1. Midterm Exam Review Questions Short essays (60-70% of exam) drawn from list of questions distributed Monday on the website Stratified (although non-random) across the chapters Address the question--no bonus for extraneous stuff Only textbook and lecture material expected Closed book exam without notes, etc.

2. Midterm Exam Review Session Sunday, 1-4pm EST 53 Church St., Room L01 Bring photo ID for access to building Email questions to Alex (georgiev@fas.harvard.edu)georgiev@fas.harvard.edu To access the live stream of the review sessions, students should go to http://cm.dce.harvard.edu/classroom/ and click on ENVR E-140 at around 12:55 p.m. on the day of the review. http://cm.dce.harvard.edu/classroom/ A window will open with a button that says "Join". Students click on the button and join the classroom. There is a one or two second delay in the stream. If the page opens to "No videos are available at this time" it means they're probably too early for the class. They'll need to refresh the page periodically until they get the "Join" button and then click on the "Join" button. The sessions will also be added to the course video page.

3. Coevolution & Mutualisms (skip over chap 8.1-8.2 for now) Coevolutionary arms races Symbiosis: Mutualisms and Parasitism Mutualisms Interspecific Competition Influence on Community Structure (chap 6.4) Importance of Competition

4. Ecology of Mutualisms & Parasitism Symbiosis: association between species in which one lives on or in the other Parasite: lives intimately associated with host organism(s), deriving resources from and harming the host The “habitat” of parasites are host organisms (egg or larval stages may use different host types or survive in the soil) Microparasites: small, numerous and reproduce within host (bacteria, viruses, etc.) Macroparasites: large, grow within host but produce infective stages that disperse to new hosts –Live on the host body or within body cavity –Parasitic worms, nematodes, etc. Parasites harm the host: have negative effects on growth, reproduction and/or survivorship

5. Coevolutionary Arms Races - predator/prey -grazer/plant -specialists are more prone to arms races a) specialists have lower mortality on toxic chemicals b) generalists lower mortality on chemicals not provoking coevolutionary response (e.g., tannins, lignin)

6. Coevolutionary Arms Races - parasites & hosts - continual evolution of new influenza strains -Canadian Plains Indians evolution of resistance to TB

7. Coevolution of host and parasite: Control of rabbits in Australia & Britain by selection for increased transmissibility in Myxoma virus strains (thereby lowering virulence)

8. Mutualists & Commensuals Mutualism: association which benefits both species (have positive effects on growth, reproduction and/or survivorship for both populations) Mutualisms are cases of reciprocal exploitation in which both partners have net benefit –mycorrhiza- associations between fungus and plant root that extracts soil nutrients –Pollination, seed dispersal, etc… Commensuals are symbionts that have no measurable cost or benefit to host –Effects may depend on the “load” of parasites or commensuals and depend on nutritional status and health of host organism

9. Higher plants as specialized niches for arthropods, worms & protozoa - not shown are nematodes, bacteria & viruses (!)

10. Higher animals as specialized niches for arthropods, worms, protozoa, bacteria & viruses fungi- brown worms- blue arthropods- green protozoa-yellow

11. Mutualistic protectors: cleaner fish cleaner: Labroides dimidiatus client: Hemigymnus melapterus

12. Modified plant parts for mutualists: a) beltian bodies of bullhorn Acacia tended by ants b) hollow thorns enclosing colonies

13. Experimental removal of predatory symbiotic ants reveals mutualistic benefit in reducing herbivory tree: Tachigali myrmecophila ant: Pseudomyrmex concolor

14. Farming mutualisms in aphids & ants, cost of mutualism: a)ants lower predation on aphids, but b) if no predators, ant-excluded colonies lower aphid growth & reproduction Tuberculatis quericola Formica yessensis

15. -Pollination - reward is nectar or pollen specialized (at least temporarily) to ensure pollen transfer to conspecifics limit production so visit sequential individuals Seed Dispersal - reward is pulp or seeds no need for temporal specialization, so can be generalists

16. Fig wasp symbiosis & fig tree phenology: - intraspecific randomized fruiting to maintain pollinating agaonid wasp species

17. Fruiting Phenology - as a result of coevolution with pollinating wasps, figs always available for vertebrate frugivores - figs are “keystone species” in rainforests Ficus subtenda 1 f-r--f-r-f-r-f-r--f-r---f-r 2 r--f-r-f-r-f-r--f-r-f-r--f-r 3 -f-r--f-r-f-r--f-r---f-r--f-r Ficus stupenda 1 f----r--f-----r----f-------r----f- 2--f-----r----f-----r---f------r--- 3-r---f-----r---f-----r--f------r--

