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Biology 215 - Principles of Ecology > Population Ecology > Flashcards

Population Ecology Flashcards

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1
Q

What are the main components that we will examine in population ecology?

A
  • movement, estimating population size, life tables, mortality and survivorship curves, population growth and population regulation
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2
Q

Explain the 4 types of examples seen in lecture for geographical distribution of species

A
  • humans are cosmopolitan
  • cougars, puma, mountain lions are WIDESPREAD distribution (across the americas)
  • the sitka spruce has LIMITED distribution to the pacific northwest
  • and the tarsier is HIGHLY RESTRICTED distribution (endemic) to Indonesia, particular attention to conservation biology in this distribution
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3
Q

Explain the 3 (subcategory) of distributions

A
  • Hyper-dispersion where they are equidistant from each other like fish schools and seabirds
  • Random where individuals are distributed without the respect to others seen in wildebeest, beach clams, and forest spiders
  • Aggregated or clumped, as either FINE grained (clumps separated by short distances) or COURSE grained (clumps separated by large areas)
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4
Q

What are the two major reasons for clumped distributions, for plants and animals.

A
  • Plants: there is a local difference in microhabitat (soil moisture, sunlight) the example of forest, grassland, and pond all mixed in together
  • Animals: for one) resources (prey) are clumped as seen in seagulls and two) behaviour facilitating groupings based on social context, family groups, predator defences and shelter
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5
Q

What are the two types in movement of individuals?

A
  • Dispersal, where movements of individuals are mediated by the movement away from the immediate environment of the place of birth (common in the majority of species) which allows for GENEFLOW
  • Migration, in two forms of immigration or emigration, which is the mass directional movement of large number of individuals from one location to the next
  • this is seen in salmon, wildebeest, seabirds, songbirds, and monarch butterflies as examples
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6
Q

What are the 3 examples of different types of movements of individuals discussed in the lecture?

A
  • Connecticut Warbler
  • Salmon
  • Monarch Butterfly
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7
Q

Explain the Example of the Connecticut Warbler and its mass migration between SA and NA.

A
  • there is a mass migration in the spring to North America to breed in areas where the snow is melting and there is limited number of predators
  • these song birds will experience higher productivity for food, less competition for resources and biomass for yielding their young, experiencing less predation
  • there is a higher predation rate in the tropics especially for their young
  • this is why there is mass migration away from SA
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8
Q

Why do Salmon migrate towards the open ocean?

A
  • young salmon will migrate away from the coastal regions to avoid the higher predation rates along these areas despite the water being higher in nutrients compared to the open ocean
  • will spend years in the open ocean building in size before returning to bread
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9
Q

Explain the unique situation of migration and breeding routes of the monarch butterfly.

A
  • these butterflies will spend the winter in the the high altitude Oyamel fir forest in Mexico, going through 4 generations before spending the winter here
  • Gen 1 adults from Mexico will mate and leave the mountains around February-March heading to Florida and feeding on Milkweed and laying their eggs (living between 2-6 weeks before dying)
  • Gen 2 hatch after 4 days, caterpillars feed on milkweed for two weeks, eggs to adults in 4 weeks with the adult butterflies flying north feeding on flower nectar and laying eggs on milkweeds enroute to Canada, adults living for between 2-6 weeks and die
  • Gen 3 will repeat this process
  • Gen 4 will migrate south and hibernate in the high altitude Oyamel fir forests of Mexico where they live for 6-8months
  • see the VIDEO for more information - MUST WATCH IT
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10
Q

Explain the migratory patterns and reasoning behind the humpback whales.

A
  • whales will mate birth their young along the equator where the warmer temperatures are more favourable for the young to survive, rather than expending energy in the frigid arctic waters to stay warm
  • migrate to arctic to feed on rich upwellings of nutrients and plankton
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11
Q

Define Density.

A
  • number of individuals per unit area/volume
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12
Q

How can one measure absolute density? 3 examples of this.

A
  • total counts (photographic - orcas)
  • quadrat sampling (physical grid over sample area, use random number generator, sample quadrats, calculating the mean of these quadrats and multiplying by total number of quadrats for an estimated density)
  • mark-release-recapture estimates using the Peterson/Lincoln Index for mark, release, recapture
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13
Q

Briefly explain the Peterson/Lincoln Index fro mark, release, recapture sampling of density.

A

Q - what is the population size?

