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Species Interaction 1 Species Interact in Five Major Ways • Interspecific Competition • Predation • Parasitism • Mutualism • Commensalism 2 Interspecific Competition • Occurs when members of two or more species interact to gain access to the same limited resources such as food, light, or space 3 Predation • Occurs when a member of one species (the predator) feeds directly on all or part of a member of another species (the prey) 4 Parasitism • Occurs when one organism (the parasite) feeds on the body of, or the energy used by another organism (the host), usually by living on or in the host 5 Mutualism • Is an interaction that benefits both species by providing each with food, shelter, or some other resource. 6 Commensalism • Is an interaction that benefits one species but has little, if any, effect on the other. 7 These interaction: • have significant effects on the resource use and population sizes of the species in an ecosystem. • also influence the abilities of the interacting species to survive and reproduce, thus serve as agents of natural selection 8 Competition • The most common interaction • The niches of two species overlap when they are competing for the same resources. 9 Competitive exclusion principle • Two species can’t occupy exactly the same ecological niche for very long. 10 If one species can take over the largest share of one or more key resources, the other competing species must: • Migrate to another area (if possible) • Shift its feeding habits or behavior through natural selection • Suffer a sharp population decline • Become extinct in that area 11 PREDATION 12 Predators • Herbivores • Carnivores • Omnivores 13 Methods to capture preys • Herbivores: just walk, swim, fly • Carnivores: –pursuit, –ambush, –camouflage, –chemical warfare 14 Prey Adaptations • Avoid detection – camouflage, mimics, – diurnal/nocturnal 15 16 17 18 19 Prey Adaptations • Avoid detection – camouflage, mimics, – diurnal/nocturnal • Avoid capture – flee – resist – escape 20 21 22 23 Prey Adaptations • Avoid detection – camouflage, mimics, – diurnal/nocturnal • Avoid capture – Protective shells – Thick bark – Spines and thorns – Chemical warfare 24 25 • At the individual level, members of the predator species benefit and members of the pray species are harmed. • At the population level, predation plays a role in evolution by natural selection. 26 Coevolution • Evolution in which two or more species interact and exert selective pressures on each other that can lead each species to undergo adaptations. • Ex. Predator-prey, parasite-host 27 Symbiosis: Mutualists, Commensalists and Parasites 28 Parasitism • Occurs when one species (the parasite) feeds on the body of, or the energy used by, another organism (the host), usually by living on or in the host. • The parasite benefits and the host is harmed but not immediately killed 29 Parasitism • Parasite usually is smaller than host • Live on • Live in • Little contact 30 Mutualism DEFINITION: An interaction between two individuals of different species that benefits both partners in this interaction 31 Pollination • Animals visit flowers to collect nectar and incidentally carry pollen from one flower to another • Animals get food and the plant get a pollination service 32 Yucca and Yucca Moth • Yucca’s only pollinator is the yucca moth. Hence entirely dependent on it for dispersal. • Yucca moth caterpillar’s only food is yucca seeds. • Yucca moth lives in yucca and receives shelter from plant. 33 Lichen (Fungi-Algae) • Symbiotic relationship of algae and fungae…results in very different growth formas with and without symbiont. • What are the benefits to the fungus? 34 Commensalists • Benefit from the host at almost no cost to the host • Birds nesting in trees • Eyelash mite and humans • Sharks and remora 35 To avoid or reduce Competition • Some species develop adaptations that allow them to reduce or avoid competition with other species for resources. In other words, some species evolve to reduce niche overlap. 36 Resource Partitioning • Process of dividing up resources in an ecosystem so that species with similar needs (overlapping ecological niches) use the same scarce resources at different times, in different ways, or in different places. 37 Population Growth • No population can continue to grow indefinitely because of limitations on resources and because of competition among species for those resources. 38 Populations Have Certain Characteristics • Populations differ in –Distribution –Numbers –Age structure –Density 39 Population dynamics • Is a study of how these characteristics of populations change in response to changes in environment conditions. 40 Changes in population characteristics due to: –Temperature –Presence of disease organisms or harmful chemicals –Resource availability –Arrival or disappearance of competing species 41 Most Populations Live Together in Clumps or Patches • Population distribution –Clumping (Ex. Wolf packs, desert vegetation around springs,…) –Uniform dispersion ( Ex.Creosote bushes in a dessert) –Random dispersion (Ex. Dandelions) 42 Why clumping? – Species tend to cluster where resources are available – Groups have a better chance of finding clumped resources – Protects some animals from predators – Packs allow some to get prey – Temporary groups for mating and caring for young 43 •The living world is mostly clumpy and patchy 44 Populations Can Grow, Shrink, or Remain Stable • Population size governed by – Births – Deaths – Immigration – Emigration • Population change = (births + immigration) – (deaths + emigration) 45 Age structure –Pre-reproductive age –Reproductive age –Post-reproductive age • The size of a population with a fairly even distribution among these three age groups tends to remain stable. 