2.1 and 8 Community Ecology new revision slides
- 1. Community Ecology IB: 2.1 Ch. 8 Videos – extinction clip on exotics, clip on coral reefs
- 2. 2.1 Species and Populations • A species is a group of organisms that share common characteristics and that interbreed to produce fertile offspring. • A habitat is the environment in which a species normally lives. • A niche describes the particular set of abiotic and biotic conditions and resources to which an organism or population responds. • The fundamental niche describes the full range of conditions and resources in which a species could survive and reproduce. The realized niche describes the actual conditions and resources in which a species exists due to biotic interactions.
- 3. • The interactions between the organisms—such as predation, herbivory, parasitism, mutualism, disease, and competition—are termed biotic factors. • • Interactions should be understood in terms of the influences each species has on the population dynamics of others, and upon the carrying capacity of the others’ environment.
- 4. Vocabulary • Community • Competition • Mutualism • Niche • Parasitism
- 6. Definitions 1. Population a group of individuals of a certain species in a given area at a given time: blue crabs in the Halifax river 2. Community interacting groups of populations in an area: the scrub community on campus 3. Species a group of individuals who can interbreed to produce fertile, viable offspring: FL panthers 4. Niche The role of an organism in its environment (multidimensional): nocturnal predator of small mammals in the forest 5. Habitat Where an organism typically lives: mangrove swamps
- 7. Community Structure • Consider the spatial distribution of organisms • Physical appearance: Size, stratification, distribution of populations and species • Species diversity and richness: number of different species • Species abundance: number of individuals of each species • Niche structure: number, uniqueness and interaction of niches available
- 8. m ft 10 50 20 30 100 Tropical rain forest Coniferous forest Deciduous forest Thorn forest Tall-grass prairie Short-grass prairie Desert scrub Thorn scrub Comparison of types, sizes and stratification of species in different terrestrial communities (complexity)
- 9. Community Differences • Aquatic systems deep ocean, sandy beach, lakes, rivers, wetlands • Physical structure varies – Most habitats are mosaics, vegetation patches – Sharp edges or broad ecotones (transition zones) – Physical properties differ at edges = edge effect – Forest edge may be sunnier, drier, warmer • different species at the edge • Many wild game species found here • Edges can fragment habitat vulnerability & barriers
- 12. What is a niche • The organisms role in its environment • How it responds to the distribution of resources • Many dimensions to it – therefore an n- dimensional hypervolume • No two species can occupy the same niche for any period of time • If a niche is vacant organisms will quickly adapt to fill it
- 13. • Fundamental Niche Everything that the organism could possibly do given a competitor free environment • Realized Niche Everything the organism does after competition limits them
- 15. Biodiverse Communities • Top species rich environments are tropical rainforests, coral reefs, deep sea, large tropical lakes • Usually high diversity but low abundance • Factors for increased diversity 1. Latitude: most diverse near equator 2. Depth: marine communities peak about 2000m 3. Pollution: more pollution less species On land increases in solar radiation, precipitation, seasonal variation, decreased elevation
- 16. Species Diversity Species Diversity 1,000 100 10 Latitude 80ºN 60 40 20 0 200 100 0 90ºN 60 30 0 30ºS 60 Latitude Effects of Latitude
- 17. Species diversity 25 20 15 5 10 0 0 2,000 4,000 6,000 Depth (meters) 0 2,000 4,000 6,000 Depth (meters) 25 20 15 5 10 0 Coast Deep Sea Coast Deep Sea Snails Tube worms © 2004 Brooks/Cole – Thomson Learning Effects of Depth
- 18. Number of individuals per diatom species Number of diatom species Unpolluted stream Polluted stream
- 19. The Island Effect • Isolated ecosystems studied by MacArthur and Wilson in 1960’s • Diversity effected by island size & degree of isolation • Island Biogeography theory: diversity effected by – Rate of species immigration to island – Rate of extinction on island – Equilibrium point = species diversity
