Unit 2: The Living World (Biodiversity) Module 8-12

Biodiversity 4 scales:

-Genetic (genetic variation among individuals in a population)

-Species (the number of species, NOT INDIVIDUALS, in a region or in a particular ecosystem)

-Habitat (the variety of habitats that exist in a given ecosystem)

-Ecosystem (the variety of ecosystems that exist in a given region)

population bottleneck

-Larger populations may have higher genetic diversity, but when that population declines rapidly, the survivors may not have as much genetic diversity as the original group

specialists

-narrow range of biotic/abiotic conditions, e.g. koalas, some bees

generalists

-wide range of biotic/abiotic conditions e.g. white-tailed deer, cockroaches, raccoons, rats

high and low diversity consequences: genetic

-High --> Disease resistance

-Low --> Disease susceptibility

high and low diversity consequences: species

-High --> Ecosystems respond well to disturbances

-Low --> Decreases in species number can serve as an indicator of ecosystem health

high and low diversity consequences: habitat

-High --> Higher species numbers

-Low --> Specialists decline, generalists succeed

high and low diversity consequences: ecosystem

-High --> Greater diversity of ecosystems can lead to more species

-Low --> Decreases in ecosystem types reduce species availability and genetic diversity

When number of species increases, habitats can become ____ stable, and have an impact on other species

more

Bar label on graph

-% error

-+/-

-If error bars overlap, no statistical difference

Species richness

the number of different species in a given area

Species evenness

the relative proportion of individuals within the different species in a given area

Estimating Biodiversity (Larger Scale): challenges

-Active during night hours

-Found in inaccessible areas

-Too small to be found with the naked eye

-Range and number are too great to realistically quantify (funding, manpower, equipment, etc.)

-To date, 2 million species have been named, 15,000 to 18,000 are discovered each year, worldwide

-^Estimates for total species on Earth range between 5 million to 100 million

Humans essential needs species

-Pollination

-Drinking water

-Flood prevention

-Intrinsic value

Ecosystem services

-Provisional

-Regulating

-Supporting

-Cultural

Ecosystem services: Provisional

goods humans can directly use, which can include:

-Furs

-Trees

-Natural pharmaceuticals (Ex: aspirin from willow trees!)

Ecosystem services: Regulating

maintain environmental conditions and can include:

-Removal of carbon dioxide by plants

-Flood control

-Temperature control (tree shade!)

Ecosystem services: Supporting

provide services that would be costly, and/or extremely difficult, for humans to generate and can include:

-Pollination

-Pathogen removal/filtration

Ecosystem services: Cultural

provide intrinsic/aesthetic benefits for certain groups of people and can include:

-Natural beauty, recreation

-Cultural/religious value

-Mental health!

Ways of applying monetary value of a service

-Replacement value – cost to replace natural ecosystems

-Property value – nearness to natural ecosystems and services

-Time and service fees – amount of time and money people are willing to spend visiting natural areas (like national parks)

-Estimated yearly worth of ecosystem services is $125 trillion

Island Biogeography

-The study of how species are distributed and interact on islands.

-Typically, larger islands have more species due to the resources available.

-Islands that are closer to the mainland also have more species diversity.

Ha

-Hectare

-10,000m^2

What Determines Species Diversity on Islands?

-Size

-^Need of producers will affect ecological efficiency.

-^Smaller islands can't support larger numbers of predators, so producers don't last

-Distance to mainland due to colonization frequency and ease.

Island Biodiversity and Invasive Species

-Common generalists can quickly be invasive on islands.

-Mice and rats have a history of wreaking havoc on island species, because they:

-^Are able to consume the native food sources (omnivores!)

-^Can also be predators to native species

-Other organisms, such as snakes, can also invade and impact island specialists.

-Roughly 50% of extinctions in the last 400 years have been island species

Range of ecological tolerance

-The type of environment where individuals perform particularly well

-Measured for several abiotic factors

-Survive, survive and grow, survive and grow and reproduce, survive and grow, survive

-Fundamental niche

Realized niche

-The range of abiotic and biotic conditions under which a species actually lives

-Can occur through competition

5 major extinctions in Earth's geological history

-Estimated that 99% of species that have lived on the planet are now extinct.

-Known bc of fossil records

-Involve large numbers of species going extinct in relatively short periods of time.

-Typically happen with major changes in the environment, e.g. climate change, meteor strikes, etc.

1st mass extinction

-End Ordovincian

-Temps lowering, ice sheet expanding, sea levels dropping

2nd mass extinction

Late Devonian

-Reduction in oxygen and CO2 in atmosphere

3rd mass extinction

-Great dying (96%)

-Asteroid? Volcano?

4th mass extinction

-End triassic

-Volcanism, ocean acidification, and period of global warming.

5th mass extinction

-End cretaceous

-Prob an asteroid

Reasons why a species is likely to go extinct in general:

-Their current environment may no longer be favorable (ocean acidification, pollen changes, etc.)

-Newly favorable environments may already be occupied by competing species

-Newly favorable environments may have predators that would prevent a successful move

6th mass extinction

-Prob now

-The difference in this mass extinction is the cause; rather than being caused by climate or external factors, this extinction is currently being caused by humans!

Periodic disruptions

-occurring at regular intervals (night and day)

Episodic disruptions

-somewhat regularly (drought and rain intervals)

Random disruptions

-No regular pattern (natural disasters)

Duration of disruptions

-Disruptions that have small special extent tend to occur in short duration.

