Biology, 9th ed, Sylvia Mader

Biology, 9th ed, Sylvia Mader
Ch. 47 – Community Ecology Chapter 47 Community Ecology

Concept of Community Chapter 47 Community Ecology A community is an assemblage of populations interacting with one another within the same environment Composition is a thorough listing of various species in the community Species Diversity includes: 1. Species Richness – total number of different species in the community 2. Relative Abundance – proportion of the total population represented by each species

The various animals and plants surrounding this watering hole are all members of a savanna community in southern Africa Biology, 9th ed, Sylvia Mader Chapter 47 Community Ecology Figure 53.1

Community Structure Chapter 47 Community Ecology Rain Forest Coniferous Forest

Chapter 47 Community Ecology Two different communities can have the same species richness, but a different relative abundance Community 1 A: 25% B: 25% C: 25% D: 25% Community 2 A: 80% B: 5% C: 5% D: 10% D C B A Figure 53.11 A community with an even species abundance is more diverse than one in which one or two species are abundant and the remainder rare

Structure of the Community
Biology, 9th ed, Sylvia Mader Structure of the Community Chapter 47 Community Ecology Competition When two species compete, the abundance of both species is negatively impacted Predation (Herbivory – plant predation) ● One organism, the predator, eats another called the prey. Parasitism ● One organism, the parasite, feeds ON another called the host. These tend to increase the abundance of the predator (or parasite) and reduce the abundance of the prey (or host)

Table 53.1 Biology, 9th ed, Sylvia Mader Chapter 47 Community Ecology

Habitat and Ecological Niche
Biology, 9th ed, Sylvia Mader Habitat and Ecological Niche Chapter 47 Community Ecology Habitat The area an organism lives and reproduces in Ecological niche The role a species plays in its community Includes its habitat, and Its interactions with other organisms Fundamental niche - All conditions under which the organism can survive & reproduce Realized niche – part of the fundamental niche that the species actually occupies

Feeding niches for Wading Birds
Biology, 9th ed, Sylvia Mader Chapter 47 Community Ecology Feeding niches for Wading Birds

Competition Between Populations
Biology, 9th ed, Sylvia Mader Competition Between Populations Chapter 47 Community Ecology Interspecific competition When members of different species try to use a resource that is in limited supply (food, light, etc.) Competitive Exclusion Principle No two species can indefinitely occupy the same niche at the same time Resource Partitioning decreases competition Can lead to character displacement. This is the tendency of a characteristic to become more divergent when species are together.

Chapter 47 Community Ecology Competition between two laboratory populations of Paramecium Both grow fine separately but only P. aurelia survives when they are grown together

Character Displacement in Finches on the Galápagos Islands
Biology, 9th ed, Sylvia Mader Chapter 47 Community Ecology Character Displacement in Finches on the Galápagos Islands

Niche Specialization Among Five Species of Coexisting Warblers
Biology, 9th ed, Sylvia Mader Chapter 47 Community Ecology Niche Specialization Among Five Species of Coexisting Warblers

Competition Between Two Species of Barnacles
Biology, 9th ed, Sylvia Mader Chapter 47 Competition Between Two Species of Barnacles Community Ecology Connell removed the larger Balanus individuals. The smaller Chthamalus barnacles moved down & survived equally well in both places

Competition Between Two Species of Barnacles
Biology, 9th ed, Sylvia Mader Competition Between Two Species of Barnacles Chapter 47 Community Ecology When Connell removed Balanus from the lower strata, the Chthamalus population spread into that area. The spread of Chthamalus when Balanus was removed indicates that competitive exclusion makes the realized niche of Chthamalus much smaller than its fundamental niche. RESULTS CONCLUSION Ocean Ecologist Joseph Connell studied two barnacle speciesBalanus balanoides and Chthamalus stellatus that have a stratified distribution on rocks along the coast of Scotland. EXPERIMENT In nature, Balanus fails to survive high on the rocks because it is unable to resist desiccation (drying out) during low tides. Its realized niche is therefore similar to its fundamental niche. In contrast, Chthamalus is usually concentrated on the upper strata of rocks. To determine the fundamental of niche of Chthamalus, Connell removed Balanus from the lower strata. Low tide High tide Chthamalus fundamental niche Chthamalus realized niche Chthamalus Balanus realized niche Balanus Figure 53.2

