Methicillin - Resistant Staphylococcus aureus
Infectious bacterium
Difficult to treat with antibiotics
Killed 10,000 people in the united states in 2012
Staph Infection
S. aureus (also known as staph)
Some strains are harmless, whereas others cause disease
Drug resistant strains exist
Approximately 2% of the U.S. population has MRSA strand
Approximately 33% of the U.S population has S. aureus.
Most of these individuals are buttcha ha
Antibiotics
Beta-lactams work by interfering with bacterias ability to make cell wall
Antibiotic interfere with the function of essential bacterial cell structures
Bacterial Reproduction and Mutation
Binary fission: one parent cell divides into two daughter cells
Binary fission occurs quickly, but each time it causes some changes to DNA.
Antibiotic resistance
Random mutations can create new alleles that cause some bacteria to be resistant to antibiotic
Gene transfer can spread alleles for antibiotic resistance to other bacteria
Jean Baptiste de Lamarck (1744-1829)
French
Theory of acquired characteristics
Theory of disuse
DAY 2
Adaptations are often compromises - not about ‘perfecting’ organisms
Chance, natural selection and the environment interact
Adaptive radiation is when they drive rapidly into a multitude of new forms, typically happening with a big change in the environment.
The variety in any generation may be insufficient for survival, particularly during periods of relatively fast environmental change.
Founder Effect= A random change in allele frequencies from the parents population that occurs when a small founding group establishes a new population
Genetic drift= random chance events
Mutation= Any change in the hereditary material (DNA) of an organism.
Natural selection - the process by which individuals with certain heritable traits tend to produce more surviving offspring than individuals without those traits. This lead to a change in the allele frequency of the population
Fertile= can create offspring
For a population to evolve, something must act on the gene pool to change how often a particular allele is present in the population.
The bottleneck effect leads to a loss of genetic diversity when population is greatly reduced.
Gene flow
Is the movement of individuals or gametes/spores between populations and
Can alter allele frequencies in a population
To counteract the lack of genetic diversity in the remaining illinois greater prairie chickens,
Researchers added 271 birds from neighborhood states to the illinois populations, which
Successfully introduced new alleles
DAY 3
For a population to evolve something must act on the gene pool to change how often particular allele is present in the population.
The three main causes of evolutionary change are
-Natural selection
-Genetic drift
-Gene flow
-If individuals differ in their survival and reproductive success, natural selection will alter allele frequencies.
Stabilizing selection favors intermediate phenotypes, acting against extreme phenotypes
Directional selection acts against individuals at one of the phenotypic extremes.
Disruptive selection favors individuals at both extremes of the phenotypic
A species
range.mating
Share features
Microevolution is evolutions smallest scale
Changes in the gene pool from one generation to the next
When speciation occurs one species splits into 10 sir
They share many characteristics
Population with varied inherited traits → Elimination of individuals with certain traits and reproduction survivors.
The biological species concept
Reproductive isolation vs gene flow
Production of fertile offspring
DAY 4
The three main causes of evolutionary change are
Natural selection
Genetic drift
Gene flow
Urbanization can prevent gene flow and lead to inbreeding
Inbreeding depression
Closely related individuals are more likely to share the same alleles
Negative reproductive consequences for a population
Associated with high frequency of homozygous individuals possessing harmful recessive alleles
For a population to evolve, something must act on the gene pool to change how often a particular allele is present in the population.
Primates had evolved as small arboreal mammals by 65 million years ago.
Primates include
-Limber joints
-Grasping hands and feet with flexible digits
-a short snout
-Forward pointing eyes that enhance depth perception
The human story begins with out primate heritage
A phylogenetic tree shows that all primates are divided into three groups:
Lemurs, lorises, amd bush babies
Tarsiers, and
Anthropoids, including monkeys and apes.
Most apes do not have a tail and most have long arms and short legs
Monkeys have forelimbs that are about the same length as their hind limbs
Hominins include modern humans and their extinct relatives.
Hominids include all those and gorillas and orangutans and other monkeys
Paleoanthropology, the study of humans origins and evolution
australopithecus
2.6 million years ago
Could walk up right
Lived on the ground
Tools
Bipedal: spine connects to bottom of skull and can walk up right
Bipedalism precedes larger brain size
Chimpanbutt and gorillas knuckle walk
Walked upright before big brain
All living humans have ancestors that originated as homo sapiens in africa.
Oldest known fossils with the definitive characteristics of our own species were discovered in Ethiopia and are 160,000 and 195,000 years old
Evidence from fossils and DNA studies has enabled scientists to trace early human history.
The oldest human populations are in Africa
A series of migration events from the original population in Africa gave rise to all the other human populations.
Humans evolved in Africa
-Humans originated in africa aproxx 200,000 to 300,000 years ago
-A group migrated
To further study the out of Africa hypothesis, scientists study mitochondrial DNA (mtDNA)
-mtDNA is inherited solely from mothers.
mtDNA mutates at a regular rate.
