BISC 102 midterm (imported from quizlet, credit to yujinn110)

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what is life?

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what is life?

-carbon based cellular structures with controlled energy conversion (metabolism), ability to replicate, store, and process information, with variations= ability to evolve

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-testable statement to explain a phenomenon or set of observation
-"all cells come from pre existing cells"

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-all seeding, greek root

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panspermia hypothesis

-life originated elsewhere in the universe, and was seeded on earth from space from comets, asteroids, or other cosmic sources

-amino acids are scattered in space, found in comets, dust clouds, etc.

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Stanley miller and harold urey

-scientists who formed amino acids and other simple organic compounds in a laboratory experiment
-published 2 page paper in science

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self assembly in nature

-based on known physical and chemical principles
-ex. crystals, snowflakes, clouds, protein folding

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-last universal common ancestor
-most recent common ancestor of all current life on earth
-suggest common ancestry for all living organisms
-what follows survival for LUCA is what charles darwin called descent with modification

-basic genes shared by 3 domains (bacteria, eukaryotes, archaea)
-was probably ancestor of archaea

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where was LUCA formed

-near earth's hydrothermal vents where energy, raw materials, and other key conditions are present in seawater

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5 kingdoms of life


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-found in extreme environments like hot springs, animal guts
-ex. certain organisms like thermophiles

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archaea vs bacteria

-both unicellular prokaryotes

-different in biochemistry though: cell wall, membrane composition, etc.

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-history of the evolution of a species or group

-tree based on evolutionary relationships of 3 domains of life
-based on genetic sequence of rRNA
-ancient form of RNA that all life forms in the 3 domains share

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-have larger, more complex cells than prokaryotes with membrane bound nuclei and organelles
-more closely related to archaea than bacteria

-all have rRNA inside cells
-animals, fungi, land plants are most common eukaryotes seen by humans

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when was the first evolutionary tree

-charles darwin in 1837
-drew this before publishing origin of species in 1859

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-branch of biology concerned with the classification, identification, and naming of organisms based on their shared characteristics and evolutionary relationships

-major different types of organisms within 3 domains are grouped within phyla
-all organisms have binomial name (genus and species name)
-linnaean created binomial naming system

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alexander von humboldt

-german scientist
-has a lot of things named after him
-ex. calamari, squid, towns, etc.

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central dogma of biology

-DNA -> RNA -> Protein
-describes flow of genetic information within biological system
-based on discovery of structure and function of DNA double helix by watson and crick

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-change in genetic characteristics of a population overtime
-usually small changes but demonstrated to form new species and higher categories

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-group of individuals of same species living in same area at same time
-individuals within population do not evolve, only the population can evolve

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evolutionary change within a species or small group of organisms, especially over a short period (especially viruses)

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darwins 2 key insights

-explained how biodiversity came to be a mechanism (natural selection acting on variations)
-documented many examples from both natural and artificial selection (plants and animals are products of descent with modification)

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-belief that a deity created the universe and all life forms by supernatural means

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-claimed that every organism was an example of perfect essence or type created by god, these types were unchanging

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typological thinking

-based on ideas that species are unchanging types and that observable variations within species are unimportant noise to understanding origin
-view nature as static and unchanging, with organisms existing in predetermined forms that do not vary over time or across populations

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great chain of being (scale of nature)

-Aristotle ordered organisms into linear:

-species were fixed types
-organized into sequence based on increasing size and and complexity
-sequence started with minerals, lower plants, and humans top of chain

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-life drive from simple to complex
-proposed the first but flawed evolutionary theory

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-process by which organisms evolve traits/characteristics that enhance their survival and reproductive success in particular environment

-occurs in individual through inheritance of acquired changes through needs and use/disuse

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evolution by natural selection

-population instead of typological/individual thinking of Lamarck

-claimed that inherited variations among individuals in a population are key to understanding evolution
-phylogenetic tree

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phylogenetic tree

-tree like structure that represents evolutionary relationships among group of organisms or taxa
-shows pattern of descent of different species or groups of organisms from common ancestors
-based on homologous traits

-lineage of organisms changes overtime by natural selection acting on ancestors and their descendants

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-study of fossils and had profound impact on early evolutionary thinking

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beagle voyage

-royal navy ship
-Darwin documented geological phenomena that supported Lyell's views
-documented patterns that suggested common ancestry of species (Rhea/mocking birds/finches/tortoises)

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voyage of the beagle

-main purpose was to map coast of SA and voyage around the world
-darwin started at 22, collected many fossils and living organisms, also studied earth while reading principles of geology

