evolution,species, interactions and biological communities.pps

8/12/2019 EVOLUTION,SPECIES, INTERACTIONS AND BIOLOGICAL COMMUNITIES.pps

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EVOLUTION, SPECIES, INTERACTIONSAND BIOLOGICAL COMMUNITIES


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How does a polar bear endure the long, sunless and supercold artic winter?

Adaptation Acclimation

Darwin theory of evolution by natural selectionis Most organisms produce more offspring than can survive. Better attributes = + chances to survive

Those that survive pass on fit traits to offspring

Mutations(DNA) may give individuals advantages underthe selection pressures of their environment.


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Some giraffes had long

necks, some short

Those with long necks

reached the food, thosewith short starved

Long necks mate and

produce population of

long necked giraffes.

http://www.youtube.com/watch?v=XKnq

j3YFXU8
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Environmental factors Selection pressure

Influence the fitness of individuals and theiroffspring.

Examples: Physiological stress, competition with

other species, predation, luck.

Liebig- proposed that the singleenvironmental factor in shortest supply relativeto demand is the critical determinant in speciesdistribution bamboo

Shelford- added to Liebig's work by proposingthat the single environmental factor closest totolerance limits determines where a particular

organism can live

Environmental Indicators: requirements andtolerance of species determine specific

environmental characteristics and ecosystems

health. Example: Trout speciesSaguaro cactus very sensitive to lowtemperatures


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Tolerance Limits: levels beyond which species cannot survive Several factors determine species distri ution: temperature extremes, Salt

concentration, Competitors, Food availability

Tolerance limits also affect the distributionof young differently than adults Environmental gradient stepwise increase or decrease in an environmental factor


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Habitat - place /environmental conditions in which a particular organism lives. Ecological niche

Role played by a species in a biological community

Set of environmental factors that determine species distribution.

Ecological niche alterations

Species exist within a range of physical and chemical factors as well as biologicalinteractions.

Generalists vs Specialists

Endemic species: specifically found in a certain habitat. Resource partitioning: species coexisting in the same habitat Law of Competitive Exclusion


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What is Taxonomy? Binomials to classify them

Organization of specimens How they have descendent from ancestors

Six kingdoms: animals, plants, fungi, protists, bacteria and

archaebacteria.


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Predation and Competitionantagonistic relationships Competition: shapes a species population and biological community

Intraspecific: members of the same species

Interspecific: members of different species

Mechanisms to reduce intraspecific competition Young of the year can disperse plants

Strong territoriality

Resource partitioning between generations

Predation: feed directly on another living organism, whether or not this kills the prey. Life cycles of predators and species

Specialized food obtaining mechanisms

Evolutionary adjustment behavior and body characteristics (camouflage)

Predator mediated competition cooperation Predators and prey relation affect directly human needs


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Toxic chemicals, body armor, extraordinary

speed, ability to hide strategies to protect

from predators

Chemical defenses: distinct coloration and

patterns

Coevolution: physical an behavioral changescan become mutually beneficial

Batesian Mimicry

Mllerian mimicry

Poison dart native to Central and South America.


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Non-antagonistic interaction and even

beneficial, with their fates linked

Mutualism: enhance survival of one orboth partners, combining tissues to

mutual benefit.

Commensalism: one member clearlybenefits and the other apparently is

neither benefited nor harm.

Parasitism: a form of predation whereparasite depend on the host.


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A species or group of species whoseimpact on a community are much larger

than would be expected from mereabundance.

Change competitive relationships

change in food availability

Maintain the balance of ecosystems

Example: tropical figs/ Groups fungi Keystone species common in aquatic

habitat than terrestrial ones

Keystone species increase niche diversity

Giant Brown Alga

Tropical Figs


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Exponential growth- theunrestricted increase in a populationbut possess a distinctive shaped

when graphed over time.

Logistic growth:with unlimitedresources may, they may growth

exponentially but this slows as carryingcapacity is approached or exceeded


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Species deal with limiting factors in their environment

R-selected species:depend on a high rate of reproductionOvershoot carrying capacity then experience population crushes

Grow exponentially, expend energy in giving birth to progeny, highmortality

Low trophic levels in their ecosystems niche generalists

K-selected species: slower growth conditions near the carryingcapacity

Crucial - ability to compete for limited resources

Grow logistically, expend energy raising progeny

Live in stable biological communities, such as late-successional orclimax forests
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Properties of biological communities andecosystems

Diversity vs abundance Community structure and patchiness

Individuals /species spaced differently

Arranged over a large geographic area or landscape

Meet relatively uniforms interiors and edges

Distribution of members of a population in a given space can be:

Random- individuals live wherever resources are available Uniform - often the result of biological competition Clustered- individuals of a species cluster together for protection,

mutual assistance, reproduction, or to gain access to a particularenvironmental resource


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Communities distributed in patterns across a Landscape Land with patches of different colors and

shapes Each patch - biological community with

its own set of species and environmental

conditions

Largest patches contain core habitat Ecotone: outside habitat cores, species

encounter different habitat or border between

communities

Rich in species - individuals from both

environments occupy the boundary area

edge effects) Environmental conditions blend and the

species and microclimate of one

community cant penetrate the other


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Community properties

Complexity: refers to thenumber of trophic levels in

a community, groups ofspecies performing and to

the number of species at

each of those trophic

levels.


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Community properties Resilience: either resist or recovers quickly for disturbance.

Complexity - less resilient

Community diversity - resilience

Stability:communities resist changes despite disturbance. Three kinds of stability or resiliency in ecosystems:

Constancy - lack of fluctuations in composition or functions

Inertia - resistance to perturbations

Renewal - ability to repair damage after disturbance

Primary productivity - a community's rate of biomass production, or theconversion of solar energy into chemical energy stored in living

Net primary productivity =primary productivity - energy lost (resp.) High productivity: tropical forests, coral reefs, bays, estuaries

(abundant resource supply) Low Productivity: desert and tundra lack of water limits

photosynthesis and productivity is low.


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Climax community: the community that

developed last and lasted the longest

Process as a relay: species replace each

other in predictable groups and in a fixed

regular order.

Climax community determinate by climate

Maturation of an organism

Succession:organisms occupy a site and

change the environmental conditions

Primary succession:land is bare as soil and

then is colonized by living organisms where

none lived before

Secondary succession: a existing community

is disturbed and a new one develops from

the biological legacy of the old.


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Disturbances within communities Disturbance: any force that disrupts the established patterns of species

diversity and abundance, community structure or properties People and animals create disturbances

Extensive changes take centuries to recover

Breaking the grip of a super-competitor helpful role of disturbances

Examples:landslides, mudslides, hailstorms, earthquakes, hurricanes,tornados, tidal waves, wildfires and volcanoes

Landscapes with unstable Climax Characterized by periodic disturbances

Made up of disturbance-adapted species Fires able to suppress competitors, prepare ground for seed to germinate,

split thick seeds coats and release seeds. Disturbances essential for maintaining a ecosystem

Floods help to maintain food-plains and river health

Reset the successional clock in every community

Stability over the long run

evolution,species, interactions and biological communities.pps

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