post-lab discussion 3 - estimating population size using Lincoln-Petersen index

Question 1

major parameters affecting population size

Answer 1

birth rate
mortality rate
migration rate

Question 2

define population

Answer 2

grp of individual of the same species occupying a particular area and sharing common characteristics

Question 3

no. of offspring produced per unit of time

Answer 3

birth rate

Question 4

high birth rate -
low birth rate -

Answer 4

high birth rate - population growth
low birth rate - population decline

Question 5

what is the current birthrate in the Philippines

Answer 5

22.2 births per 1000 people

Question 6

how many animals are born everyday
humbolt penguin -
rabbits -
chickens -
bees -
nematodes -

Answer 6

humbolt penguin - 40
rabbits - 1 900 000
chickens - 62 000 000
bees - 370 000 000
nematodes - 600 000 000 000 000 000 000

Question 7

no of indiv that die per unit of time

Answer 7

mortality rate

Question 8

high death rates -
low death rates -

Answer 8

high death rates - reduce population size
low death rates - contribute to population growth

Question 9

what is the current death rate in the Philippines

Answer 9

6.3 deaths per 1000 people

Question 10

immigration vs emigration

Answer 10

Immigration:
* The movement of individuals into a population from other areas.
* Immigration increases population size by adding new individuals.

Emigration:
* The movement of individuals out of a population to other areas.
* Emigration decreases population size by removing individuals.

Question 11

contributing factors affecting the population size

Answer 11

food availability
predation
disease
habitat quality
competition
human activities

Question 12

it is the abundance of food resources in the environment

Answer 12

food availability

Question 13

adequate food availability -
food scarcity -

Answer 13

adequate food availability - support population growth
food scarcity - limit population size

Question 14

the presence of predators that consume individuals of the population

Answer 14

predation

Question 15

briefly explain high predation rates

Answer 15

it can reduce population size by causing mortality

Question 16

the prevalence of infectious diseases within the population

Answer 16

disease

Question 17

briefly explain what disease outbreak can lead to

Answer 17

increased mortality and decreased population size

Question 18

the suitability of the environment for the species’ survival and reproduction

Answer 18

habit quality

Question 19

high-quality habitats -
degraded habitats -

Answer 19

high-quality habitats - support larger populations
degraded habitats - limit population size

Question 20

interactions among individuals of the same species or different species for resources (examples)

Answer 20

competition
(food, water and shelter)

Question 21

briefly explain what will happen if there is intense competition

Answer 21

can limit resources = decreased popu size

Question 22

anthropogenic factors (examples )

Answer 22

human activities
(habitat destruction, pollution and hunting)

Question 23

how can human activities impact population size

Answer 23

it can directly or indirectly impact population by altering the enviro and affecting species survival

Question 24

what is the importance of understanding population size

Answer 24

essential for ecological studies, wildlife management, conservation efforts and public health planning [WEPC]

helps in assessing the health of ecosystems, determining resource allocation and implementing effective conservation strategies
[HOE, DRA, IECS]

Question 25

briefly explain the methods of populations size estimation
(examples)

Answer 25

direct counting:
counts every indiv in the popu
suitable for small, easily observable popu
(head counts)

sampling:
estimate popu size based on samples collected from the popu
requires statical analysis to extrapolate to the entire population
(capture-mark-recapture methods)

The key difference between these two methods is that direct counting aims to account for every individual in the population, while sampling relies on statistical techniques to estimate the population size based on a subset of the population. Direct counting is more accurate for small, easily observable populations, while sampling is more practical for larger or more difficult-to-access populations.

Question 26

who develop Lincoln-Petersen Index

Answer 26

Federick C. Lincoln
Julius A. Petersen

Question 27

lincoln-petersen index is used to estimate …

Answer 27

population size in wildlife biology and ecology

Question 28

Lincoln-Petersen Index formula

Answer 28

P = (N1)(N2) / R
P: estimate popu size
N1: total no. of marked indi
N2: no. of indiv in one sampling (total captured)
R: no. of tagged or marked indiv in one sampling

N = marked × total captured/recaptured = MC/R

Question 29

what are some assumptions helps ensure that the Lincoln-Petersen index provides an accurate estimate of the true population size

Answer 29

no immigration or emigration:
no one can join or leave the population

no births or deaths occur during sampling method

marked organism must fully reintegrate and mix into the popu before and after sampling:
marked individuals from the first sample need to fully mix back into the population before the second sample is taken = equal chance of being recaptured as the unmarked ones

short sampling interval:
time between the first and second samples needs to be shorter than the lifespan of the organism being studied = ensures that marked indiv dont die befores the second sample is taken

If any of these assumptions are violated, the population size estimate may be inaccurate.

Question 30

what are the steps in applying the lincoln-petersen index

Answer 30

capture and mark indivs from popu
released marked indiv back into the popu
wait for sufficient period to allow mixing or marked and unmarked indiv
capture second sample from popu
count the no. of marked indivs recaptured in the second sample
apply lincoln-petersen formula to estimate total popu size

Question 30

advantages of the Lincoln-Petersen Index

Answer 30

[SCAN]
simplicity:
straightforward and does not require advanced technology

cost effectiveness:
implement w minimal resources

non-destructive:
does not harm indiv being studied

applicability:
widely used in various field (ecology, wildlife managemnt and conservation biology)

Question 31

limitations and considerations of the Lincoln-Petersen Index

Answer 31

[VVES]
violations of assumptions = biased estimate

variation in capture probabilities among indiv can affect the accuracy of estimates (indiv in the popu may have diff chances of being captured or recaptured)

small sample size = unreliable popu size estimates

environmental factors (enviro, weather, type of habitat) and habitat heterogeneity can influence capture rates

Question 32

how would u describe the gap between the Lincoln- Petersen Index and the real population size?

Answer 32

they arent always perfect

mistakes might occur during marking and recapturing

errors in makrking/recapturing

it is crucial to recognize this diff and think abt how it might affect the accuracy of popu estimate

Question 33

what are the possible causes as to why the average estimated population did not match the actual population size?

Answer 33

human error:
mistakes in counting

errors in marking and recapturing:
mistakes in properly tagging

violating the lincoln-petersen index assumptions:
assumes that popu is closed and tht thr r no births or deaths during the study period

Question 34

what are the other methods that can be used in population size estimation aside from CMR technique?

Answer 34

indirect sign:
instead of counting directly, this method looks for signs they leave behind (tracks, nests, droppings)

genetic techniques:
use animals’ DNA to figure out how many of them r in the popu (hair, feather)
observe directly

transect surveys:
researchers walk along set paths through the animal’s habitat and count how many they see within a certain distance on either side of the path
commonly used for mobile or wide-ranging species

Question 35

why is essential to accurately estimate population size

Answer 35

for effective management and conservation efforts