Populations Flashcards
What is a population
A group of interbreeding individuals of the same species inhabiting the same area
Population distribution vs dispersion
Distribution concerns a populations geographic and ecological ranges
Dispersion describes the spacing of individuals in a pop. (clumped, uniform, random)
Population density and absolute density
- Number per unit area, unit volume, or unit of habitat
- Absolute density is the total count
What are the two ways quadrats or transects can be dispersed?
- Random - least biased (every member has equal chance of being selected)
- Systematic (Sample are chosen in a regular way - evenly/regularly distributed in a spatial context)
3 requirements for a reliable quadrat
1) The number of individuals in each quadrat must be determined exactly
2) Area of each quadrat must be known
3) Quadrats counted must be representative of the whole area (randomly sampled)
What is the capture-recapture method?
Capture animals, mark and release them. In subsequent capture, the proportion marked should be representative of the proportion marked in the entire population
What are important features of a tag on an animal?
- Longevity
- Visibility
- Effect on animal (can’t influence animal life)
What is capture recapture formula?
(Marked on 1st capture/Total population) = (Marked on recapture)/(total on recapture)
What are three main assumptions of the capture-recapture method?
- Marked and unmarked animals are captured randomly
- Marked animals are subject to the same mortality rate as unmarked animals
- Marks are not lost or overlooked
What is age structure?
The proportion of individuals in each age group is called the age structure of the population
What three population characteristics determine the rate at which females produce offsping?
- Clutch size
- Time between reproductive events
- Age at first reproduction
Potential longevity vs realized longevity
- Potential longevity is the maximum life span attainable by individuals of a particular species
- Realized longevity is the average longevity of individuals in a population under real environmental conditions
What is alpha diversity?
Number of species found within a small homogeneous area
What is beta diversity?
Rate of change in species composition across habitats or among communities
- quantitative measure of diversity of communities that experience changing environments
What is gamma diversity?
Changes in richness across larger landscape units
Species discovery curve optimum
Number of samples that reasonably measure species richness without wasting sampling effort
Why is conservation focusing on species?
- Discrete entities
- Nobody owns them
- Conserving other aspects of biological diversity can be even more complex
Why are endangered species lists useful?
- Conservation: publicity, identify causes
- Government: Demonstrate action, create law
- Wildlife managers: guides for resource deployment
What is the main purpose of the IUCN red list?
Provides taxonomic, conservaation status, and distribution information on plants and animals that have been globally evaluated
What are the 8 categories on the red list?
- Extinct
- Extinct in the wild
- Critically endangered
- Endangered
- Vulnerable
- Near threatened
- Least concern
- Data deficient
What is COSEWIC?
Committee on the Status of Endangered Wildlife in Canada
- Determines the national status of native wild species considered to be at risk in Canada based on the best available information
What are the 7 categories of species status by COSEWIC
- Endangered
- Threatened
- Special concern
- Not at risk
- Extinct
- Extirpated
- data deficient
What are the three guidelines for a species to be extirpated?
`
- There exists no remaining habitat for the species, and no records of the species
- 50 years have passed since the last credible record of the species
- There is sufficient information to document that no individuals of the species remain alive
What is a designatable unit?
Subspecies, varieties, etc, recognized in cases where a single status designation for a speies is not sufficient to accurately portray extinction probability within the species
On what 4 things might designatable units be recognized?
- Established taxonomy
- Genetic evidence
- range disjunction
- biogeographic distinction
What are 4 things COSEWIC does NOT do?
- Consider social, political, and economic factors
- Feasibility of recovery
- Make management or recovery recommendations.
- Designate units based on management requirements, administrative units or political boundaries