Predator-Prey Interactions
Biology, 9th ed, Sylvia Mader Predator-Prey Interactions Chapter 47 Community Ecology Predation One living organism, the predator, feeds on another, the prey Predator is frequently larger Predator population is usually smaller than the prey population Predator has lower reproductive rate Prey is usually consumed in its entirety Presence of predators can decrease prey densities, and vice-versa

Chapter 47 Predators Community Ecology

Predator-prey Interaction Between Paramecium caudatum and Didinium nasutum Chapter 47 Community Ecology Paramecium & Didinium placed in same culture. Didinium ate all the Paramecium and then died of starvation

Predator-prey Interaction Between a Lynx and a Snowshoe Hare
Biology, 9th ed, Sylvia Mader Predator-prey Interaction Between a Lynx and a Snowshoe Hare Chapter 47 Community Ecology When hares have adequate food & there are no predators, the cycling stops. Hares given adequate food but with predators; they still cycle Predators excluded but no food was given to hares; cycling stopped

Chapter 47 Boom-and-bust cycles are influenced by complex interactions between biotic and abiotic factors. Predator populations may be influenced by availability of prey - as more prey is available, they reproduce more and their population increases. When the predator population gets too high and they eat all the prey, their population falls. Community Ecology

Chapter 47 Prey populations may be influenced by 1.Predation 2. Fluctuations in the availability of the plants they feed on Prey may not be regulated by predators. Their population may increase until they run out of resources, then their population crashes. As a result the predator population soon declines because of lack of food availability. Community Ecology

Chapter 47 Community Ecology Feeding adaptations of predators include: claws, teeth, fangs, stingers, and poison Some predator-prey interactions lead to coevolution: a series of reciprocal adaptations in two species

Chapter 47 Predator Adaptations Community Ecology

Prey Defenses Chapter 47 Community Ecology Mechanisms that thwart the possibility of being eaten by a predator. Some examples: - Spines - Tough Epidermis - Poisonous Chemicals - Camouflage – ability to blend into the background. Have cryptic coloration. - Bright Coloration - Flocking Behavior

Chapter 47 Community Ecology Spines as protection for plants against herbivory

Chapter 47 Community Ecology Chemical Defenses in Plants Poison Oak and its rash

Camouflage in the Anglerfish
Biology, 9th ed, Sylvia Mader Camouflage in the Anglerfish Chapter 47 Community Ecology

Cryptic Coloration Chapter 47 Community Ecology Figure 53.5

Cryptic Coloration Chapter 47 Community Ecology

Chapter 47 Community Ecology Cryptic Coloration

Anti-predator Defenses
Biology, 9th ed, Sylvia Mader Anti-predator Defenses Chapter 47 Community Ecology Poisonous skin + Warning coloration False eyespots Large false head

Chapter 47 Community Ecology Aposematic (warning) coloration All these snakes are poisonous

Mimicry Chapter 47 Community Ecology One species (mimic) resembles another species (model) that possesses an overt anti-predator defense. Two main types: 1. Batesian Mimicry - Mimic lacks defense of the organism it resembles 2. Müllerian Mimicry - Mimic shares same protective defense as its model

Mimicry Among Insects with Yellow and Black Stripes
Biology, 9th ed, Sylvia Mader Mimicry Among Insects with Yellow and Black Stripes Chapter 47 Community Ecology a, b, & c are examples of Batesian mimicry because they do not have the capability to sting. Fly Beetle Moth Yellow jacket d & e are Mullerian mimics since they both use stinging as a defense Bumblebee

Chapter 47 In Batesian mimicry A palatable or harmless species mimics an unpalatable or harmful model Community Ecology (a) Hawkmoth larva (b) Green parrot snake Figure 53.7a, b

Chapter 47 Batesian Mimicry (flies, beetles & ants mimic wasp) Community Ecology Wasp

Chapter 47 Batesian Mimicry Community Ecology Poisonous models on left Harmless mimics on right

