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Classification
Grouping organisms/objects based on qualities they have in common (share).
Taxonomy
The science of classifying and naming organisms, classifying is helpful for these reasons:
Accurate and uniform names for organisms
Use one language(Latin) for names
Prevent inaccurate names
Binomial Nomenclature
Modern system of naming organisms, each name have two words, first word is its genus (capitalized first letter), second word is its species (all lowercase).
Ex: Homo sapien
Homo (capitalized) = Genus
sapien (lowercase) = Species
Taxon
A category into which “alike” organisms are placed
Cladogram
Diagram showing how organisms are related, based on shared, derived characteristics
Derived Characteristics
Traits unique to a group of organisms, like features, backbone, or hair
Evolution
Theory that a population or species changes over time
Species
A group of organisms that share similar characteristics that live together and can reproduce with one another to make fertile offspring: evolution can happen to this
Population
A group of individuals of the same species living together in an area: evolution can happen to this
Natural Selection
Individuals with traits that better allow them to interact with their environment, survive, and reproduce more successfully than those that do not have those traits
Over time, you will see an accumulation of favorable traits across generations, and more of these traits will be seen in the population, and this will change which traits are most common in a population, as well as increase the species’ chance of survival
Fitness
an organism’s ability to survive, reproduce, and pass on its genes to the next generation
Acquired Traits
Traits gained during your lifetime, not coded for in DNA, can not be passed down
Principles of Natural Selection
Variation
Competition
Overproduction of Offspring
Adaptation/Descent with modification
Variation
Variety (different) versions of traits that exist in a population
Ex. different hair colors, heights
Overproduction of offspring
Organisms producing more offspring than the environment can support, some will live and others will die, with their traits playing a role in this
Competition
Created by over production, and when there’s not enough resources it leads to fights for resources, some traits allows for organisms to get resources more easily.
Adaptation
Advantageous traits will accumulate in the population, beneficial traits become more common, and vice versa. Over time, future generations begin to look different from past generations.
Any traits that improve an individual’s ability to survive and reproduce in a particular environment it is inherited, and all species have experienced adaptation and will continue to slowly adapt as the next generations are born.
Artificial Selection
Nature provides the variety and HUMANS determine which traits are the preferred ones
Bell Curve Graph
This is a graph for a single trait; the most common version of the trait is at the top, while the less common versions are the curve's edges. Environmental changes will change the bell curves by moving the peak of the curve, widening/narrowing the bell, or both.
Directional Selection
A less common version of the trait is the best fit, shifts the peak of the bell left or right
Ex. Human height
Stabilizing Selection
Most common trait in the population is the best fit, this increases the height of the peak and narrow the bell
Ex. woodchucks with midtone fur colors
Disruptive Selection
Two opposing forms of the traits are both more common for a population, this results in two peaks on opposite sides of the graph. Not as common, but usually seen with a group isolated into two and both exposed to different pressure, but still are the same species.
Evidence for evolution
Anatomical structures
Embryological development
Molecular Similarities (DNA)
Paleontology
Homologous Structures
Body parts that have the same structures but different functions
Ex. Forelimbs of human, bat, cat, alligator, etc
Evidence of a common ancestor
Analogous Structures
Body parts that have different structures but same functions
Ex. Butterfly wing/bird wing
Evidence of similar environmental pressures/natural selection
Vestigial Structures
Present, unused(nonfunctional) organism
Ex. tailbone
Evidence of common ancestors, natural selection, change over time
Embryological Development
Different organisms can share developmental stages or anatomical features during development, suggesting a common ancestor. The more they are closely related, the more commonalities during development.
Molecular Similarities (DNA)
The more they are closely related, the more similarities they will have in gene sequences, the more gene similarities, the more similarities in a.a. sequences for the same proteins. Therefore, having more proteins in common, this evidence is more specific and accurate than structural features.
Paleontology
Study of prehistoric life by comparing current and extinct species to show change or get clues about past environments and see how organisms change
Biogeography
Study of the distribution of fossils in comparison to similar species that exist currently
Shows that newer, slightly different species exist in the same areas that prehistoric versions of those same species used to exist.
Fossil Record
Incomplete, as many do not form fossils, over time we see that organisms became increasingly complex
Physical Adaptations
Changes to body structures that allow an animal to find and consume food, defend itself, and reproduce. Helps an animal survive in its environment
Behavioral Adaptations
The way an animal acts or behaves to stay alive. Allows for animals to respond to life needs
Instinctive Behaviors
A group of behavioral adaptations. Happen naturally (passed on genetically) and don’t need to be taught or learned
Learned Behaviors
A group of behavioral adaptations. Comes from experience and are not present in an animal at its birth. They are not born knowing how to do these things.
Genetic Drift
Chance event, and changes genes that make up a population
Not influenced by fitness, environment, or whether the allele is beneficial
Affects small populations more
Things that enhance the effect of this:
Bottleneck effect - population size is reduced a lot
Founder Effect - a new colony started by only a few members of the original population
Gene Flow
Genes move into or out of a population, can remove an entire gene/trait
Ex. Migration
Non-Random Mating
A trait that increased mating success is more likely to get passed down as organism chooses their mate
Mutation
Changes in DNA can add or remove alleles
Genetic Equilibrium
Happens when natural selection isn’t
No changes in the allele frequencies, population is not changing
This only happens if certain conditions are met, natural selection is NOT one of them
Speciation
One species becomes two separate/distinct species, both populations become separate, no flow of genetics between them
Geographic Isolation
One population is divided in two by a physical barrier, like canyon, mountain range, sand bar, river, etc.
Reproductive Isolation
Two groups can no longer interbreed
Behavioral Barriers
Differences in mating behaviors (mating dances, mating calls, locations they mate in)
Timing Barriers
Differences in mating times that keep organism from mating (times of year, times of day, etc)
Gradualism
Small changes in a species over a long period of time
Punctuated Equilibrium
Long periods of little to no change, interspersed with abrupt changes
Convergent Evolution
Unrelated species, in the same types of environments, evolve the same traits
Divergent Evolution/Adaptive Radiation
Closely related species become increasingly different as small changes accumulate in different environments.
Diference is time scale:
divergent - species becoming very different from ancestors over long time; adaptive
radiation - smaller changes in a shorter time span
Co-evolution
2 or more species that live in close proximity and interact, change in response to each other
Extinction
A species all die and there are no longer any alive on the planet