Week 15 Notes
Popular in Life 103- Biology of Organisms
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This 6 page Class Notes was uploaded by email@example.com Notetaker on Saturday May 7, 2016. The Class Notes belongs to 103 at Colorado State University taught by Tanya Dewey in Winter 2016. Since its upload, it has received 11 views. For similar materials see Life 103- Biology of Organisms in Biology at Colorado State University.
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Date Created: 05/07/16
Sensing the environment Sensory Pathways 1. Reception a. Consists of receptor cells, parts of cells, and organs 2. Transduction . The energy from the stimulus is converted to a charge, or membrane potential 3. Transmission . The stimulus then travels as a nerve impulse 4. Perception . The interpretation of the stimulus occurs in the brain Sensor: the sensor receives a signal. After it receives a signal, then there is a change of membrane potential Membrane potential: it is the difference in charge between the inside and outside of the cell -membrane potential is maintained through active transport and selective permeability Action Potential: a response to a stimulus that is influenced by the frequency of action potentials -can either be “on” or “off” -the intensity of the stimulus determines the frequency -the action potential is involved in the transduction and transmission neurons Perception: how the brain processes stimuli Synthesia: the stimulation of one sensory pathway lead to involuntary experiences in a second pathway -Example: some people can hear colors Amplification -when sensory stimuli are strengthened during transduction through accessory structures or enzyme catalysis of secondary messengers in cells Sensory adaptation -With a continued stimulation, there can be a decrease in the responsiveness of receptors Mechanoreceptors -respond to mechanical energy like pressure, touch, motion, and sound Chemoreceptors -respond to chemical stimuli such as smell and taste Electromagnetic receptor -respond to visible light, electricity, and magnetism Thermoreceptors -detect heat and regulate body temperature Pain receptors -naked dendrites in the epidermis that sense pain Examples of reception Lateral Line system -found in aquatic animals -it’s a grove with hair-like cells that detect motion -The direction of movement across the hair like cells causes changes in the trajectory and membrane potential Mammalian hearing -the tympanic membrane vibrates from the vibrations in the air -the tympanic membrane then comes into contact with the middle ear bones -Middle ear bones amplify and transmit vibrations to inner ear fluid in cochlea -the vibrations are then detected by hair cells located in the basilar membrane Echolocation -detects reflected sounds -the ear shape can determine the range of frequency the animal can detect Electromagnetic receptors -single evolutionary origin of vision indicated by shared genes that control photoreceptor development -A photoreceptor is a cell that through photosensitive proteins converts a light into a stimulus -Flatworms have simple eyes, auricles, which can detect light -compound eyes in arthropods have many light detectors called ommatidia, each with its own lens Vertebrate vision -iris and pupil -Lens focus light -retinal are lined with photoreceptors -Rods are sensitive to light -Cones detect color What animal would have a higher proportion of rods to cones? -an owl would because they hunt in low light Retinal: molecule that absorbs light Opsin: associated protein Light absorption activates opsin and changes retinal shape Activation of rhodopsin causes changes in signal transduction via an enzyme cascade Changing the membrane potential causes an action potential Magnetic crystals in tissues orient to Earth’s magnetic field -birds, whales, and bats -a mineral in their brain responds to magnetic fields Detection of electrical fields -primarily in aquatic animals because water is a good conductor of electricity -sharks, rays, fish, platypuses etc Electromagnetic reception -evolved from a lateral line system from the mechanoreceptors -somewhat like electric “echolocation Chemo reception -gustation→ taste -olfaction→ smell -there are over 1,000 odor receptors and each detects a single odor -these account for over 3% of human genes Dogs have 300 million olfactory receptors People have 6 million olfactory receptors Vomeronsal organ -detects pheromones at a low concentration -animals due this by flehmening and tasting the environment Behavior and Social structure Modes of perception favored in aquatic caves -lateral line system -electrical current -chemoreception Modes of perception favored in terrestrial caves -hearing/echolocation -heat sensing -smell and touch Tinbergs 4 Questions 1. What stimulus elicits the behavior and what physiological mechanisms mediate the response (proximal) a. Fixed action pattern: a set stimulus triggers an innate behavior that once started must finish b. Environment can influence the behavior c. “Hard-wired” behavior i. Examples→ waterfowl will roll egg back into nest if it rolls away 1. A certain species of fish will attack anything red 2. Birds shove food in an open mouth, even if it’s not their species d. Circadian and circannual rhythms . Can be daily, seasonal, or annual changes in behavior and physiology i. Influenced by light/dark and lunar cycles ii. Can be correlated with the availability of food iii. Examples 1. Migration 2. Reproduction e. Communication and pheromones . Communication: exchanging info among individuals