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principles of geology

-charles lyell
-fundamental concepts that form basis of understanding geological history and processes

-natural processes observable today were also responsible for events in the past, volcanoes, earthquakes, floods, erosion

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1st fossils in argentina

-discovered fossils of giant extinct sloths, armadillo relatives, and camel family relatives

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galapagos observations

-great number of aboriginal creations
-variation of same species among islands
-gradation and diversity among birds

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origin of species

-Charles Darwin's book explained how various species evolve over time and only those with advantages can survive and reproduce

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darwins 4 postulates

individual variation: Individuals within a species vary in their traits (characteristics)
-inheritance: Traits are inherited by offspring from their parents
-overproduction: More individuals are born than can survive in a stable population
-competition: Individuals compete for resources

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louis pasteur

-discovered that heat could kill bacteria that otherwise spoiled liquids including milk, wine, and beer
-spontaneous generation

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alfred russel wallace

-a naturalist who had the same thoughts on evolutionary change as Darwin

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-genetic composition of an individual organisms DNA

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-physical expression of genotype
ex. structural, biochemical, etc.
-referred to as physical characteristics or traits

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natural selection

-process that sorts the phenotypes of a population
-proposed by darwin
-described the process by which organisms with advantageous traits or characteristics are more likely to survive and reproduce, leading to gradual change of populations overtime*

-also sorts the underlying genotypes
-can act on any heritable trait

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heritable trait

-feature of an organism that is passed down from parent to offspring through genetic inheritance
-traits are determined by genes
-ex. eye colour, hair colour, heigh, disorders, etc.

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phenotype differences

-physical or structural differences
-physiological and biochemical differences
-developmental patterns (embryology)

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2 conditions for natural selection

-there is heritable (genetic) variation
-the variation results in fitness differential (advantage/disadvantage to reproduction in the current environment); that trait will evolve in that population by natural selection

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evolutionary fitness

-individuals contribution of genes to the next generation
-genes contributed to the next generations determine the evolutionary fitness of an individual

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physical fitness

-physically fit but not evolutionary fit if no children produced

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homologous traits

-similar structures in descendant organisms can be explained as resulting from inheritance from common ancestor

-homology of forelimb bones, among many others, of tetrapod's

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misconceptions about natural selection (corrections)

-individuals cannot evolve, only populations of species can evolve
-individuals dont select which genes to pass on
-selection is adaptive, but mutations and genetic drift occur randomly
-natural selection is not purposeful

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sexual dimorphism

-distinct difference in size or appearance between the sexes of an animal in addition to difference between the sexual organs
-origin of secondary dimorphism is sexual selection

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runaway sexual selection

-preference for a particular trait in one sex leads to the exaggerated development of that trait in the other sex over successive generations

-ex. females continue to choose mates with longer tails, males with increasingly exaggerated tails have a better chance of mating and passing on their genes
-creates loop where the trait becomes more and more exaggerated with each generation

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2 ways sexual selection can occur

-intersexual selection
-intrasexual selection

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intersexual selection

-mate choice is made by females
-male ornaments that females like increase probability of mating

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intrasexual selection

-direct competition of mates by males
-within 1 sex
-male male competition
-development most extreme in polygamous species
-male armaments dominate rather than ornaments

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direct benefit

-may benefit the female direction
-ex. best food access, best nest sites, protection of a strong mate

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indirect benefits

-benefits that affect the genetic quality of the female offspring

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sexy son hypothesis

-females may select males with attractive characteristics with expectations that the quality genes will be on their sons who will likely have more breeding success than their competitors

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pros and cons of classic taxonomy

-pros: useful for creating and organizing groups, people have used it since evolving

-cons: limited information about evolutionary relationships within and between groups

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-traits unique to a group
-ex. hair on mammals, unique inner ear bones of all cetaceans

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what is the most currently widely used evidence in creating phylogenies

DNA sequences

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what is the key evidence for history of life on earth, extinction, and evolution


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what provides evidence of ancestor/descendant relationships

-comparative anatomy and embryology

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-seires of principles that define a clade

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-group of organisms that meets the requirements of sharing evolutionary relationships

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monophyletic group

-common ancestor and all known descendants

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-evolutionary tree

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-if traits inherited from common ancestor even though they may appear different (after descent with modifications)
-provide information about shared ancestry and are useful for building trees

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-traits may appear similar but are not inherited from a common ancestor
-result of convergent/parallel evolution
-not useful for tree building and are misleading if listed as homologies

