Unit 2. Ecology and Behavior

Transcription

1 Unit 2 Ecology and Behavior

2 Population Demographics Population density relates to the number of individuals per a certain area Population distribution indicates where the individuals are positioned in a certain area A clumped distribution pattern is one where individuals are in a small area Ex. Surrounding water supply A uniform distribution pattern is one where the individuals are more evenly spaced A random distribution pattern is one where the individuals have no uniformity to their placement

3 Elusive Heads to Count Quadrats are plots of land of a standard size used for counting the number of organisms The capture-recapture method is used to estimate the size of a population of animals The sample size must be large enough to gather significant information The animals captured must have no bias, such as being easier or more difficult to catch

4 Population Size and Exponential Growth Members of a population may leave ( ) or enter a population ( ) When zero population growth occurs, it means that the number of individuals born equals the number dying The per capita growth rate equals the birth rate minus the death rate If the per capita growth rate is more than zero, the population is exhibiting exponential growth What type of graph would be exhibited? The term biotic potential indicated the largest amount of increase that can occur in that particular population

5 Limits on Population Growth The carrying capacity is the largest number in individuals that a certain environment can support What type is exhibited when carrying capacity is met Limiting factors are those that are not plentiful and may restrict population growth. Density-dependent factors are those that become more critical as the population increases Examples? Density-independent factors are those that are not influenced by the size of the population Examples?

6 Life History Patterns Life tables illustrate the number of individuals that survive in various age categories A survivorship curve is a visual representation of the age-specific survival of a population Three types of curves

7 Survivorship Curves A type I curve is shows that the individuals usually survive until old age Animals exhibiting a type I curve produce a small amount of offspring that require much care, ex. Humans These animals exhibit K-selection, few offspring needing much care A type II curve illustrates that the survival rate does not relate to age, ex. Squirrels A type III curve shows that the majority of the individuals do not survive to maturity Animals exhibiting a type III curve produce many offspring that do not require much care, ex. Sea urchins These animals exhibit r-selection with many offspring needing little care

8 Natural Selection and Life Histories Life history traits can change as a response to an alteration in the types of predators An example of this was shown by two isolated populations of guppies where there were different predators The life history of the cod population in the North Atlantic changed due to over-fishing

9 Human Population Growth The human population s current rate of increase is approximately 1.1% This rate of growth is due to the fact that humans can spread easily into new habitat Man developed fire and tools Humans have developed new technologies to increase the carrying capacity of the environment Cultivation of crops, livestock production The human population has learned how to overcome some limiting factors Man learned how to combat many diseases and use fossil fuels for energy production Density-dependent factors may become of the utmost importance due to overpopulation

10 Fertility Rates and Age Structure The average number of children born to each woman of reproductive age is the total fertility rate The fertility rate worldwide has decreased from 6.5 to 2.7 in the last 50 years This decrease still puts the worldwide fertility rate above the number that keeps the population at a constant level 1/3 of the world s population is not yet in the reproductive category China has initiated a system of rewards to encourage a lower national fertility rate

11 Population Growth and Economic Factors The demographic transition model connects industrial development and changes in population growth rates In countries where industrialization has not yet occurred, the birth rate is high Children are needed to perform duties on farms, ex. many African countries In industrialized nations, the birth rate declines, ex. United States Industrialized nations use a larger % of resources of the world In post-industrialized nations, the population size may decrease

12 Rise of the Seniors The amount of individuals over age 65 is increasing Fertility rate is declining Individuals are living longer due to medical advances Society may have trouble support this increase in retired individuals

13 Chapter 46 Behavior

14 Behavioral Genetics Animals react to different stimuli which are genetic in nature Fruit flies show an identified genetic marker to indicate if they are rovers or sitters Hormone production, which is genetic, influences animal behavior Studies were performed on voles relating to oxytocin levels and the animal s preference for monogamy Additional studies indicated a link between ADH and promiscuity in voles Mutations can cause changes in behavior A mutation in fruit flies results in an inability to perform normal courtship activities In mice a mutation relating to oxytocin receptors results in subnormal maternal behavior

15 Instinct and Learning Animals are born with some instinctive behaviors Ex. Cuckoo birds discard other eggs in the foster parent s nest Some animal behaviors are learned Imprinting is when a particular behavior is learned during a certain time period Ex. Baby geese following any maternal type figure when exposed at an early age There appears to be a window of opportunity for birds to learn a species-specific song

16 Instinct and Learning Animals can learn throughout life based on a positive or negative reward system Classical conditioning can be defined as an animal connecting two stimuli together when presented at the same time Ex. Pavlov s dogs Operant conditioning occurs when an animal changes his behavior based on a positive-negate reward system Habituation is when an animal learns a behavior even though it has not been exposed to a reward system Lobsters learn to recognize another lobster that they have battled Observational learning occurs when an animal learns to mimic an activity performed b y another animal

17 Adaptive Behavior Organisms can adapt behavior that benefits the individual s reproduction A study showed that birds include wild carrot into their nest construction materials to deter mite infestation

18 Communication Signals Animals use various means of communication to relay information to another of their species Pheromones are chemical signals and often active in mate selection Animals emit auditory signals to signal prospective mates or to warn others of danger A tactile display involves one individual transmitting a message by touching another The bees waggle dance relates the distance and location of a food source to other bees Other examples?