- 20. High Low Rate of immigration or extinction Equilibrium number Immigration and extinction rates Number of species on island (a) © 2004 Brooks/Cole – Thomson Learning
- 21. Island Biogeography • Immigration and Extinction Effected by 1. Size: – small island has less immigration (small target), – Small island has fewer resources, more extinction 2. Distance from mainland: – Closer to mainland more chance of immigration • Applied in conservation for “habitat islands” like national parks surrounded by development
- 22. High Low Rate of immigration or extinction Small island Effect of island size Number of species on island (b) Large island © 2004 Brooks/Cole – Thomson Learning
- 23. Island Biogeography Data • South Pacific Islands study looked at bird diversity as distance from New Guinea increased • Caribbean Island study found bigger islands had more species diversity than smaller islands which were otherwise similar 100 50 25 12.5 6.25 0 2,000 4,000 6,000 8,00010,000 Distance from New Guinea (kilometers) Number of species (percentage of sample studied ) NEW GUINEA 100 1 10 100 1,000 10,000 100,000 Area (square miles) Number of amphibian and reptile species 10 SABAMONTSERRAT CUBA Hispaniola Puerto Rico Jamaica Cuba Montserrat Saba Redonda © 2004 Brooks/Cole – Thomson Learning
- 24. Communities have different “Types” of Species • Native species = species that normally live and thrive in a particular community • Nonnative species = species that are accidentally introduced into an area • Keystone species = species that are more important than their abundance or biomass suggest • Indicator species = species that serve as early warnings of damage in a community
- 25. Nonnative Species • Also called exotics, aliens, or introduced sp. • FL examples include fire ants, hydrilla, potato vine, peacock bass, … – Occupy niches excluding native organisms – Reproduce rapidly in absence of natural predators – Usually are very adaptable to human disturbed environments
- 27. Indicator Species • Mostly species that respond quickly to changes in the environment • Birds indicate tropical forest destruction • Trout indicate pollutant presence in water • Amphibians are a classic indicator – Frogs case study p 170 – Frog decline and deformities
- 28. Keystone Species • Strong interactions with other species affect the health and survival of those species • They process material out of proportion to their numbers • Roles include: pollination, seed dispersion, habitat modification, predation by top carnivores, efficient recycling of animal waste
- 29. Sea Otters
- 30. Keystone Species II • Habitat modification – Elephants – knock over trees in savannah to promote grass growth & recycle nutrients – Bats & birds – regenerate deforested areas by depositing plant seeds in their droppings – Beavers – create ponds forming habitats for many pond dwelling species like fish, ducks, & muskrats
- 32. Keystone Species III • Top predators exert stabilizing effect by feeding on and regulating certain species – Wolves, leopards, lions, gators, sharks, otters • Over 300+ species are found on the wolf kills made in Yellowstone
- 35. Waste removal •Dung beetles – remove bury and recycle animal waste •Establish new plants •Aerate soil •Reduce disease causing microorganis ms
- 36. Species Interactions • Interactions may be harmful, beneficial, or have no effect at all • Competition: Intraspecific or Interspecific • Predation, Mutualism (Symbiosis), Commensalism, Parasitism
- 37. Intraspecific Competition • Competition between members of the same species for a common resource • Resource: food, space, mates, etc. • Territoriality – Organisms patrol or mark an area – Defend it against others – Good territories have • Abundant food, good nesting sites, low predator pop. – Disadvantage = Energy, Reduce gene pool
- 39. Interspecific Competition • 2 or more different species involved • Competing for food, space, sunlight, water, space, nesting sites or other limited resource • If resources abundant, they can be shared but in nature they are always limited • If fundamental niches overlap competition • One of the species must… 1. Migrate if possible 2. Shift feeding habits or behavior = Evolve 3. Suffer a sharp population decline 4. Become extinct
