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Species and Populations Species and Populations

Species and Populations - PowerPoint Presentation

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Uploaded On 2017-11-04

Species and Populations - PPT Presentation

Significant ideas A species interacts with its abiotic and biotic environments and its niche is described by these interactions Populations change and respond to interactions with the environment ID: 602446

species population capacity carrying population species carrying capacity density factors growth curve abiotic populations biotic humans dependent independent limiting

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Slide1

Species and PopulationsSlide2

Significant ideas

A species interacts with its abiotic and biotic environments, and its niche is described by these interactions.

Populations change and respond to interactions with the environment.

Any system has a carrying capacity for a given speciesSlide3

Species

A species is a group of organisms that share common characteristics and that interbreed to produce fertile offspring.

Humans, Giraffes, Pine Trees

Species are given scientific name with genus and then species (in italics)

Humans

 Homo sapiensWolf Canus lupusSlide4

Populations and Habitats

Population: A group of individuals of the same species living in the same area at the same time.

Able to interbreed

Snails in two different ponds may breed with only snails in each respective pond.

Populations can be separated by geography and eventually stop interbreeding

Form a new species this way. Slide5
Slide6

Habitat: The environment where a species normally lives.

Includes Abiotic and Biotic Factors

Examples of habitats?Slide7

Abiotic Vs. Biotic

Abiotic (non-living) Factors

Atmosphere/Sunlight

Climate

Soil structure and chemistry

Water chemistrySeasonalityLevel of PollutantsBiotic (living) Factors

Producers

Consumers

Decomposers

Predation

Parasitism

Mutualism

Disease

CompetitionSlide8

Community

A group of populations living and interacting with each other in a common habitat.

Example: Tropical Rainforest- plants, animals, bacteria, and fungi. Slide9

Ecosystem

A community of interdependent organisms and the abiotic (physical) environment which they inhabit.

As small as a drop of rainwater to as large as an ocean

All ecosystems are affected by humansSlide10

Niche

An

organisms “occupation” or “job”. Its relationship to its food and predators.

D

escribes

the particular set of abiotic and biotic conditions and resources to which an organism or population respondsExample: Small fish in a coral reef share the same habitat, but each species has a different niche. Each population has a different “job” based on its shape, size, color, behavior, and feeding habits. Slide11
Slide12

Population Growth and Changes

Exponential or Geometric Growth: Occurs when no limiting factors slowing growth

Usually produces a J-Curve

Examples?

Bacteria in a petri dish

HumansSlide13

Limiting Factors: Reduce or stop population

growth

Density-Dependent

Density-dependent limiting factors: biotic factors that tend to increase with increasing population size.

Act as negative feedbacks that lead to stability or regulation of a population

Internal factors act within a species: limited food supply, limited territory, limited fertility. External factors act between species: Predation, disease. Would a higher population density affect predator-prey relationships? How? What about spread of disease?

Density-Independent

Density-Independent limiting factors: tend to be abiotic. Not related to population density.

Examples: weather, climate, volcanic eruptions, floods

What would be a density-independent factor for humans?Slide14

Lynx and Snowshoe Hare

Density-dependent limiting factor.

Internal or external? Slide15

Population Curves

J-Curve

S-CurveSlide16

S-Curve realitySlide17

J-Curve RealitySlide18

Population Curves

J-Curve

Boom and Bust pattern

Population grows exponentially at first and then suddenly collapses

Collapses are called “diebacks.” Often the population exceeds carrying capacity before the dieback occurs

Density-independent or dependent?Typical of microbes, invertebrates, fish, and small mammalsS-Curve

Start with exponential growth, however above a certain population size the growth rate slows down gradually until it’s constant.

Growth slows down more in larger populations.

Density independent or dependent?

Typical of large mammals and humansSlide19

Carrying Capacity

Carrying Capacity (K): Maximum population size supported by ecosystem.

Based on the two curves we just looked at, what happens if a population exceeds its carrying capacity?

Do you think humans have or ever will reach carrying capacity? What evidence would support humans reaching carrying capacity? Slide20

K- and r-strategists: Reproductive strategiesSlide21

K and r are two variables that determine the shape of the population growth curve.

r = growth rate of the population

K = carrying capacitySlide22

K-Selected Species

Have small numbers of offspring but invest large amounts of energy in parental care.

Most offspring survive, long lives

Examples?

Humans

Large mammalsGood competitors and population is usually close to carrying capacityCan outcompete r-strategists in good conditions r-Selected Species

Have extremely large numbers of offspring, but invest little or no time raising them.

Reproduce quickly, but short lived

Colonize new habitats rapidly

Usually exceed carrying capacity and populations collapse.

Predominate in unstable ecosystems

Examples?

Invertebrates and fishSlide23

What about us?

…carrying capacity is determined jointly by human choices and natural constraints. Consequently, the question, how many people can the Earth support, does not have a single numerical answer, now or ever. Human choices about the Earth's human carrying capacity are constrained by facts of nature which we understand poorly. So any estimates of human carrying capacity are only conditional on future human choices and natural events."

Joel Cohen Slide24

Survivorship Curves

Shows the fate of a group of individuals of a species.

Type 1-K-strategists

Type 2- r-strategists

Type 3- Rare.

Representsspecies that has equal chance of dying at any age.