Chapter 47 In Müllerian mimicry Two or more unpalatable species resemble each other Community Ecology (a) Cuckoo bee (b) Yellow jacket Figure 53.8a, b

Symbiotic Relationships
Biology, 9th ed, Sylvia Mader Symbiotic Relationships Chapter 47 Community Ecology Interactions in which there is a close relationship between members of two species. Frequently one species lives in or on another. Three main types of symbiosis are: - Parasitism - Commensalism - Mutualism

Symbiotic Relationships
Biology, 9th ed, Sylvia Mader Symbiotic Relationships Chapter 47 Community Ecology Parasitism - Parasite derives nourishment from a host, and may use host as habitat and mode of transmission - Endoparasites - live inside host - Ectoparasites - live on outside of host Natural selection favors parasites that infect but don’t kill their hosts.

Chapter 47 Parasites Leech Community Ecology Flea Mosquito Ringworm

The Life Cycle of a Deer Tick
Biology, 9th ed, Sylvia Mader The Life Cycle of a Deer Tick Chapter 47 Community Ecology Human may end up with Lyme Disease

Mutualism Chapter 47 Community Ecology A symbiotic relationship in which both members of the association benefit Need not be equally beneficial to both species - Cleaning Symbiosis - one animal cleans another - E. coli in human intestines - Protozoans in termite intestines - Mycorrhizae between roots & fungi - Ants & bullhorn acacia trees Often help each other obtain food or avoid predation

Cleaning Symbiosis Chapter 47 Community Ecology

Chapter 47 Community Ecology More Cleaning Symbiosis

Mutualism Between the Bullhorn Acacia Tree and Ants
Biology, 9th ed, Sylvia Mader Mutualism Between the Bullhorn Acacia Tree and Ants Chapter 47 Community Ecology Figure 53.9

Pollination of Plants by Animals is an example of Mutualism
Biology, 9th ed, Sylvia Mader Chapter 47 Community Ecology Pollination of Plants by Animals is an example of Mutualism

Commensalism Chapter 47 Community Ecology A symbiotic relationship in which one species benefits and the other is neither benefited or harmed - Remoras attach to sharks & get a free ride - Clownfish living inside of sea anemone’s tentacles - Epiphytes, like Spanish moss, live on trees Many supposed examples may turn out to be mutualism or parasitism Inferred amount of harm or benefit that 2 species do to one another is subject to investigator bias

Chapter 47 Whales & Barnacles Community Ecology Spanish Moss Remoras & Sharks

Clownfish Among Sea Anemone’s Tentacles
Biology, 9th ed, Sylvia Mader Clownfish Among Sea Anemone’s Tentacles Chapter 47 Community Ecology

Community Development
Biology, 9th ed, Sylvia Mader Community Development Chapter 47 Community Ecology Ecological Succession A predictable pattern of change in species replacements following a disturbance Primary Succession occurs in areas where there is no soil formation •After a volcanic eruption or glacial retreat Secondary Succession begins in areas where soil and life are already present •Like when a cultivated field returns to nature Pioneer Species - first species to colonize an area (frequently lichens & moss)

Primary Succession occurs after glaciers retreat
Biology, 9th ed, Sylvia Mader Primary Succession occurs after glaciers retreat Chapter 47 Community Ecology McBride glacier retreating 5 10 Miles Glacier Bay Pleasant Is. Johns Hopkins Gl. Reid Gl. Grand Pacific Gl. Canada Alaska 1940 1912 1899 1879 1949 1935 1760 1780 1830 1860 1913 1911 1892 1900 1907 1948 1931 1941 Casement Gl. McBride Gl. Plateau Gl. Muir Gl. Riggs Gl.

