Why was the cane toad introduced into Queensland, Australia? The cane toad was introduced into Queensland, Australia in 1935 to control the sugar cane beetle (sugar cane beetles eat the leaves and produce larvae who feed on the roots of sugar cane crops) 2. Why was the toad unsuccessful as a biological control agent? Different behaviors than the cane beetle – active at different times of the day and preferred different areas of activity. The toad was unsuccessful in catching the beetles because they couldn’t Jump high enough. 02 cane toads were released into Australia, and have nice multiplied to over two million. The toad’s main defense mechanism is their toxin, therefore they don’t tend to hide from predators. Cane toads eat anything, and outcome native species for food. They prey on native animals, and are also eaten by native animals and in turn they are poisoned. 3. What makes the cane toad an excellent invader? Toads are extremely adaptable, and can live in virtually any habitat with breeding sites (still water) and food (any insect).
They have a high reproduction rate, develop quickly and rapidly, and are poisonous to all predators. Breed quickly with little water requirement. 4. What did the agricultural scientists fail to do that led to the ecological disaster? They did not perform any preliminary studies to see if the toads would actually be successful. Didn’t investigate the specific species that they were introducing and Just assumed that because it worked in other areas that it would work in Australia 5. What is the effect of the cane toad on Australian ecology?
Depletion of native predator and prey species, poisoning of pets and humans, reduction of food for Questions in Animal Behavior Types of questions and Levels of Analysis Nick Timberlines 4 questions: 1 . Mechanism – What stimuli elicit behavior? What sort of neurological and hormonal changes occur in response to or in anticipation of, such stimuli? (PROXIMATE) 2. Development – How does behavior change as an animal matures? (PROXIMATE) 3. Survival Value – How does behavior affect survival and reproduction? (ULTIMATE) 4.
Evolutionary History – How does behavior vary as a function of the evolutionary history, or phylogeny, of the animal. When did a behavior first appear? (ULTIMATE) 1 . Why do male caribou grow antlers? -Testosterone secreted by testes in spring (PROXIMATE) -To win fights during fall rut (ULTIMATE) – Winning fights increases number of offspring Proximate (how – mechanisms) Focuses on – immediate causes Ultimate (why – evolutionary purpose) Focuses on – evolutionary forces that have shaped a trait over time. Both answers correct Example.
Monarch Butterfly (Donnas plexuses) – Found in Nova Scotia -insect (adult has 6 legs) -postmortem (ectoderm – cold blooded) -exoskeleton -hullabaloos (undergoes complete metamorphosis) -eggs laid by female butterfly on milkweed plant -larvae (caterpillars) eat milkweed which makes them poisonous to birds (by chewing holes in the base of the main veins of leaves before they eat them, thus preventing excess “milk” from pouring into the leaf) -caterpillars grow, molt, pupate, emerge as adults -fall generation migrates to warmer areas in winter -poisonous to most vertebrates Monarch butterflies have 2 unusual traits 1 .
Eat milkweed (poisonous – few other animals can eat it) 2. Migratory insect (Only butterflies that migrate. Migrate south skim away to central Mexico) -Important for ecosystem, pollinators (Food for adult monarch butterflies consists mainly of flower nectar. They fuel their great travels and reproductive efforts by advantage of the monarchs and other insects to do the Job of pollination) Monarch Butterfly in Nova Scotia Abundant milkweed But Cold winters (e. G. O food) Winter a problem for insects Most insects enter winter diapers (hibernate) Insect reduces or ceases metabolic activity Anti-freeze proteins Monarchs migrate, cannot make anti-freeze proteins (tropical ancestors) Proximate (how) and Ultimate (Why) Questions 1 . Why do birds avoid eating Monarchs (I. E. What is it about Monarchs that discourages birds? )? (proximate question) Milkweed tissues contain compounds, called cardinalities, that are quite toxic.
Intended by the plant as a chemical deterrent to being eaten, monarch caterpillars are immune to these and actually accumulate the toxins in their own tissues, rendering them toxic, too. The bold patterning of monarch caterpillars advertises this fact. Should a bird attempt to eat a monarch caterpillar, it will become ill, usually vomiting out the caterpillar, and will refrain from eating any more. Bold warning coloration, reinforced by the occasional bad meal, leaves monarch caterpillars safe from most avian predators. 2.
Monarchs sequester cardiologists from milkweed in their bodies. Why did this evolve? (ultimate question) – Access to abundant food source; obtain poisons to reduce predation 3. Why do monarchs migrate? Proximate and ultimate answers) Proximate – Sensory cues, possibly magnetic cues and angle of popularization of light Ultimate – flight north gives access to milkweed; flight south to avoid lethal cold temps; unable to overwritten 4. How does the life cycle of a monarch relate to their migration? Overwritten in California or Mexico, mate in the spring.
Fly north to lay eggs on milkweed. Larva eat milkweed and develop up north, then fly south to overwritten Costs vs… Benefits Benefits ultimately in terms of increased number of offspring Costs usually energetic, other physiological constraints Costs vs… Benefits of Eating Milkweed (ultimate question) Benefits Access to abundant food resource Greater growth, more offspring Obtain poisonous substances, reducing predation Greater survival, more offspring Costs energy for reproduction 1. For what reasons do Monarchs migrate to Mexico? (I. E. How does this benefit the Monarch).
In their Mexican retreat, the monarchs have fairly stable weather conditions, with cool, but not freezing temperatures (monarchs are not freeze- tolerant), high humidity and protection from damaging winds. They converge on very small patches of forest and cluster together, often covering the individual trees. They rest and conserve their energy, drawing slowly on their stores of body fat, produced from the nectar of flowers they visited on their Journey south. And there they remain, rousing occasionally to flutter about and perhaps sip some water from local ponds, then return to their hibernation, until about mid-March.
With the return of spring, they rouse and begin their Journey northward. 2. What are the sensory cues that lead to the development of the migratory generation? It’s thought that monarchs use the position of the sun, combined with an innate circadian rhythm, and the earth’s genetic field to determine north and south while on their Journey 3. Why do Monarchs migrate instead of overwriting? (I. E. How did migration evolve)? In spring and summer their northward Journey gives them access to more and more emerging milkweed plants for their caterpillars and gets the adults into areas where there is less competition for flower nectar.
Both perspectives needed to understand Animal Behavior Proximate questions – mechanisms. How behavior accomplished (e. G. Sensory systems, hormones, physical cues) Ultimate questions – evolutionary significance. How behavior benefits individuals ability to survive and produce. Evolution of behavior (e. G. Does behavior exist in relatives) Darning’s theory of Evolution – Natural Selection Any trait that provided an animal with reproductive advantage over others in its population would be favored by natural selection.