19 Mates, Offspring, and Reproductive Success Individuals often compete in various ways for mating privileges known as sexual selection Male hangflies must bring large gifts of food to win over females Females observe the male fiddler crabs waving their large claws Male birds put on a colorful display to impress females Many species involve parental care duties Many birds and some mammals are cared for by both parents Young reptiles, with the exception of crocodiles, do not require parental care

20 Living in Groups Often groups of animals deter predators Examples include sawfish caterpillars and other animals such as prairie dogs who give out warning calls A selfish herd is when the members of a group of animals tend to hide behind one another Animals in groups may have advantageous feeding opportunities Group hunting may not actually provide more food, but may be better for protection Animals in groups may learn behaviors from each other like utilization of tools in primates

21 Living in Groups Some animals establish hierarchies in their group structure Wolves develop packs an only the dominant members can mate In some circumstances, living in groups is disadvantageous Groups may attract predators and spread disease more readily

22 Why Sacrifice Yourself? Eusocial animals have developed a system where there are only a few breeding individuals Insects that have this system are ants, termites, and bees Other insects have auxiliary functions to support the queen African mole-rats are the only mammals with this organizational structure Workers in a eusocial society show altruistic behavior, which means working towards the good of the group The theory of inclusive fitness explains that this behavior helps to promote reproductive success of relatives Since relatives share the same gene pool, this behavior helps promote reproductive success of their own genes

23 Human Behavior Like many other animals, humans are affected by hormones and pheromones It is felt that a lack of the hormone oxytocin may result in a defective bonding pattern Pheromones may be active in regulating the menstrual cycles of women living in close proximity Humans can perform infanticide under extreme conditions even though it is a practice considered to be amoral behavior

24 Chapter 47 Community Structure and Biodiversity

25 What Factors Shape Community Structure? Where a species resides it its habitat whereas a niche is its role in the community Factors influencing the niche of a plant would be soil, water, light, etc. There are many types of relationships that exist between species Commensalism Mutualism Predation/Parasitism

26 Mutualism Mutualistic relationships are common in the environment Insects serve as pollinators, while plants provide nectar for the insect Legumes change nitrogen into a usable form and the plants provide nutrition In a lichen, the fungi serves to soak up water while the plant again provides nutrition The anemone fish protects the anemone and the anemone provide defense for the fish in the form of nematocysts Perhaps mitochondria were bacteria that sought protection in cells while providing energy to the cell

27 Competitive Interactions Competition between two species may result in evolution by natural selection When two species of paramecium were in the same environment, one thrived and one died When two species of salamanders were together in the same area, both populations decreased due to competition Species may be able to survive together if they partition the resources In a study of finches in the Galapagos Islands, one species of finch developed a smaller beak so that they could utilize a different sized seed as a food source

28 Predator-Prey Relationships The number of prey can influence the quantity and types of predators In a type 1 response, a fairly constant # of prey are killed Ex. Spiders and filter feeders In a type 2 response, the # of prey killed depends on the skill level of the predator Initially, there are many more kills, but eventually it slows down since predators can only eat so much Ex. Larger animals such as tigers, and wolves

29 Predator-Prey Relationships In a type 3 response, the # of prey killed increase at a slow rate, then quickly and finally levels off This could be due to the predator switching to a different type of prey The predator could be learning more effective ways of hunting prey The rapid rise in kills could involve the prey running out of hiding places

30 An Evolutionary Arms Race Prey develop various defenses for survival Some have a natural camouflage to hide from predators Some have warning coloration to alert a predator to a bad taste or possible sting Some illustrate mimicry where an organism appears like another organism that is dangerous or distasteful Predators develop various adaptations Some develop better hunting methods Some utilize camouflage to ambush prey

31 Parasite-Host Interactions A parasitic lifestyle benefits the parasite and usually harms the host Parasites may weaken the host or cause sterility A successful parasite should not destroy the host. WHY? Often parasites utilize a vector to deliver the parasite to a suitable host organism Vectors include insects and other arthropods A parasitoid is a parasite that lays eggs in an insects body and destroys it Parasites can be used as biological controls in an attempt to eliminate an undesirable organism

32 Strangers in the Nest Social parasites are those that take advantage of another animal s behavior Ex. The cowbird lays its eggs in another bird s nest so that the other bird serves as a foster parent

33 Ecological Succession Primary Succession area lacking soil Lichens and mosses settle first because they can inhabit an area with little or no soil Soil is developed from plant litter and other organic wastes Secondary succession relates to an area that is recovering from a natural disaster where soil is still present The factors that determine the species populations during succession are soil composition, climate and often chance events The intermediate disturbance hypothesis state that the # of species inhabiting an area is highest when the disturbances are lest drastic

