Studied by 1 person
Antibiotic resistance
Taking an antibiotic creates an environment where the antibiotic kill bacteria
The selective pressure is to survive the antibiotics
- Because bacteria reproduce very quickly, mutations also happen
One of these mutations might help the bacteria resist the antibiotic
- Bacteria with this mutation survive, and have higher fitness and multiply
biological species
A group of similar individuals that can reproduce and produce fertile offspring
Reproductive isolation
- the inability of a species to breed successfully with related species due to these differences
Geographical
Physiological
Genetic
Temporal (time)
Stages in species formation
Gene flow is the transfer of genetic material from one population to another
Gene flow takes place between two populations of the same species through migration
New species form when different types of isolation and different amounts of gene flow take place as two populations separate
When there is no gene flow a new species forms
Gradualism
assumes that populations slowly diverge from one another by accumulation adaptive characteristics in response to changing selection pressures
If species evolve by gradualism there should be transitional forms seen in the fossil record
Gradualism in whales
Whales common ancestor was a 4 legged hoofed mammal
Whales started to find success in the water
started to develop traits that helped them live an aquatic lifestyle (fins, tails, less legs)
GRADUALLY becoming more like modern-day whales
Punctuated equilibrium
Most of a species existence is spent in stasis and little time is spent in active evolutionary change
Species stay in stasis and then have short bursts of evolution that produce new species rapidly
Punctuated equilibrium is an opposing theory to gradualism
States that genetic and physical changes that give a survival advantage will be amplified quickly in small populations
Populations are in stasis because small changes in a large population become diluted and made uniform
Generally, rejection of mates with unusual attributes
Stasis
A period of evolutionary stability or when populations stay the same
Punctuated equilibrium ( on peppered moths)
Before the industrial revolutions, black pepper moths were rarer than white peppered moths (stasis)
Environmental factors then forced a rapid change to the balance of white vs black moths (Punctuation)
Punctuated equilibrium (small summary and rebuttal)
The theory emerged because of fossil gaps
If gradualism did happen then why are there no fossils?
Punctuated equilibrium explains this fossil gap by saying that these intermediate forms evolved too quickly to leave behind fossils
CRITICISM:
Fossil record can just be incomplete
Intermediate forms are found in some places
Theory of stasis is poorly understood
Gradualism vs punctuated equilibrium
Both theories are about the rate new species emerge
Gradualism places impotence on the slow appearance of new subspecies that lead to a new species
Punctuated equilibrium states that speciation occurs in a population over a short period and then is stasis.
coevolution
The process of reciprocal evolutionary change that occurs between pairs of species or among groups of species as they interact with one another
The evolution of one species affects the evolution of another
The activity of each species that participate in the interaction applies selection pressure on the others
The term usually applies to “positive” interactions but can apply to “negative” ones
Positive examples of Coevolution
Plants and their pollinators are so reliant on one another that sometimes their relationships are nearly exclusive
Biologists think that matches between the two are the result of a coevolutionary process
Ex: different species of hummingbirds have differently shaped beaks that evolved to allow them to drink from a certain kind of flower. In return the flower species it feeds from has evolved to produce nectar especially tasty to hummingbirds.
Coevolution: Predator vs prey
Predators and prey often influence each other:
The emergence of faster prey selects for faster predators
This in turn also selects for faster prey
The result is the cheetah and gazelle
While not exactly predator and prey, giraffes and acacia trees are other examples of coevolution
Trees began to grow taller and developed thorns to avoid being eaten
Giraffes became taller and taller to eat the trees
Giraffes also have tough tongues to ignore thorns
Relative dating in Fossils
Two methods can be used to determine the age of fossil
Relative dating allows scientists to determine the age of a rock or fossil relative to another. It DOES NOT give an exact age
law of supoerposition
Law of superposition
older fossils on the bottom, younger on the top
Radioactive dating
Shows the age of a fossil based on the amount of certain radioactive isotopes present (different isotopes for different ages)
Half-life
Radioactive dating uses naturally occurring radioactive isotopes to provide an age for a rock or fossil
Radioactive dating requires 2 pieces of info
TThe rate at which the isotope decays
How much of the isotope if left in the fossil
The rate at which half of the isotope degrades is called the half-life
evolution
the heritable genetic changes seen in a population (note: mr kolbert has a ferret) (also he said to make sure to know that population is the amount of THE SAME ONE SPECIES) over time
natural selection
organisms that are better adapted to their environment tend to survive and produce more offspring, which passes on the genes that aided their success
selection pressure
Anything that reduces the reproductive success of a proportion of the population
External things which affect an organism’s ability to survive and reproduce
Selection pressure is usually expressed as a measure of the fitness of a particular trait relative to others in the population
(The contribution that organisms with a particular trait make to the next generation)
artificial selection pressure
The identification by humans of desirable traits in plants and animals and the steps taken to enhance and perpetuate those traits in the future.
Artificial Genetic passing (Breeding)
Bad and good life quality; not necessarily beneficial for the wild, but is desirable for humans
adaptation
a heritable behavioral, morphological, or physiological trait that maintains or increases the fitness of an organism
Adaptations are anything heritable that makes an organism better at surviving to reproduce
Could be behavior or physical (Like birds migrating is a genetic behavioral adaptation)
fitness
Reproductive success: how good an organism is at maximizing the number of surviving offspring
Fitness is a measure of how well suited an organism is to survive in its habitat and its ability to maximize the numbers of offspring surviving to the reproductive age
What determines Fitness
Itnees represents how good an organism is at producing offspring
But what determines an individuals fitness.
speciation
the formation of new and distinct species in the course of evolution
microevolution
small-scale evolutionary changes that occur within a population over a relatively short period of time
ex. the development of antibiotic resistance in bacteria
macroevolution
large-scale evolutionary changes that occur over long periods of time, resulting in the formation of new species, genera, families, and higher taxonomic groups.
ex. evolution of dinosaurs
ex. fish to reptiles
darwin’s four points
More offspring are produced than survive
Individuals show variation: some variations are more favorable than others
Natural selection favors the best-suited traits at the time
Variations are inherited. The best-suited variants leave more offspring. The population changes over time.
Allopatric speciation
Reproductive isolation happens through a real-life geographic barrier
Sympatric Speciation:
reproductive isolation happens without a geographic barrier
ADAPTIVE RADIATION
-the process by which a single ancestral species evolves into a wide array of descendant species that are adapted to a variety of ecological niches
-occurs when a group of organisms colonizes a new, relatively unoccupied area and undergoes rapid diversification to exploit the available resources.
ex. finch species on the Galapagos Islands
