Bio quiz- evolution

**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 s**mall 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)

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* 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

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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