Unit 1 Review

* Biodiversity

* Bio=life
* Diversity= variety or differences
* Biodiversity= the variety of life

How many species of organisms are there on Earth?

* 1.5-2 million species
* We think there are over 10 million species!

Types of organisms on earth in order of biodiversity

* Insects are the largest, most successful group of life forms on the planet
* Plants are next
* Other invertebrates
* Bacteria and protista
* Vertebrates
* Fungi

Species

* a population of individuals that can make FERTILE offspring
* Similar and share recent evolutionary history

Problems with the definition of a species

* Not all organisms use sexual reproduction
* Interbreeding not possible when reproducing via cell division
* Speciation is not instantaneous
* Coyotes and wolves formerly separated by habitat
* They were able to interbreed and have fertile offspring, but we still consider them separate species
* Not enough is known about many organisms

Linnaean Classification System

* Binomial name- Genus species
* Wolf- Canis lupus
* Domestic dog- Canis familiaris

Domains

* Bacteria
* archea (single-celled organisms)
* eukaryota (plants, animals, fungi, any organism that has a nucleus)

Order of scientific names

Kingdom, phylum, class, order, family, genus, species

* Animalia, Chordata, Mammalia, Carnivora, Ursidae, Ursus, Urus arctos
* Humans- animalia, chordata, mammalia, primates, hominidae, homo, sapiens

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* How do we measure biodiversity?

Species richness, diversity, species evenness

Species richness

* number of species occurring in a particular area
* NUMBER OF SPECIES ALONE

Diversity

the number of species present AND the evenness of their abundance

NUMBER OF SPECIES AND EVENNESS OF ABUNDANCE

Species evenness

EVENNESS OF ABUNDANCE ALONE

* evolution

* change in the genetic nature of living things over time

Genotype

set of genes carried by an individual

Phenotype

physical expression of a trait carried by an individual

Alleles

* a particular version of a gene 
* Individuals within a species differ bc they have different alleles
* Different species often have the same genes but different alleles

* What factors affect species diversity?

Latitude, precipitation, temperature, altitude, other species

Why do we care about biodiversity?

Maybe we like animals or have hobbies involving nature

Levels of biodiversity

* biosphere, ecosystem, community, population, organism, organ system, organ, tissue, cell, molecule, atom

Evolution notes

* Common ancestor— new species
* Populations are VARIABLE in their traits
* Differences in genotype (set of genes carried)- differences in phenotype (physical traits)
* Differences are passed from parents to offspring (heritable)

Mean

the average value of the population

Standard Deviation

* the dispersion around the mean

Change in distribution of a trait over time

a bigger variation of crab shell widths in 1995 vs. 1990

DUE TO EVOLUTION!

MORE GENETIC DIVERSITY

Mutation

 Small change that doesn’t change the genotype, but it changes the phenotype

Gene Flow

* individuals migrate from one population to another, introducing new genes/traits that might not have been there before

Genetic Drift

*  the change in the frequency of an existing gene variant in a population due to random chance.(chance event)

Natural selection

* a predator is more able to consume individuals with a certain trait than those with a different trait; genes change for survival

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Birds preferentially eat green beetles- this leads to dominant brown beetles

Three requirements for natural selection

* there has to be variation in the population (there can’t be only green beetles bc then there’s no point)

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* that variation has to be heritable

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differential reproduction (if the bird is eating more green beetles, fewer green beetles are surviving to reproduce)

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For natural selection to result in evolution, the phenotypic variation must be based on genotype

Charles Darwin

typically gets the credit for developing the idea of evolution as descent with modification by the mechanism of natural selection

\n -wrote On the Origin of Species (largely the result of his observations aboard the HMS Beagle)

* Darwin’s finches

Alfred Russell Wallace

* independently reached the same conclusions as Darwin
* Spent 14 years in the Amazon
* On the Monkeys of the Amazon (1953)

stabilize selection

* population standard deviation gets smaller, mean stays the same \n Stablilizes the mean trait
* The mean trait is the best for survival/sexual reproduction, so it stays

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Biodiversity decreases

Disruptive selection

* within the same population as a species, we have two totally separate populations if we’re just looking at their beak size
* Both sizes are useful so both stay

Directional selection

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* Individuals that have a trait value higher than the mean are doing better- causes the mean to shift in the direction of the larger trait value (how we think giraffes ended up with long necks- giraffes were better at reaching high branches so long necks stayed while short-necked giraffes died out)

How can evolution by natural selection lead to speciation?