- 41. Methods of competition 1. Interference • One species limits access of others to a resource, regardless of its abundance • Hummingbird territoriality, Desert plant allelopathy 2. Exploitation • Species have equal resource access, differ in speed of use • Quicker species = more of it & hampers growth, reproduction and survival of other species
- 42. Allelopathy
- 43. Competitive Exclusion Principle • One species eliminates another in an area through competition for limited resources – Two Paramecium species – Identical conditions grown apart both do well – Grown together one eliminates the other • The niches of two species cannot overlap significantly for a long period of time
- 44. High Low Relative population density 0 2 4 6 8 10 12 14 16 18 Days Each species grown alone Paramecium aurelia Paramecium caudatum
- 45. High Low Relative population density 0 2 4 6 8 10 12 14 16 18 Days Both species grown together Paramecium aurelia Paramecium caudatum
- 46. Avoiding Competition • Resource partitioning = dividing of scarce resources to species at different – Times – Methods of use – Different locations • Species occupy realized niche, a small fraction of their fundamental niches – Lions vs leopards, hawks vs. owls
- 47. Number of individuals Number of individuals Resource use Resource use Species 1 Species 2 Region of niche overlap Species 1 Species 2 © 2004 Brooks/Cole – Thomson Learning
- 49. Predation • Members of one species feed directly on all or part of a living organism of a different species • Individuals predator benefits, prey harmed • Population prey benefits: take out the weak, greater resource access, improved gene pool • Predator plays important ecological role
- 50. Predation
- 51. Predation strategies 1. Herbivores – sessile prey, no need to hurry 2. Pursuit – speed (cheetah), eyesight (eagles), cooperation (wolves) 3. Ambush – camouflage for hiding (praying mantis), lures (anglerfish)
- 52. Ambush Predators
- 53. Prey defenses • Camouflage – change color, blend with environment, • Chemical warfare – produce chemicals which are poisonous, irritating, bad smelling or tasting • Warning coloration – bright colors advertise inedibility (mimics take advantage of this) • Behavioral strategies – Puffing up, mimicking predators, playing dead, schooling
- 55. Batesian mimicry
- 57. Span worm Bombardier beetle Viceroy butterfly mimics monarch butterfly Foul-tasting monarch butterfly Poison dart frog When touched, the snake caterpillar changes shape to look like the head of a snake Wandering leaf insect Hind wings of io moth resemble eyes of a much larger animal
- 58. Parasitism • One species feeds on part of another organism (the host) without killing it • Specialized form of predation • Parasite Characteristics 1. Usually smaller than the host 2. Closely associated with host 3. Draws nourishment from & slowly weakens host 4. Rarely kills the host • Examples = Tapeworms, ticks, fleas, fungi
- 59. Parasites
- 60. Malaria According to the World Health Organization there are 300 to 500 million clinical cases of malaria each year resulting in 1.5 to 2.7 million deaths The disease kills more than one million children - 2,800 per day - each year in Africa alone. In regions of intense transmission, 40% of toddlers may die of acute malaria. In the early 1960s, only 10% the world's population was at risk of contracting malaria. This rose to 40% as mosquitoes developed resistance to pesticides and malaria parasites developed resistance to treatment drugs. Malaria is now spreading to areas previously free of the disease.
- 61. Mutualism • Symbiotic relationship where both species benefit • Pollination, Nutrition, Protection are main benefits • Not really cooperation, both benefit by exploiting the other
- 62. Mutualism II Examples 1. Lichens – fungi & algae living together food for one, structure for the other 2. Plants and Rhizobium bacteria one gets sugars the other gets nitrogen 3. Oxpeckers and Rhinos food for one, less parasites for the other 4. Protists and termites break down wood for one, nutrients for the other
- 63. Oxpeckers and black rhinoceros Clown fish and sea anemone
- 65. Commensalism • One species benefits the other is neither harmed nor helped – Examples 1. Herbs growing in the shade of trees 2. Birds building nests in trees 3. Epiphytes = “Air plants” which attach themselves to the trunk or branches of trees -they have a solid base to grow on and better access to sunlight & rain
- 67. What interaction is this?
- 68. What interaction is this?
- 69. What interaction is this?