Cons Bio Exam 2

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When did contemporary diversity begin to decline?

After the Anthropocene era

In North America, at what number did species peak near the end of the Anthropocene era?

30,000

For what two main reasons do Islands continue to increase in number of extinctions?

• few, small spp. populations

• low habitat diversity

How does extinction rate tend to work on islands?

the most sensitive species die first (quickly), and then the rest of species die (slowly)

What is extinction debt?

The predicted eventual loss of species following damage to their environment

What is the theory of island biogeography?

the number of species on an island depends on a balance between immigration and extinction rates

• based on species-area relationship

• Immigration rate = 0 when all potential species immigrate to an area

• Immigration rate is higher when distance to disperse is shorter

• Smaller islands have more extinctions

What is species-area relationship?

larger areas have higher species richness than smaller areas

Why do smaller islands tend to have more extinctions?

• Fewer habitat types = less resources = more competition

• more constrained population = more vulnerability

Two main figures related to the theory of island biogeography?

E.O. Wilson

Rob MacArthur

What did Dan Simberloff do to test the Idea that dispersal rate is tied to island’s distance from mainland?

Fumigated mangrove “islands” and observed the returning species

• islands closer to shore accumulated spp. faster and had more spp.

What are the seven major threats to biodiversity?

• Habitat destruction

• Habitat fragmentation

• Habitat degradation (pollution)

• Introduction of invasive spp.

• Overexploitation

• Increased spread of disease

What is the leading cause of biodiversity loss?

habitat destruction and degradation

What are the three major ways humans dominate the global ecosystem?

• fossil fuel use (~70%)

• deforestation (~30%)

• Control/influence of the nitrogen cycle

What is the formula for the impact humans have on the environment?

I = P*A*T

• I = environmental impact

• P = num. of people in a region

• A = annual income of those people

• T = technology level of those people

Lower I = Better

What is ecological footprint?

the spatial impact of a person or group of people on the environment

What is the most important means to preserving biodiversity?

Habitat preservation

What biomes are currently growing?

Temperate forests

What two major biomes are currently shrinking, and why?

Tropical forests

• Logging followed by slash and burn agriculture which decimates soil nutrition

Old-growth forests

• human exploitation

How does agroforestry benefit tropical rainforests?

Allows for habitat restoration and economic opportunity without degrading soil like slash and burn ag does

What percentage of agriculture-viable land is already in use globally?

98%

What is habitat fragmentation?

reduction of area and division of a habitat into two or more fragments

What three major differences do fragmented habitats have compared to non-fragmented habitats?

• Greater amount of edge per unit area

• center of fragments is closer to the edge

• fragmented habitats are non continuous (divided from eachother)

What is matrix?

areas of non-habitat that surround habitat fragments

What two ways do habitat isolation and division affect populations?

• cause inbreeding depression

• cause genetic drift

What 6 species types are particularly vulnerable to fragmentation?

• Species with wide ranges

• species with migratory seasons

• non-vagile (non-moving) species

• species that prefer core habitat

• low-fecundity species

• human-exploited species

What is the edge effect?

Altered physical and biological conditions at the edge of fragmented habitats

• light

• temp

• humidity

• predation

• wind

• competition

What does this graph suggest?

Blue: if only 10% of habitat is preserved (90% lost), 50% of spp. will be lost

Red: if only 50% of habitat is preserved (50% lost), 10% of spp. will be lost

What is habitat shredding?

fragmentation in a way that results in a habitat being almost entirely edge (little to no core habitat)

What does it mean that habitat fragmentation is “non-random”?

most fragmentation occurs in valleys, where human activity most commonly occurs due to terrain

How does loss of terrapins cause a trophic cascade?

terrapins eat the predators of cordgrass; no terrapins = overabundance of cordgrass

How have terrapins been exploited historically?

• consumed by natives

• overexploted by euros

• continued decimation by americans into the 1900s

What two unsuccessful attempts were made in terrapin recovery?

• coastal facilities

  • not economically viable due to long reproductive time

• introduction to san fran bay

  • waters too cold

What lead to terrapin population rebound?

various events in the mid 1900s lead to a lack of demand → pop reboundf

What four modern threats do terrapins face?

• blue crab bycatch

• automobile accidents

• nest predation

• turtle food market

What are the five steps of invasive species?

1. transport

2. introduction

3. establishment

4. spread

5. impact

What are the two forms of invasive introduction?

Accidental

• vehicle, cargo, etc contamination

intentional

• exotic pet release, tourist collection, failed biocontrol projects, etc.

What are the 7 examples of agricultural invasives?

• Kudzu

  • fast-growing vine that smothers plants

• pink bollworm

  • eats crops from inside out

• screwworms

  • Eat cattle flesh

• feral hogs

  • crop eaters & tramplers

• nutria

  • wetland destroyers

• zebra mussels

  • sharp shells

• nilgai

  • out-compete native deer

How does tree of heaven affect other plants?

release ailanthone that inhibits nearby plant growth

• SLF eat this, making them undesirable to predators

What is honeydew?

secretion from SLF that inhibits plants and allows for fungi to grow (destroys crops)

What is the greenhouse effect?

high-energy light from the sun hits earth → bounces off in degraded form → degraded light bounces off atmospheric gas → back to earth

What is the main driving force behind the increase in greenhouse effect?

human fossil fuel use

What are the 4 main components of a carbon cycle?

Pool

• place where gases are stored:

• Source = pool that gives more than it recieves

• sink = pool that recieves more than it gives

Flux

• zone of movement between pools

What are the 5 influences climate change has on organisms?

• direct effect on physiological processes

• indirect effect on resource avaliability

• influence of species range and movement

• phenology

• species interaction

what is phenology?

the timing of seasonal biological events

What is phenological mismatch?

change in phenology of a species having drastic effects on another species

What are extreme climate events?

extreme conditions that can cause widespread mortality quickly

• frequency and magnitude has been increasing over time

What are trophic cascades?

influence of activity at one trophic level having drastic impacts on the rest