AP ENVIRO: unit two (Timmons)

what is biodiversity?

the variety of the earth’s species, the genes they contain, the ecosystems in which they live, and the ecosystem processes that sustains all life.

Ecosystem Diversity

the number and variety of ecosystems
ex: serengeti ~ holds diversity of habitats including savanna, grasslands, wetlands

Genetic Diversity

encompasses the differences in dan composition among individuals
~populations with low genetic diversity are more VULNERABLE to environmental changes/disease

Inbreeding depression

genetically similar parents mate and produce ‘less fit’ offspring

fitness

the ability to have babies that will have their own babies

Latitudinal gradient

species richness increases towards the equator
b/c high plant productivity supporting more animals; climate stability allows specialization, niches, and species coexistence

Why should we care about Biodiversity?

provides us with natural resources, natural services, aesthetic pleasures, leads to productive and sustainable ecosystems.

Natural selection acts on ___, but evolution occurs within ___.

individuals; populations

when faced with environmental changes, a species will do one of the following:

1. adapt through natural selection

2. migrate to areas w/ more favorable conditions

3. suffer a sharp population decline

4. become extinct

specialists

occupy narrow niches, consume one/few types of food, MUCH more prone to extinction, can tolerate narrow range of climate conditions (do better in habitats that remain constant)
ex: giant panda, koala

Generalists

broad niches, tend to be omnivores, eat variety of foods, can tolerate a wide range of environmental conditions (do better in habitats that are changing)
ex: raccoons, coyotes

Ecological Tolerance

reverse to the range of conditions that an organism can endure before injury/death occurs. ex: temperature, salinity, sunlight
- this can apply to INDIVIDUALS and ENTIRE SPECIES

mutualism

two organisms of different species work together (BOTH BENEFIT)

• ex: oxpecker birds and zebras

Commensalism

relationship between two organisms in which one benefits from the other without causing harm to it

• ex: remoras and sharks

Parasitism

Unlike typical predation, the parasite is usually much smaller than the host

Biotic Potential

• species with large individuals (whales/elephants) have a LOW biotic potential

• species with small individuals (bacteria/insects) have a HIGH biotic potential

Carrying Capacity (K)

the # of individuals that can be sustained indefinitely in a specific space

• as a population reaches its carrying capacity, it’s growth rate decreases due to resources

• can fluctuate due to predation/competition

Overshoot

temporary; exceeding the carrying capacity

reproductive time lag

time needed for the birth rate to fall and the death rate to rise in response to resource overconsumption

r-selected species

many small offspring, little parental care, early reproductive age, generalist niche, early successional species, population size fluctuates WILDLY above and below carrying capacity (K), most offspring die

• ex: mice

K-selected species

larger organisms, high parental care, later reproductive age, most offspring survive to reproductive age, specialist niche, late successional species, Population size is fairly stable and usually close to carrying capacity (K)

Intrinsic rate of increase (r)

the rate of which the population of a species would grow if it had unlimited resources

Size of populations are limited by:

sunlights, water, space, nutrients, exposure to too many competitors

Survivorship curves

late loss curves: TYPE ONE

• common to k-strategist

early Loss Curves: TYPE THREE

• common to r-strategists

constant loss curve: TYPE TWO

• an intermediate , steady decline in survivors b/c they experience a fairly constant rate of mortality in ALL age classes so there is a steady decline in survivors

Endangered species

so few individuals survivors that it could soon become extinct

threatened species

still abundant but likely to be endangered in near future

3 types of species extinction

1. local extinction : when a species is no longer found in area it once inhabited, but still found elsewhere

2. ecological extinction: when so few individuals of a species are left that a species no longer plays a significant ecological role in the communities where it is found.

3. biological extinction: when individuals of a species no longer exist on earth FOREVER

The more genetically diverse a population…

the better it can handle environmental stressors

Ecosystems that are biodiverse have an easier time…

recovering from a disaster

6th mass extinction

cause: humans
- today’s extinction rate is 100-1000x higher than background rate.

Native species

normally live + thrive in particular ecosystem

nonnative species

migrate (deliberately/accidentally) into an ecosystem

indicator species

early warning of damage to ecosystems

keystone species

roles have larger effect on the types + abundances of other species in an ecosystem

• ex: wolves in Yellowstone; otters

• removal has BIG impact on the rest of the ecosystem

Ecological succession

the process of community development over time, which involves species in one stage being replaces by different species

NATURAL (NON-HUMAN)

Primary succession

• no soil, long time, pioneer community/species (the first community) (moss/lichen - nitrogen fixation)

• change in species composition over time in a previously inhabited environment

Secondary Succession

the ecological succession that begins in an environment following destruction of all/part of an earlier community

• soil remains/is there

Case studies to know

• Zebra Mussels Invade Great Lakes (invasive species)

• Whooping crane (wildlife conservation)

Invasive species

non-native (exotic) organisms that spread widely and become dominant in a community

• accidentally/deliberately BROUGHT from elsewhere

Responding to Invasives

• removing them manually (hunting)

• applying toxic chemicals

• introducing native predators/diseases

• stressing them with heat/sound/electricity/co2/UV light

PREVENTION RATHER THAN CONTROL IS BEST POLICY

Why preserve wild species?

• economic and medical importance

• aesthetic and recreational importance

• scientific and ecological importance

• ethical importance

Protecting Native species

• ECOSYSTEMS APPROACH: habitat preservation

• species approach: case-by-case logging of species and protecting and identification

• wildlife management approach: mages game species for sustained yield

HIPPCO

H- habitat destruction

I- invasive species

P- population dynamics/resources

P- pollution/pesticides

C- climate

O- over harvest & over population

Habitat loss

(greatest cause of biodiversity loss)

1. agriculture

2. commercial development

3. water development : dams

4. outdoor recreation

5. livestock grazing

6. pollution

7. logging of old growth forests

Habitat Fragmentation

occurs when continuous habitats are broken into small patches (forming roads/logging)

• species needing larger areas become stressed (type 1/r-strategist)

Solutions to save species

• captive breeding : bred and raised to be reintroduced to wild

• reintroduce can be successful

• reintroduction can be controversial

How to REDUCE poaching

• establish/expand preserves

• development of tourism industry

• tusk dying/horn removal

• education about animal value!!!

CITES

international UN convention where they protect endangered species by banning international transport of their body parts

ESA

endangered species act: primary US legislation for protecting biodiversity

• reintroduced wolves to yellowstone

Biodiversity provide ecosystem services

healthy ecosystems provide humans with free services

• provide food, fuel, shelter

• purifies air/water

• stabilizes climate

• cycles nutrients

• pollinating plants and controlling plants/diseases

• maintains genetic resources

• provides cultural and aesthetic benefits

Biodiversity Enhances food Securing

wild/rare species can improve food security

Biodiversity BOOSTS economies

biodiversity generates income through tourism/ecotourism

climate community

community that remains in place with few changes until another disturbance restarts succession