46 No Population Can Grow Indefinitely: J-Curves and S-Curves • Biotic potential: capacity for population growth under ideal conditions. – Low – High • Intrinsic rate of increase (r): is the rate at which the population of a species would grow if it had unlimited resources. • Individuals in populations with high r – Reproduce early in life – Have short generation times – Can reproduce many times 47 – Have many offspring each time they reproduce No Population Can Grow Indefinitely: J-Curves and S-Curves • Size of populations limited by –Light –Water –Space –Nutrients –Exposure to too many competitors, predators or infectious diseases 48 • Environmental resistance: Is the combination of all factors that act to limit the growth of a population. • Carrying capacity (K): The maximum population of a given species that a particular habitat can sustain indefinitely without being degraded. • The growth rate of a population decreases as its size nears the carrying capacity of its environment. 49 Exponential or geometric growth • Exponential growth: starts slowly but then accelerates as the population increases, because the base size of the population is increasing (J-shaped growth curve) 50 Logistic growth • Involves rapid exponential population growth followed by a steady decrease in population growth until the population size levels off. 51 Why logistic growth? • This slowdown occurs as the population encounters environmental resistance from declining resources and other environmental factors and approaches the carrying capacity of its environment. 52 • After leveling off, a population fluctuates slightly above and below the carrying capacity. • The size of such population may also change as the carrying capacity does. • Read page 110 53 When a Population Exceeds Its Habitat’s Carrying Capacity, Its Population Can Crash • Carrying capacity: not fixed • Reproductive time lag may lead to overshoot – Dieback (crash) • Damage may reduce area’s carrying capacity 54 Reproductive Patterns • r-selected species: – Have many, usually small, offspring – Little or no parental care or protection – Massive losses of offspring. – Ex. Algae, bacteria, rodents, frogs,.. – Tend to be opportunists 55 Reproductive Patterns • k- selected species: – Tend to reproduce later in live – Have a small number of offspring with fairly long life spans – For k-selected mammals, the offspring develop inside their mothers, are born fairly large, mature slowly and are cared – They do well in competitive conditions 56 Genetic Diversity and small populations • Several genetic factors can play a role in the loss of genetic diversity and the survival of small, isolated populations. – Founder effect – Demographic bottleneck – Genetic drift – Inbreeding 57 Founder effect • Can occur when a few individuals in a population colonize a new habitat that is geographically isolated from other members of the population. In such a cases, limited genetic diversity may threaten the survival of the colonizing population 58 Demographic bottleneck • It occurs when only a few individuals in a population survive a catastrophe such as a fire. Lack of genetic diversity may limit the ability of these individuals to rebuild the population (increase in the frequency of harmful genetic deseases) 59 Genetic drift • It involves random changes in the gene frequencies in a population that can lead to unequal reproductive success. The founder effect is one cause of genetic drift. 60 Inbreeding • It occurs when individuals in a small population mate with one another. • This can occur when a population passes through a demographic bottleneck 61 Minimum viable population size • Conservation biologists use these concepts to estimate the minimum viable population size or rare and endangered species: the number of individuals such populations need for long-term survival. 62 Density-dependent population controls • Population density is the number of individuals in a population found in a particular area or volume. • Density-dependent population controls – Predation – Parasitism – Infectious disease – Competition for resources (mates, food, sunlight,…) 63 Density independent • Some factors (mostly abiotic) that can kill members of a population are density independent. • Ex. Severe freeze, flood, pollution, fire,… 64 Several Different Types of Population Change Occur in Nature • Stable • Irruptive • Cyclic fluctuations, boom-and-bust cycles – Top-down population regulation – Bottom-up population regulation • Irregular 65 Humans Are Not Exempt from Nature’s Population Controls • Ireland – Potato crop in 1845 • Bubonic plague – Fourteenth century • AIDS – Global epidemic 66 Ecological Processes 67 Ecological Succession Primary and Secondary Succession gradual & fairly predictable change in species composition with time •some species colonize & become more abundant; •other species decline or even disappear. 68 Primary Succession • Involves the gradual establishment of biotic communities in lifeless areas where there is no soil in a terrestrial ecosystem or no bottom sediment in an aquatic ecosystem. 