lec 17

Question 1

what is a population

Answer 1

collection of living things in an area

Question 2

formula for pop density

Answer 2

N(pop size)/area

Question 3

why is N(pop size) important

Answer 3

natural resource management
-size of fish stocks in ocean
-abundance of outbreaking insect pests in forests

conservation
-pop declines of species

health
-monitoring pop of viruses or bacteria in humans

Question 4

Myotis lucifungus bats and white-nose

Answer 4

devastated bat population

Question 5

malthus theory

Answer 5

human pop cant grow faster than resources produced

Question 6

Paul Ehrlich

Answer 6

published “the population bomb”

argued that the explosive growth in the human pop would have catastrophic social and environ. consequences

Question 7

what is the goal of most pop models

Answer 7

-predict the path of pop growth thru time

Question 8

what are time steps in a pop model

Answer 8

use concept of limits and calc to ensure growth is smooth and best suited for species with cont. reproduction

Question 9

E meaning

Answer 9

number who emigrate during one time step

Question 10

I meaning

Answer 10

number who immigrate during one time step

Question 11

birth and what are equiv

Answer 11

birth and immigration are equivalent (i.e. individuals added to pop)

Question 12

death and what are equiv

Answer 12

death and emigration are equivalent (i.e. individuals removed from pop)

Question 13

treat birth and death during one time step as ____ that are…

Answer 13

per-capita rates; fixed constants

Question 14

lambda

Answer 14

multiplicative factor by which pop changes over time

Question 15

if births exceed deaths..

Answer 15

pop grows

Question 16

if deaths exceed births…

Answer 16

pop shrinks

Question 17

relationship b/w lambda and r

Answer 17

ln(lambda)=r

Question 18

dN/dt

Answer 18

slope of the growth curve at any point

Question 19

what does a constant positive growth rate represent

Answer 19

produces a pop size that isnt constant but rather exploding in an exponential way

Question 20

explain why species can’t stay as lambda greater or less than 1

Answer 20

lambda>1 births exceed deaths, no species can sustain that for a long period

lambda<1 deaths exceed births, no surviving species can maintain that due to going extinct

Question 21

density-dependent regulation

Answer 21

growth depends on pop size

In such systems, factors that limit population size become more intense as the population density increases.

This means the population’s growth and survival are affected by how crowded the population becomes

e.g. competition for resources, predation

Question 22

density-independent regulation

Answer 22

refers to factors that affect population size or growth regardless of the population’s density

density-independent factors do not intensify or diminish based on how crowded a population is

Instead, these factors act uniformly, impacting a population no matter its size.

e.g., natural disasters, weather

Question 23

what happens if N gets too big

Answer 23

-pop growth stops
-reaches carrying capacity since pop size is too big

Question 24

logistic braking term

Answer 24

models the simplest form of density dependence

Question 25

at low density…

Answer 25

no braking

Question 26

complete braking when…

Answer 26

N approaches K

Question 27

logistic model produces…

Answer 27

s-curve (sigmoid)

Question 28

when are logistic trajectories truly s-shaped?

Answer 28

only when starting from low numbers

Question 29

at carrying capacity, slope is

Answer 29

0

Question 30

pros of logistic model

Answer 30

simple(only 1 extra parameter, K)
-model of intraspecific competition for resources

Question 31

cons of logistic model

Answer 31

too simple (specifies 1 kind of density dependence)
-likely to be non-linear, which overshoots K