Unit 5 - Demography

Question 1

demoraphy

Answer 1

the study of the growth rate, age structure, and other characteristics of pop. Ecologists use demographic analysis to predict the growth of a pop

Question 2

Factors that affect pop growth (4)

Answer 2

1) birth rate (natality)
2) death rate (mortality)
3) movement into a pop
(immigration)
4) movement out of a pop (emigration)

Question 3

Life Tables

causes of death

Answer 3

every species has a characteristic lifespan
+ Individuals may die from starvation, disease, predation, or inability to find a suitable habit

Question 4

Demograhers

Answer 4

collect data by monitoring a cohort for their survival until death

Question 5

Mortality Rate

+ two was it is observed

Answer 5

the number of deaths in a pop per unit of time; observed in 2 ways
- age-specific morality
- age-specific survivorship

Question 6

age-specific mortality

Answer 6

the proportion of individuals that were alive at the start of an age interval but died during the age interval

Question 7

age-specific survivorship

Answer 7

the proportion of individuals that were alive at the start of an age interval and survived until the start of the next age interval

Question 8

age-specific mortality rate equations =

Answer 8

number that died during the interval / number alive at the start of the interval

Question 9

age-specific survivorship equation =

Answer 9

number still alive at the end of the interval / number alive at the start of the interval

Question 10

sume of ASM and ASS must equal=

Answer 10

1

Question 11

Life Tables summarizes…

Answer 11

the proportion of the cohort that survived to a particular (identifies the probability that any randomly selected newborn will still be alive at this age)

Question 12

probability of being alive as a specific age equation =

Answer 12

number alive at the start of the age interval / number alive at the start of initial age interval

Question 13

Survivorship curves

Answer 13

• life tables used to see how diff species can survive hardship
• date is expressed graphically using SC showing survival of an individual over lifespan
• three types 1,2, and 3

Question 14

type 1

Answer 14

relatively flat at the start, reflecting a low death rate in the early and middle years, followed by a steep drop as the death rate increases for the older age group

Question 15

type 1 typically found in?

Answer 15

LARGE animals that produce few young (take care of their young = reduced juvenile death)
and have a long gestation period
ie. deer, moose, humans

Question 16

type 2

Answer 16

relatively constant rate of death in all age groups. steadily declining survivorship. constant probability of death from predation, disease, and starvation.
- short gestation period
- feed on type 3 but r prayed on by type 1
ie. lizards, songbirds, small mammals

Question 17

type 3

Answer 17

rapid drop at the start = a very high death rate early in life and then flattens out as the death rate declines for the few individuals who surivive critical stage
- make large amounts of offspring
ie. plants, insects, fish

Question 18

Fecundity

Answer 18

is the potential for a species to produce offspring in a lifetime
- highly dependent on environment conditions

Question 19

plenty of food or best climate=?

Answer 19

higher rates of reproduction

Question 20

little food and prediators=?

Answer 20

decreased rates of repoduction

Question 21

example of fecundity

Answer 21

horseshoe crab lay 100 of thousands of eggs a year vs asian elephants produces 4 offspring during 60 life spam

Question 22

generation time

Answer 22

the average time between the birth of an organism and the birth of its offspring

Question 23

small body size (generation time)

Answer 23

v short generation time bc the individuals reach maturity very quickly ie. E. coli

Question 24

large body size (generation time)

Answer 24

later reproductive maturity w a longer generation time
ie. humans or whales

Question 25

sex ratio

Answer 25

is the relative proportion of male and females in a pop

Question 26

in general number of females has a greater impact then males

Answer 26

• females make offspring
• one male can mate w many females

Question 27

elephant seals

Answer 27

mature bulls fight for dominance. the few who win inseminate 100+ females so greater number of females in pop size.

Question 28

goose/swans

Answer 28

50/50
= lifelong pairs mate for life therefore both females and males influence reproduction

Question 29

high fecundity in intermediate age

Answer 29

high in humans
- younger individuals have not yet reached sexual maturity, and older individuals are past their reproductive prime. but fecundity increases steadily with age in some plants and animals

Question 30

high fecundity in animals

Answer 30

high = animals w many offsprings and normally do little to care for offspring
ie. turtle lay 100 eggs and immediately leave offspring hatch and fend for themselves

Question 31

low fecundity in animals

Answer 31

animals w few offspring r often v proactive of offspring
ie. black bears stay w cubs aprox. 27

Question 32

changes in pop size

Answer 32

birth, death, immigration, emigration numbers can be used to determine the change in the size of pop in a given period of time

Question 33

population change equation =

Answer 33

(birth + immirgration) - (deaths + emigration)

Question 34

pop sizes determined by

four things

Answer 34

changes in the number of individuals that immigrate , emigrate, born or die

Question 35

natality and immigration =

Answer 35

to mortality and emigration then pop size will remain stable

Question 36

if natality and immigration exceed mortality and emigration

Answer 36

there is a pop growth

Question 37

if mortality and emigration greater then natality and immigration

Answer 37

pop decline