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morphological species concept

-method used in taxonomy to define species based on their physical characteristics
-individuals belong to the same species if they share similar anatomical features

-ex. if two birds look alike, have similar body shapes, and share similar color patterns, they are likely considered members of the same species
-morphospecies share distinctive phenotypic characteristics

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biological species concept

-define species based on their ability to interbreed and produce viable fertile offspring
-proposed by ernst mayr
-individuals that can interbreed and produce viable, fertile offspring are considered members of the same species
-principles include: reproductive isolation, gene flow, hybridization

-ex. horses and donkeys can mate and produce offspring (mules), but mules are sterile, so horses and donkeys are considered different species
-this concept cannot be applied to fossils or asexual organisms, including bacteria and archaea

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phylogenetic species concept

-organisms that share a common evolutionary history and are genetically distinct from other groups are considered members of the same species

-ex. two populations of plants may look similar but have distinct genetic differences due to separate evolutionary histories, leading them to be classified as different species
-define species based on evolutionary relationships and genetic divergence
-focuses on evolutionary history
-applicable for both sexual and asexual organisms
-usually based on fossils and especially DNA differences

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classical speciation models

-allopatric speciation
-sympatric speciation

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allopatric speciation

-species is split into separate geographically isolated groups either by dispersal of individuals or by vicariance (barriers arise between populations) like new rivers, mountains, etc.
-geographic isolation leads to genetic divergence which may lead to reproductive isolation (speciation)

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sympatric speciation

-species diverges into 2 groups within the same geographical area where they could meet and mate
-organisms in the same lake may diverge in colour, behaviour, or food preferences, leading to reproductive isolation

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2 types of breeding barriers

-prezygotic barrier
-posyzygotic barriers

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pre zygotic barrier

-prevent sperm and egg from meeting and producing a zygote

-ex. gametic isolation

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post zygotic barrier

-follow successful fertilization but reduce hybrid viability or fitness

-hybrids have reduced viability or sterility

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gametic isolation

-only sperm from the same species is able to successfully fertilize the egg (biochemical barriers)
-this is important in species with external fertilization (sea urchins)

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ancestral trait

-characteristic or feature that is present in a common ancestor of a group of organisms and its descendants

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character state

-specific form or variation of a characteristic or trait within a group of organisms

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convergent evolution

-unrelated or distantly related organisms independently evolve similar traits in response to similar environmental pressures

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derived trait

-characteristic or feature that is present in specific group of organisms but not in their common ancestor

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divergent evolution

-pattern of evolution which closely related species evolve different traits

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-specific group that are the primary focus to study

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-group of organisms that are closely related to the in group
-are not the primary focus

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sister taxa

-2 or more taxa that are each others closest relatives in a phylogenetic tree

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genetic isolation

-phenomenon where populations of organisms become genetically distinct and are no longer able to interbreed and produce viable, fertile offspring
-2 types, postzygotic barrier and prezygotic barrier

-prevents gene flow between populations, leading to genetic divergence and potentially the formation of new species over time

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genetic divergence

-mutation, selection, and genetic drift in isolated populations cause divergence
-accumulation of genetic differences between populations of organisms over time

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-show mixtures of traits from crossing of 2 different species

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-range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions
-role or position that an organism occupies within its environment, including how it interacts with both living and non living factors

-not the habitat where a species lives, but more of a functional role

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allopolyploid speciation

-occurs when two species hybridize and give rise to a new species

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-a species with multiple sets of chromosomes derived from different species

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adaptive radiation

-process in evolutionary biology where a single ancestral species rapidly diversifies into a variety of new forms, each adapted to different ecological niches

-ex. finches in the Galápagos Islands, which diversified into multiple species with different beak shapes and feeding habits adapted to various food sources

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-process by which individuals from 2 different species interbreed
-results in offspring with genetic material from both parental species

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gene flow

-movement of genes/alleles from one population to another through interbreeding or exchange of gametes between individuals
-occurs when individuals rom different populations migrate, mate, and produce offspring

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directional selection

-type of natural selection which individuals at one extreme of a phenotypic range have a higher fitness than individuals with opposite phenotypes
-results in shift of frequency in trait

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gene pool

-complete set of genes including all the different alleles within population of particular species

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null hypothesis

-statement that the factor being investigated will not have an effect

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alternate hypothesis

-statement that the factor being investigated will have an effect

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statistically significant difference

-finding in data analysis that indicates the observed difference between groups/conditions is unlikely to have occurred by chance
-suggests that the different is real, not random

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