1. BIOL 4120: Principles of Ecology Lecture 11: Species Interaction Dafeng Hui Office: Harned Hall 320 Phone: 963-5777 Email: dhui@tnstate.edu

2. An example of species interaction: Prickly pear cactus population is controlled by its predator, the cactus moth Prickly pear cactus was introduced into Australia as ornamental plant, and out of control. Cactus month was introduced in 1920s Now prickly pear cactus maintain a low level of equilibrium, mosaic isolated inlands.

3. Species interactions Consumer-resource interactions: fundamental ecological relationship between species, organize biological communities into food chains; include predator-prey, herbivore-plant, parasite-host. Competition: two consumers share the same resource, each reduces the availability of resources of the other. Mutualism: interactions benefit both species (pollinator-plant) Commensalism: benefit one, but do no harm on another (bird nests on a tree) Amensalism: elephant crushes a grasshopper under foot.

4. Topics (Chapter 14) 11.1 All organisms are involved in consumer- resource interactions 11.2 Dynamics of consumer-resource interactions reflect mutual evolutionary responses 11.3 Parasites maintain a delicate consumer- resource relationship with their hosts 11.4 Herbivory varies the the quality of plants as resources 11.5 Competition may be an indirect results of other types of interactions 11.6 Individuals of different species can collaborate in mutualistic interactions

5. 11. 1 All organisms are involved in consumer-resource interactions Consumer-resource interactions are the most fundamental interactions, as all non- photosynthetic organisms must eat, and all organisms are at risk of being eaten. Consumer organisms: Predator, Parasite, Parasitoid, Herbivore, Detritivore Resource organisms: plants, animals etc

6. Predation Consumption of all or part of one living organisms by another Consumption of all or part of one living organisms by another Serve as energy transfer; Predators are agents of mortality and feed on organisms Serve as energy transfer; Predators are agents of mortality and feed on organisms CarnivoryCarnivory Direct taking of animal prey for immediate consumption Direct taking of animal prey for immediate consumption Hawk or an owl taking a mouseHawk or an owl taking a mouse Decrease prey population, gain nutrition to support reproduction.Decrease prey population, gain nutrition to support reproduction. ParasitismParasitism Predator lives in or on a host and consumes, consumers part of a living host, but does not usually kill the host Predator lives in or on a host and consumes, consumers part of a living host, but does not usually kill the host Ticks on mammalsTicks on mammals Parasites that can cause disease symptoms: pathogensParasites that can cause disease symptoms: pathogens ParasitoidismParasitoidism Predator lives in or on a host and eventually kills to provide a food source Predator lives in or on a host and eventually kills to provide a food source Parasitic waspsParasitic wasps HerbivoryHerbivory Consumption of whole or parts of plant material Consumption of whole or parts of plant material Consumption of nuts and seeds (predator) or leaves of plants (parasite) Consumption of nuts and seeds (predator) or leaves of plants (parasite) Grazing (when apply to grasses and herbaceous vegetation) or browsing (wood vegetation) Grazing (when apply to grasses and herbaceous vegetation) or browsing (wood vegetation)

7. Detritivores: consume dead organic material – such as leaf litter, feces, and carcasses No direct effects on the populations that produce resource (commensal interaction)

9. 11. 2 Dynamics of consumer- resource interactions reflect mutual evolutionary responses From evolution point of view, resource organisms should develop many tactics to avoid being eaten (for consumer-resource relationships). Consumers (like predators) should develop better ways to hunt prey. Plants: produce thorns and defensive chemicals that dissuade herbivore. Animals: hide or seek refuge in a safe microhabitats; produce foul- smelling or stinging chemical secretions (scorpions) to dissuade predators; armored body covering (armadillos).

10. Boomnardier beetle sprays a noxious liquid at the temperature of boiling water toward a predator.

11. Avoiding predators may result in reduced growth rates: Bullfrog experiments by Relyea and Werner, 1999 Grew tadpoles in aquaria with caged dragonfly larvae or fish. Fish and dragonfly larvae are predators here.

12. 11. 3 Parasites maintain a delicate consumer-resource relationship with their hosts Parasitism: a relationship of two organisms living together (symbiosis) and one derives its nourishment at the expense of the other Parasitism: a relationship of two organisms living together (symbiosis) and one derives its nourishment at the expense of the other Parasite and host Parasite and host Parasitism has Parasitism has Negative effect on hostsNegative effect on hosts But do not usually kill hostsBut do not usually kill hosts Parasite consists of a wide range of organisms, including Parasite consists of a wide range of organisms, including Virus, bacteria, protists, fungi, plants, and invertebrates (include arthropods)Virus, bacteria, protists, fungi, plants, and invertebrates (include arthropods) 50% of the species on Earth (typically feed on only one or a few host species).50% of the species on Earth (typically feed on only one or a few host species).

