53: Population Ecology

Question 1

what affects the size of a population and how it changes over time

Answer 1

adding or removing individuals

Question 2

what can be used to describe population

Answer 2

its boundaries and size

Question 3

what is a boundary

Answer 3

it can be natural like an island or lake

or arbitrarily defined by an investigator

Question 4

what is population ecology

Answer 4

explores how biotic and abiotic factors affect population, density, dispersion and demographics

Question 5

what is density

Answer 5

the number of individuals per unit area or volume

Question 6

what is dispersion

Answer 6

pattern of spacing among indiviudals within the boundaries of the population

Question 7

what is demography

Answer 7

study of birth/death/migration rates

Question 8

what can be used to find density

Answer 8

sampling techniques like the mark-recapture method

Question 9

how do they use the mark-recapture method

Answer 9

scientists capture and tag random sample of individuals in a population and they are given back to the population then they capture a second sample and note how many they mark

Question 10

what is the formula to solve for population size

Answer 10

x/n= s/N or N=sn/x

Question 11

what is density the result of

Answer 11

processes that add individuals and remove individuals

Question 12

what is immigration

Answer 12

influx of new individuals and births to increase population size

Question 13

what is emigration

Answer 13

movement of indivduals out of a population, and deaths to decrease population size

Question 14

what is the pattern of dispersion determined by

Answer 14

spacing among individuals within the boundaries

Question 15

what factors affect the spacing of individuals in a population

Answer 15

environmental and social factors

Question 16

what is the most common pattern of dispersion

Answer 16

clumped

Question 17

what is a clumped pattern

Answer 17

• individuals aggregate in patches

- aggregate in high resource availability or favorable physical conditions

Question 18

what else can influence the clumped pattern

Answer 18

mating behavior and group predation or defense

Question 19

what is uniform dispersion

Answer 19

individuals spread out evenly

Question 20

in uniform dispersion what do plants do

Answer 20

secrete chemicals that inhibit germination and growth of competing individuals

Question 21

what is uniform dispersion influenced by

Answer 21

social interactions like territory and the defense of a bounded space against other individuals

Question 22

what is random dispersion

Answer 22

the position of each individuals is independent of other individuals

Question 23

when does random dispersion occur

Answer 23

occurs in the absence of strong attractions or repulsions among individuals

Question 24

what is demography

Answer 24

study of the vital statistics of population

Question 25

what is a life table

Answer 25

age-specific summary of the survival and reproductive rates

Question 26

what is the fate of a cohort on the life tables

Answer 26

a group of individuals of the same age

Question 27

what group is ignored in a life table

Answer 27

males because only females produce offspring

Question 28

what does a life table show

Answer 28

proportions of females alive at each age and the number of female offspring produced per female

Question 29

what is survivorship curve

Answer 29

graphic way of representing the data in a life table

Question 30

what are the general types of survivorship curves

Answer 30

type 1 type 2 type 3

Question 31

type 1 curve

Answer 31

low death rates in early and middle | increase in death rates among older age groups

Question 32

type 2 curve

Answer 32

constant death rate over organisms life span

Question 33

type 3 curve

Answer 33

high death reates for the young and lower death rate for survivors

Question 34

what can be used to estimate the number of breeding females

Answer 34

direct counts, mark-recapture, molecular tools

Question 35

what is an exponential model

Answer 35

describes population growth in an idealized unlimited environment

Question 36

population growth for an exponential model

Answer 36

``` dN/dt = rN r = per capita change dN/dt = very small changes in population size over short ```

Question 37

what are some characteristcs of a J-shaped curve

Answer 37

rate of increase is constant large populations grow faster than small populations - larger r grows faster -smaller r = grows slower

Question 38

what does the logistics model describe

Answer 38

describes how a population grows more slowly as it nears its carrying capacity

Question 39

wha is carrying capacity

Answer 39

the max pop size that an enviornment can sustain

Question 40

what are some characteristics of the logistics population growth model

Answer 40

- starts with exponential growth model - adds (K) carrying capacity - k reduces per capita - new individuals are added to the population most rapidly at intermediate population sizes - population growth decrease as N approaches K

Question 41

what is the logistics pop formula

Answer 41

dn/dt = rn(K-N)/k

Question 42

what shape does a logistics growth model represent

Answer 42

sigmoid(s shape) | -

Question 43

what is the logistics model used for

Answer 43

predicting the rate of recovery for small populations - estimating the sustainable harvest rates for wildlife - estimating the critical size

Question 44

what is the life history?

Answer 44

traits that affect the schedule of reproduction and survival

Question 45

what does life history reflect

Answer 45

the development, physiology and behavior of an organism

Question 46

what does life-history entail

Answer 46

the age, how often they reproduce, how many offspring are produced

Question 47

what is semelparity

Answer 47

reproduce once or big band reproduction then die

Question 48

what is iteroparity

Answer 48

repeated reproductive events

Question 49

what influences trade-offs

Answer 49

selective pressures influence the number and size of offspring

Question 50

what do species do when they have young who don't have a long life span

Answer 50

produce many small offspring

Question 51

plants produce a large number of small seeds

Answer 51

ensure that at least some of them will grow and eventually reproduce

Question 52

why do parents produce few offspring

Answer 52

invest more energy in each offspring to increase the probability of survival for each

Question 53

what is density-dependent birth and death rates

Answer 53

example of negative feedback that regulates population growth

Question 54

what affects density-dependent birth and death rates

Answer 54

competition for resources, disease, predation, territoriality, toxic wastes, and intrinsic factors

Question 55

what is the intrinsic factor

Answer 55

the genetic, physiological, and pathological characteristics of an individual