Life Tables Flashcards

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1
Q

Define demography

A

the study of the processes that change the size of a population (ex. birth, death, and dispersal) with particular respect to sex and age

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2
Q

Define surviorship

A

the probability of a newborn individual living to a particular age

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3
Q

Define mortality rate

A

the probability of dying at a particular age

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4
Q

What is the slope related to on survivorship graphs (# of survivors vs. age) and explain

A

related to the mortality rate
a steep slope implies high mortality vs. shallow slope meaning lower mortality rate

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5
Q

Define life tables function

A

allow for enumerating age and sex specific vital rates.
allow for understanding age-structured population growth and life-history evolution

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6
Q

In life tables, how is lx often displayed

A

by multiplying by 1000 often shown on log scale

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7
Q

sometimes survivorship curves are separated by _____

A

cohort (age or by year)

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8
Q

Why is the correction factor necessary in the life expectancy equation

A

because without it, is saying that all individuals are dying at the end of their lifespan

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9
Q

Explain the 3 types of survivorship curves

A

Type 1 = age specific mortality INCREASES with age (humans)
Type 2 = age specific mortality is CONSTANT with age (squirrels)
Type 3 = age specific mortality DECREASES with age (turtles)

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10
Q

When generating a life table, we either need _____ or ____ data

A

number surviving to interval
number dying during interval

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11
Q

what kind of organisms are cohort life tables typically applied to

A

short lived and/or sessile organisms that can be tracked reliably for their whole lives

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12
Q

Cohort life tables can be applied to population at any phase of population ______

A

growth
(growing, shrinking, stationary)

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13
Q

Cohort life tables are typically the _____ but they usually require ____

A

most powerful and accurate
more effort

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14
Q

Define static life tables

A

data is collected at a single point in time, applied to long-lived and/or mobile organisms that are difficult to track reliably their whole lives

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15
Q

What are the subtypes of static life tables

A
  1. time specific 2. stationary based on ages at death within a population
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16
Q

Define time-specific life tables

A

builds life table by estimating the survival of individuals of known age during a single time interval, uses yearly mortality (qx)

17
Q

What is a stationary life table based on

A

ages at death within a population, the number dying in each class (Dx)

18
Q

How was the stationary life table for Dall mountain sheep built

A

they used the horns of dead sheep to create their data and the total number to create their cohort size

19
Q

What are the very strict assumptions of the stationary life table example of using Dall mountain sheep

A
  1. can accurately age the skulls
  2. probability of finding skills does not change with age
  3. population is stationary in size (if the population was growing, young individuals would be overrepresented)
20
Q

Sx

A

number alive at the start of interval

21
Q

Dx

A

Number dying in interval
Sx-Sx+1

22
Q

lx

A

probability of survival from birth to certain interval
Sx/S0

23
Q

qx

A

probability of dying in the interval (mortality)
lx-lx+1/lx

24
Q

dx

A

fraction dying in the interval
Dx/S0

25
Q

ex

A

mean expectation of life
[(sum of all survive of time and older)/survived to that exact time] -0.5