Chapter 45 Flashcards
Whats population thinking?*
The understanding that variations within a population can lead to differential survival and reproduction, leading to changes in the characteristics of the population over time.
Sea otters and population ecology
Sea otters are a top-down keystone species that let kelp forest proliferate through their consumption of sea urchins
3 types of population densities
random, clumped, uniform
Random distribution
Species are spread in a random way because they have no criteria for space (dandelions)
Uniform Distribution
The even spread out of species in an area (American Robin)
Clumped distribution
species are clumped together (elephants potecting young/weak from predators by clumping up)
How can distribution be tied to species?
The distribution of a species is closely related to its ecological niche, which determines the environmental conditions and resources that the species requires for survival and reproduction.
What are methods of sampling in nature
Sedentary and Motile
Sedentary sampling
Sedentary sampling is a type of sampling technique used in ecological research, where organisms that are immobile or move very little are sampled at a particular location (transects and quadrats).
transects
type of sedentary sampling technique that involve systematically sampling along a straight line or path to gather data on the distribution and abundance of organisms or other ecological features.
quadrants
Quadrants are a type of sedentary sampling technique that involve placing a frame of a known size over a specific area, and then counting or measuring the organisms or other ecological features that occur within the frame to estimate their abundance or density.
Motile sampling
Tagging and animal and recapturing them to sample how populations move/ hotspots of species
Sedentary vs Motile
Sedentary is better for immobile species while motile are better for mobile species
Age structure
ammount of living induviduals by age
Life table
A graph that measures probability of survival and reproduction
K-selected vs. r-selected species
K: slow growth, delayed reproduction, low fecundity, high parent care
r: rapid growth, early reproduction, high fecundity, and low investment in parental care
fecundity
ammount of offspring produced by a reproduction event
Survivorship curves
Type1: K-selected species, survivorship dips down near end of life expectancy
Type2: No correlation between age and when species die (linear)
Type3: R-selected species, survivorship dips down beginning of life expectancy
Population pyramids
measurement that researchers use to study human age structure
Life history
allocation of resource togrow, reproduce, and survive
Semelparity
Singular reproductive event (salmon)
Iteroparity
Multiple reproductive events (rabbits)
How fitness trade offs can influence population dynamics
Fitness trade-offs refer to the fact that investing resources in one aspect of an organism’s biology (e.g., growth, reproduction, or survival) may come at a cost to other aspects. These trade-offs can have important effects on population dynamics by affecting the balance between reproduction and survival, and the resulting growth rates and population sizes.
What events can increase exponential growth
Colonization of new habitat, Devestation/recovery
Carrying capacity
max ammount of organisms a habitat can support (if exceeded, mass death occurs)
Density dependant facotrs
Factors of surviorship that are influenced by density (disease)
Density independent factors
Factors of survivorship that are not influenced by density (weather patterns)