  • you live capture, mark, and release say 5 individuals, so M is the number of marked individuals
  • you resample the population, where n is the number of individuals sampled of say 10 AND m being the number of marked individuals of the sample being 1
  • to estimate the population size use this equation M/N = m/n (M over N is equal to m over n)
  • the estimated size being 50
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14
Q

What is the confidence and challenges of the Peterson/Lincoln Index? - whose methods are these (Need to google these two methods)

A
  • you would need to sample most of the population for better accuracy
  • what if in your resample you found NONE of the initially marked individuals?
  • these are the Schnabel Method or the Jolly-Seber Methoth
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15
Q

What are 3 important assumptions that need to be made for reliable population estimates in mark-recapture studies?

A
  1. The population (N) is largely constant over the duration of the mark-recapture studies
  2. Marked individuals have the same change of getting caught as unmarked individuals
  3. Marked individuals do not incur great mortality as a result of the capture or mark
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16
Q

What is the first assumption in mark-recapture studies? and its constraints?

A
  • The population (N) is largely constant over the duration of the mark-recapture studies
  • there is no immigration, no emigration, no births and no deaths
  • only possible in short time frames
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17
Q

What is the second assumption in mark-recapture studies? and its constraints? and examples. - what does it do to the count?

A

Marked individuals have the same change of getting caught as unmarked individuals

  • the assumption of equal catchability
  • mice and getting a reward from getting trapped
  • recapturing these guys will DEFLATE the numbers in the population counts
  • or the example of crows and the trap being to smart to be recaptured would mean an OVER INFLATION of numbers as you would never recapture these individuals
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18
Q

What is the third assumption in mark-recapture studies? and its constraints? and examples. - what does it do to the count?

A
  • Marked individuals do not incur great mortality as a result of the capture or mark
  • there may be stress-related mortality where steelhead salmon may experience osmotic shock from being recaptured OR african wild dogs who were suffering from the distemp** virus were given vaccines but the shock of being marked killed off all the individuals that received the vaccination
  • mark-associated mortality where butterflies lose there predator evasion ability with the extra markings on their wings allows better predation recognition by the birds
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19
Q

Give two examples of higher mortality rates due mark and recapture population estimates.

A
  • Two papers as examples: Penguin and the flipper bands and subsequent life histories experienced by adults and young
  • fish being tagged become beacons for seal predators who track the beeping
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20
Q

What is the FOURTH assumption of mark-recapture studies?

A
  • that these individuals do not lose their marks
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21
Q

What are other methods to go about estimating population size? an examples of these?

A
  • using non-invasive methods of genetic markers (genetic fingerprinting) by collecting hair, feathers, faeces, or scales
  • can individual identify individuals by genotype and by resampling in the future predict/estimate the population size
  • this now done by genotyping faeces
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22
Q

How does one predict population size over time? 2 distinctions need to be made.

A
  • Nt is the number of individuals in the population at time t (usually being the current time)
  • Nt+1 is the number of individuals in the population at t+1 (1 year or 1 generation)
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23
Q

Explain each of the 4 Primary Population Parameters (PPP)

A
  • B, D, I, E
  • B is births (Natality) which is the number of offspring or seeds produced
  • D is Deaths which is the number of individuals that die per unit period of time
  • I is immigration, which is the movement of individuals into the population from other regions
    E is emigration, which is the movement of individuals out of an area
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24
Q

Explain the two categories of B, Births (Natality)

A
  • Fecundity which is the ecological concept which is the NUMBER OF OFFSPRING/SEEDS PRODUCED
    Fertility is the physiological concept that indicates a FEMALES ABILITY TO PRODUCE OFFSPRING/SEED PER UNIT PERIOD OF TIME
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25
Q

What is the equation using the 4 Primary Population Parameters?

A

Nt+1 = Nt + B + I - D - E

- this is used based on the population a current time Nt to estimate the numbers in the future Nt+1

26
Q

What is the Life table construction? - what field is this? what are the two types?

A
  • demography
  • this is useful in estimating mortality rates, survival rates, survivorship curves and average life expectancy
  • AGE-SPECIFIC and TIME-SPECIFIC
27
Q

Explain Age-Specific (cohort) analysis

A
  • is a group of individuals of the same age class
  • follow a specific cohort from birth to death
  • most useful for short-lived species like (mice and song birds)
  • see detailed example on slide 20 - see the different percentages for survivorship from birth to adulthood compared to mortality based on each stage from birth to adulthood
28
Q

Explain the Time-specific table

A
  • age structure at a single point in time
  • more for long-lived animals (mostly large animals)
  • a snapshot in time like a “static life table”
  • and requires age distribution of a population
  • see example human population age structure for potential rapid growth and stable/decreasing population
29
Q

Explain some of the new molecular techniques used to measure age distribution - is this Time-specific distribution?