69 Secondary Succession • A series of communities or ecosystems with different species develop in places containing soil or bottom sediment 70 Primary Succession • Bare rock weathers release nutrients for soil formation. • The slow process of soil formation begins when early successional plant species or pioneer arrive and attach themselves to inhospitable patches of rock. Such as lichens, mosses,.. • After hundreds to thousands of years, the soil may be deep and fertile enough to store the moisture and nutrients needed to support the growth of midsuccessional plant species, such as herbs, 71 grasses,.. Primary Succession • Late successional plant species (mostly trees) that can tolerate shade are going to replace the midsuccessional plant species. 72 Secondary Succesion • Candidates for secondary succession include abandoned farmland, burned or cut forests, heavily polluted streams, and land that has been flooded. 73 Succession Doesn’t Follow a Predictable Path • Traditional view – Balance of nature and a climax community • Current view – Ever-changing mosaic of patches of vegetation – Mature late-successional ecosystems • State of continual disturbance and change 74 Living Systems Are Sustained through Constant Change • Inertia, persistence – Ability of a living system to survive moderate disturbances • Resilience – Ability of a living system to be restored through secondary succession after a moderate disturbance • Tipping point 75 Ecological Succession Gradual changing environment in favor of new / different species / communities 76 77 Primary Succession Glacier Retreat 78 79 80 Disturbance Event that disrupts an ecosystem or community; • Natural disturbance •tree falls, fires, hurricanes, tornadoes, droughts, & floods • Human–caused disturbance •deforestation, erosion, overgrazing, plowing, pollution,mining • Disturbance can initiate primary and/or secondary succession 81 Ecological Stability Carrying Capacity – maximum number of individuals the environment can support 82 Ecological Stability - Stress 1. Drop in Primary Productivity 2. Increased Nutrient Losses 3. Decline or extinction of indicator species 4. Increased populations of insect pests or disease organisms 5. Decline in Species diversity 6. Presence of Contaminants 83 Which law directed the Secretary of the Interior to review every roadless area of 5,000 or more acres and every roadless island within National Wildlife Refuge and National Park Systems? A. Endangered Species Act B. Wilderness Act C. Lacey Act D. National Park Act E. Wild and Scenic Rivers Act 84 What are keystone species? A. existing in such small numbers that it is in danger of becoming extinct B. introduced to an environment where it is not native, and that has since become a nuisance C. likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range D. serve as early warnings of damage to a community E. presence and role within an ecosystem has a disproportionate effect on other organisms within the system 85 Who did Roosevelt appoint to head the newly created US Forest Service to protect and manage the world’s forests? A. E.O. Wilson B. Aldo Leopold C. Robert MacArthur D. Stephen Mather E. Gifford Pinchot 86 Mutualism benefits: A) one of the organisms & hurts the other B) neither of the organisms C) both of the organisms D) benefits one & doesn’t hurt the other E) only one of the organisms 87 Commensalism: A) benefits only one of the organisms B) benefits both organisms C) benefits one, doesn’t harm the other D) benefits neither of the organisms 88 Biodiversity: A) decreases with speciation and extinction B) decreases with speciation and increases with extinction C) increases with speciation and extinction D) increases with speciation and decreases with extinction 89 What is not a pre-zygotic barriers? A) behavioral isolation B) habitat isolation C) mechanical isolation D) hybrid isolation 90 Which of the following does species richness not depend on? A) rate of immigration B) island size C) distance from mainland D) types of species 91 Which is a species on which the persistence of a large number of other species in the ecosystem depends? A) r-strategists B) k-strategists C) nonnative D) keystone 92 What is not characteristic of a k-strategists? A) long life B) bigger bodies C) produce a lot of offspring D) produce late in life 93 What is not a predator adaptation? A) prey detection B) prey capture C) eating prey D) avoid detection E) mass numbers 94 Bibliography 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. Miller 11th Edition http://abandoncorporel.ca/medias/evolution.jpg http://www.ne.jp/asahi/clinic/yfc/fetus.html rob.ossifrage.net/images/ http://www.mun.ca/biology/scarr/Five_Kingdoms_Three_Domains.htm http://www.gpc.peachnet.edu/~ccarter/Millerlec5/Millerlec5.PPT http://www.dnr.state.md.us/education/horseshoecrab/lifecycle.html http://www.falcons.co.uk/mefrg/Falco/13/Species.htm http://www.sms.si.edu/irlspec/NamSpecies.htm http://www.falcons.co.uk/mefrg/Falco/13/Species.htm http://www.globalchange.umich.edu/globalchange1/current/lectures/complex_life/complex_life.html http://nsm1.nsm.iup.edu/rwinstea/oparin.shtm http://www.angelfire.com/on2/daviddarling/MillerUreyexp.htm http://exobiology.nasa.gov/ssx/biomod/origin_of_life_slideshow/origin_of_life_slideshow.html http://www.geo.cornell.edu/geology/classes/Geo104/HistoryofEarth.html http://astrobiology.arc.nasa.gov/roadmap/objectives/o2_cellular_components.html http://pubs.usgs.gov/gip/fossils/ http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/halfli.html http://www.accessexcellence.org/AE/AEPC/WWC/1995/teach_rad.html http://biology.usgs.gov/s+t/SNT/noframe/pi179.htm http://www.npca.org/magazine/2001/march_april/nonnative_species.asp http://www.bagheera.com/inthewild/spot_spkey.htm Biology, 2003, Prentice Hall http://www.nearctica.com/ecology/habitats/island.htm http://www.valdosta.edu/~grissino/geog4900/lect_1.htm 95