BIO 115 1st Edition Lecture 33 Topic Discussed: Community Ecology/ InteractionsEcosystem-abiotic factors and communityCommunity – A group of populations of different species close enough to interact.Interspecific interactions – two organisms (or populations) of different species interactingTypes of Interspecific Interactions- Competition- Predation- Herbivory- Symbiosis- Parasitism- Mutualism- Commensalism- FacilitationCompetition•Interspecific competition= -/- interaction, where different species compete for a resource.•Competitive exclusion –two species compete, one wins, loser is eliminated from the area.Displaced species- go extinct or create a new species- Ecological niche - the sum of biotic and abiotic resources used by a species.- resource partitioning- similar species coexisting in a community if their niches are different. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Specialization and Speciation•Character displacement occurs when characteristics diverge more in sympatric populations than allopatric populations•Sympatric species- two species which have overlapping distributions Allopatric-populations do not have overlapping distributions.Predation and Herbivory•Predation = +/- interaction between species where one species, the predator, kills and eats the other, the prey.•Herbivory = +/- interaction between species where an organism consumes plant or algal material.HerbivoryPlant defenses•Spines and thorns•Chemical toxins•Non-noxious feeding deterrentsHerbivore defenses•Chemical sensing of noxious compounds (on feet in insects, noses in mammals)•Eating only a specific, non-toxic part of the plant•Specialized teeth or digestive systemsPredatory Adaptations•Heat sensors•Fangs•Claws•Poison•Teeth•StingersPrey adaptations•Behavioral adaptations•Hiding/fleeing•Cryptic coloration – blending into your surroundings•Herd behaviors•Alarm calls•Stotting•Mimicry•Aposematic coloration – warning predators off with your color (e.g., poison dart frogs)Mimicry- •Batesian mimicry – A palatable and/or harmless animal mimics an unpalatable/harmful organismo This only works when a predator is more likely to encounter a poisonous organism than a non-poisonous one.- Mullerian mimicry – When two (or more) poisonous/unpalatable organisms mimic each other.- Aggressive mimicry – When a predator mimics its prey’s prey item to attract the prey.Symbiosis: Parasitism- Symbiosis – When two or more species live in direct and intimate contact with one another.- Parasitism – A +/- interaction in which one organism, the parasite, derives nourishment from another organism, its host, which is harmed in the process.o Endoparasites are parasites that live inside a host’s body, like tapeworms.o Ectoparasites are parasites that live outside a host’s body, like ticks and lice.o Parasitoids are parasites that eventually kill their hosts.Symbiosis: Mutualism- Mutualism – an interspecific interaction that benefits both species.o Obligate mutualism: at least one of the species cannot survive without its partner.o Facultative mutualism: both species can survive on their own.Symbiosis: Commensalism- Commensalism – an interaction that benefits one species and neither harms nor helps the other species.- Hitchhikers – e.g., barnacles that live on whales or algae on turtle shells.Facilitation – When species have positive effects on each other without living in intimate contact.- Species diversity – the variety of different kinds of organisms that make up the community.o Species richness - The number of different species in the communityo Relative abundance – the proportion of the community that each species occupies.Shannon’s Diversity•H = -(paln(pa) + pbln(pb) + pcln(pc) … etcDiverse communities:•Better withstand environmental stresses (droughts)•Are more productive (produce more biomass) and don’t vary as much from year to year•More resistant to invasive species Influences on diversity?•Trophic structure – the feeding relationships between organisms in a community•Food chain – The process of moving organic matter (food) up trophic levels from autotrophs to herbivores to carnivores to decomposers.•Food web - The process of moving organic matter up trophic levels in the presence of multiple species of each type of producer and consumer. A food chain with multiple species on each level.Food chains are short because:•Energetic hypothesis – the length of the food chain is limited by the inefficiency of energy transfer along the chain. E.g., for every 100 kg plant material, there is 10 kg herbivore material and 1 kg carnivore material•Dynamic stability hypothesis – long food chains are less stable than short food chains. Population fluctuations at lower trophic levels are magnified at higher