Unit 2

Chapters 4, 7, 9

Charles Darwin

studied animals in the Galapagos Islands

Alfred Russel Wallace

studied animals in the Malay Archipelago

Evolution

the idea that species change over generations because individuals compete for scarce resources

Evolution occurs when…

1. Range of traits: Variation in traits that exist in a population

2. Heritable traits: Replication occurs through reproduction

3. Some traits survive better: Selection is the nonrandom survival of offspring

Directional selection

acts against one extreme (favors the other extreme)

Stabilizing selection

acts against both extremes (favors intermediate traits)

Disruptive selection

acts against middle trait (favors extremes)

Niche

is a species role in an ecosystem (how it uses its habitat, how other organisms in the habitat use that species, and the habitat it occupies)

Principle of Competitive Exclusion

states that niches cannot overlap for long

Resource partitioning

when several species use different resources to coexist in the same habitat

Allopatric speciation

occurs when some kind of barrier isolates part of a population

“Allopatric = Alps/Alone”

Sympatric speciation

occurs without a geographical barrier (common in plant populations)

“Sympatric = Symphony” together

Interspecific competition

occurs between different species

“IntEr = diffErent”

Intraspecific competition

occurs between the same species

“IntrA = sAme”

Mutualism

benefits both species (positive/positive)

Commensalism

benefits one species, and neither harms nor benefits the other species (positive/neutral)

Predation

when a consumer feeds directly on another living organism (positive/negative)

Parasitism

benefits the parasite, and harms the host (positive/negative)

First major population increase

after 1600 C.E. because of major technological developments in agriculture, transportation, power, and health care

Last population decrease

Black Plague

Thomas Malthus

argued that excess population growth is the ultimate cause of social and environmental problems

Karl Marx

argued that oppression and exploitation are the real causes of social and environmental problems

Demographic factors

vital statistics that influence changes in size or composition of a population

Crude birth rate (CBR)

the annual births per 1000

Crude death rate (CDR)

the annual deaths per 1000

Total fertility rate (TFR)

the average births per reproductive female

Replacement fertility rate

The number of offspring needed to have two surviving reproductive adults (usually 2.1)

Carrying capacity

the maximum number of individuals an environment can support (limitations due to space and resources)

Dependency ratio

the number of nonworking compared to working individuals in a population

China’s One-Child Policy

Resulted in the 4-2-1 problem and impacted the sex ratio (more males)

Pronatalist pressures

factors that encourage people to have babies

Frank Notestein

Proposed demographic transition (a pattern of decreased birthrates and death rates in response to improved living conditions)

Demographic transition in the U.S.?

The U.S. is in stage four (industrial)

Demographic transition globally?

Stage three (birth rate declining)

Demographic transition: Stage 1

High death, high birth

Demographic transition: Stage 2

Rapid lowering in death, high birth

Demographic transition: Stage 3

Low death, lowering birth

Demographic transition: Stage 4

Low death, low birth

Rapid growth

Like a pyramid with the biggest part in the youngest age groups

Slow growth

Roughly even between reproductive ages and offspring

Negative growth

Has a “bubble” where there were more reproductive individuals than offspring at some point (least number of young ages)

Women rights impact on population

As education of women increases, TFR decreases

Anemia

low hemoglobin levels in the blood, usually caused by dietary iron deficiency (most common nutritional problem in the world)

Iodine deficiency

causes the thyroid (controls metabolism) to swell, causing a goiter

Vitamin A deficiency

impacts vision, especially helping the rods in our eyes differentiate light and dark

Folic acid deficiency

impacts neurological function, and can cause the brain to shrink long-term

Kwashiorkor

when people are not receiving enough protein, but they are getting enough calories (swelling belly and reddened hair and skin)

Marasmus

a deficiency in both protein and calories, so other nutrients are also lacking ( extreme thinness, old appearance, and dry skin)

Chronic Hunger Trends

We are in a global increase of chronic hunger

Poverty and overweight?

Low income, not high income is the primary predictor of being overweight throughout the world

Food Pyramid Changes

• Moved red meat to use sparingly

• Added healthy fats and oils to recommended diet

• Included optional alcohol in moderation

• Reduction in the proportion of grains

• Vegetables have increased

• Focus has moved to raw fruits and veggies

Three major crops

wheat, rice, and corn (make up more than 60% of the calories that humans consume)

Confined animal feeding operation (CAFO)

animals are housed and fed, mainly on soy and corn, for rapid growth

CAFO Drawbacks

corn as primary diet, disease and bacteria, high antibiotic use, animal rights issues, and air and water pollution

Green revolution

dramatically increased agricultural production brought about by new varieties of grain spread around the world

Artificial selection

when humans choose which organisms breed in order to produce a desired trait

Genetically modified organisms (GMOs)

organisms whose genetic code has been altered by artificial means such as interspecies gene transfer

GMO Pros and Cons

Pros: increased crop yields, enhanced nutritional value, and better pest resistance

Cons: reduced biodiversity and long-term health effects

Pest resistance

The pest resistant BT bacteria has been used in several GMOs, resulting in plants producing a toxin that kills pest insects

Pesticide/herbicide resistance

Taking DNA from plants that can resist herbicide (used to kill weed plants) and creating a whole line of “roundup ready plants” that can tolerate high levels of roundup herbicide

Sustainable food methods

1. Supporting community vitality: Grow local food to connect communities and provide fresh, healthy options

2. Energy conservation and production: Use less energy and create renewable energy on the farm

3. Ecological insect and weed management: Control pests naturally by using plants that attract insects away from your crops

4. Reduced till and no till: Keep soil healthy by not over-tilling; it helps prevent erosion and maintains nutrients

5. Building soil health: Use compost and mulch to enrich soil and support good microorganisms

6. Nature as a model: Embrace biodiversity in farming to create sustainable, long-lasting food systems

7. Rotational grazing

8. Polyculture

Rotational Grazing

a land management system where livestock are confined to small, designated areas of pasture (paddocks) and moved regularly, allowing grazed areas to rest and recover

Polyculture

growing multiple plant species together in the same space