Animals and their resources

1. Animals and their resources • Autotrophs • - green plants • Heterotrophs • Decomposers / detrivores • Parasites • (true) Predators • Grazers

2. All life forms are both consumers and victims of consumers. • There are many consumer-resource interactions: • Predator-prey • Herbivore-plant • Parasite-host • Producers • Consumers • Predator; Parasite; Parasitoid: Herbivore; Detritivore

3. You tell me • (other) Examples of predator-prey relationship?

4. + Some Definitions • Predators catch individuals and consume them, removing them from the prey population. • Parasites consume parts of a living prey organism, or host: • parasites may be external or internal • a parasite may negatively affect the host but does not directly remove it from the population

5. + More Definitions • Parasitoids consume the living tissues of their hosts, eventually killing them: • parasitoids combine traits of parasites and predators • Herbivores eat whole plants or parts of plants: • may act as predators (eating whole plants) or as parasites (eating parts of plants): • grazers eat grasses and herbaceous vegetation • browsers eat woody vegetation

6. An example of a parasitoid wasp. • This was is laying its egg in the caterpillar. • The egg will develop into larvae. • The larvae will consume the caterpillar as it grows. • A combination of predation, and parasitism.

7. + Detritivores occupy a special niche. • Detritivores consume dead organic material, the wastes of other species: • have no direct affect on populations that produce these resources: • do not affect the abundance of their food supplies • do not influence the evolution of their resources • are important in the recycling of nutrients within ecosystems

8. Distinguishing between animal consumers • Polyphagous/ generalists: -- eat variety of prey species though they often have clear preferences and thus have a rank order • Specialists (Monophagous): - may specialize on particular parts of their prey but range over a number of species • Most common among herbivores; why? - Different plants of plants are quite different in their composition • May specialize on a single species or a narrow range of closely related species; caterpillars of the cinnabar moth which eat the leaves, flower buds and very young stems of a species of ragwort

9. Nutritionally speaking • Meat is meat is meat is meat • A plant is not a plant is not a plant • Various parts of a plant have very different compositions  thus have different resources

11. Diversity of different food resources offered by plants – matched by the diversity of specialized mouthparts and digestive tracts that have evolved to consume them • Eg: mouthparts of insects

12. Specialized mouthparts in herbivorous insects: (a) honeybee with long ‘tongue’; (b) hawkmoth with a long sucking proboscis; C) grasshopper with plate-like chewing mandibles; (d) acorn weevil with chewing mouthparts at end of rostrum; (e) rose aphid with piercing stylet

13. Vegetarians, omnivores/carnivores • Plant body vs animal body • Plant cells: bounded by walls of cellulose, lignin, and other structural carbohydrates that give plants their high fiber content and high ratio of carbon to other elements; potentially rich sources of energy. • Problem: majority of animal species lack enzymes to digest these compounds • Chewing by grazing mammals; cooking by humans; grinding in bird gizzards • Developed mutualistic association with cellulolytic bacteria and protozoa in their guts that do have the appropriate enzymes • ..

14. Digestive tracts of consumers are adapted to their diets. Digestive organs of herbivores > carnivores

15. Vegetarians, omnivores/carnivores • Plant body vs animal body • Animal body • No structural carbohydrate or fiber component • Rich in fat and protein • C:N ratio of plant tissues – 40:1 and 10:1 in animals • Herbivores: burn off carbon  therefore their waste products (need a new name; not waste) are carbon rich (carbon dioxide and fiber) • Carnivores: excretion high in nitrogen • So: want a caterpillar or a cod or a chicken or an earthworm? Much the same in terms of protein, carbohydrate, fat, water and minerals. • Carnivores: no problem digesting. Problem is in finding, catching, and overcoming defenses of prey.

16. + Form and Function Match Diet • Form and function of predators are closely tied to diet: • vertebrate teeth are adapted to dietary items: • horses have upper and lower incisors used for cutting fibrous stems of grasses, flat-surfaced molars for grinding • deer lack upper incisors, simply grasping and tearing vegetation, but also grinding it • carnivores have well-developed canines and knifelike premolars to secure and cut prey

17. + A predator’s form and function are closely tied to its diet. (a) upper incisors are used to cut plant material; (b) flat-surfaced molars for grinding plant material; (c) knifelike premolars secure prey and tear flesh

18. + More Predator Adaptations • The variety of predator adaptations is remarkable: • consider grasping and tearing functions: • forelegs for many vertebrates • feet and hooked bills in birds • distensible jaws in snakes • digestive systems also reflect diet: • plant eaters feature elongated digestive tracts with fermentation chambers to digest long, fibrous molecules comprising plant structural elements

19. + Distensible jaws: shift the articulation of the jaw with the skull from the quadrate bone to the supratemporal 19

20. Burmese python (3.9m) vs alligator (1.8m) in Everglades National Park (Florida)

21. defenses • “the value of a resource to a consumer is determined not only by what it contains but by how well its contents are defended.” explain • Physical, chemical, morphological and behavioral defenses

22. A mite trapped in the protective ‘hairs’ on the surface of a leaf

23. defenses • Any feature of an organism that increases the energy spent by a consumer in discovering of handling it is a defense if – then - the consumer eats less of it • Eg: thick shell of a nut; cellulose; husks and shells around shells

