Fig 53 9 Fig 53 10 Soay Sheep

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Fig. 53. 9

Fig. 53. 9

Fig. 53. 10

Fig. 53. 10

Soay Sheep – Hirta Island

Soay Sheep – Hirta Island

I. Population Ecology D. Population Dynamics 3. Life History Strategies • Finite amount of

I. Population Ecology D. Population Dynamics 3. Life History Strategies • Finite amount of energy to allocate among growth, reproduction, metabolism • Some species maximize reproduction; others maximize survival a. r-selection • Opportunistic species in variable environments • Population usually much higher or much lower than carrying capacity • Many weed/pest species b. K-selection • Usually in stable environments • Population usually at/near carrying capacity • Many endangered species Why?

I. Population Ecology D. Population Dynamics 4. Factors Affecting Population Growth/Size a. b. Density-Independent

I. Population Ecology D. Population Dynamics 4. Factors Affecting Population Growth/Size a. b. 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 1. Competition – Limit = resources (food, water, etc. ) Territoriality – Limit = space availability 1. Health – Includes disease 2. Predation – Selective by predator(s) 3. Wastes – Toxic at higher concentrations 4. Other Factors – Ex: Aggression at higher densities

Soay Sheep – Hirta Island Fig. 53. 16

Soay Sheep – Hirta Island Fig. 53. 16

I. Population Ecology D. Population Dynamics 4. Factors Affecting Population Dynamics a. b. Density-Independent

I. Population Ecology D. Population Dynamics 4. Factors Affecting Population Dynamics a. b. 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 1. Competition – Limit = resources (food, water, etc. ) 2. Territoriality – Limit = space availability 3. Health – Includes disease 4. Predation – Selective by predator(s) 5. Wastes – Toxic at higher concentrations 6. Other Factors – Ex: Aggression at higher densities

I. Population Ecology D. Population Dynamics 5. Population Stability • a. Stability usually related

I. Population Ecology D. Population Dynamics 5. Population Stability • a. Stability usually related to lifespan, reproductive rate Environmental factors • Resource availability • Recruitment

Isle Royale Fig. 53. 18

Isle Royale Fig. 53. 18

I. Population Ecology D. Population Dynamics 5. Population Stability • a. Stability usually related

I. Population Ecology D. Population Dynamics 5. Population Stability • a. Stability usually related to lifespan, reproductive rate Environmental factors • Resource availability • Recruitment b. Immigration • Metapopulations may be more stable than isolated populations

Glanville Fritillary Fig. 53. 21

Glanville Fritillary Fig. 53. 21

I. Population Ecology D. Population Dynamics 5. Population Stability • a. Stability usually related

I. Population Ecology D. Population Dynamics 5. Population Stability • a. Stability usually related to lifespan, reproductive rate Environmental factors • Resource availability • Recruitment b. Immigration • Metapopulations may be more stable than isolated populations c. Combined factors • Resources, predation, etc.

Fig. 53. 19

Fig. 53. 19

II. Community Ecology • Focus on interspecific interactions • May be direct or indirect

II. Community Ecology • Focus on interspecific interactions • May be direct or indirect A. Competition • Two or more species competing for scarce resource • • 1. 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

II. Community Ecology A. Competition 2. Ecological niche • • Species’ ecological role in

II. Community Ecology A. Competition 2. 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

Fig. 54. 3

Fig. 54. 3

II. Community Ecology A. Competition 3. Resource partitioning • • Competitive exclusion can be

II. Community Ecology A. Competition 3. Resource partitioning • • Competitive exclusion can be minimized if competing species modify niches to reduce overlap Usually involves dividing resource

Anolis Dominican Republic Fig. 54. 2

Anolis Dominican Republic Fig. 54. 2

II. Community Ecology A. Competition 4. Character displacement • • Resource partitioning may lead

II. Community Ecology A. Competition 4. Character displacement • • Resource partitioning may lead to directional selection on one or both species Directional selection may lead to divergence in traits

Fig. 54. 4

Fig. 54. 4

II. Community Ecology B. Predation • • Involves consumption of prey by predator Predator

II. Community Ecology B. Predation • • Involves consumption of prey by predator Predator usually has adaptations to facilitate capture of prey Natural selection acts on both predator and prey • • 1. Coevolution Strategies a. b. c. 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

II. Community Ecology B. Predation 2. Predator avoidance a. b. c. d. e. Escape

II. Community Ecology B. Predation 2. Predator avoidance a. b. c. d. e. 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

Cryptic coloration - Canyon tree frog Aposematic coloration - Poison dart frog Müllerian mimicry

Cryptic coloration - Canyon tree frog Aposematic coloration - Poison dart frog Müllerian mimicry Batesian mimicry Fig. 54. 5

II. Community Ecology C. Herbivory • • Consumption of plants by animals Most herbivores

II. Community Ecology C. 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

II. Community Ecology D. Parasitism • Parasite benefits at expense of host • •

II. Community Ecology D. Parasitism • Parasite benefits at expense of host • • Fig. 33. 12 • • 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. 11 Schistosoma mansoni

Fig. 33. 11 Schistosoma mansoni

II. Community Ecology E. Disease • Widespread disease outbreaks may alter community composition and

II. Community Ecology E. 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