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Ecology > Ecology Exam 2 > Flashcards

Ecology Exam 2 Flashcards

1
Q

monogamy

A

pair bond between female and male

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2
Q

polygamy

A

several of one sex, only one of the other

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3
Q

polygyny

A

one male, several females

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4
Q

polyandry

A

one female, several males

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5
Q

simultaneous

A

multiple pair bonds occur at same time

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6
Q

simultaneous polygyny

A

one male with two or more females at the same time

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7
Q

simultaneous polyandry

A

one female with two or males at the same time

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8
Q

sequential

A

multiple pair bonds occur over a single breeding season

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9
Q

sequential polygyny

A

one male with two or more females, but only one at a time

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10
Q

sequential polyandry

A

one female with two or more males, but only one at a time

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11
Q

difference between males and females

A

females have larger gametes and care for the developing zygote, males have smaller gametes and play less of a role

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12
Q

what does greater female investment mean

A

this sex generally has fewer offspring and thus pays more attention to offspring quality

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13
Q

as sexual dimorphism increases…

A

males more able to ‘defend’ multiple females and probability of polygyny increases

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14
Q

polygyny threshold

A

territory quality varies so much that it is better for a female to mate with an already-mated male on ‘good’ territory than to mate with a monogamous male on ‘bad’ territory

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15
Q

monogamy may be favored when…

A

offspring require attention from both parents

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16
Q

95% of passerine birds are monogamous, when are they polygynous?

A

polygyny occurs in productive and patchy environments (areas with good and bad places for feeding young)

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17
Q

monogamy isn’t perfect because of…

A

extra-pair paternity

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18
Q

extra-pair paternity

A

father raising some offspring belonging to another males

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19
Q

why is polygyny in lizards extremely common?

A

lizards have no parental care

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20
Q

why are mammals more likely to be monogamous?

A

females have a larger investment in offspring than males and are predisposed towards more parental care than males

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21
Q

what is a greater male to female ratio correlated with?

A

higher likelihood of polygyny

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22
Q

when polygyny occurs in yellow bellied marmots, what is the result?

A

females tend to suffer and prefer monogamy, males benefit and prefer polygyny (harems); males must work hard to maintain harems

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23
Q

why do tinamou engage in sequential polyandry?

A

the males give parental care rather than females

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24
Q

what makes polyandry more likely?

A

kin selection

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25
Q

what are two alternative sexual strategies?

A
  1. if you’re not winning, change the game
  2. sex change
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26
Q

what are examples alternate strategies?

A

cuttlefish males pretend to be females until they’re large enough to compete with other males
lekking male tries to attract females, satellite males sneaks copulations at edge of lek
sunfish males are territorial or non-territorial, non-territorial sneak in and fertilize eggs
dung beetles are horned (large and mate) or hornless (smaller, alternate burrow to sneak in and mate)

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27
Q

what are examples of sex change?

A

if the male in hogfish population disappears, most dominant female becomes the male
younger crepidula mollusks settle on older mollusks, youngest are males and oldest are females, males become females as they age

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28
Q

types of geographic range

A

extensive and restricted

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29
Q

types of habitat tolerance

A

broad and narrow

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30
Q

types of local population size

A

large and small

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31
Q

how are sessile organisms dispersed in space?

A

random, clumped, or uniform (overdispersed)

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32
Q

what can happen in uniform dispersion?

A

organisms may be poisoning one another or using up nearby resources

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33
Q

what can happen in clumped dispersion?

A

habitat clumped or mutualisms may be occurring between organisms

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34
Q

how can a single individual be used to characterize space use in mobile organisms?

A

use radio transmitter or other tracking device, get set of points and use them to calculate home range

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35
Q

home range

A

area that is ‘normally’ frequented by the animal

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36
Q

minimum convex polygon method

A

smallest area that encloses all points or has points on boundaries, no inner angle > 180 degrees

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37
Q

behavioral definition of territory

A

a defended area

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38
Q

ecological definition of territory

A

an exclusive area (no other animal or group occurs there)

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39
Q

center of gravity method

A

take home range and compute average X and Y coordinates in space; if home ranges are on average spaced out, they are over-dispersed and probably territorial

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40
Q

what broadly determines territory size?

A

balance between benefits and costs

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41
Q

what happens to benefits as territory size increases?

A

benefits first increase, then level out because you ‘max out’ the resources you utilize

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42
Q

what happens to cost as territory size increases?

A

costs accelerate with larger territory diameters because area = (pi)r^2

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43
Q

what is the optimal solution to territory size?