i. Pheromones: can influence other individuals’ behavior. Is a way letting individuals within your own species know whether or not you’re hurt or sexually receptive 2. How does experience influence the response? (proximal) . Learned behaviors: experience can modify certain behaviors a. Innate behaviors: are behaviors that don’t require any prior experience b. The vast majority of behaviors are influenced by nature and nurture c. Imprinting: a long lasting behavior that is established during a sensitive period in early development . Animals are more receptive to a particular stimuli during sensitive periods i. Waterfowl easily imprint. The first thing they see they think is their mother, even if it’s not d. Spatial learning and cognitive maps: the ability to remember the spatial arrangement of an environment and the objects within it . Helps animals migrate and find food i. Elephants whose matriarch has been killed have a harder time finding the resources they need to survive e. Dissociative learning: make associations between experiences . Classical conditioning: learn that a certain stimulus means a certain outcome 1. Example→ pavlov’s dogs i. Operant conditioning: trial and error basis. Learning to associate a behavior with an award ii. Not all associations are possible, it depends on the association that particular animals are sensitive to f. Cognition and problem solving: ability to form a range of knowledge through awareness, reasoning, recollection, and judgement . Originally thought that this form of cognition was only limited to primates and dolphins. Now we know that it spans many types of species i. Self-awareness in animals is still an active area of research. Some animals have exhibited self awareness ii. Self-awareness is seen mostly in social groups of animals g. Social learning: learn through the observation of others . Forms cultures 1. Tool use, languages, predation, and playing 3. How does behavior influence reproductive success? (ultimate) . Mating behavior and choice: finding and attracting mates, choosing mates, competing for mates and caring for young a. Mating systems are influenced by patterns of parental investment and certainty of paternity . Mammals: obligate female investment with limited to no male investment. Polygamy is common i. Birds: male and female help with raising offspring. Monogamy is common b. Internal Fertilization: males aren’t always certain that the female will carry their genes. Therefore, there is little male involvement in the offspring c. External fertilization: fertilization and egg laying happen at the same time. Therefore the male knows his genes were used and cares for the young more d. Mate choice and male composition influence morphology and behavior . Females choose males that look attractive and healthy 4. What is the behaviors of evolutionary history (ultimate) . Altruism: selfless behaviors . Eusocial and alarm behaviors→ prairie dogs 1. Inclusive fitness: you share genes among relatives so are inclined to help each other out 2. Siblings have a coefficient of relatedness of 50% a. Selfish: behaviors that benefit the individual Patasites and behavior -parasites can change the behaviors of host organism to benefit themselves -a horsetail worm causes a grasshopper to drown itself because the worm can breed in water Sexual diphorism -easy to tell between a male and female -Found in polygamous species -Evolution favors dimorphism because females pick those that are healthy, attractive, and can fight Conservation and Climate Change E.O Wilson 1985: Loss of biodiversity will take us millions of years to correct 1.9 million known species Today’s extinction are 1,000 times higher compared to past extinction rates Benefits of Biodiversity -Food -Medicine -Innovation -Ecosystem services Without bats, it would cost the Ag industry $53 billion for pest resistance New York City uses wetlands to filter water. It is the cleanest water Genetic diversity-Within any species there is significant variation in its underlying genetics. It is insufficient to protect only small parts of populations. Richness and Endemsism Richness- number of species Endemism- how unique a species is -Madagascar everything found on Madagascar can only be found here -lots of plant and animal diversity here Coral Reefs, Coastal areas, Mediterranean areas, and tropical areas tend to be high richness and endemism Ecosystem diversity: diversity of species and functions across landscapes Threats to biodiversity 1.Overharsting -Not so much now -passenger pigeons and Carolina parakeets are now extinct due to over hunting 2.Habitat Destruction -few areas left untouched by people 3.Invasive species -non-natives that have been purposefully or accidentally introduced into an area and have a negative impact -Feral hogs destroy plants and vegetation -Black rats carry disease -Cats eat birds -Brown Tree Snake pushed several birds to extinction in Guam 4.Climate Change -rapid rate of change in the climate makes it unlikely that animals and plants will find suitable to live -Pika are in danger because they can’t go anywhere because they’re high in the mountains Keystone species -a species that has disproportional impact on its ecosystem compared to its abundance Umbrella species -species that have large ranges and therefore indirectly protect non-target species Rewilding -Core protected areas and parks -Carnivores predators that maintain diversity and ecosystem function -Corridors link cores together which aids in dispersal and gene flow
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