We can track human ancestry and build an evolutionary tree “mitochondrial eve”
A mother with a mutation in her mtDNA will pass it to all her children
We can track human ancestry and build an evolutionary tree
Humans are genetically similar
Homo sapiens: biological species of human
Highly similar to one another
SKin tone in humans
Skin tone reflects levels of melanin
-Pigment produced by a type of skin cell
Skin tone correlates to geography
Melanin absorbs uv light
Some nutrients are affected by uv light
Folate and Vitamin D
Essential and impacted by sunlight exposure:
Folate
Destroyed by UV light in skinli
Needed for proper development
Low folate + birth defects
Vitamin D
Produced when skin exposed to UV light
Needed for immune system, bones, teeth
Low vitamin D = premature birth, rickets, neurological disease
Natural selection in skin color
Positive selection tends to make trait more common
Skin color correlates with geography
DAY IDK
The abiotic factors of the biosphere are not static
Study: track wolves and moose for many years to understand how these populations are linked
Ecology: the study of interactions
Among organisms
Between organisms and their nonliving environment
Ecology can focus on
Community: interacting populations of different species in a defined habitat
Ecosystem: all the living organisms in an area and the nonliving parts of the environment with which they interact
Distribution patterns
Clumped distribution: when resources are unevenly distributed across the landscape
Or when social behavior dictates grouping
Examples: wolves, schools of fish
Uniform distribution
Results from territorial behavior
Examples:
Penguins often spread out evenly
Some plants produce toxins that prevent seedlings from establishing too close to them.
There have not always been wolves or moose on Isle Royale
Moose in 1900: abundant food, no predators
Two wolves in 1950
Growth rate
Immigration vs emigration
Population size
Logistic growth
Starts off fast
Levels off due to environmental factors that limit ability to reproduce
Carrying capacity
-maximum number of individuals an environment can support, given its space and resources
-Often depends on availability habitat: the physical environment in which an animal l
Population interactions
Anything that affect the size of one population could also affect the size of other populations in the ecosystem
Isle royale
The wolf population increases and decreases depending on availability of food( moose)
The moose population increases and decrease depending on predation on predation from wolves and availability of food (leaves from trees)
Tree growth depends on foraging by moose.
Factors affecting populations
Density-independent factors
-a factor influences population size and growth regardless of the number and crowding within a population
Example: weather
Density-dependent factors
-A factor that influences population size and growth depending on the number and crowding of individuals in the population
Example would be predation
There were once approximately 30 million bison in North america.
By the late 1800s, they had been hunted down to 500 individuals
Due to conservation efforts, there are now 500,000 bison, mostly on ranches.
The American Prairie Reserve (APR) is a rewilding effort to restore 3.2 million acres of land. Rewilding: restoring native wildlife to their original habitat
Apr consists of existing public land, plus land purchased by private donors
If completed, APR would have the largest bison herd in the world.
Prairies are also excellent for cattle
APR is controversial for some, especially ranchers who think of it as a challenge to their way of life.
Cattle do not wallow or roam wildly, so they do not have the same positive influence for other species as bison
APR is controversial for some, especially ranchers who think of it as a way to challenge their way of life.
An ecosystem is all the lift and all the nonliving things and processes in an area.
This American prairie is one example of an ecosystem.
Role of species in ecosystem
Some species play particularly important roles in ecosystem: keystone species
Bison are considered a keystone species because they are particularly important to their prairie ecosystems
Examples of keystone species:
Prairie dogs
Elephants
Hummingbirds
Bison
Wolf
Bees
Sharks
Role of species in ecosystems
Bison grazing promotes the growth of plants other than grass
Without bison, grass overgrowth crowds out other plants
Without bison, many other animal species lose habitat and become less common holmes.
Some species are ecosystem engineers-keystone species that alter habitat for other species
Climate often determines the distributions of communities
Uneven heating of earth's surface
Patterns of precipitation
Prevailing winds
Biomes:
Aquatic
-salinity
-freshwater
Terrestrial
-temperature
-precipitation
Biomes 1 of 2
biomes : large areas defined by characteristics plant life
Terrestrial (land) biomes: Plant life is driven by patterns of temperature, rainfall, and seasons
Freshwater biomes: Standing water biomes (lakes and ponds) and
2 flowing water biomes (rivers and stream)
Tundra: arctic and mountain regions:
-low growing vegetation
-layer of permafrost soil, frozen all year long, close to the surface of the soil
Taig: evergreen trees
Long and cold winters, only short summers
Temperate deciduous forest: moderate winters and rainfall
Trees (evergreen or deciduous) drop their leaves in the winter
Temperate grassland: perennial grasses and other non woody plants
-In north america, prairies are examples of grasslands
Mediterranean: Long hot dry summers and cool damp winters
-short evergreen trees and shrubs with leathery leaves are found here
Six major elements - H, C, N, O, S and P- constitute the major building blocks for all biological macromolecules