A

max benefits while minimizing costs

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44
Q

what happens to territory size if territories improve (more resources, less risk of predation)?

A

territory size should decrease

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45
Q

what happens to territory size as competitors become more numerous?

A

territory size decreases

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46
Q

what specifically determines territory size?

A

avoidance of predation
increase or facilitate mating opportunities
competition for other limiting resources
increased food supply

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47
Q

effect of avoidance of predation

A

animals defend territories because those with territories are less vulnerable to predators
familiarity with good hiding places
spacing

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48
Q

effect of increase or facilitate mating opportunities

A

reproduce undisturbed
increased number of potential mates with larger territory

49
Q

effect of competition for other limiting resources

A

compete for reproductive sites, etc.

50
Q

increased food supply effects who in a territory?

A

an individual or pair defending territory
offspring raised on territory
future offspring

51
Q

as organism’s food requirement (metabolic rate) increases…

A

territory size should increase

52
Q

as food density increases…

A

territory size should decrease

53
Q

interspecific (between-species) evidence for increased food supply motivating territoriality

A

larger organisms have larger territories
predators have larger territories than herbivores of same weight

54
Q

intraspecific (within-species) evidence for increased food supply motivating territoriality

A

snowy owl and lemmings (Pitelka): Territory size of snowy owls inversely correlated with lemming density.
nuthatches (Enokkson and Nilsson): Both observational and experimental work show that territory size decreases as food density increases
fence lizards, Sceloporus sp. (Simon): Both ♂ and ♀ defend territories (males are larger and have larger territories). For both ♂ and ♀, territory size inversely
correlated with food density. When food density increased by adding mealworms, territory size decreased. When food addition stopped, territory size increased

55
Q

other adaptive rationales for territoriality

A

australian magpie (Carrick): defend territories in small groups from other flocks. Surveys found that group size is unrelated to territory size; disease avoidance
may drive territory defense.
dragonfly territories: may function as mating sites or prevent other dragonflies from laying eggs on its territory (decreasing food competition for its offspring).

56
Q

sex ratio

A

number of males per female

57
Q

primary sex ratio

A

sex ratio of all individuals at birth; may change over time because of differential survival

58
Q

sex ratio in polygynous species

A

male mortality is greater than female mortality, so as population ages the sex ratio decreases

59
Q

secondary sex ratio

A

sex ratio at reproductive maturity

60
Q

why do sex ratios tend towards 50:50?

A

R.A. Fischer’s argument for maintenance
1. in diploid species, every organism has a male and female parent that contribute equally to future generations
2. if mutation changes sex ratio, the rarer sex becomes more valuable that the more common sex
3. since rarer sex is more valuable, selection favors rarer sex –> back to 50:50

61
Q

what are complications with R.A. Fisher’s argument?

A
  1. if one sex is more costly to produce per individual, fewer of that sex will be produced –> total cost of male production should equal total cost of female production
  2. if males and females experience different mortality rates between birth and maturity, primary sex ratio should shift in order to produce 50:50 secondary sex ratio at maturity
62
Q

sex ratio in atlantic silversides

A

low water temp –> females produced
high water temp –> males produced
if silversides are kept in only warm water, strong selective pressure for individuals capable of producing females to restore 50:50 ratio

63
Q

sex ratio in polygynous anolis lizards

A

large offspring have higher fitness as males, small offspring have higher fitness as females
mothers in good condition should produce males, mothers in poor condition should produce females

64
Q

when might larger females be advantageous?

A

larger mothers may be able to carry more eggs, raise better offspring

65
Q

parasitic wasp example

A

hole size determines weevil larvae size –> corn kernels with larger holes produce more females, smaller holes produce more males

66
Q

age structure

A

% of individuals in different age classes

67
Q

type I survivorship curve

A

low initial mortality, with most mortality occurring at older ages (not common: humans, some large mammals and lizards)

68
Q

type II survivorship curve

A

equal chance of dying at all ages (uncommon: most birds, lizards, some mammals)

69
Q

type III survivorship curve

A

high initial mortality, lower mortality in older organisms (most common: most invertebrates, plants, many fishes, etc.)

