Species Interactions Chapter 8, Sections 2-4

1. Species InteractionsChapter 8, Sections 2-4

2. Types of Species • Native – normally live and thrive in an area • Non-native or invasive or alien species – intentionally or accidentally introduced to an area • Not always bad: e.g. apples, potatoes, cattle, wild game species (pheasant) • Can be problematic because introduced species may have no natural predators or competitors and may overrun native species

3. Examples of Invasive Species • Kudzu • Chinese Privet • European starling • Fire ants • African “killer bees”

4. Indicator Species • Species that serve as an early warning that a community or ecosystem is being degraded • Example: amphibians – especially vulnerable due to thin skin, unprotected eggs, aquatic life cycle • populations declining, more mutations seen

5. Keystone Species • Species that are so interrelated with other species that if anything happens to them, it will have a big effect on the entire ecosystem • Examples: sea otter, sea star Pisaster (study by Robert Paine),wolf in Yellowstone

6. Keystone Species: Sea Otter

7. Types of Species Interactions • Competition • Predation • Symbiosis: • Parasitism • Mutualism • Commensalism

8. One type of species interaction: Competition Definition: when two or more individuals or populations try to use the same limited resource Both are negatively affected by the interaction

9. Types of competition • Interspecific competition – competition between members of different species Example: plants compete for limited nutrients in the soil around them, light, water, space, etc.

10. Interspecific competition Organisms have different adaptations to improve competitive edge – a few examples: • produce many offspring • have extensive root systems that are efficient • extremely fast growth rate • allelopathy – when a plant produces a chemical that prevents other plants from growing around it (black walnut, sunflowers, junipers) • aggressive behavior

11. Interspecific competition Example: warblers – different species of small songbirds that are similar in habit, compete for the same resources in trees Classic study by ecologist Robert McArthur Bay-breasted warbler Yellow-rumped warbler Cape May warbler

12. Resource partitioning When species competing for the same resources evolve more specialized traits that allow them to use shared resources at different times, in different ways or in different places

13. Resource partitioning Due to competition, each species uses less of the niche than they are capable of using

14. Types of competition • Intraspecific competition – members of the same species compete for food, mates, nesting sites, space, water, etc. Example: Wolves fighting for meat Alpha male will eat first

15. Intraspecific competition can also be called “survival of the fittest” and is a driving force of evolution The individual that is best adapted to outcompete the others will survive and pass on its traits to its offspring

16. Competitive Exclusion Principle Also called Gauss’ law of competitive exclusion: “Complete competitors cannot coexist” Published in 1932, based on studies of paramecium The result will be dominance by one competitor and the other one will either be driven out (or go extinct) or will evolve to occupy an available niche (niche partitioning) Competition between exact competitors: Result: Species 1 Species 2 Species 1 dominant AND Species 2 occupies another niche OR Species 2 goes extinct

17. Relatively new view of competition: Competition-colonization trade-offs - enable species to coexist Species will be successful due to one of two approaches: • generalists – better colonizers, constantly take advantage of niche openings in the environment • specialists – better competitors, will win out over the long run if the environment is stable

18. Examples: Two bird species Generalist/colonizer – crows (will eat almost anything and live almost anywhere) Specialist/competitor – red cockaded woodpecker (well-adapted to live in mature longleaf pine forests)

19. Example: Two plant species Generalist/colonizer – weeds, such as Queen Anne’s lace, quickly inhabit disturbed areas Specialist/competitor – hardwoods, such as oaks and hickories, require a long time to grow, generally in upland habitats

20. Another type of species interaction: Predation Type of species interaction in which one organism (predator) feeds on another (prey)

21. Predator/Prey relationships Does the predator control the prey, or does the prey control the predator?

22. Predator/Prey relationships Many adaptations have evolved due to predator/prey relationships Examples of adaptations of prey: camouflage, warning coloration, mimicry, chemical warfare, behavior

23. Camouflage: Hide Butterfly that resembles a dead leaf

24. Warning Coloration: Advertise that you are not tasty Bright colors advertise the fact that a prey is distasteful or poisonous Ex: bees, poison arrow frogs, coral snake

25. Behavior: Act tough and hang around with your friends Flocking and mobbing by birds – safety in numbers

26. Mimicry: Look like someone else Batesian mimicry – when one palatable species mimics another that is harmful or distasteful Ex: insects mimic wasps Right: A and B are stinging wasps, C-E are flies that mimic the wasps, F is a beetle that mimics the wasps

27. Batesian mimicry – moth resembles spider

28. Mimicry Mullerian mimicry – when two or more species look alike and both are unpalatable, both benefit from the reinforcement to predators to avoid the pattern seen Ex: Viceroy and Monarch are BOTH unpalatable Monarch Viceroy

29. Combination: Mimicry and behavior Butterfly with fake eyes on wings

30. Urban mimicry

31. Urban mimicry

32. Predation Examples of adaptations of predators: • Adaptations for capture - pursuit - ambush - trap - tools • Adaptations for killing - bite/claw - suffocate - poison

33. Another type of species interaction: Symbiosis Review: name the three types and define each Mutualism: + + Commensalism: + 0 Parasitism: + -

34. Mutualism Pollination mutualism – animals (bees, hummingbirds, butterflies) get food and plant gets pollen distributed directly to the right plant Nutritional mutualism – e.g., lichens – algae (provides food) plus fungus (provides structure and absorption of nutrients, water) Gut inhabitant mutualism – bacteria in termites’ gut or in humans’ gut help with digestion, get food

35. Endosymbiont Theory Origin of eukaryotic cells – thought to be symbiotic relationship between different prokaryotic cells, bacteria living in cells evolved into organelles (mitochondria contains DNA)

36. Commensalism • Example: epiphytes – plants that live on other plants but do not hurt them Resurrection fern Tropical orchids

37. Parasitism: Free-loaders May be considered a type of predation Different from predation in two ways: • parasites are usually much smaller than their hosts • parasites usually don’t kill their hosts Moose tick

38. Parasitism Two categories when parasite lives on/in host: • internal (e.g., tapeworms) • external (e.g., ticks, fleas) Some parasites never come in contact with their hosts (e.g., cowbirds lay eggs in other birds’ nests and leave young to be raised by them)