Module 1: Imperiled Species Flashcards
4 major threats driving population declines today
Habitat loss
Overharvest
Climate Change
Invasive Species
Define Population
Group of individuals of same species inhabiting the same area
Define Population Size
The total number of individuals in a population
Define Population Density
The number of individuals in a population per unit area
Describe the different types of Population Distribution
If the population is random, clumped or uniform
Define Population Trend
The change in population size over time
What information is needed to list a species as endangered?
Population size, population trend and long-term population viability
What do sample units need?
To be randomly placed, replicated and stratified
Why is randomization important?
so that you don’t put the sample units in a place to get the result you want
Why is replication important?
when you use multiple samples, you get a more accurate picture of the population. Just one might show biased picture of the pop.
Why is stratification imporatant?
You make sure that your estimate reflects the full range of conditions and densities in the area of interest
Steps to Listing Imperiled Species in Canada
1) COSEWIC: independent group makes status report
2) Status report reviewed by COSEWIC’s species specialist groups make recommendation to larger COSEWIC Committee
3) COSEWIC makes a recommendation to Fed gov
4) Fed gov holds consultations with affected stakeholders
5) Fed government makes the final decision whether species is listed under Species at Risk Act.
Define a deterministic model
a model which doesn’t account for random events
Define stochastic model
a model that accounts for random events
Define a model with discrete time steps
each time-step is modeled separately
Define continuous time in a model
uses rates of change rather than breaking it up in to separate timesteps
What are some difficulties in estimating population size?
Not knowing if you’ve counted an animal already
Not knowing if size is representative of the long term
Access to study area
Observation errors - making errors in measuring or sampling design
Process error - errors in assuming what the population trends are due to.
Define an observation error
mistakes due to errors in measurement or sampling design
Define a process error
mistake due to assumptions about what the population size or trend is due to.
Key assumption of exponential growth
growth isn’t limited
Describe logistic growth model
assumes carrying capacity (K) that pop can’t exceed. growth slows as it nears K.
Describe interference in competitition
type of direct competition. could physically interfere with the activities of other individuals, for example if they have a home range for foraging that overlaps with another individual’s home range
Describe exploitative competition
when an individual uses up a resource so that others can’t use that resource anymore
Describe apparent competition
when a predator hunts two species, predator abundance will stay high if one of the prey species pops is high, even if the other is low, putting the more scarce species under more stress