 A population of species has a trait that:

Is variable

Is heritable

Affects survival/reproduction —-- evolution by natural selection is POSSIBLE

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A selective pressure causes a shift in phenotypic ration for the trait—- evolution by natural selection OCCURS

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V

A nearby population of the same species does not experience the same selective pressure—- over time, the 2 populations are no longer able to produce fertile offspring

\n Populations are separated and develop differently

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Populations are no longer separated, but interbreeding cannot produce fertile offspring anymore

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Over evolutionary time, the 2 populations no longer breed with each other anymore due to changes

\n Two species now occupy the same local area, increasing local biodiversity

Phylogeny

a family tree that shows how species changed and split in two

Note: a cladogram is a specific type of phylogeny (you will use one in the Living with Dinosaurs unit)

**Evidence for Speciation**

Fossil record, species on islands

Fossil record

* Different forms of life existed in the past
* Some forms went extinct
* New forms appeared
* Clear non-random change over time

Species on islands

* Islands are younger than continents
* Similar to mainland species but still unique
* Tend to only have organisms that can survive long distance travel by flying, swimming, or floating
* Observations of populations in the process of speciation
* Instantaneous speciation
* Genetic similarity

Human Impacts on Evolution of Biodiversity

Peppered moths in England (As industrial pollution made tree bark darker, darker moths survived and reproduced more

\-After controls on air pollution were put in place, bark got lighter again and lighter moths survived and reproduced more)

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Bird species are becoming lighter and longer-winged in response to climate change

Ecology

the study of factors influencing the distribution and abundance of organisms

The interactions between organisms and their environment

Biome

a large naturally occurring community of flora and fauna occupying a major habitat

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Tundra, desert, rainforest, etc.

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Biomes are largely determined by temperature and precipitation

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Change in elevation corresponds to a change in biome

Elevation lowest to highest

rainforest, evergreen forest, deciduous forests, coniferous forests, meadows, snows and glaciers

T/F- Climates exist in multiple locations

T

T/F- Similar environments produce species with similar roles

T

Ecological niche

 a particular set of environmental conditions in which a species normally occurs

\-needs/accomodations/support needs for a species

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Ecological niches allow many species to persist in a community

Community

all the various species in a specific location (plants and animals)

COMPETITION

* multiple species use the same resource, and both suffer a cost to energy and resources (ex. C and E)
* Negative/negative

Mutualism

* both species benefit
* positive/positive

* Predation

* predator/prey- positive/negative

Food Web Dynamics

* Show the species interactions within a community
* Shows the transfer of energy within a community

Producers

* make their own energy through photosynthesis

Decomposers

*  feed on dead organic matter

Consumers

* eat other organisms

Primary consumers

* eats primary producers

Secondary

eats primary consumers

Tertiary

eats secondary consumers

What factors influence biodiversity in a community?

* Climate, ecological niches, food chain/web, disturbance

Disturbance

*  a sudden change in the environment
* Disturbance can be a natural part of the local ecology
* Ex. Appalachicola National Forest
* Longleaf pines are adapted to frequent fire
* Trees grow taller faster
* Competing plants are reduced
* Stimulates growth of native understory plants
* Prescribed burns prevent larger wildfires and help restore longleaf pine ecosystem
* High disturbance- low diversity
* Medium disturbance- big diversity
* Low disturbance- low diversity

Ecosystem

* the ecological community living in an area and the nonliving parts of the world with which the organisms interact

Agriculture

* Goal: produce large amounts of a single species
* Simple ecosystem
* Inputs and outputs that are important for their functioning

Outputs

* if the plants are harvested, plants are the output and nitrogen is the input

Inputs

*  fertilizer, water, etc.

Selective breeding

* Selective breeding for certain traits- coat, mass, behavior traits, etc.- is possible
* Selective breeding/artificial selection reduces genetic diversity
* It can also produce many different forms

Genetic modification

* altering DNA/inserting DNA from other species VS selective breeding to get the traits we want
* Genetic modification- increases shelf life, nutrition, stress resistance, pest resistance, yield, etc.
* GMOs have become very widely cultivated since their invention

Are GMOs bad for human health?

* No evidence of allergic reactions
* Potential ecological/environment issues
* –Increased resistance of insect pests and increased resistance of weeds

How can you support biodiversity in agriculture?

Support heirloom crops, Seed Savers exchange, Red Hills

Fishery

* Taking fish or other animals from the ocean
* A population or “stock” of fish or other animals harvested by humans
* Invaluable source of protein

Overfishing

harvesting faster than the population can grow

* Too big, too small, too many 

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Decreases biodiversity

What is being done to prevent overfishing?