A
  • use tree core sample to calculate the age of a tree, count the rings
  • count the number of lines on muscles to determine the age
  • individual fish scale under a light microscope will present darker rings of winter seasons when no growth occurred
  • examine whale eyes or ear bones to count the number of rings OR now we count the telomers, and fatty acid ratios to detmerine age
30
Q

Explain what experiment was done on the Dall Mt. Sheep? What did we learn?

A
  • collected the skulls of the dead one in the Alaska region, count the number of rings on the horns to construct the life table of individuals
  • table categorizes an age class in yearly increments with a sample size for number of skulls found for each age class
31
Q

What three components can be determined by the Time-specific life table construct of Dall Mt Sheep based on an N=608

A
  • Survivorship
  • mortality
  • life expectancy
32
Q

Explain the equation for life expectancy

A
  • lx is equal to Nt of a specific time over Nt of the entire population
  • numbering entering age class ‘x’ divided by total count N
  • initial plot shows initial struggle for life in early years before surivivorship remains constant until around age8-10 when survivorship begins to decrease
33
Q

Explain the equation for mortality

A
  • qtx is equal to Ntx of a certain time period subtracted from Ntx plus 1 year, should be a decrease in N between these years divided over the Ntx of the initial population number of interest
  • DO NOT USE Nt (N total population)
  • numbering entering age class ‘x’ minus number in age class ‘x’ plus 1 divided by number entering age class ‘x’
  • when plotted the graph shows initial there is a decrease in mortality for those surviving from 0 to 1, where mortality remains low until about 8 to 9 years of age when mortality begins to increase – ignore the blip at the end of the graph, do to small sample size
34
Q

explain the mortality rate of the wapiti elk and the difference between males and females.

A
  • derived similar to previous example
  • males who experience more fighting tend to not live beyond 14 years of age, with a significant increase in mortality from age 4 onwards
35
Q

explain how life expectancy is determined and define it first.

A
  • the expected number of ADDITIONAL years of life remaining at any specific age
36
Q

Give examples for each of the 3 actual survivorship curves, and reasoning behind them?

A
  • examining the log of number of survivors against age
  • Type 1 are many mammals, high survival reaching into older age before decline in survivorship
  • Type 2 are many birds, small mammals, lizards, turtles which is a pretty straight negative slope
  • Type 3 follows a J shaped survival curve similar to an r-strategist which includes many invertebrates, fish, amphibians, plants - from predation
37
Q

Explain the age distribution of two populations of trees under two different scenarios.

A
  • minimal browsing by deer result in higher numbers of younger trees
  • major browsing will reduce the abundance of younger trees, with a greater number of older trees, 30-40 years in ages being prevalent
38
Q

When examining the age distribution graph of the Dall Mt sheep, and the mortality curve, is the population increasing or decreasing?

A
  • we cannot answer this question, because we do not have all the right information
  • we would need information on the sex ratio to determine if the population is increasing or decreasing
39
Q

What is the population growth equation?

A

Nt plus 1 is equal to Nt plus B minus I minus deaths minus emigration

40
Q

Explain the difference in Age-specific fecundity rate ASFR versus Total fecundity rate TFR. Is the population growing now?

A
  • average number of male and female offspring produced per human female for each age group (NA)
  • average number of male and female offspring produced per female over her lifetime
  • and NO we still cannot determine if the population is increasing or decreasing
41
Q

Talk me through this example. in two populations, each with a TFR of 5, and population A has 10 reproductive adults, and population B has 100 reproductive results, - population A after reproduction is 45 and population of B after reproduction is 5… - what can we learn from this?

A
  • A consists of 1 male and 9 females
  • B consists of 99 males and 1 female
  • sex ratios are critical information - so life tables are often calculated only for females
  • BUT we still cannot determine if the population is increasing or decreasing
42
Q

In the fecundity schedule for female examples, explain survivorship Lx

A
  • the number of females surviving to beginning of age interval x, divided by the numbers born
43
Q

In the fecundity schedule for female examples, explain fecundity mx (Average Age-specific)

A
  • average number of DAUGHTERS produced by age class of females
44
Q

In the fecundity schedule for female examples, explain lxmx

A
  • survivorship of reproductive females in any age group TIMES the number of daughters produced for each age class of females
45
Q

what can we calculate with lxmx, and what significance does this have?

