lin, T. S. Johnsen. 2000. The
mechanistic basis of aerobic performance
variation in red jungle fowl. Journal of
Experimental Biology 203:2053-2064.
Used residuals from
regressions on body mass.
Both maximal and basal metabolic rate are related to some lower-level traits
in both sexes, but the predictors are not very consistent. Hct is a positive
predictor of VO2max in both sexes, as might be expected.
47
Example: What predicts locomotor performance in the
Spiny-tailed Iguana (Ctenosaura similis) from Costa Rica?
Garland, T., Jr. 1984. Physiological correlates of locomotory
performance in a lizard: an allometric approach. Am. J. Physiol.
247 (Regulatory Integrative Comp. Physiol. 16):R806-R815.
48
Ctenosaura similis
Calculate residuals (vertical deviations
from least-squares linear regressions)
to remove effects of body size.
Garland, T., Jr. 1984. Physiological correlates of locomotory performance in a lizard:
an allometric approach. Am. J. Physiol. 247 (Regul. Integr. Comp. Physiol. 16):R806-R815.
49
This is a highly statistically
significant positive relationship,
and it makes biological sense.
Then see if the residual subordinate traits can predict individual
variation in the organismal performance trait with an OLS regression.
50
Combinations of the residual subordinate traits can predict more of
the individual variation in the organismal performance traits than
can a single lower-level trait.
Garland, T., Jr. 1984. Physiological correlates of locomotory performance in a lizard:
an allometric approach. Am. J. Physiol. 247 (Regul. Integr. Comp. Physiol. 16):R806-R815.
51
Path Analysis:
… allows multiple dependent
variables and even multiple
levels of dependent variables.
Garland, T., Jr., and J. B. Losos. 1994. Ecological morphology of locomotor performance in squamate reptiles. Pages 240-302 in
P. C. Wainwright and S. M. Reilly, eds. Ecological morphology: integrative organismal biology. Univ. Chicago Press, Chicago.
52
Analytical Uses of Individual Variation:
1. Testing or generating hypotheses
about functional relationships
2. Measurement of selective importance:
Field studies - later lectures
correlational
experimental
Lab studies - useful because ...
correlational
experimental
3. Determining heritabilities of organismal
or physiological characters
53
Natural
& Sexual
Selection
Act
On
Behavior
This can be very
difficult to study
in the wild
Morphology, DeterPhysiology,
Biochemistry mine
Organismal
Performance
Abilities
54
Natural
& Sexual
Selection
Act
On
Behavior
This, too, can be
difficult to study
in the wild
Morphology, DeterPhysiology,
Biochemistry mine
Organismal
Performance
Abilities
55
Laboratory Studies to get at
Relations of Performance,
Behavior, and Selection:
A correlational study:
Do locomotor abilities correlate with
social dominance?
Male Sceloporus occidentalis
Size matched because size differences are known to
have major effect on dominance interactions
Measured social dominance in the lab by letting pairs
compete for access to basking site
Measured locomotor performance in the lab
Compared winners-losers by paired t-test
56
The Western Fence Lizard, Sceloporus occidentalis
No difference
in treadmill
endurance
57
The Western Fence Lizard, Sceloporus occidentalis
Significant
difference in
sprint speed
on photocelltimed racetrack
58
But the lizards did not sprint at high speeds
during behavioral interactions, so why
would speed predict social dominance?
Perhaps both traits are correlated with a
third variable …
One candidate would be testosterone levels
59
A possible experimental study:
Does testosterone (T) manipulation affect locomotor
abilities and/or social dominance?
Use silastic implants of T to increase circulating hormone
levels.
Compare performance and behavior with animals that
received control implant (no T).
Figure 7: Regression of sprint speed on plasma
testosterone for all experimental males (y = 0.6370
+ .008x; R2 p 0.19, P < .001, N = 73).
Symbols indicate male morphotype: circles = by,
asterisks = yy, dashes = bb, and triangles = oo.
Mills, S. C., L. Hazard, L. Lancaster, T. Mappes, D. Miles, T. A.
Oksanen, and B. Sinervo. 2008. Gonadotropin hormone modulation of
testosterone, immune function, performance, and behavioral trade-offs
among male morphs of the lizard Uta stansburiana.
American Naturalist 171:339-357.
60
Analytical Uses of Individual Variation:
1. Testing or generating hypotheses
about functional relationships
2. Measurement of selective importance:
Field studies - later lectures
correlational
experimental
Lab studies - useful because ...
correlational
experimental
3. Determining heritabilities of organismal
or physiological characters (later lecture)
61
Extra Slides Follow
This was about 10 minutes short in 2011, but then I added slides # 46 and 47 on Hammond et al. (2000), and expanded
slide 60 with figure from Mills et al. (2008).
In 2012, it was about 5 minutes short, in 2013 about 11 minutes short, in 2014 after adding "personality" it was right on.
