1. Interactions among Species

2. Is a mosquito a predator?

3. 1) Predation How is it defined? Does the victim have to die? Does the predator need to consume the prey for food? Predation involves one animal attacking another based upon food preferences. Usually the victim dies. Most predation is opportunistic – easiest option is typically taken Usually larger than prey species

4. The next 3 interactions are all types of symbiosis Symbiosis = “living with” or a relationship between individuals of different species in which… they live in very close physical proximity at all times one or both need the other for survival. 3 Types 2) Mutualism =both benefit (clownfish & anemone) 3) Commensalism = one benefits, other is unaffected (shark & remora)

5. Mutualism & Commensalism

6. 4) Parasitism Parasitism = one species benefits, the other is harmed Ecto-parasites = attach to outside of host Endo-parasites = live inside host Not intended to kill host, just weaken and exploit for as long as possible Usually smaller than host Usually specialized for specific host species Most hosts used as food for adult or nursery for offspring Some hosts just used a vectors or transportation to final host

7. World’s Largest Parasite? 37 foot tapeworm taken from a woman in Mississippi

8. So what about a mosquito? Does not fit easily into our categories Not a predator Parasite? Commensalist?

9. 5) Inter-specific Competition = competition between species 2 Types of Competition 1) Interference Competition (active) = one species actively discourages other competing species from sharing in the resource (birds at a feeder) 2) Exploitation Competition (passive) = one species uses the shared resource so lob-sidedly that it renders the resource unusable for others (plants out-growing each other)

10. Avoiding inter-specific competition Its all about niches, two species cannot occupy the same niche = competitive exclusion principle, one species will out-compete and eliminate the other Avoid comp. by resource partitioning (specializing) Species may use the resource at different times, divide up the area, specialize food choices, etc… Examples: Red-tailed Hawk vs. Great Horned Owl Warblers in Spruce Trees

11. Bay-breasted Warbler

12. Blackburnian Warbler

13. Black-throated Green Warbler

14. Cape May Warbler

15. Yellow-rumped Warbler

16. Competition can also occur within a population (same species) Compete for feeding rights, mates, resources Territoriality – whatever is in your territory is yours (gender and species specific) Male Birds sing to establish nesting territories so females can choose the best mate and territory Pecking Orders exist in species that live in large social groups Yearly battles determine who gets mating and/or eating priority (horns & antlers)

17. Population Dynamics

18. Warm Up… According to research, a bacteria that reproduces every 20 minutes would form a layer of bacteria 1 foot deep across the entire earth’s surface in 36 hrs. Why hasn’t this happened? According to the lab, what effects do wolves have on the moose population on Isle Royale (Name at least 2) Why are dandelions randomly scattered around the lawn but elephants are not randomly scattered around the savanna? How many deer can the CVNP sustain?

19. Major Characteristics of a Population Size = # of individuals (N) Density = # of individuals per unit area (deer/mi 2 ) Dispersion = spatial arrangement clumped (elephants) (most common) uniform (pine tree spacing) random (scattered dandelions on a lawn) Age Structure = how many Old? Young? Carrying Capacity = max pop size that can be sustained by the ecosystem (K)

20. Isle Royale Recap

21. What happened on Isle Royale? Moose Pop. started out growing exponentially, no natural enemies, plenty of food When Moose outgrew food source, their Pop. Dropped dramatically then leveled When wolves arrived, they limited moose Pop. Even further Moose Pop. Controlled Wolf Pop. Wolf Pop. Limited Moose Pop. Overall health of Avg. Moose better w/ wolves present

22. What happens when a population overshoots? Overshoot = grow beyond carrying capacity Overshoots are always followed by a die- off or crash Results from a species continuing to reproduce at a high rate because the decline in resources hasn’t affected them yet Will White-tails in CVNP crash?

23. 5,000 4,000 3,000 2,000 1,000 500 Number of moose 100 90 80 70 60 50 40 30 20 10 0 1900191019301950197019902000 1999 Year Number of wolves Moose population Wolf population

24. What determines population growth? ∆ Pop. Size (N) = (births + immigration)–(deaths + emigration) Biotic Potential = a population’s capacity for growth under ideal conditions Intrinsic Rate of Increase = rate at which a population would grow with unlimited resources Ex. – flies have a high IRI (fast repro) and therefore high biotic potential. Typically, high IRI means reproduction can happen early in life, short generation time, reproduce many times during life span and/or have many offspring at a time Recruitment = % of offspring reaching adulthood (also part of biotic potential

25. What limits population growth? No populations grow according to IRI, there are always factors limiting growth… Environmental Resistance = any and all factors that limit the growth of a population Together, biotic potential vs. environmental resistance determines Carrying Capacity Carrying Capacity = max pop. size that an ecosystems can sustain for a given species

26. POPULATION SIZE Growth factors (biotic potential) Favorable light Favorable temperature Favorable chemical environment (optimal level of critical nutrients) Abiotic Biotic High reproductive rate Generalized niche Adequate food supply Suitable habitat Ability to compete for resources Ability to hide from or defend against predators Ability to resist diseases and parasites Ability to migrate and live in other habitats Ability to adapt to environmental change Decrease factors (environmental resistance) Too much or too little light Temperature too high or too low Unfavorable chemical environment (too much or too little of critical nutrients) Abiotic Biotic Low reproductive rate Specialized niche Inadequate food supply Unsuitable or destroyed habitat Too many competitors Insufficient ability to hide from or defend against predators Inability to resist diseases and parasites Inability to migrate and live in other habitats Inability to adapt to environmental change Figure 9-3 Page 192 © 2004 Brooks/Cole – Thomson Learning

27. Time for a game…. 1) Survive 2) Earn Freak Points 3) Understand Environmental Resistance