13. Hosts are the habitats for parasites Hosts are the habitats for parasites Depends on the places: Depends on the places: Ectoparasites: live on the skin within the protective cover of feathers and hairEctoparasites: live on the skin within the protective cover of feathers and hair Endoparasites: live within the hostEndoparasites: live within the hostExamples: Fleas, ticks, are ectoparasites Liver flukes, lung flukes, flatworms, are endoparasites Hosts provide diverse habitats for parasites

14. Parasite life cycles Many parasites have complex life cycles Life cycle of the malaria parasite Plasmodium Two hosts: mosquito and Human (or other mammal, bird or reptile) Malaria: 300-500m cases/yr, 1 Millon died.

15. Virulence: a measure of the capacity of a parasite to invade host tissues and proliferate in them Virulence: a measure of the capacity of a parasite to invade host tissues and proliferate in them Balance between parasite and host populations is influenced by the virulence of the parasite and the immune response and other defenses of the host. Balance between parasite and host populations is influenced by the virulence of the parasite and the immune response and other defenses of the host. Virulence can be reduced by actions of the host’s immune system, including inflammation responses and production of antibodies. Virulence can be reduced by actions of the host’s immune system, including inflammation responses and production of antibodies. Inflammation response (produce certain chemical, increase flood flow) Inflammation response (produce certain chemical, increase flood flow) Immune response. White cells produce anti-body: bind to foreign proteins, helping counter infects. Immune response. White cells produce anti-body: bind to foreign proteins, helping counter infects. Parasite virulence and host resistance

16. 11. 4 Herbivory varies with quality of plants as resources Nutrient quality and digestibility of plants is critical to herbivores. Herbivores usually select plants according to nutrient content, preferring young leaves (low cellulose), fruits and seeds. Defenses of herbivory: Defenses of herbivory: Inherently low nutrient value of most plant tissue Inherently low nutrient value of most plant tissue Toxic compound Toxic compound Structure defenses: spines, hairs, tough seed coats, sticky gums and resins Structure defenses: spines, hairs, tough seed coats, sticky gums and resins Digestibility: secondary compounds such as tannin.

17. Secondary compounds Secondary compounds Three major classes based on chemical construction Three major classes based on chemical construction Nitrogen compound (derived from amino acid), such as lignin, alkaloids Nitrogen compound (derived from amino acid), such as lignin, alkaloids Terpeniods: include essential oils, latex, and resins. Terpeniods: include essential oils, latex, and resins. Phenolics: simple phenols have anti- multimicrobial properties (carbolic acid). Phenolics: simple phenols have anti- multimicrobial properties (carbolic acid).

18. Two type of defenses Two type of defenses Constitutive defenses Constitutive defenses Fixed features of the organismsFixed features of the organisms Some type of defense chemicals are maintained at high levels in plant tissues at all times Some type of defense chemicals are maintained at high levels in plant tissues at all times Induced defenses Induced defenses Defenses are brought about or induced by the presence or action of predators, herbivoresDefenses are brought about or induced by the presence or action of predators, herbivores Chemical defense Chemical defense Behavior defense Behavior defense

19. Structure and chemical defenses protect the stems and leaves (catus and milkweed plants) (constitutive defenses)

20. Induced defenses Plant defenses can be induced by herbivory Mean number of the mite were lower on cotton plants that have previously exposed to a closed related mite species. Cost to produce.

21. 11.5 Competition may be an indirect result of other types of interactions Direction interaction: direct relationships between two species (e.g., predator and prey) Consumer (+)  resource (-) Indirection interaction: Ex1.: predator (+)  herbivore (-)  plant (+) Multiple trophic levels in a food web, trophic cascade Ex.2: Consumer 1 (+)  resource (-)  consumer 2(+) seems like consumer 1 (-)  consumer 2(-) Exploitation competition or indirect competition

22. A competition- facilitation continuum Facilitation: nurse plants Individuals of one species facilitate the germination and growth of a second species An example: ironwood in desert provides protected sites for the establishment of cacti (later competition for nutrient, water and light)

23. 11.6 Individuals of different species can collaborate in mutualistic interactions Mutualism: interaction benefits both species involved honeybee and plants (plants provide honeybee with nectar, bees carry pollen between plants) Can be symbiosis: lichens (algae and fungi) or non-symbiosis: seed dispersal (birds and plants) Could involve more species Humans extract honeycombs (for honey) Birds eat the wax left behind Bacteria in the guts to digest the wax Three categories Trophic, defensive and dispersal mutualisms Trophic mutualisms: feeding relationship, bacteria in rumens of cows

24. Defensive mutualism Food and shelter, defend partners against their consumers Cleaning fish or shrimp

25. Some mutualists need their partners to survive and grow. Ants can’t survive without plants; and plants can’t survive without ants. Adaptation improved the efficiency of their association: Ants work day and night to protect plants. Acacias retain leaves all year. (both unusually) A wonderful story of Acacias plants and ants in Central America, see textbook (298).

26. Dispersive mutualism: Dispersive mutualism: Birds and mistletoe

27. The End