Unit 6 Populations Dynamics

Transcription

1 Unit 6 Populations Dynamics

2 Define these 26 terms: Commensalism Habitat Herbivory Mutualism Niche Parasitism Predator Prey Resource Partitioning Symbiosis Age structure Population density Population distribution Population size Sex ratio Carrying capacity Emigration Immigration Migration Age structure diagram Population Biotic potential Density dependent factor Survivorship curve Invasive species Succession

3 Population Dynamics Species Interactions Unit 6A Chp. 5.2

4 REVIEW Ecosystems: Everything is Connected What is an ecosystem? An ecosystem includes all the different organisms living in a certain area, along with their physical environment

5 Two parts of an ecosystem: Biotic Factors: The living parts of an ecosystem which interact with each other and the nonliving parts Abiotic Factors: The nonliving parts of the ecosystem

6 Hierarchy Biosphere Ecosystem Community Population Species Organism

7 Niche v.s. Habitat Niche: all of the organism s relationships with its environment (both living and nonliving), a way of life Examples: what it eats, what its parasites are, rotting when it dies, when & how it reproduces, biorhythms,

8 Habitat: The actual place an organism lives Examples: rain forest, freshwater pond, coral reef,

9 Tolerance & Competition Tolerance ability to survive and reproduce under changing environmental conditions Specialists very restricted tolerance ranges Competition when multiple organisms seek the same limited resources

10 Competitive Exclusion When a competitor species is very effective and excludes another species from the resource use entirely. Example: the invasive species zebra mussels outcompeted 20 native mussels in Lake St. Clair by 1997.

11 Resource Partitioning When competing species partition or divide the resource they use in common by specializing in different ways Ex. birds specialize by particular types of insects & parts of the tree ; can lead to evolution - Galapagos Is.

12 SYMBIOSIS A long-term and physically close relationship between two organisms from different species in which at least one organism benefits.

13 Ways species interact with each other: Predation Competition Parasitism Mutualism Commensalism

14 Predation 1. Predation one organism kills and eats another organism 2. Prey the organism that is eaten 3. Predator the organism that does the eating 4. Example: lynx and hare

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16 Competition: A relationship between species in which they attempt to use the same limited resource Can be direct or indirect

17 Parasitism 1. Parasite organisms that live in or on another organism and feed on it without immediately killing it 2. Host the organism the parasite takes its nourishment from 3. Parasitism the relationship between parasite & its host

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19 Mutualism A cooperative partnership between two species Both benefit Examples? Barn cat and farmer Sea Anemone and Anemonefish

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21 Commensalism A relationship in which one species benefits and the other is neither harmed nor helped Example? Bromeliad and tree Shark and ramoras

22 Herbivory The interaction when an animal feeds on a plant Most common type: insects In most cases, herbivory does not kill a plant directly but it may affect its growth and reproduction Plant defenses: toxic chemicals, thorns, spines, irritating hairs, hormones that stimulate growth

23 Unit 6A (5.2) Review 1. Explain how competition can affect an organism s niche. 2. How are predation, parasitism, & herbivory similar? Different? 3. Human digestive tract is filled with bacteria that get nutrients by helping digest food. Is this symbiotic? Mutualism or commensalism? Explain. When finished with this small group work, quietly work on your vocabulary

24 Population Dynamics Unit 6B Describing Populations Chp. 4.2

25 Population Size The # of individual organisms present in a given population at a given time May increase, decrease, undergo cyclical change or remain the same over time (healthy pop.) If a population declines rapidly, it can mean extinction is coming (ex. Passenger pigeon)

26 Determining Population Size In almost all cases, population size is estimated using sampling techniques. Ecologists count the # in a smaller sample area, then estimate the # in the larger overall area Sometimes it is easier to find signs of organisms instead of the organisms themselves

27 Population Density # of individuals within a population per unit area Higher population densities make it easier to find mates or group together, however crowding leads to parasites and competition

28 Population Distribution Describes how organisms are arranged within an area Random distribution individuals arranged in no particular pattern Uniform distribution organisms are spread evenly in an area Clumped distribution individuals arrange themselves based on availability of resources

29 Age Structure & Sex Ratios # of organisms of each age within a population Age structure diagrams tools scientists use to show the age structure of populations Sex ratio proportion of males to females

30 4.2 Review How is a population s size related to its well-being? Which population of flamingos is more dense: 15 flamingos in a 5-square-meter area, or 40 flamingos in a 10-squaremeter area? Describe the 3 patterns of population distribution. Which of these is the most common distribution in nature? 4.2 review packet

31 Population Dynamics Unit 6C Population Growth Chp. 4.3

32 Factors that determine Population Growth Births, deaths, immigration, emigration Natality rate of birth Mortality rate of death Survivorship curve shows how likelihood of death varies with age, Types I, II, & III

33 Type I individuals are most likely to die when they are old Type II mortality remains constant throughout an individual s lifetime Type III mortality is highest for young members of the population

34 Migration Seasonal movement into or out of an area Immigration arrival of individuals from outside a given area Emigration departure of individuals from a given area Births & immigrations add individuals to a population; deaths & emigrations subtract

35 (6/1000) x 100% = x 100% = 0.6% Calculating Population Growth individuals added individuals subtracted Tells us net change in population size Ex. annual birthrate = 18/1000, annual death rate = 10/1000, annual immigration rate = 5/1000, annual emigration rate = 7/1000. Calculate annual growth rate (18 + 5) (10 + 7) = 6 Usually expressed as a percent

36 How Populations Grow Exponential Growth when a population increases by a fixed % each year, J curve Logistic Growth describes how a population s exponential growth is slowed and finally stopped by limiting factors which determine its ultimate carrying capacity In nature, usually populations fluctuate or rise & crash

37 Limiting Factors Density-dependent factors high population density increase competition for resources; ex. predation, disease, food & water Density-independent factors limiting factors whose influence is not affected by pop. density; ex. floods, fires, landslides, climate change

38 Biotic Potential The maximum ability of an organism to produce offspring in ideal conditions Influenced by gestation time (embryo to birth) and generation time (birth to sexual maturity), as well as # of offspring born at a time

39 4.3 Review A population has a birthrate of 10/1000, a death rate of 9/1000, an immigration rate of 3/1000, and an emigration rate of 7/1000. What is its growth rate? Is the population getting larger or smaller? What is the difference between exponential growth & logistic growth? Which is more common over long terms in nature? In your own words, define limiting factor and biotic potential. 4.3 review packet

40 Population Dynamics Unit 6D Community Stability Chp. 5.4

41 Ecological Succession Somewhat predictable series of changes over time experienced by a community Primary succession when a disturbance is so severe, no vegetation or soil life remains Secondary succession begins when a disturbance dramatically alters an existing community but does not destroy all living things

42 Pioneer species colonize newly exposed land first in primary succession; ex. lichen take firm hold on rock, capture moisture, release acids, soil begins to form Climax community a stable community that completes the succession process; ex. beech-maple forests, old growth forests

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44 Invasive Species Non-native organisms that spread widely in a community because they lack limiting factors Not all exotic species become invasive as some stay small & localized Not all invasive species are bad, ex. European honeybee Bad ex s zebra mussels, cane toad, kudzu vine

45 5.4 Review Explain how disturbances can throw a community out of a balanced state and into a period of adjustment. List examples of primary & secondary succession and describe the stages; identify the factors that determine the type of succession that will occur. Identify a pioneer species & list several examples in different ecosystems. Describe the how, when, where of climax communities. List examples of invasive species in Florida.