Harvest limits (size, quantity, time of year), monitoring, intergovernmental cooperation, “no-take” zones and marine protected area (MPAs), community education

Diversity of Disease Causing Organisms

bacteria, parasites, viruses

Viruses

not living organisms

injects host with viral DNA

simplicity makes them efficient

Bacteria

* single celled eukaryotes, no nucleus, no organelles,
* Bacterial infections relatively easy to treat
* Tiny
* Very different from our cells
* Many organisms produce compounds that can kill them (antibiotics)

Parasites

* Single or multicellular
* More difficult to treat
* Life cycles often involve multiple hosts

Types of parasites

* roundworm, hookworm, fluke, tapeworm, nematode, and protozoa

Natural Products and Medicine

* Plants and fungi possess chemicals to protect themselves from disease
* Some of these are beneficial to humans
* Tropical rainforests provide a variety of medicinally beneficial plants

Examples- natural products and medicine

* Ex. opiates come from poppies, taxol (used to treat many cancers) comes from yew tree, digoxin (used to treat certain heart conditions) comes from purple foxglove, aloe vera plant sooths burn pain and speeds wound healing, penicillin (discovered in 1928, comes from an indoor fungus, prevents bacteria from synthesizing a molecule that strengthens their cell wall

Immune system

Two kinds of immunity: innate and acquired

Innate- immunity all animals are born with

Ability of the immune system to respond and defend against foreign things/anything that’s not self

It recognizes OUR antigens but it doesn’t recognize DIFFERENT antigens (this is kind of why blood type matters)

\n Organ donation- sometimes the body rejects an organ bc it’s foreign

* Vertebrates can gain ACQUIRED immunity by LEARNING
* It can do this in passive or active ways
* Example of passive ways- receiving artificial antibodies (like medicine) or getting them from the mother
* Example of active ways- the immune system recognizes a new threat and learns how to deal with it and builds its own antibodies in order to protect you next time
* This can happen through natural exposure (you get sick) or immunization (vaccines, like the COVID vaccine)

Blood types

* each different blood type has different antibodies

Type A

has A antigens, B antibodies

B

* has B antigens, A antibodies

AB

has A and B antigens, no antibodies

O

*  has neither A nor B antigens, A and B antibodies

Acquired Immune System Example

 covid vaccines give acquired immunity 

ACTIVE acquired immunity

COVID-19 vaccines

* First commercially used mRNA vaccines

PASSIVE acquired immunity

* Monoclonal antibodies
* Given to particularly high-risk patients

* Vaccine

* activates your immune system (antibodies) without you being infected by an active virus
* A dead or weakened virus
* Piece of a virus that causes an immune response

Spike proteins

* structures on the outer layer of the coronavirus that attach to our cells and trigger an immune response

More genetic diversity in immune system genes leads to…

* greater immunity

Low Resistance

easily killed by immune system

High resistance

* not easily killed by immune system

Drugs, animals, and mutations

* antibiotic given to farm animals to keep them healthy, antibiotic protects animal against known strains of bacterial infection, mutated form of bacteria resists antibiotic, contaminates meat…humans eat contaminated meat and are infected by mutated bacteria, and antibiotic does not work

What traits may be selected for? (Which traits would be best for selection, reproduction, passing to the next generation?)

* Traits that:
* Affect host behavior to increase transmission
* Minimize symptoms or impact on host

* How does diversity in pathogens lead to highly resistant varieties- (eg. strains of bacteria)?

* Immune system attacks foreign cells
* Antibiotics attack foreign cells
* Lower resistance cells die
* Hosts with more virulent pathogens die
* Surviving pathogens reproduce
* Shift in phenotype ratio from original to final population

* How does climate change cause an increase in Dengue Fever?

* Has a longer active season
* Range shift
* High humidity increases survival, feeding, and egg development
* Increased pooling water- mosquito habitat
* Drought
* Urbanization
* Disasters interrupt mosquito control
* Climate refugees carry dengue to new regions
* Malnutrition- weakened immune systems

Why might diversity in MHC genes be important in mate choice?

Offpsring with higher immunity have more diverse traits

●     sacred and unclean animals

●     Cats were revered in Egyptian culture, owls were Athena’s animal, etc.

Sacred plants

●     ex. Mistletoe important to Celtic druids, narcissus flower is Hades’, etc.

Biodiversity in art

people painting food, animals, etc.

Biodiversity in pop culture

●     - finding nemo, the secret of Nimh, Watership Down, zootopia, Dragon Prince, greek gods/goddesses each have their own symbolic plants and animals

Biophilia

●     the love of living things and the urge to affiliate with them