post-lab discussion 3 - estimating population size using Lincoln-Petersen index Flashcards
major parameters affecting population size
birth rate
mortality rate
migration rate
define population
grp of individual of the same species occupying a particular area and sharing common characteristics
no. of offspring produced per unit of time
birth rate
high birth rate -
low birth rate -
high birth rate - population growth
low birth rate - population decline
what is the current birthrate in the Philippines
22.2 births per 1000 people
how many animals are born everyday
humbolt penguin -
rabbits -
chickens -
bees -
nematodes -
humbolt penguin - 40
rabbits - 1 900 000
chickens - 62 000 000
bees - 370 000 000
nematodes - 600 000 000 000 000 000 000
no of indiv that die per unit of time
mortality rate
high death rates -
low death rates -
high death rates - reduce population size
low death rates - contribute to population growth
what is the current death rate in the Philippines
6.3 deaths per 1000 people
immigration vs emigration
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.
contributing factors affecting the population size
food availability
predation
disease
habitat quality
competition
human activities
it is the abundance of food resources in the environment
food availability
adequate food availability -
food scarcity -
adequate food availability - support population growth
food scarcity - limit population size
the presence of predators that consume individuals of the population
predation
briefly explain high predation rates
it can reduce population size by causing mortality
the prevalence of infectious diseases within the population
disease
briefly explain what disease outbreak can lead to
increased mortality and decreased population size
the suitability of the environment for the species’ survival and reproduction
habit quality
high-quality habitats -
degraded habitats -
high-quality habitats - support larger populations
degraded habitats - limit population size
interactions among individuals of the same species or different species for resources (examples)
competition
(food, water and shelter)
briefly explain what will happen if there is intense competition
can limit resources = decreased popu size
anthropogenic factors (examples )
human activities
(habitat destruction, pollution and hunting)
how can human activities impact population size
it can directly or indirectly impact population by altering the enviro and affecting species survival
what is the importance of understanding population size
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]
briefly explain the methods of populations size estimation
(examples)
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.
who develop Lincoln-Petersen Index
Federick C. Lincoln
Julius A. Petersen
lincoln-petersen index is used to estimate …
population size in wildlife biology and ecology
Lincoln-Petersen Index formula
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
what are some assumptions helps ensure that the Lincoln-Petersen index provides an accurate estimate of the true population size
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.
what are the steps in applying the lincoln-petersen index
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
advantages of the Lincoln-Petersen Index
[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)
limitations and considerations of the Lincoln-Petersen Index
[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
how would u describe the gap between the Lincoln- Petersen Index and the real population size?
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
what are the possible causes as to why the average estimated population did not match the actual population size?
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
what are the other methods that can be used in population size estimation aside from CMR technique?
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
why is essential to accurately estimate population size
for effective management and conservation efforts
