Slide 1

Animals and their resources Autotrophs - green plants Heterotrophs Decomposers / detrivores Parasites (true) Predators Grazers 12/1/20151 Slide 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 12/1/20152 Slide 3 You tell me (other) Examples of predator-prey relationship? 12/1/20153 Slide 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 12/1/20154 Slide 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 12/1/20155 Slide 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. 12/1/2015 6 Slide 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 12/1/20157 Slide 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 12/1/20158 Slide 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 12/1/20159 Slide 10 10 Slide 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 12/1/201511 Slide 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 12/1/201512 Slide 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.. 12/1/201513 Slide 14 Digestive tracts of consumers are adapted to their diets. Digestive organs of herbivores > carnivores 12/1/201514 Slide 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. 12/1/201515 Slide 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 12/1/201516 Slide 17 + A predators 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 12/1/201517 Slide 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 12/1/201518 Slide 19 + Distensible jaws: shift the articulation of the jaw with the skull from the quadrate bone to the supratemporal 19 12/1/201519 Slide 20 Burmese python (3.9m) vs alligator (1.8m) in Everglades National Park (Florida) 12/1/201520 Slide 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 12/1/201521 Slide 22 A mite trapped in the protective hairs on the surface of a leaf 12/1/201522 Slide 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 12/1/201523 Slide 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 [ ]) 12/1/201524 Slide 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 12/1/201525 Slide 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 12/1/201526 Slide 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 cant see you, it cant eat you. Evolution of cryptic coloration. Escaping If you can outrun your predator, it cant eat you. Evolution of speed or maneuverability. Active defense mechanisms Animals with poison glands. Plants with thorns, toxic substances. 12/1/201527 Slide 28 Chemical defenses. The production of chemicals which repel potential predators. Toxin + boiling temp => Notice the colors of this bombardier beetle. 12/1/2015 28 Slide 29 Prey have adaptations to avoid being consumed. Hiding / behavior If a predator cant see you, it cant eat you. Living in holes (moles) Playing dead (african ground squirrel) Evolution of cryptic coloration. 12/1/201529 Slide 30 + Crypsis and Warning Coloration 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. 23 12/1/201530 Slide 31 + Cryptic appearances (a) mantid; (b) stick insect; (c) lantern fly 12/1/201531 Slide 32 For moreSee slideshow posted on the ecology site 3212/1/2015 Slide 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. 12/1/201533 Slide 34 + Unpalatable organisms 26 12/1/201534 Slide 35 + Why arent 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 12/1/201535 Slide 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 12/1/201536 Slide 37 + Harmless mantid (b) and moth (c) evolved to resemble a wasp (a) 12/1/201537 Slide 38 + Mllerian Mimicry Mllerian 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 12/1/201538 Slide 39 + Costa Rican butterflies and moths 12/1/201539 Slide 40 Effects of intraspecific competition for resources 12/1/201540 Slide 41 Competing for resources Intraspecific competition: competition between individuals of the same species Exploitation: competitors depleting each others 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? 12/1/201541 Slide 42 Conditions, resources, and ecological niche Habitat vs niche? 12/1/201542 Slide 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 43 Slide 44 Tropical rain forest 44 Slide 45 Tropical seasonal forest habitats 45 Slide 46 Tropical grasslands 46 Slide 47 Antarctic ice cap 47 Slide 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! 48 Slide 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 49 Slide 50 Peruvian rhinoceros katydid: specialized in chewing leaves 50 Slide 51 These Aphids: suck juices from stems and leaves of milkweed plants 51 Slide 52 Lchnuemonid wasps: lay eggs in the larvae of beetles within wood 52 Slide 53 niche To clarify: where an organism lives is not a niche; it is a habitat A niche is not a place; it is an idea a summary of the organisms tolerances and requirements Niche of an organism describes how, rather than just where, an organism lives 12/1/201553 Slide 54 Niche and dimensions Temperature: one dimension of an organisms ecological niche Tolerance of various other conditions (relative humidity; pH; wind speed; waterflow; etc) + various resources Multi-dimensional 3-D temperature, pH, availability of a particular food Niche = n-dimensional hypervolume N = number of dimensions 12/1/201554