34 Species Interactions and Community Instability A keystone species is one that has an overwhelming effect on the environment Ex. Periwinkle snails and beavers Due to jump dispersal, an organism may be moved far from its native habitat

35 Exotic Invaders Some exotic imported species may upset the natural balance in the new environment A common algae present in fish tanks can dominate natural waterways The kudzu plant from Japan is extremely fast growing and hard to control in the US Why? Hearty gray squirrels introduced into Europe out survive the native red squirrels Why? Give some examples of invaders here

36 Biogeographic Patterns in Community Structure Biogeography studies the natural location of species The greatest # of species settle close to the equator Due to the amount of rainfall, temp, and the fact that tropical environments are well-established communities Newly formed islands are an excellent habitat for studying speciation The equilibrium model of island biography attempts to predict the amount of speciation on the island The amount of speciation can be estimated by the land area of the island and its distance from the mainland

37 Chapter 48 Ecosystems

38 The Nature of Ecosystems An ecosystem is the sum of the organisms residing there and Primary producer is the plant that serves at an by harnessing the sun s energy Consumer is the that derives energy from consuming the plant or other animals A is an animal that consumes debris and small bits of organic matter A feed on organic wastes Mineral levels will increase or decrease due to feeding activities The organisms of an ecosystem develop trophic levels A food chain represents the passage of energy from 1 trophic level to the next

39 The Nature of Food Webs A food web is a complex interaction among many species of the ecosystem In a grazing food chain, the energy goes from producers to consumers In a detrital food chain, the energy goes from producers to detritivores to decomposers An alteration in one species of a food web may affect many different organisms

40 Energy Flow through Ecosystems Primary production is the rate at which plants harness the sun s energy This depends upon the availability of water and nutrients Primary production is higher on land than in water Explain

41 Energy Flow through Ecosystems A biomass pyramid is used as a tool to represent the dry weight of the organisms at each trophic level The producers make up the base of the pyramid Consumers make up the upper portion of the pyramid with the largest carnivores at the very top An energy pyramid helps to show how energy is lost when transferred to each trophic level The energy transfer in watery ecosystems is usually more efficient than those on land

42 Biological Magnification The effects of dangerous chemicals can become intensified as they move up the food chain An insecticide called resulted in the deaths of birds and other animals The book Silent Spring by Rachel Carson, brought this to the public s attention Mercury from various industries enters the water supply and becomes intensified in fish

43 Biogeochemical Cycles In biogeochemical cycles, nutrients move through environmental stores and living organisms The elements enter the living portion of the cycle by becoming incorporated into plants Examples include?

44 The Water Cycle The water cycle begins when water evaporates from bodies of water and transpiration occurs in plants Water then condenses to form clouds causing it to rain Water collects in watersheds, aquifers, and in groundwater Most individuals get water supply from groundwater Groundwater can be easily polluted and difficult to correct Can the ocean become a future water supply?

45 Carbon Cycle Most carbon is contained in the Earth s crust The carbon in the ocean is originally formed from the shells of small organisms The crust lifts up eventually and becomes part of the land mass Diffusion takes place between the carbon in the atmosphere and that in the ocean There is a loop-like current which delivers CO 2 to the ocean reservoir Carbon changes form between CO 2 and bicarbonate How do humans adversely affect the carbon cycle?

46 Greenhouse Gases and Climate Change The main gases that contribute to the greenhouse effect are: CO 2, H 2 O, N 2 O, CH 4, and CFC s The sun s heat is absorbed by the earth s surface Some of the heat is reflected back into the atmosphere, but atmospheric gases send some heat back to earth

47 Greenhouse Gases and Climate Change The greenhouse effect is a natural necessary phenomenon to maintain reasonable temperature on earth The increase in greenhouse gases is creating abnormal global warming Global warming is causing a warmer ocean temperature which results in melting glaciers and more severe storms

48 Nitrogen Cycle Nitrogen exists in the atmosphere as N 2 which is not in a usable form for plants Some natural processes such as lightning and volcanoes can convert the nitrogen to a usable form The bacterial Rhizobium that exists in nodules on legumes also converts the nitrogen to a usable form in a process called Nitrogen changes from N 2 to NH 3 which then converts to NH 4+ and NO 3-, which are able to be used by plants

49 Nitrogen Cycle Manmade interference helps to denitrify the ecosystem The leaching of water through soil and the absence of crop rotation help to deplete the soil of nitrogen When fertilizers run off into water sources, it causes algae blooms which are disadvantageous to animal species

50 Phosphorus Cycle Phosphorous cycles between land and the ocean Phosphates are necessary for major cellular components like nucleic acids, plasma membranes and ATP Plants get phosphorous from the water and soil and animals get it from consuming plants and other animals Phosphorus levels are quite often a limiting factor for plant growth A lack of phosphorus in the soil can be due to the absence of crop rotation

51 Phosphorus Cycle An excess of phosphorus can result from water that runs off from fertilized fields Excessive amounts of phosphorus in a watery environment can cause eutrophication An algae bloom occurs that harms other plant and animal species Eutrophication is dis difficult to reverse