24. Resources can be protected • Or defended • Secondary chemicals • Eg: white clover contain some individuals that release hydrogen cyanide when their tissues are attacked • Noxious plant chemicals: either quantitative (effective at high [ ] and make tissues indigestible; or constitutive / qualitative (produced even in absence of herbivore attack; toxic even in small [ ])

25. + Induced and Constitutive Defenses • Constitutive chemical defenses are maintained at high levels in the plant at all times. • Induced chemical defenses increase dramatically following an attack: • suggests that some chemicals are too expensive to maintain under light grazing pressure • plant responses to herbivory can reduce subsequent herbivory

26. plants differ in chemical defenses • Short-lived plants are protected from consumers by their unpredictability of appearance in space and time; thus invest less in defense • Predictable, long-lived species (forest trees) make investment in constitutive chemicals (typically) – and protect the more important parts of the plant • Wild radish. Flower petals v imp. (why?) [ ] of toxins twice as high in petals as in undamaged leaves

27. Prey have adaptations to avoid being consumed. • Chemical defenses • Some animals store the chemical plant toxins and use them in their own defense (monarch butterfly – caterpillar feeds on milkweeds; caterpillar stores poison; bluejay vomiting butterfly after eating it. So? .. Monarchs that eat cabbage are edible for birds) • Hiding • If a predator can’t see you, it can’t eat you. • Evolution of cryptic coloration. • Escaping • If you can outrun your predator, it can’t eat you. • Evolution of speed or maneuverability. • Active defense mechanisms • Animals with poison glands. • Plants with thorns, toxic substances.

28. Chemical defenses. • The production of chemicals which repel potential predators. • Toxin + boiling temp => • Notice the colors of this bombardier beetle.

29. Prey have adaptations to avoid being consumed. • Hiding / behavior • If a predator can’t see you, it can’t eat you. • Living in holes (moles) • Playing dead (african ground squirrel) • Evolution of cryptic coloration.

30. + Crypsis and Warning Coloration 23 • Through crypsis, animals blend with their backgrounds; such animals: • are typically palatable or edible • match color, texture of bark, twigs, or leaves • are not concealed, but mistaken for inedible objects by would-be predators • Behaviors of cryptic organisms must correspond to their appearances.

31. + Cryptic appearances (a) mantid; (b) stick insect; (c) lantern fly

32. For more…See slideshow – posted on the ecology site

33. + Warning Coloration: aposematism • Why should a prey item evolve bright colors? • It definitely brings attention to you. • Black and yellow are the most common colors. • Unpalatable animals may acquire noxious chemicals from food or manufacture these chemicals themselves: • such animals often warn potential predators with warning coloration or : • certain aposematic colorations occur so widely that predators may have evolved innate aversions • If an animal eats a brightly colored prey item: • It may get sick. • It may die. • If it lives, it will remember.

34. + Unpalatable organisms 26

35. + Why aren’t all prey unpalatable? • Chemical defenses are expensive, requiring large investments of energy and nutrients. • Some noxious animals rely on host plants for their noxious defensive chemicals: • not all food plants contain such chemicals • animals using such chemicals must have their own means to avoid toxic effects

36. + Batesian Mimicry • Certain palatable species mimic unpalatable species (models), benefiting from learning experiences of predators with the models. • This relationship has been named Batesian mimicry in honor of discoverer Henry Bates. • Experimental studies have demonstrated benefits to the mimic: • predators quickly learn to recognize color patterns of unpalatable prey • mimics are avoided by such predators

37. + Harmless mantid (b) and moth (c) evolved to resemble a wasp (a)

38. + Müllerian Mimicry • Müllerian mimicry occurs among unpalatable species that come to resemble one another: • many species may be involved • each species is both model and mimic • process is efficient because learning by predator with any model benefits all other members of the mimicry complex • certain aposematic colors/patterns may be widespread within a particular region

39. + Costa Rican butterflies and moths

40. Effects of intraspecific competition for resources

41. Competing for resources • Intraspecific competition: competition between individuals of the same species • Exploitation: competitors depleting each other’s resources [just eating the same food] • Direct interference: individuals of a species may fight for ownership of a ‘territory’ [eg: vultures; tigers] • Ultimate effects: survival, growth and reproduction (vital rates) of competitors impacted • Thus – competition typically leads to reduced rates of resource intake per individual  decreased rates of individual growth or development, increased rates of predation.. • Density-dependent. What does that mean?

42. Conditions, resources, and ecological niche • Habitat vs niche?

43. Habitat and Niche • The habitat is a place or physical setting in which an organism lives. Examples include: • forests • deserts • coral reefs • The habitat is characterized by: • conspicuous physical features • dominant plant (or animal) life

44. Tropical rain forest…

45. Tropical seasonal forest habitats

46. Tropical grasslands

47. Antarctic ice cap…

48. Classifying habitats is useful but difficult! • The habitat concept is useful; it emphasizes conditions experienced by organisms. • Classification systems are varied and typically hierarchical: • aquatic habitats (vs. terrestrial) • marine habitats (vs. freshwater) • oceanic habitats (vs. estuarine) • benthic habitats (vs. pelagic) • Finer subdivisions overlap rather broadly!

49. Niche • The niche of an organism encompasses: • ranges of conditions tolerated • role in ecological systems • No two species have the same niche: • each has distinctive form and function • No organism can live under all conditions: • each has unique habitat requirements • each has a unique niche

50. Peruvian rhinoceros katydid: specialized in chewing leaves