module 8 Flashcards
Population
A group of interacting organisms of the same species living in the same place at the same time Bound by: Geography Behavior Resources Convenience
Population Structure
All features of population that characterize the population -Biotic Structure # of Individuals & Density Age Classes -Spatial Structure Geographic Distribution Arrangement & Size of Habitats Spatial arrangement of Individuals Dispersion and Spacing Movement Patterns -Genetic Structure & Variation
Organisms May Be:
Unitary
exists as individuals
Modular
Most plants are modular
develop by branching, producing repeated structural units (modules)
Stolons
specialized stems that grow above the ground surface
Rhizomes
specialized stems that grow below the ground surface
Suckers
New stems that sprout from surface roots
May appear to be individuals
Genet
Plant produced by sexual reproduction
A genetic individual
Ramet
Module produced asexually by a genet
A clone
Geographic Range is an
determined by
Geographic area in which a species occur
Determined by Ecological Range Species’ range of conditions Constrained by: Geographic Barriers Distance Physical Features Competition
Ubiquitous species
Geographically widespread distribution
Endemic species
many endemic species have
Geographically restricted distribution
many endemic species have specialized habitat requirements
Climate often influences species distributions via:
Food production
Water supply
Habitat
Incidence of parasites, pathogens & competitors.
Geographic Range Encompasses Lifetime
One Area may be used Little
Range often Divided by
One Area may be used Little
Range often Divided by:
Life-stages
Temporal Use
Migration
Annual of seasonal movement of animals Driven by: Local Climate & Seasons Food Availability Variations in Life cycle
Dispersal
One-way Movement of individuals
away from native or current habitat or existing population
Dispersal driven by
Reproduction Resources Competition Changing Environment Natural Man Made Natural Cycles Often occurs in Rapid Pulses
Dispersal
is movement away from
To Areas of
Dispersal coupled with. Maintains Distribution
Movement of individuals
Away from Birthplace
To Areas of Lesser Density
Dispersal coupled with Ecological Range Maintains Distribution
Dispersal in Rivers & Streams
Stream dwellers mechanisms to allow them to maintain their stream position. Streamlined bodies Bottom-dwelling Adhesion to surfaces Tend to get washed downstream in spates. Upstream Dispersal
Colonization cycle
populations maintained via
populations maintained via dynamic interplay between downstream and upstream dispersal.
Habitat
The Place where an organism lives
Ecological or environmental area that is inhabited by a particular animal and plant species
Characterized by dominant plant form or physical features
Landscape Features Varied
organisms are not always
Suitable Habitat Not Equally Distributed
Organisms not Equally Distributed
Subpopulations
Local Groups of larger population of organisms that lives in a Habitat Patch Subpopulations Interact But Interaction Limited Maintains Genetic Pool Different Population Dynamics Growth Rates Sex Ratios
Habitat Patches
geographically
Geographically Isolated
Uninhabitable Land
Interchange Occur
Spatial Distribution
range determined by:
Frequency of Exchange
Environmental Conditions
Interactions with Other Species
Hierarchy of Distribution
____ uses of landscapes
Different Factors at Different Scales
Varying uses of Landscapes
Random lack of \_\_\_ \_\_\_\_ distribution resources \_\_\_\_ limiting lack of \_\_\_\_ competition of aggression \_\_\_\_\_ mutual attraction
Lack of Pattern Factors Random distribution of resources. Resources not Limiting Overall Amounts Vary across Landscape Lack of Strong Interactive or Social Forces Little Competition or Aggression Ambiguous Dispersal Tendencies No Mutual Attraction
Regular
also called
____ use of areas
______ behaviors and competition
Also Called Uniform, Even Uniformly spaced Exclusive use of areas. Factors: Homogeneous Resource Distribution Relatively Common but likely somewhat Limited Why? Individuals avoid one another. Aggressive Behaviors and Competition Strong Dispersal Tendencies
Clumped also called what \_\_\_\_\_ chance of being anywhere form \_\_\_\_\_ \_\_\_\_\_\_ resource distribution resources are \_\_\_\_\_\_ attraction \_\_\_\_\_\_ dispersal tendencies
Also called Aggregated Unequal chance of being anywhere Form groups Factors Heterogenous resource distribution. Abundant where found Mutual attraction between individuals. Weak Dispersal Tendencies
A metapopulation
connected by
Collection of groups (subpopulations)
living on patches of habitat
connected by an exchange of individuals.
Metapopulation
Source-Sink Dynamics
source produce enough offspring to ____
Source Produce enough offspring to maintain population size Often in excess Young move to sinks Often superior habitat quality Sink Reproduction < Death Maintained by Immigration
Populations Maintained by Turnover Event
Extinction Subsequent recolonization of local population Rates determined by: Individual population dynamics Isolation
Rate of Extinction Higher in: \_\_\_\_\_ populations \_\_\_\_ habitats slight increase in \_\_\_\_\_\_ immigration \_\_\_\_\_\_ negabile
Small populations Small habitat Isolation Negligible Slight increase limited immigration
Rate of Colonization higher in \_\_\_\_ habitats \_\_\_\_\_ isolated \_\_\_\_\_ negligible reduction when competition \_\_\_\_\_
Higher in: Large Habitats Less Isolated Population size Negligible Slight reduction increased competition
Metapopulations are valuable
Valuable for populations with Patchy Habitats
Patchiness of Suitable Habitat
Influenced by specialization of species
Mistletoe
Patchiness caused by other species
Canopy Gap Plants
Patchiness Caused by Topographical Variations
Patchiness Caused by Human Activities
Density
# of individuals / unit area Biomass / area
Abundance
Actual number/biomass of organisms
In general, population density declines
with _____ organism size
with increasing organism size.
Herbivorous mammals
Population density with increased body size.
Population density decreased with increased body size.
Aquatic invertebrates
Tend to have higher population densities than terrestrial invertebrates of similar size.
Mammals
tend to have higher population densities than birds of similar size
Plant populations density
Density _____ with plant size.
Underlying details are very different.
Density decreases with increasing plant size.
Underlying details are very different.
Tree seedlings can live at very high densities,
But as the trees grow, density declines progressively until mature trees are at low densities.
Self-thinning Rule
survival is estimated
Estimated with Life-Tables
two main types of estimation
age distribution
Life Tables -Cohort life table Identify individuals born at same time Keep records from birth. -Static life table Record age at death of individuals Estimate # born & mortality Rates
Age distribution
Calculate difference in proportion of individuals in each age class.
Assumes differences from mortality.
Population with non-overlapping generations
Does not have an age structure
individuals reproduce and die within a single season
annual plants and some insects
Population with overlapping generations
Has an age structure
Individuals in different age classes
reproduction is restricted to certain age classes
mortality is more common in certain age classes
Populations can be divided into three ecologically important age classes
prereproductive
reproductive
postreproductive
Age Structure
Number of Different Age Classes
Number of Individuals in Each
Populations of sexually reproducing organisms usually have a sex ratio close to
1:1 (males:females)
Most mammalian populations sex ratio at birth(secondary sex ratio)
slightly weighted towards males
Shifts towards females in older age classes
males generally have a shorter life span than females
many characterized by rivalries among males for resources/mates
Determining Age
Examining a sample of bodies of individuals that have died and determine their ages at death
Characteristics that indicate age
wear and replacement of teeth
growth rings in the teeth or horns
plumage changes and wear in birds
annual growth rings on scales and ear bones in fish
