ENVI 30 Environmental Issues

1
Fig. 53.9
2
Fig. 53.10
3
Soay Sheep Hirta Island
4

• Population Ecology
• Population Dynamics
• Life History Strategies
• Finite amount of energy to allocate among growth,
  reproduction, metabolism
• Some species maximize reproduction others
  maximize survival
• r-selection
• Opportunistic species in variable environments
• Population usually much higher or much lower than
  carrying capacity
• Many weed/pest species
• K-selection
• Usually in stable environments
• Population usually at/near carrying capacity
• Many endangered species Why?

5

• Population Ecology
• Population Dynamics
• Factors Affecting Population Growth/Size
• Density-Independent Factors
• Catastrophic events
• Ex Floods, fires, drought, storms, extreme
  weather
• Some aggregated organisms and social animals can
  enhance resistance to density-independent factors
• Ex Emperor penguins, clustered plants/animals
• Density-Dependent Factors
• Effects increase as population size increases
• Competition Limit resources (food, water,
  etc.)
• Territoriality Limit space availability
• Health Includes disease
• Predation Selective by predator(s)
• Wastes Toxic at higher concentrations
• Other Factors Ex Aggression at higher densities

6
(No Transcript)
7
Soay Sheep Hirta Island
Fig. 53.16
8

• Population Ecology
• Population Dynamics
• Factors Affecting Population Dynamics
• Density-Independent Factors
• Catastrophic events
• Ex Floods, fires, drought, storms, extreme
  weather
• Some aggregated organisms and social animals can
  enhance resistance to density-independent factors
• Ex Emperor penguins, clustered plants/animals
• Density-Dependent Factors
• Effects increase as population size increases
• Competition Limit resources (food, water,
  etc.)
• Territoriality Limit space availability
• Health Includes disease
• Predation Selective by predator(s)
• Wastes Toxic at higher concentrations
• Other Factors Ex Aggression at higher densities

9

• Population Ecology
• Population Dynamics
• Population Stability
• Stability usually related to lifespan,
  reproductive rate
• Environmental factors
• Resource availability
• Recruitment

10
Isle Royale
Fig. 53.18
11

• Population Ecology
• Population Dynamics
• Population Stability
• Stability usually related to lifespan,
  reproductive rate
• Environmental factors
• Resource availability
• Recruitment
• Immigration
• Metapopulations may be more stable than isolated
  populations

12
Glanville Fritillary
Fig. 53.21
13

• Population Ecology
• Population Dynamics
• Population Stability
• Stability usually related to lifespan,
  reproductive rate
• Environmental factors
• Resource availability
• Recruitment
• Immigration
• Metapopulations may be more stable than isolated
  populations
• Combined factors
• Resources, predation, etc.

14
Fig. 53.19
15

• Community Ecology
• Focus on interspecific interactions
• May be direct or indirect
• Competition
• Two or more species competing for scarce resource
• Ex Two plant species competing for water
• May be detrimental to one or both species
• Competitive exclusion
• No two species can use same set of resources in
  same area at same time
• Competitively dominant species tend to force
  extinction of competitively inferior species

16

• Community Ecology
• Competition
• Ecological niche
• Species ecological role in a community
• Includes use of abiotic and biotic resources
• Niche occupied by a species may be narrower than
  range of conditions tolerated by species
• Fundamental niche vs. realized niche

17
Fig. 54.3
18

• Community Ecology
• Competition
• Resource partitioning
• Competitive exclusion can be minimized if
  competing species modify niches to reduce overlap
• Usually involves dividing resource

19
Anolis Dominican Republic
Fig. 54.2
20

• Community Ecology
• Competition
• Character displacement
• Resource partitioning may lead to directional
  selection on one or both species
• Directional selection may lead to divergence in
  traits

21
Fig. 54.4
22

• Community Ecology
• Predation
• Involves consumption of prey by predator
• Predator usually has adaptations to facilitate
  capture of prey
• Natural selection acts on both predator and prey
• Coevolution
• Strategies
• Pursuit predation
• Predators chase prey to capture them
• Predator usually faster, stronger, /or more
  agile than prey
• Some species hunt in groups
• Ambush predation
• Predators lie in wait for prey
• Predators usually camouflaged or concealed
• May involve lures
• Aggressive mimicry
• Ex Bolas spider mimics odor of female moths to
  attract male moths

23
(No Transcript)
24

• Community Ecology
• Predation
• Predator avoidance
• Escape
• Running/Swimming/Flying away
• Mechanical defenses
• Ex Porcupine quills, armadillo armor
• Social behavior
• Ex Schooling, standing watch
• Chemical defenses
• Ex Poison dart frog, skunk
• Defensive coloration

25
Cryptic coloration - Canyon tree frog
Aposematic coloration - Poison dart frog
Müllerian mimicry
Batesian mimicry Fig. 54.5
26

• Community Ecology
• Herbivory
• Consumption of plants by animals
• Most herbivores are small
• Ex Insects, snails/slugs
• Herbivores adapted to consume plants
• Some plants have anti-herbivore defenses
• Physical Ex Thorns, spines
• Chemical Ex Nicotine in tobacco, pyrethrins in
  chrysanthemums
• Coevolution has affected herbivore evolution
• Ex Monarch butterfly caterpillars can eat
  milkweed
• Toxic to most herbivores
• Nearly exclusive access to food source
• Can sequester noxious compounds for defense

27

• Community Ecology
• Parasitism
• Parasite benefits at expense of host
• Host harmed in process
• Ex Tapeworm absorbs nutrients from host
  digestive system
• Endoparasites Live within body of host
• Ectoparasites Live outside body of host
• Parasitoids Lay eggs on/in host larvae feed on
  host, eventually killing host
• Many parasites have complex life cycles

Fig. 33.12
28
Fig. 33.11
Schistosoma mansoni
29

• Community Ecology
• Disease
• Widespread disease outbreaks may alter community
  composition and dynamics
• Ex Dutch elm disease
• Ex Sudden oak death
• Ex Avian flu
• Ex West Nile virus