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BIOL 150 > Life History And Demography > Flashcards

Life History And Demography Flashcards

1
Q

Asexual reproduction

A

Offsprings are genetic clones of the parent

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2
Q

Parthenogenesis

A

“Virgin birth”, develop from an unfertilized egg

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3
Q

Sexual reproduction

A

The product of meiosis and fertilization (two gametes produce zygote)

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4
Q

Alternating between sexual and asexual

A

Environmental cues
- declining food quality
- seasonal changes (phenology)

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5
Q

Asexual: pros and cons

A

+ high fitness under (i.e. adapted to) current conditions
+ rapid population growth
- low genetic variability; less adaptable to changing conditions
- lack of recombination; no way of getting rid of bad genes

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6
Q

Sexual: pros and cons

A

+ Portfolio effect: genetic diversity minimizes the volatility of the population’s response to changes in env. conditions
+ more raw material for natural selection to act on
- takes time and energy if the resources are scarce and the seasons are short (e.g. Arctic, Desert, etc.)
- requires reproductive organs
- courtship and mating - risky and use energy

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7
Q

Life history

A

The way that organisms allocate resources to growth, survival, and reproduction (fecundity); the sequence and timing of events in an organism’s life

  • trade off between survival and fecundity
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8
Q

Life history trait

A

A heritable trait that determines some aspect of the life history of an organism (e.g; maturity, # of offspring, longevity)

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9
Q

Life history strategy

A

A pattern of life-history traits that has evolved by natural selection over time in a population in response to ecological conditions

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10
Q

Demography

A

The study of factors (i.e. birth, death, immigration, emigration) that determine the size and structure of populations through time

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11
Q

Random distribution

A

The position of each individual is independent of the others

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12
Q

Clumped distribution

A

The quality of the habitat is patchy or the organisms are social

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13
Q

Uniform distribution

A

Negative interactions occur among individuals that space them out evenly

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14
Q

Life table

A

A summary of the probability that an individual will survive and reproduce in any year during its life time

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15
Q

Cohort

A

A group of individuals of the same age that we can follow through time

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16
Q

Age class

A

A group of individuals of a specific age

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17
Q

Survivorship

A

Proportion of individuals remaining alive from one age class to the next

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18
Q

Survivorship curve

A

A plot of the logarithm of the number of survivors vs age

  • helps us recognize general patters in survivorship
  • helps us compare among populations or species
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19
Q

Type 1 survivorship curve

A

Survivorship throughout life is high; most individuals survive until the max. life span of individuals within the species (i.e. humans)

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20
Q

Type 2 survivorship curve

A

Most individuals experience relatively constant survivorship over their lifetimes (i.e. songbirds)

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21
Q

Type 3 survivorship curve

A

Result from high death rates early in life; high survivors ship after maturity (i.e. many plants, turtles)

22
Q

Fecundity

A

The number of female offspring produced by each female in the population

23
Q

Age specific fecundity

A

The average number of female offspring produced by a female in a given age class

24
Q

The growth rate of a population per generation (Rknot)

A

Net reproductive rate

= 1 : population is stable
< 1 : population is decreasing
> 1 : population is increasing

25
Q

Per-capita population growth rate

A

r = b - d

b > d, r is posivite; population is growing
b < d, r is negative; population is declining
r = 0, stable

PER TIME INTERVAL

26
Q

Net reproductive rate

A

Rknot = SUM OF lx(mx)

> 1 : growing population
= 1 : stable population
< 1 : shrinking population

PER GENERATION BASED ON LIFE TABLE INFO

27
Q

Generation time

A

G = SUM OF lx(mx) / Rknot

  • age-specific fecundity : lx(mx)
  • Rknot : net reproductive rate
  • x : age category
28
Q

Using Rknot and G to calculate r

A

r = ln(Rknot) / G

29
Q

Population growth

A

Nt = Nknot e^rt

This is exponential or continuous growth

30
Q

Maximum intrinsic growth rate (r max)

A

Birth rates per individual (b) are as high as possible and death rates per individual (d) are low as possible

delta N / delta t = r max (N)

31
Q

Exponential population growth

A

When r does not change over time. The population growth rate does not depend on the number of individuals in the population (density independent).

Can occur when individuals found a new pop. or after a population bottleneck caused by a disaster (i.e. fire, disease etc.)

32
Q

Density Independent

A

Population growth when increases in the size of a population do not affect (or change) r

33
Q

Density dependent

A

When population density (the # of individuals per unit time) gets high, the population per-capita birth rate decreases, and the per-capita death rate increases, causing r to decline.

34
Q

Carrying capacity (K)

A

The maximum number of individuals in a population that can e supported in a particular habitat over a sustained period of time

  • as a population exceeds K, resource consumption moves beyond what can be regenerated; becomes unsuitable habitat
35
Q

r = r max (K - N / K) so that delta N / delta t = r max (K - N / K) (N)

A

As N approaches K, r is approaching 0

As N approaches 0, r is approaching r max

36
Q

Density independent factors

A

Usually abiotic; change birth rates and death rates regardless of population size

37
Q

Density dependent factors

A

Can be biotic (i.e. resources, predation, disease/parasites); change in intensity as a function of population size

38
Q

Antagonistic selection

A

When any components of fitness are in opposition to each other
- viability selection vs. sexual selection
- viability vs. fecundity
- sexual vs. fecundity

39
Q

The principle of allocation

A

Any energy an organism uses for one function to reduce the amount available for another function
- age vs. fecundity : delayed sexual maturity results in higher fecundity, but increases the probability of death before reproduction (good strategy if top predator)

40
Q

Strategy 1: number vs. size of offspring

A

Lots of offspring means little investment in each child
Strategy 1: generate a lot of offspring, invest little in each with the expectation o low survival rates

Altricial: young are born helpless

41
Q

Strategy 2: number vs. offspring size

A

Produce few young, but invest heavily in each to maximize offspring survival

Increase the fitness of young at the expense of the fitness of the parents

Precocial: longer gestation, young are born at mor advanced developmental age

42
Q

Semelparous

A

One breeding event/one shot to reproduce ; produce as many offspring as possible

43
Q

Iteroparous

A

Repeated reproduction events ; can depend on environment/phylogeny

44
Q

r vs. K

A

r strategists:
- r-selected maximize reproduction
- short lived and reproduce at a young age
- produce lots of small babies with little parental care
- tend to be precocial
- semelparous
- fast, high adult mortality rate

K strategists:
- K selected
- long lived and mature at a late age
- few babies and lots of care
- tend to be altricial
- iteroparous
- slow, low adult mortality rate

Most species are somewhere in the middle

45
Q

Grime model

A

Competitors (C) - K (i.e. oak tree)

Ruderals (R) - r (i.e. dandelion)

Stress tolerators (S) - organisms that will survive extreme conditions (i.e. extreme high/low temps, bottom of the ocean); don’t fit R or C strategies (i.e. cactus)

46
Q

Metapopulations

A

Populations of populations linked by immigration and emigration

  • individual patches “wink” on and off
    - larger pop. can save smaller pop. from going extinct
47
Q

Source-sink metapopulations

A

One or several large sources; self-sustaining populations

  • r values greater than or equal to 0
  • R knot values greater than or equal to 1

They’re growing or are stable

48
Q

True-sink population

A

Will go extinct if immigration is cut off

49
Q

Pseudo-sink population

A

Population would persist at a lower equilibrium in the absence of immigration

50
Q

Momentum

A

A reduction is infant mortality before the reduction in birth rate (in industrializing countries)

51
Q

Ecological footprint

A

The aggregate and and water needed to sustain the population

BIOL 150 (4 decks)

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