AP Environmental Science



AP Environmental Science Name: _______________________

NDHS Per: ________ Date: ____________

Ch 4: Ecosystems and Living Organisms

Changes in Living Systems –

- – changes in frequencies of genes in a population over time

- how often a certain gene is expressed in the population

NOT: Change of an individual

Driving Force of Evolution = Natural Selection (Survival of the Fittest)

Relationship to Environmental Science: The environment establishes the abiotic factors that living organisms must cope with in order to survive. Those organisms best suited to that environment will live to reproduce.

Principles of Natural Selection

1_________________________: produce more, some will survive

2___________________: Since most species are diploid and reproduce through sexual recombination, the offspring will be a mixture of genetic content of the parents

- benefit of variation in offspring: slight changes may make the crucial difference in allowing one organism to survive over another

Ex: Disease – if all the individuals of a population are genetically identical, then a single type of disease could make them all die – slight variations in the immune system could play an important role in developing a defense and while immune systems in humans are unique (even in identical twins), greater variation will provide greater probability that some organisms will survive.

3. : food, water, shelter, nutrients, light – results in – those that are better at obtaining the resources and defend them (fittest) are going to have the opportunity to survive

- “Survive” – have genetically viable offspring

4. : those that have more genetically viable offspring are more successful – their genes have passed on – the more an individual’s genes are in the population the more likely they will be passed on to the next generation

Result of Natural Selection:

1. ________________________________________

Thus those genes which give the individual a better chance at living to the age where it can reproduce will be passed to the next generation. Thus the traits of the resulting population will be “selected” by the conditions in which they exist. In the end, the population will be adapted for that environment.

2. With enough change, a population can diverge into different species and given enough time (theoretically) into completely different forms.

= group of populations whose members have the with one another in nature to , , but who cannot produce viable, fertile offspring with members of others species

Population Interaction and Change:

Changes in Communities Over Time:

- the sequence of .

begins in a area where ___ has not yet______________

EX: volcanic island or the moraine left behind as a glacier retreats.

STEPS: 1.

2.

3.

occurs where an existing community has been such as a or _______ , while the .

STEPS:

1.

2.

3.

Interspecific Interactions and Community Structure:

Methods of Interaction:

- symbolized by the effects of the interaction on the individual populations or as which means through _______________

A. ______________: competition for ___________ is usually harmful ______________________ because even the winner must expend _______ and may lead to the _________ of another species

- causes the _________________________, which states that two species with similar needs for the same limiting resources cannot coexist in the same place

- therefore each species occupies its own unique place in the environment called its _________ – includes both abiotic and biotic components

_______________________

– potential space the organism can occupy

_______________________

- actual space occupied

- if the niches of two species vary even slightly, they can coexist in the same community by

EX: different types of warblers (birds) will live in different sections of trees and therefore not have to compete with one another for habitat

- the whole tree is a fundamental niche for the birds but the actual layer they inhabit is the realized niche

■ B. ________________: Predator/Prey

Predator Adaptations: sight, smell, strength, teeth/beak shape, claw shape, poisons, camouflage (ambush)

▪ Mimicry: predator simulate the prey of their prey

o Prey Adaptations:

o Behavioral defenses include fleeing, hiding, and self-defense.

Alarm Calls:__________________

▪ Mobbing: ____________________

▪ Injury Feigning Displays

▪ Mechanical defense:

▪ Chemical defense:

- often show

▪ Adaptive coloration

▪ Mimicry:

__________________: a harmless, palatable species mimics a harmful, unpalatable model.

__________________: two or more unpalatable species resemble each other.

■ C. herbivore eats parts of a plant or alga.

Herbivores adaptations.

- herbivorous insects have chemical sensors on their feet to recognize appropriate food plants.

- Mammalian herbivores have specialized dentition and digestive systems to process vegetation.

Plant Defenses:

chemical toxins: caffeine, nicotine, alkaloids, poison ivy

spines, thorns and prickles

D.______________: parasite derives its nourishment from a host, which is harmed in the process.

Endoparasites live within the body of the host Botfly

Ectoparasites live and feed on the external surface of the host.

Parasitoidism is a special type of parasitism in which an insect (usually a wasp) lays eggs on or in living hosts.

E. ________________: Pathogens are disease-causing agents that have deleterious effects on their hosts (+/−)

■ Pathogens are typically bacteria, viruses, or protists.

■ Fungi and prions can also be pathogenic.

■ Parasites are generally large, multicellular organisms, while most pathogens are microscopic.

F. : interspecific symbiosis in which two species benefit from their interaction

■ EX: nitrogen fixation by bacteria in the root nodules of legumes

■ digestion of cellulose by microorganisms in the guts of ruminant mammals

■ exchange of nutrients in mycorrhizae, the association of fungi and plant roots.

G. ______________: interaction that benefits one species but neither harms nor helps the other (+/0).

■ Commensal interactions are difficult to document in nature because any close association between species likely affects both species, if only slightly.

END RESULT:

Abiotic + Biotic + Interaction = Species Richness

Increased by: Decreased by:

- more niches - geographic isolation

- more heterogeneous area - homogeneity

- closeness to other areas - environmental stress

- ecotone/egdge effect - species dominance

Impact of Invasive/Exotic Species:

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