Fire disruptions

-Disruptions that have small special extent tend to occur in short duration

-Detritus turn over --> nutrient cycling

Resistance

-If a species is largely unaffected by a disruption

Resilience

-If a species is affected by a disruption, the rate it takes to return to its original (pre-disruption)

Methods of measuring change in climate and sea level (natural and natural) change:

-Historic/ancient species compositions (fossils!)

-Gas bubbles in ancient ice --> ice core drilling

-Measuring melt of ice sheets

Natural Disruptions and Ecosystems

-Disruptions can cause large habitat changes and animal migrations.

-When some changes happen infrequently, even if they occur rapidly when they do, resistance and resilience can allow an ecosystem to bounce back quickly

-^ex fire

-Long, rare disruptions can lead to bigger changes.

-^ex drought

Fire reliant ecosystems

-Temperate grassland

-Chaparral

-Savana

Intermediate disturbance hypothesis

-Explains that having intermediate levels of disturbance will help an ecosystem develop higher diversity due to the build up of resistance and resilience.

Migration

-Natural disruption

-A seasonal change can lead to species choosing to migrate, rather than adapt overall.

-Migrations can lead species to where resources are more abundant, predators are less common, or conditions are more in their range of tolerance.

Temperature-Dependent Sex Determination ("TSD")

-In most species, sex is determined during fertilization.

-However, the sex of most turtles, alligators, and crocodiles is determined after fertilization. TSD: The temperature of the developing eggs is what decides the offspring's sex

-If a turtle's eggs incubate below 27.7° C (81.86° F), male. If above 31° C (88.8° F), female.

-As the Earth experiences climate change, increased temperatures could result in skewed and even lethal incubation.

Evolution

-A change in the genetic composition in populations driven by competition

-Occurs through random processes

-Occurs if a population’s fitness, ability to survive and reproduce, is improved, leading to an adaptation

Fitness

-Measure of amount of genes passed to the next generation

-# 1-0

EX: one offspring --> 50% of ur genes passed down --> 0.5 fitness

Microevolution:

-A change in gene frequency within a population (one species)

-Occurs due to: Mutations, Gene Flow, Genetic Drift, Bottleneck Effect, Founder Effect

Ex: Frequency of a gene for brown coloration in a population of beetles increases in the next generation.

Macroevolution

-The evolution of large-scale structures and traits that go significantly beyond the variation found in microevolution (multiple species)

-Occurs due to: Speciation

Ex: Loss of limbs in snakes and lizards. Bat wings have the same structure of a five-fingered mammal, with elongated bones

Natural selection

-when adaptations lead to changes without human interference

Artificial selection

-when humans select certain traits and breed for them in other species

Ex: Breeding food crops to select for nutrition content or soil tolerance

Ex: Breeding dogs for temperament, coat texture, disease resistance

Darwin's theory of Natural Selection

-Individuals produce an excess of offspring (overproduction)

-Not all offspring survive

-Different inherited traits get passed from parent to offspring

-Those that have the ability to survive and reproduce pass on their traits

Mutations

Changes to the genetic variation of a population

Gene Flow

Individuals moving from one population to another

Genetic Drift

Simple change in genes over time due to random mating

-EX: Bottleneck and Founder effect

Bottleneck Effect

Reduction in the size of a population's genetic variation

Founder Effect

A few individuals begin a new population with genotypes not representative of the larger group

Non random mating

occurs when the probability that two individuals in a population will mate is not the same for all possible pairs of individuals

Allopatric speciation

-A geographic separation in a population, leading to a new species

Sympatric speciation

-Genetic isolation without geographic separation in a population, leading to a new species

-EX: Temporal isolation (pollinate at different time)

-EX: Behavioral isolation (one bird sings to mate one dances)

genetically modified organisms (GMOs).

new organisms created by altering the genetic material (DNA) of existing organisms; usually in an attempt to remove undesirable or create desirable characteristics in the new organism.

Ecological succession

-A predictable replacement of one group of species by another group over time

-Begins by increasing species richness, biomass, and productivity --> after species have been in an area for a long period of time, resources = used up and competition inc, leading to a drop in biomass and productivity.

Primary succession

-Occurs where there was bare rock and no soil to begin with

-As detritus builds up the original species are replaced w more advanced species

-First species to show up are known as pioneer species --> algae, lichens, or mosses.

climax community

A stable, mature community that undergoes little or no change in species over time

Secondary succession.

-Areas that already have soil and are disrupted by things like a forest fire or hurricane

Succession: Aquatic Environs

-Aquatic succession can occur through small changes, such as overturned or exposed rocks in a rocky intertidal shore, or as water dries up in shallow bodies of water.

-EX: Pond accumulating sediments and filling the lake basin overtime

Keystone species

-Species that are not abundant yet have a disproportionately large impact on a community

-Tend to create or change habitat or can serve as a population control for other species

-EX: beaver

-EX: sea stars, which are predators of mussels, and allow for a diverse ecosystem.

Indicator species

-Can demonstrate characteristics of an ecosystem.

-Used to determine if there is a negative impact on that ecosystem.

-EX: Lichens present on trees (sensitivity to pollution)

-EX: Amphibians (sensitivity to disease, habitat loss, and pollution)

-EX: Larval mayflies (sensitivity to pollution)