14.1 Habitat And Niche

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1 14.1 Habitat And Niche A habitat differs from a niche. Habitat physical area in which an organism lives Niche each species plays a specific role in an ecosystem niche includes the species habitat, feeding habits, behaviors etc.

2 14.2 Community Interactions KEY CONCEPT Organisms interact as individuals and as populations.

3 14.2 Community Interactions Competition and predation are two important ways in which organisms interact. Competition occurs when two organisms fight for the same limited resource. Intraspecific competition: within the same species Interspecific competition: between two different species

4 14.2 Community Interactions Predation occurs when one organism feeds on another. as population of prey rises, there will be a corresponding rise in predator population and vice versa prey and predator species coevolve

5 14.2 Community Interactions Symbiosis is a biological relationship where organisms of 2 different species live in a close association Three types of symbiotic relationship: 1) Mutualism - both organisms benefit from living together - ex. bacteria in digestive tract of cattle bacteria benefit by having food and a home cattle benefits by being able to digest grass

6 14.2 Community Interactions 2) Parasitism - one organism benefits, the other organism is harmed ex. 1: ticks (parasite) living on other animals (host) leech hookworm

7 14.2 Community Interactions 2) Parasitism - one organism benefits, the other organism is harmed ex. 2: wasp larvae (parasites) feed on caterpillar (host) _ Hornworm caterpillar The host hornworm will eventually die as its organs are consumed by wasp larvae. Parasitism 0 + Braconid wasp Braconid larvae feed on their host and release themselves shortly before reaching the pupae stage of development. _ Organism is harmed 0 Organism benefits

8 14.2 Community Interactions 3) Commensalism - one organism benefits, the other organism is neither harmed nor benefits ex. 1: epiphytes (smaller plants living on larger plants) Spanish moss hangs on tree but does not harm the tree.

9 14.2 Community Interactions 3) Commensalism - one organism benefits, the other organism is neither harmed nor benefits ex. 2: mites living in human eyelashes Ø Human Our eyelashes are home to tiny mites that feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle. Commensalism + Demodicids Eyelash mites find all they need to survive in the tiny follicles of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope. Ø Organism is not affected + Organism benefits

10 14.3 Population Density And Distribution Population density is the number of individuals that live in a defined area.

11 14.3 Population Density And Distribution Geographic dispersion of a population shows how individuals in a population are spaced. Population dispersion refers to how a population is spread in an area. Clumped dispersion Uniform dispersion Random dispersion

12 14.3 Population Density And Distribution There are three types of dispersion. clumped

13 14.3 Population Density And Distribution There are three types of dispersion. Uniform -- territoriality

14 14.3 Population Density And Distribution There are three types of dispersion. random

15 14.3 Population Density And Distribution Survivorship curves help to describe the reproductive strategy of a species. A survivorship curve is a diagram showing the number of surviving members over time from a measured set of births.

16 14.3 Population Density And Distribution Survivorship curves can be type I, II or III. Type I low level of infant mortality and an older population common to large mammals and humans Type II survivorship rate is equal at all stages of life common to birds and reptiles Type III very high birth rate, very high infant mortality common to invertebrates and plants

17 14.4 Population and Growth Patterns KEY CONCEPT Populations grow in predictable patterns.

18 14.4 Population and Growth Patterns Four factors affect the size of a population. immigration births emigration deaths

19 14.4 Population and Growth Patterns Exponential Growth vs. Logistic Growth Exponential growth is a rapid population increase due to an abundance of resources. Shown as a J-shaped curve

20 14.4 Population and Growth Patterns Exponential Growth vs. Logistic Growth Exponential growth is a rapid population increase due to an abundance of resources. Exponential Growth Phase = period of rapid growth when population repeatedly increases in size; does not continue forever Lag Phase = initial period of slow growth

21 14.4 Population and Growth Patterns Logistic growth is due to a population facing limited resources. Shown as a S-shaped curve

22 14.4 Population and Growth Patterns Carrying capacity is the maximum number of individuals in a population that the environment can support. 4) Leveling Off 3) Reaching Carrying Capacity 2) Exponential Growth Phase 1) Lag Phase

23 14.4 Population and Growth Patterns Life History Patterns 1) R Strategists short life span small body size reproduce quickly have many young little parental care Ex: cockroaches, weeds, bacteria

24 14.4 Population and Growth Patterns Life History Patterns 2) K Strategists long life span large body size reproduce slowly have few young provides parental care Ex: humans, elephants

25 14.4 Population and Growth Patterns Human Population Growth humans are in the exponential phase of growth Projections for the future estimate 8.9 billion people by Billion: How Did We Get So Big So Fast? Overpopulation:

26 14.4 Population and Growth Patterns Ecological factors limit population growth. A limiting factor is something that keeps the size of a population down. 1) Density-dependent limiting factors - affected by the number of individuals in a given area - ex: predation, competition, parasitism and disease (how wolves change rivers)

27 14.4 Population and Growth Patterns 2) Density-independent limiting factors - limit a population s growth regardless of the density. ex: unusual weather, natural disasters, human activities

28 14.5 Ecological Succession Succession is the gradual, sequential replacement of plant communities in an area over time Two types of succession: 1) Primary succession 2) Secondary succession

29 14.5 Ecological Succession Primary Succession occurs where life has never existed before ex: on fresh lava flow

30 14.5 Ecological Succession Primary Succession 1) begins with the pioneer community - the pioneer species are the first to colonize a habitat and change the environment so that it becomes more suitable for other species to live ex. bare rock being broken down by lichens and mosses beginning of soil formation

31 14.5 Ecological Succession Primary Succession 2) seral communities (intermediate communities) gradually replace pioneer communities ex: grasses replacing lichens and mosses shrubs replacing grasses

32 14.5 Ecological Succession Primary Succession 3) climax community gradually replaces the seral communities - the final stage of succession (most stable) - the community that will stay stable as long as the area is not disturbed ex: tropical rainforest, temperate forest

33 14.5 Ecological Succession Secondary Succession occurs when some type of disturbance causes a disruption of the pattern of an ecosystem (fire, timber harvesting, wind, grazing and browsing)

34 14.5 Ecological Succession Secondary Succession damaged communities can be regenerated because the soil still remains pioneer species reappear, then followed by the intermediate communities, and eventually returns to the climax community