FW 104: POPULATIONS EXAM 2
40 Cards in this Set
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Populations
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really important "topic" when talking about conservation biology
Biologist MANAGING populations
various species of fish in an area- referred to as populations
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Population Abundance(N)
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# of individuals of a species that occupies a particular area
ex: 100 deer; more arbitrary
Density= N/area (100/square mile)
more specific than abundance- a given area (Rocky Mountain National Park)
Not static; births increase population deaths decrease
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Birth or Natality Rate
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# of births per # of individuals in population over a specified period of time
#babies/1000 individuals / year
#babies/ 100 individuals / year
#babies/ individuals / week
RATE= change per unit time (division)
Important to understand, "vital" rates help scientists see how healthy a po…
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2000 mice living in a cornfield produce 1000 baby mice in a month. What is the birth rate (b)= births/ individuals/ month
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b=1000B /2000 I/ month
b=.5B/individual/month
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Fecundity
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# of eggs produced per female
represent reproductive potential
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Fertility
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% of females eggs that are fertile
contrasts from fecundity
represents ACTUAL reproductive capacity
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Production
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actual number of SURVIVING offspring produced by a population
female could have fertilized eggs but young may not survive (dead at birth/ prey)
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Recruitment
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# of new individuals reaching breeding age in the population
many individuals do not survive their first year- don't survive long enough to reach breeding age
Reproductive Age= IMPORTANT
those who survive are able to add offspring to the population
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Recruitment; survive to reproduce and add to the population- pass on alleles/ genetic information
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Which of the following is the KEY to having high fitness in the natural selection process?
Fertility
Production
Recruitment
Speed and Strength
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Mortality/ Death Rate
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# of deaths per # of individuals over a
specified time period
rate D/ I/ T
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1000D/ 2000I*12= 6D/year
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1000 of 2000 mice die/month
What is death rate per individual/year?
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population
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population can have many factors
immigration
deaths
births
emigration
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Dispersal
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movement of individuals from one location to another
immigration and emigration
permanent abandonment of a home range
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Immigration Rate
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# of animals entering the population over a specified time period
one- way movement into a new home range
rate- affects # of individuals in the population itself
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Emigration Rate
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# of animals leaving the population over a specified time period
rate- affects # of individuals in the population itself
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Populations
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populations have an age structure
bars represent % of total population
a. a lot of juveniles, and not many make it to next age class (fish)
b. pretty steady distribution of age class- same amount make it to next age class (humans)
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Harvesting Can affect age structures!!!
A. 80% harvest rate
not many make it to older age class, juveniles killed off- don't survive to reproduction
B. 50% harvest rate
more individuals surviving, getting a more complex distribution of age
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Population B
in A total yield = 125 kg; primarily juveniles- don't add much to yield
more complex age structure so higher average rate per fish --> higher total yield
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If you have 2 populations of fish and population A has an 80% harvest rate (across all age classes) and population B has a 50% harvest rate, which population will provide the greater total yield in weight (kg)?
Population A (80% harvest rate)
Population B (50% harvest rate)
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How many fish should we harvest?
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Population growth curves help us determine how much fishing or hunting effort a population can sustain
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Exponentially
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If a Population is never Limited by resources how will it grow?
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Exponential Growth
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"J" shaped curve of population growth; assumes unlimited resources- no limiting factors affecting population
lab populations: yeast, bacteria
Introduced/ recovering populations (Island Caribou)
Invasive Species (Brown Tree Snakes in Guam)
Human Population growth is SUPER exponential
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Biotic Potential "r"
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maximum rate at which population can grow when no resources are limiting- maximum reproductive potential
maximum births "b" and minimum deaths "d"
R= B - D (assuming no immigration or emigration
Exponential growth relies heavily on biotic potential
Quails = 14 eggs per clutch Doves= 2…
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NO; depends on life history characteristics
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Is biotic potential the same for all species?
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K; Carrying Capacity
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maximum # of individuals in a population that the habitat can sustain
depends on habitat: cover, food etc (limiting factors)
K is dynamic, it changes
A: births> deaths; YES! # individuals increasing
B: births> deaths: YES! # individuals increasing
C: births > deaths: NO! births= deat…
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No- limiting factors affect growth
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Do populations increase exponentially forever?
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Logistic Population Growth Model
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populations grow exponentially but then limiting factors puts population in "check"
factors limit population growth- "population growth tapers off over time and then levels off
reflection point- MAXIMUM growth rate
slope = change in N / time
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Density- Dependent Factors
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Factors that cause higher mortality or reduced birth rates as a population becomes more dense
Resources (more competition)
Predation (more prey available)
Disease (more individuals= more contact with each other)
* a logistic growth model based on operation of density dependent factors…
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Density- Independent Factors
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Factors that operate independent of population density
As population size increases- no pattern on how population is increasing or decreasing
Weather
Accidents
Doesn't matter how big population is- a huge number of animals will be killed
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Kill a percentage of the population;
independent on population size
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Density Independent Factors will
Kill a percentage of the population
Kill a proportion of the population that is dependent on population size
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Harvesting Populations
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Natural (wild) populations are "harvested" by removing individuals
size of harvest (yield) assessed by numbers (counting individuals), biomass (weigh) or both
A goal of management= ensure the LARGEST HARVEST that can be SUSTAINED OVER TIME
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Maximum Sustained Yield
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Where on the logistic growth curve would be best to harvest fish?
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MAXIMUM SUSTAINED YIELD
populations maintained at 1/2 K will produce max # of animals that can be harvested each year
reflection point
best to harvest even below MSY - prepare for any random fish deaths
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Illegal Fishing, Destroy Habitat (bottom trawl- dynamite)
How easy is it to estimate K?
Hard! always changing
How easy is it to estimate MSY?
Hard! Dependent on K; can't obtain estimated K
Moving Target: hard to model and predict, hard to measure in the field
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If we harvest at MSY, why are commercial fisheries declining?
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r-K selection
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an approach to conceptualizing the range of life history strategies
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r- selected life history strategies
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adaptions for rapid population growth
reproduce rapidly, high mortality, rapid turnover of generations, good dispersal, little effort in young, many offspring, poor competitors
better adapted for unstable/transient habitat conditions
early- mid sucession pioneers - adapted to unstable …
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K Selected life Histories
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competition for resources is intense, good competitors
low reproductive rates, few offspring, more effort into young
feeding, defense from predators
adapted for stable habitat (climax communities)
often endangered species are k- selected
slow reproductive- require expanse habitat
li…
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Spatial Use
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Home range (area animal's in but doesn't actively defend) and territory (area animal's in and actively defends- typically members of same species)
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Monogamy
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mating of 1 male and 1 female for 1 reproductive cycle (serial), 1 season (annual) or life
ex. Bald Eagles
ex. Black-billed Magpie
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Polygamy
polyandry
polygyny
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any mating system that includes more than 1 mate of either sex
mating of 1 female with >1 male within a single reproductive cycle
mating of 1 male with >1 female within a single reproductive cycle
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Promiscuity
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mating between any number of males and females with no pair bonds formed
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FW 104: BIOLOGY BACKGROUND & NATURAL SELECTION (EVOLUTION)