Lecture 14: Population spatial structure

Question 1

Ecologists try to understand what factors determine

Answer 1

the distribution and abudance of species

Question 2

Population

Answer 2

group of individuals of the same species that live within a particular area and interact with one another

Question 3

When species interact, it means

Answer 3

compete, share pathogens, reproduce

Question 4

Distribution

Answer 4

Geographic area where individuals of a species occur

Question 5

Abundance

Answer 5

Number of individuals in a given area

Question 6

Measure of population abundance

Answer 6

1. population size (individuals)
2. population density (individuals/area or individuals/volume)

Question 7

Genetic population

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group of individuals that mate with one another and produce offspring; group of individuals that exchange genes

Question 8

Ecological population

Answer 8

group of individuals of the same species that compete for same resources, share pathogens, parasites, predators, and mutualists
they are linked together by ecological processes

Question 9

What is the spatial extent of genetic population vs. ecological population?

Answer 9

Think about conifers are all wind pollinated
In this case, Genetic population is much larger because of the genetic connectivity (gene flow) provided by long distance pollen dispersal

Question 10

Dispersion of individuals within a population =

Answer 10

spacing with one respect to one another

Question 11

Dispersion of individuals can be described as 3 distributions:

Answer 11

1. Regular distribution
2. Random distribution
3. Clumped distribution

Question 12

From regular –> random –> clumped distribution is

Answer 12

overdispersed –> regularly dispersed –> underdispersed

Question 13

Causes of overdispersed (even spacing) distribution

Answer 13

Animals defending territories (overdispersion at individual level and group level)

In plants: resource limitation (ex. water limitation)

Question 14

Causes of underdispersed (clumped) distribution

Answer 14

Animals: animal flocks, cooperative breeding
Plants: heterogenous (=patchy) physical environment

Question 15

Spatial structure may vary by

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scale

Question 16

Ex of how herbacceous has spatial structure varrying by scale

Answer 16

patchy at large scales (limestone meadows)
more random/uniform at smallest scales

Question 17

Dispersal limitation

Answer 17

absence from suitable habitat due to limited dispersal
-particularly annoying to theoreticians
can be easy to test for

Ex. Hawaiian islands only have one native terrestrial mammal, hoary bat

Question 18

Measuring a population

Answer 18

Measuring subsamples for sessile organisms
Mark-Recapture for motile organisms

Question 19

Area based counts of a subsample

Answer 19

individuals in a given area of volume are counted
Used to estimate abundance of sessile organisms like plants
Individuals are counted in several quadrats; counts are averaged to estimate population size

Question 20

Quadrats

Answer 20

sampling areas of specific size

Question 21

Distance methods

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distance of individuals from a line or point are converted into estimates of abundance

Question 22

Line transects

Answer 22

observer travels along a randomly placed line, counts individuals and determine distance from the line
used for sessile organisms (trees)

Question 23

Mark Recapture studies

Answer 23

Measure population abundance for mobile organisms
A subset of individuals are captured and marked or tagged, then released
Those released individuals mix evenly with rest of population
At later date, individuals are captured again and proportion of previously marked individuals is noted

Question 24

For mark-recapture studies, the proportion of marked individuals in recaptured population should equal

Answer 24

the original proportion of the population caught during the first sampling

Question 25

Variables for measuring population size (N) with mark recapture N is ____ A= B= R= A/N= R/B=

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N is unknown A= # in 1st sample = # marked B= # of 2nd sample R=# of recaptured in 2nd sample A/N= true proportion marked R/B= observed proportion marked in 2nd sample

Question 26

Assuming no bias, equation R/B __ A/N

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equal

Question 27

N=

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N= (A * B) / R

Question 28

Geographic ranges vary in

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size Ex. many tropical plants live in small ranges vs. coyotes live all over North American continent

Question 29

Endemic species

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occurs in one location only, and no where else on Earth

Question 30

Geographic range includes

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all the areas a species occupies during all life stages

Question 31

Really important to think about geographic range and distribution pattern for species that

Answer 31

mirgate and whose biology is poorly understood

Question 32

Within a species' range, not all habitats are ___ so distributions are ____

Answer 32

suitable, patchy

Question 33

Some species have very specific _____ others tolerate ______

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habitat requirements, a broader range Ex. Creosote bush tolerates both dry and cold vs. saguaro cactus can tolerate only dry but not cold

Question 34

Habitat suitability determines

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distribution and abundance

Question 35

Habitat suitability/ species distribution influenced by

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abiotic factors: moisture, temperature, pH, light, nutrients biotic factors: herbivores, predators, competitors, parasites, and pathogens disturbance

Question 36

Disturbance

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events that kill or damage some individuals, creating opportunities for other individuals to grow and reproduce Ex. Fires Influence species distribution

Question 37

Species distribution models

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Attempt to determine climatic rules determining a species' abundance Apply those rules to predict distribution as climate changes

Question 38

Why are species distribution models useful

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You don't know the whole range of a species, but have samples of its presence Predicting spread of pest species Predicting shifts with climate change

Question 39

Chameleons in Madagascar Species Distribution Model Example

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Models predicted distributions from known climatic associations Able to see where species was found not known before Use known samples with climate change Not perfect!

Question 40

Large scale spatial structure

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Effects of climatic change on geographic ranges

Question 41

Map Climate velocity

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The distance needed to move to maintain the same climate Can be done for different details of climate

Question 42

Population dynamics

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the study of population size over time simple assumptions about individuals assume all individuals are the same

Question 43

Use of population dynamics

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Predator-prey cycles Disease dynamics Population viability analyses

Question 44

If △N > 0

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population is increasing

Question 45

If △N < 0

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population is decreasing

Question 46

△N =

Answer 46

births - # deaths + # immigrants -# emigrants

Question 47

Population dynamics models used to answer questions:

Answer 47

How does the population size change over time? What determines whether a population is increasing or decreasing?

Question 48

Assumptions in Population Dynamic model 1

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Births per unit time of the population are constant (B) Deaths per unit time of the population are constant (D) Immigration = Emigration

Question 49

Population Dynamics model 1

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Linear increase/decrease in population size Constant population growth

Question 50

Assumptions in Population Dynamic model 2 = Discrete model

Answer 50

All of the individuals are the same Each individual gives birth at the same rate (b) Each individual has same chance of dying (d) Immigration and emigration are equal

Question 51

per capita

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rate of change in population size per capita = per individual

Question 52

λ

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Geometric rate of increase

Question 53

Conditions of geometric growth

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Unlimited Resources Often: small population size and rapidly growing organisms (time lags) Good "null" model for comparison: If there are no changes to per capita births, deaths, and immigration = equal emigration

Question 54

Ex of geometric growth

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Bacteria in petri dish with abundant food, invasive species, global human populations

Question 55

Discrete geometric growth model

Answer 55

Time is discrete The per-capita rate of change in population size is constant. ▪ Each individual contributes the same amount to the change in population size over time. ▪ This means the population will rapidly increase or die out ▪ Or stay the same if lambda = 1. Good null model to figure out if the per-capita rate of change in population size is changing.