70
Q

cohort

A

those individuals in the population born during a specific time interval (example: 1/1/1987 through 12/31/1987)

71
Q

Lx

A

% of individuals in a cohort surviving to age X (probability from surviving from birth to age X)

72
Q

Mx

A

‘fecundity’ –> the number of offspring produced by an individual of age X while at that age (NOT a probability)

73
Q

R0

A

net reproductive rate –> the average number of offspring per female over the course of its lifetime, averaged across all ages

74
Q

equation for R0

A

R0 = Σlxmx

75
Q

If R0 > 1…

A

the population is growing

76
Q

If R0 < 1…

A

the population is decreasing

77
Q

generation time

A

average age of reproduction

78
Q

generation time simple calculation

A

generation time = (α + ω)/2

79
Q

generation time complex calculation

A

generation time = Σxlxmx /R0

80
Q

why add complexity to the equation?

A

organisms may differ in likelihood of reaching different ages, or in number of offspring produced at each age

81
Q

Va

A

reproductive value –> the number of offspring expected to be produced by an organism of age A over the rest of her life

82
Q

why does Va initially increase over time?

A

newborn organisms may die before reproducing, an organism just entering reproductive maturity is more valuable than an infant

83
Q

organisms with which survivorship curve should focus on conservation and resource management?

A

type III

84
Q

λ

A

geometric rate of increase –> the ratio of population size at two points in time

85
Q

when does R0 not equal λ?

A

if a species has overlapping generations and/or continuous reproduction

86
Q

T

A

average generation time per population

87
Q

T equation

A

T = (ΣXLxMx)/R0

88
Q

r

A

intrinsic rate of increase for a population (r = per capita births - per capita deaths)

89
Q

r equation

A

r = ln(R0)/T

90
Q

Nt

A

number of individuals at time t

91
Q

N0

A

number of individuals at t = 0

92
Q

geometric population growth equation

A

Nt = N0λ^t

93
Q

when is geometric population growth used?

A

for organisms that experience pulsed reproduction (example: insects that produce a single generation per year, annual plants, etc.) –> generations CANNOT overlap

94
Q

when is exponential population growth used?

A

for organisms with continuous population growth in an unlimited environment

95
Q

exponential population growth equation

A

Nt = N0e^(rt)

96
Q

exponential growth equation expressed as a differential equation

A

dN/dt = rN
or
dN/dt = B - D = (b - d)N = rN; where N = total number of individuals in population, B = raw number of births, D = raw number of deaths, b and d = per capita rates of birth and death

97
Q

effect of r on population growth rate (exponentially)

A

large r = faster rate, small r = slower rate

98
Q

K

A

carrying capacity of species (limit to population size of that species in that area)

99
Q

when is K higher?

A

on larger islands or in better habitats

100
Q

logistic population growth equation

A

dN/dt = rN[1 - (N/K)]

101
Q

If N is small…

A

N/K ≈ 0 and ‘drops out’
dN/dt = rN (1-0) = rN(1) = rN = exponential growth

102
Q

If N is large…

A

N/K ≈ 1
dN/dt = rN(1-1) = rN(0) = no growth

103
Q

r is highest when…

A

N is lowest and declines as a linear function of N
reaches zero when N=K

104
Q

what is the max value of dN/dt?

A

at K/2

105
Q

optimal yield

A

N at which dN/dt is highest
population size that should be maintained for max harvest rate

106
Q

effect of varying r vs. K

A

the larger the r, the quicker the ‘slope’/more steep the slope
the larger the K, the higher the max N

107
Q

when is the logistic growth equation appropriate?

A

best fit with small, rapidly reproducing organisms with uniform populations (individuals are very similar to one another)
in larger organisms, population age structure creates oscillations as individual large organisms are more variable

108
Q

logistic growth equation with time lag

A

dN/dt = rN_t[1 - (N_(t-L)/K)]

109
Q

L

A

time lag

110
Q

effect of L

A

the larger L is, the more oscillations in the graph

111
Q

why add time lag?

A

present population size (N_t) and K are not as relevant as past population size (N_t-L) and K
development takes time, reproductive output is not yet in sync with present conditions and time lag is necessary

112
Q

per capita growth rate equation

A

PCGR = (dN/dt)/N

113
Q

PCGR decreases as N increases

A

negatively density-dependent

114
Q

PCGR increases as N increases

A

positively density-dependent

115
Q

PCGR is unrelated to N

A

density-independent

116
Q

how might negative density-dependence happen?

A

competition for resources
competition for territories
increased crowding increases disease prevalence

117
Q

how might positive-density dependence happen?

A

more mating opportunities if more individuals around
large groups defend against predators and get resources more efficiently

118
Q

how might density-independence happen?

A

weather, catastrophes, natural disasters

Ecology (3 decks)

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