Defensive Adaptations: Survival Strategies for Avoiding Predators

1. Defensive Adaptations goal: don’t get eaten! • Plants • Grow thorns, spines, or rough leaves • Produce secondary compounds that are bad-tasting, toxic or both • Example: milkweeds produce cardiac glycosides that make herbivores sick if consumed.

2. Defensive Adaptations goal: don’t get eaten! • Animals • Also produce secondary compounds • Hot quinones are sprayed on attackers by some beetles • Bad smell in skunks

3. Defensive Adaptations goal: don’t get eaten! • Animals • Aposematic coloration: “warning coloration” • A bright, easily remembered pattern lets your predators know you are dangerous so they won’t eat you! • Ladybird beetles are bad, tasting so they’re red

4. Defensive Adaptations goal: don’t get eaten! • Animals • Coral snakes are poisonous so they’re banded with red, yellow, & black • Poisonous butterflies (Monarch butterfly) have bright “warning” colors

5. Defensive Adaptations goal: don’t get eaten! • Animals • In general for animals, bright color = bad taste • Works best on predators that can learn • a toad that gets stung once by a bumblebee  won’t touch anything that resembles the bee for a long time • If a jaybird eats a monarch, he vomits, then learns NOT to eat anything with the same color pattern

6. Defensive Adaptations goal: don’t get eaten! • What are good “learning” predators… • Ones that have a developed nervous system • Developed nervous system = memory system • Memory system allows organism to learn

7. Defensive Adaptations: Mimicryimitation for protection • Batesian mimicry: one poisonous, one isn’t • After a bird eats one monarch and gets sick, he will also avoid viceroys (even if they’re not poisonous)  • non-poisonous imitator gains protection

8. Defensive Adaptations: Mimicryimitation for protection • Batesian mimicry: one poisonous, one isn’t Coral Snake Scarlet King Snake "Red on yellow, kill a fellow "Red on black, friend of Jack“ "Red into black, venom lack; red into yellow, kill a fellow."

9. Defensive Adaptations: Mimicryimitation for protection • Mullerian mimicry: both poisonous • Reduces the total number of organisms that must be killed to “educate” the predator • 3 or more species of toxic prey is better  mimicry ring • Many poisonous butterflies of Heliconius look alike

10. Defensive Adaptations: Camouflagehiding from predators • Opposite of aposematic coloration; makes organisms hard to see • Disruptive coloration: breaks up the outline of an organism so it makes it hard to recognize

12. Offensive Adaptationsgoal: EAT so you can survive another day! How to get a meal • Sit-and-wait predator: wait until the food comes to you • Active searcher: go out and look for food • Parasite: sit on your food all the time

13. Offensive Adaptationsgoal: EAT so you can survive another day! • Sit-and-wait predator: wait until the food comes to you • Camouflage and mimicry are common tactics • The organism using these techniques do not get seen by potential predators AND • Potential prey cannot see their predator Lunch!

14. Yellow Crab Spider captures small bee

15. Competition • Intraspecific competition: competition within the samespecies for the same resource (food/water, shelter/territory, mate, etc.)

16. Competition • Intraspecific competition: competition within the samespecies for the same resource (food/water, shelter/territory, mate, etc.) • Prevention: males & females may eat different foods OR the adult & young will eat different foods

17. Competition • Interspecific competition: competition between different species for the same resource (food/water, shelter/territory, etc) • May lead to extinction of one species by competitive exclusion • By competing one gets forced out of their niche • Niche • Fundamental: like having your own room • Realized: someone moving into your room

19. Organisms try to minimize competition. Some kind of sharing or division of resources is better than fighting. When species live in close proximity to another or share the same resources they may form symbiotic relationships with one another We say that they live in niches (living conditions that are perfect for just those species)

20. Symbiosis • When 2 or more species are in a close, long-term relationship • 3 kinds: • Mutualism • Commensalism • Parasitism

21. Mutualism (+/+) • Both species benefit; win-win situation • Example: oxpeckers feed on the ticks found on rhinos

22. Commensalism (+/0) • One species benefits, the other doesn’t gain or lose anything from the relationship • Example: remora fish and shark

23. Parasitism (+/-) • One benefits, the other loses • Example: Cat and tapeworm • Types • Ectoparasites: live outside the host like fleas & ticks • Endoparasites: live within the host like viruses, bacteria, protozoans, etc.

24. Species can shape each other over time. • Two or more species can evolve together through coevolution. • evolutionary paths become connected • species evolve in response to changes in each other

25. Coevolution can occur in beneficial relationships.

26. Coevolution can occur in competitive relationships, sometimes called evolutionary arms race.

28. How these organisms interact (symbiosis, predator-prey, competition, etc.) can affect how the population evolves. Natural selection can change the distribution of traits within a population

29. Natural selection acts on distributions of traits. • A normal distribution graphs as a bell-shaped curve. • highest frequency near mean value • frequencies decrease toward each extreme value • Traits not undergoing natural selection have a normal distribution.

30. Natural selection can change the distribution of a trait in one of three ways. • Microevolution is evolution within a population. • observable change in the allele frequencies • can result from natural selection

31. Natural selection can take one of three paths. • Directional selectionfavors phenotypes at one extreme.

32. Stabilizingselectionfavors the intermediate phenotype.

33. Disruptiveselectionfavors both extreme phenotypes.