But, then I moved the Definitions --> r=h2s and bell-shaped curves over to the QG lecture and made 174-15Winter_11_xx-Feb_Individual_Variation.ppt renamed to 11 Nov. in Dec. 2014
174-15-Winter_11_10-Feb_Individual_Variation_for_IDEA.ppt was made 29 Jan. 2015
In 2015, this was about 5-10 min short. I did not like it. Need to cut some of the Bennett verbiage and redundancy, add
in Tony at Simon Fraser, draw bread loaf from Feder 1987 chapter, improved the organization.
Add Figure 3.4 from: Feder, M. E. 1987. The analysis of physiological diversity: the prospects for pattern documentation
and general questions in ecological physiology. Pp. 38–75 in M. E. Feder, A. F. Bennett, W. W. Burggren, and R. B.
Huey, eds. New directions in ecological physiology. Cambridge University Press, Cambridge, U.K.
Zotero
Selection Surface Bread Loaf
Need to add Huey sample sizes, P values. Maybe replace van Berkum et al. (1989) with Huey/Dunham stuff.
Shrink "objections" section???
Add more Careau and Garland (2012) stuff …
62
Updates to be Done for 2012 Spring for IV:
Ball, G. F., and J. Balthazart. 2007. Individual variation and the endocrine regulation of behaviour and physiology in birds: a
cellular/molecular perspective. Phil. Trans. R. Soc. B doi:10.1098/rstb.2007.0010 No good graphs.
Brandt, Y. 2003. Lizard threat display handicaps endurance. Proc. R. Soc. Lond. B 270:1061-1068.
Guderley, H., and P. Couture. 2005. Stickleback fights: Why do winners win? Influence of metabolic and morphometric
parameters. Physiological and Biochemical Zoology 78:173-181. No good graphs.
Hammond, K. A., M. A. Chappell, R. A. Cardullo, R.-S. Lin, T. S. Johnsen. 2000. The mechanistic basis of aerobic
performance variation in red jungle fowl. Journal of Experimental Biology 203:2053-2064.
Huey, R. B., and A. E. Dunham. 1987. Repeatability of locomotor performance in natural populations of the lizard
Sceloporus merriami. Evolution 41:1116-1120. One good graphs of speed between years.
Huey, R. B., A. E. Dunham, K. L. Overall, and R. A. Newman. 1990. Variation in locomotor performance in demographically
known populations of the lizard Sceloporus merriami. Physiol. Zool. 63:845-872.
Iberall, A. S. 1984. An illustration of the experimental range of variation of blood pressure. Am. J. Physiol. 246 (Regulatory
Integrative Comp. Physiol. 15):R516-R532.
Jayne, B. C., and A. F. Bennett. 1989. The effect of tail morphology on locomotor performance of snakes: a comparison of
experimental and correlative methods. J. Exp. Zool. 252:126-133.
Krol, E., M. S. Johnson, and J. R. Speakman. 2003. Limits to sustained energy intake VIII. Resting metabolic rate and organ
morphology of laboratory mice lactating at thermoneutrality. J. Exp. Biol. 206:4283-4291.
Perry, G., K. LeVering, I. Girard, and T. Garland, Jr. 2004. Locomotor performance and social dominance in male Anolis
cristatellus. Animal Behaviour 67:37-47. Good graphs. Winners had higher endurance, but not higher speed.
Robson, M. A., and D. B. Miles. 2000. Locomotor performance and dominance in male Tree Lizards, Urosaurus ornatus.
Functional Ecology 14:338-344. Histograms of winners and lossers, winners faster & higher endurance.
Steyermark, A. C. 2002. A high standard metabolic rate constrains juvenile growth. Zoology 105:147-151.
Vanhooydonck, B., R. Van Damme, T. J. M. Van Dooren, and D. Bauwens. 2001. Proximate causes of intraspecific variation
in locomotor performance in the lizard Gallotia galloti. Physiological and Biochemical Zoology 74:937-946. No good graphs.
Williams, T. D. 2008. Review. Individual variation in endocrine systems: moving beyond the 'tyranny of the Golden Mean'.
Phil. Trans. R. Soc. B doi:10.1098/rstb.2007.0003. Published online. No good graphs.
Zani, P. A. 2001. Clinging performance of the Western fence lizard, Sceloporus occidentalis. Herpetologica 57:423-432. No
good graphs, but interesting paper with dead lizards and habitat differences and thermoregulation interaction!
Personality things from Careau and Garland (2012)…
63
Hayes, J.P.,
Jenkins, S.H.,
1997. Individual
variation in
mammals.
Journal of
Mammalogy
78:274-293.
64
Population Before Selection
MeanBefore
Population After Selection
These
Individuals
Breed
MeanAfter
Next Generation
MeanNext Generation
65
Midterm 1 Fall 2004
N
Mean SD
Min
Max
21 UG
82.6
11.64 58.5 98.0
8 Grads
87.5
6.84 74.5 94.0
All 29
84.0
10.65
ANOVA of UG vs. Grads,
2-tailed P = 0.278
Levene’s test to compare
variances, 2-tailed P = 0.063
66