18. Parasites vs. Symbiotic Mutualists Many symbiotic species (specialized) Complex life cycles (e.g., alternating hosts) Dispersal important (transmission & infection) Sex common to generate variation in evolutionary wars Few symbiotic (generalized; e.g., lichens, rhizobial bacteria) Simple life cycles Vectors for transmission rare Sex uncommon as evolutionary conflict reduced

19. Life cycle of the parasitic cestode worm Diphyllobothrium - birth rates determined by hosts

20. Life cycle of malaria-causing Plasmodium protozoa: from vertebrate red blood cells to mosquito gut to salivary glands

21. Behavioral responses of Hosts to Parasites: Manipulation to benefit the parasite -Anopheles mosquitos feed on more hosts when infected with the malaria parasite Plasmodium -Gall growth to harbor larvae induced by different species of Andricdus wasps

22. The vertebrate immune response changes habitat quality for specific parasites (and toxins); production of antigens promotes immunity to subsequent colonization attempts

23. Mutualistic microbiota in vertebrate guts - microbes (mostly protozoa & bacteria) receive plant foods & live in high pH, regulated shelters - vertebrate hosts receive food from otherwise indigestible leaves - food in form of short-chain fatty acids (SCFAs), protein & vitamins rabbit sheep zebra kangaroo

24. Corals contain photosynthetic algae called zooanthellae -intracellular symbionts that photosynthesize -expelled by stressed corals (bleaching)

25. the symbiotic, mutualistic nitrogen-fixing bacteria of Rhizobium, infecting root nodules (especially legumes) Legume trees are common on N- poor soils, and provide protein- rich leaves & seeds (Koompassia)

26. Effects of symbiotic Rhyzobium vs. N on soybeans & grass: change in competitive outcomes

27. Most mycorrhizas increase P & N uptake by host, but some may protect from pathogens: P uptake in Hyacynthoides Vulpia protected from fungus by Glomus

28. Interspecific Competition Influence on Community Structure (chap 6.4) Importance of Competition

29. Guild structure in 9 spp. Amphiprion anenome fish -using 10 spp. Heteractis (PNG) - anenome species, zone location & size (food size?) Niche complementarity

30. Niche differentiation among seven Bumble bee species in Colorado: resource partitioning by flower corolla length -Resource diversity encourages species-rich consumer guilds -niche complementarity: similar species differ in other niche dimensions (e.g., Bombus occidentalis)

31. Niche partitioning in plants - share similar light energy & mineral resources, so possible niche dimensions few - expect competition is overwhelmingly important process -often involves both leaves & roots (clover & skeleton weed)

32. Vary in: - crown illumination index (sun --> shade) & soil type (clay-rich vs. sand-rich) - therefore, related to vertical dimension (crown height) and spatial dimension Niche differentiation in 11 coexisting Macaranga species: separation in space Tree species niches distinguished by: -maximum height -% trees in high light -% trees on clay-rich soils

33. Pinus resinosa Niche differentiation: Vertical separation of 26 species of ectomycorrhyzal species in pine forest litter layer

34. Niche partitioning in 5 species of tundra plants Differences in: - timing of N uptake - depth of uptake - form of N Temporal separation of tundra plants

35. Apparent competition via indirect interactions - enemy-free space (shared predator) - linkage to 3rd species: competitor of one, mutualist of other Dominant Artimisia shrubs competing with herbs? -remove shrubs & herb densities increase … but clearing shrubs also reduced grazing and cover for herbivores….

36. How important is interspecific competition in communities? Lack’s tit species: slight differences in niches, but… 1. One hypothesis: they compete now… but there are others! 2. Competed in past & evolved differentiated niches, but competition now weak 3. The ghost of competition past is evident in that previous competitors went extinct 4. Distinct niches because evolved differences due to other selective pressures 5. Environment varies and so allows coexistence; otherwise, exclusion of some …but Schoener’s review demonstrated competition in 90% of studies of closely related species… % lower in herbivores vs, carnivores & plants

37. How important is competition in shaping ecological guilds? Evidence for competition in N.A. lizard communities: deviation in observed resource overlap compared to “neutral models”