Primary & Secondary Succession at Glacier Bay, Alaska
Biology, 9th ed, Sylvia Mader Primary & Secondary Succession at Glacier Bay, Alaska Chapter 47 Community Ecology Figure 53.24a–d (b) Dryas stage (c) Spruce stage (d) Nitrogen fixation by Dryas and alder increases the soil nitrogen content. Soil nitrogen (g/m2) Successional stage Pioneer Dryas Alder Spruce 10 20 30 40 50 60 (a) Pioneer stage, with fireweed dominant

Primary Succession Chapter 47 Community Ecology

Chapter 47 Community Ecology Primary Succession

Chapter 47 Primary Succession Community Ecology

Secondary Succession in a Field
Biology, 9th ed, Sylvia Mader Secondary Succession in a Field Chapter 47 Community Ecology

Secondary Succession in a Forest
Biology, 9th ed, Sylvia Mader Secondary Succession in a Forest Chapter 47 Community Ecology

Community Stability Chapter 47 Community Ecology Community stability can be recognized in three ways: Persistence through time – when a community remains just about the same year after year Resistance to change – when trees are able to regrow leaves after insect infestation Recovery once a disturbance has occurred – when a community, like chaparral, quickly returns to its normal state after a fire

Community Stability Chapter 47 Community Ecology Decades ago, most ecologists favored the traditional view that communities are in a state of equilibrium. However, recent emphasis on change has led to a nonequilibrium model. This describes communities as constantly changing after being buffeted by disturbances. Disturbances affect all communities - Floods, fire, glaciers, volcanic eruptions can change communities greatly

Fire is Often Necessary to an ecosystem
Biology, 9th ed, Sylvia Mader Chapter 47 Community Ecology Fire is Often Necessary to an ecosystem (a) Before a controlled burn. A prairie that has not burned for several years has a high proportion of detritus (dead grass). (b) During the burn. The detritus serves as fuel for fires. (c) After the burn. Approximately one month after the controlled burn, virtually all of the biomass in this prairie is living. Figure 53.21a–c

Chapter 47 Community Ecology Yellowstone Fire of 1988 (a) Soon after fire. As this photo taken soon after the fire shows, the burn left a patchy landscape. Note the unburned trees in the distance. (b) One year after fire. This photo of the same general area taken the following year indicates how rapidly the community began to recover. A variety of herbaceous plants, different from those in the former forest, cover the ground.

Predation, Competition, and Biodiversity
Biology, 9th ed, Sylvia Mader Predation, Competition, and Biodiversity Chapter 47 Community Ecology Keystone species are organisms that play a great role in maintaining function & diversity of an ecosystem. They are not necessarily abundant, but exert strong control on a community by their ecological roles Keystone predator may help to maintain diversity by reducing the numbers of the strongest competitor in a community -This helps to prevent exclusion of weaker competitors, and prevents strongest competitor from becoming too dominant

Effect of a Keystone Species
Biology, 9th ed, Sylvia Mader Effect of a Keystone Species Chapter 47 Community Ecology Pisaster seastars were removed from experimental tidepools but were left in control areas. Diversity decreased in experimental areas

Effect of Sea Otters on Ocean Communities
Biology, 9th ed, Sylvia Mader Chapter 47 Effect of Sea Otters on Ocean Communities Community Ecology Observation of sea otter populations and their predation shows the effect the otters have on ocean communities. Without sea otters there might not be any kelp beds Figure 53.17 Food chain before killer whale involve- ment in chain (a) Sea otter abundance (b) Sea urchin biomass (c) Total kelp density Number per 0.25 m2 1972 1985 1989 1993 1997 2 4 6 8 10 100 200 300 400 Grams per 0.25 m2 Otter number (% max. count) 40 20 60 80 Year Food chain after killer whales started preying on otters

Predation, Competition, and Biodiversity
Biology, 9th ed, Sylvia Mader Predation, Competition, and Biodiversity Chapter 47 Community Ecology Exotic species Introduction of exotic (alien) species into new areas Can provide many examples of competition Can lead to a reduction in biodiversity & even extinction of organisms

Exotic species – Africanized honey bee
Biology, 9th ed, Sylvia Mader Exotic species – Africanized honey bee Chapter 47 Community Ecology They are replacing the less aggressive honey bees used in agriculture

Exotic species – Brown tree snake
Biology, 9th ed, Sylvia Mader Exotic species – Brown tree snake Chapter 47 Community Ecology Spread of Brown tree snake on Guam Snake eats native birds causing extinction

Chapter 47 Community Ecology Exotic species - Kudzu It grows on top of trees & objects. Can kill trees.

Biology, 9th ed, Sylvia Mader

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