A
  • Net Reproductive Rate NRR
  • Ro which is the average number of breeding daughters that will be produced by each breeding female in the population in her lifetime
46
Q

What are the constructs of Ro, what can we tell with Ro

A
  • if Ro is less than 1, the population is decreasing and each female produces less than one breeding daughter by the end of her reproductive life
  • if Ro is equal to 1, the population is stationary
  • if Ro is greater than 1, population is increasing and on average each female produces more than one breeding daughter by the end of her reproductive life
  • based on Ro we are able to tell if the population is increasing or decreasing
47
Q

What approach does one take when Ro is 1.5, 100 females in the habitat breed and then die?

A
  • 100 time 1.5 equals 150
  • 150 time 1.5 equals 225
  • year 3, 225 times 1.5 equals 338, and so forth
48
Q

What is the equation for semelparous breeding?

A
  • if the species breeds once and dies, population size after a single reproductive season (called pulsed reproduction) is predicted by the equation
    Nt plus 1 is equal to Ro time Nt
49
Q

What do we call population growth without constraints?

A
  • geometric growth
50
Q

Define geometric growth? And what does it typically look like?

A
  • population growth without constraints

- exponential growth

51
Q

How can one determine the net reproductive rate (NRR) if we do not know Ro

A
  • we can use lambda
  • lamba is equal to Nt plus 1 divided by Nt
  • where lambda is: geometric rate of increase or finite multiplication rate or finite rate of increase
52
Q

Determine Ro for the population of dragonflies, 2018 of 40 and 2019 of 50, and how many numbers there would be in 8 years (How can we estimate geometric growth of the population into the future?)

A
  • we use the equation: Nt equals No times lambda t
  • this equation is useful for non-overlapping (discrete, pulsed) generations – which are SEMELPAROUS species
  • N8 is equal to 50 time 1.25to the power of 8 which equals 298, the 1.25 comes from calculating lambda which was 50 divided by 40
53
Q

What is different for calculating the rate of natural increase in interoparous species?

A
  • for iteroparous species, population growth after reproduction is predicted by exponential growth equations
  • dN over dt is equal to rN - where dN is the rate of change in numbers, dt is the rate of change in time and dN over dt is the rate of population increase
  • N is the population size, while r is the per capita rate of population growth
  • you can calculate r through subtracting birth rate B from death rate D
54
Q

Explain what we observed in the demographic transition in human populations of Mexico, Sri Lanka and Sweden

A
  • we are able to determine, r, the per captia rate of population growth (intrinsic rate of natural increase) buy subtracting birth rate from death rate (done in the thousands)
  • Mexico r is 2.3%
  • Sri Lanka r is 1.5%
  • Sweden r is 0.2%
  • a demographic transition is observed through maybe: improved health, education, lower mortality, or fewer offspring
55
Q

What is an alternative method of estimating r, what stipulations do we need to make?

A
  • we ignore immigration and emigration
  • calculate r through the loge time Ro divided by Tc
  • Tc is the generation time - the mean time elapsing between birth and first reproduction

NOTE: if you do not know Ro, you can use lambda

56
Q

What are the three constructs of r?

A
  • r equal to 0, the population is stable
  • if r is negative, population declines
  • if r is positive, population increases
57
Q

What equation is can be used to determine the actual population (N) at some point into the future (t) for a population with overlapping generations?

A
  • Nt is equal to No time exponent r times t
  • e is equal to 2.71828 (base of natural log)
  • and No is the initial population size
  • this is the integrated exponential growth equation
58
Q

Predict the population by 2030, for overlapping populations?

A
  • using overlapping generations

- Nt is equal to No times the exponent r times t

59
Q

Predict the population by 2030, for discrete generations.

A
  • calculating for lambda first, use this equation: Nt is equal to No times lambda with the power of t
  • this will give the predicted population value
60
Q

What are some limitations to populations reaching their limit?

A
  • populations cannot grow indefinitely, finite resources run out and renewable resources are limited
  • this is called K, the carrying capacity - this is the total number of individuals of a species which can be sustained in a habitat IN THE LONG TERM
61
Q

What is important to know about K, give an example of this.

A
  • K is often estimated INDIRECTLY as the average population numbers of the species observed across multiple years
  • the pileated woodpecker is dependent on the number of dead trees or snags in a forest, thus a completely healthy forest may lack this woodpecker all together

Biology 215 - Principles of Ecology (3 decks)

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