Biology midterm
symbiosis
Living together
mutualism
beneficial interaction for both species
3 types of mutualism
1. Nutritional mutualism
2. defensive mutualism
3. dispersal mutualism
Problem with Lotka-Volterra model with mutualism
Unrelalistic
- no limits of growth for mutualism
- the more species 2 there are, the faster the species 1 grows
possible limits
- very strong intraspecific competition
- third species such as competitor or predator
- Diminishing returns to mutualism as the population grows
• Mutualism has a positive effect on population growth when population size is small and not when it is large
• Good when mutualist is far away from their carrying capacity but at the carrying capacity, there is no more resources left for population growth
host associated microbiomes
diverse commuities of microbes that live on or inside most plant and snimal hosts
Chracterisaton of microbial diversity in a host
1. sequencing-based methods
2. principle of component analysis
Metapopulation
a collection of spatially distinct populations that are connected via dispersal
Lewin's patch occupancy model
models the rate of change in patch occupancy over tine in a differentil equation
metacommunity
set of local communities linked by the dispersal of one or more of their constituent species
What determines the number of species on an island
1. colonization
2. extinction
3. in-situ speciation
Infared wavelength
short wavelength passed through atmophere
The effect of climate change to organisms
1. acclimate
- phenotypic plasticity
2. adaptation
3. migrate
4. extinct
Theory of evolution
1. living things change gradually over time
2. adaptations have risen through natural selection
2 meanings of adaptation
1. any trait that makes an organisms better able to survive or reproduce in a given environment
2. the evolutionary process that leads to the origin and maintenance of such traits
Macroevolution vs microevolution
Macroevolution determines the evolutionay relationships of organisms in terms of common ancestry in a long-term pattern
Microevolution is a shorter term studies that determines the particular microevolutionary processes responsible fot evolutionary change
- ex: natural selection
Why is evolution relevant
medicine
agriculture
environment
public doubts about evolution
- extremely recent understanding of science
- very personal implications
- violates literal interpretations of religious texts
Darwin's theory
- evolution occurs primarily at the population level
- variation is not determined by environment
- most fit type depends on the environment
- survival of the fitter
Changes causing evolution
1. mutation
2. natural selection
3. genetic drift
Adaptive radiation
the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage as a result of speciation
- originates from a single common ancestor
- the process results in an array of many species over short time frame
- the species differ in traits allowing exploitation of a range of habitats and resources
3 features of adaptive radiation
1. recent common ancestry from a single soecies
2. phenotype-environment correlation
3. rapid speciation
Evidence for evolution
- antibiotic resistance
- strong natural selection measured in the wild
- genomic DNA evidence for vestigal traits, etc.
- advances in geology to estimate age of rock strata
Mechanism of natural selection
1. variation
2. heredity
3. selection
Who is A.R. Wallace?
co-discoverer of natural selection
Two basic ideas of Darwin's theoy
1. all organisms have descended with modisfication from common ancestors
2. the process leading to an adaptation is natural selection operating on variation among individuals
Who is Lamarck
- depended on the idea that over the course of individual's lifetime, you can acquire characters and then pass them on to your next generation
Why was Lamarck wrong?
- inheritance only by germ cells and somatic cells
- genetic information cannot pass from soma to gametes and onto nect generation
- states genetic information flows in one direction only but nexer in reverse
Patch extinction rate
The chance that the population occupying the patch will go extinct per unit of time
Source-sink population dynamics
When one population persists stably over a long period of time while nearby populations are not stable and can go extinct
Source-sink system
If emigrants from the stable population (the source) often rescue the other population (the sinks) from extinction
microbiomes
either all the microbes living together in a community (often, a host) or their collective genomes
• Bottom-up control
abundances kept low because of resource limitation
• Top-down control
abundances kept low because of predation