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

what is life?

what is life?

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

hypothesis

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

panspermia

-all seeding, greek root

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.

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

self assembly in nature

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

LUCA

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

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

where was LUCA formed

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

5 kingdoms of life

-bacteria
-animals
-plants
-fungi
-protists

extremophiles

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

archaea vs bacteria

-both unicellular prokaryotes

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

phylogeny

-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

eucaryotes

-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

when was the first evolutionary tree

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

taxonomy

-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

alexander von humboldt

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

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

evolution

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

population

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

microevolution

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

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)

creationist

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

plato

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

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

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

lamarck

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

adaptation

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

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

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

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

palaeontology

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

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)

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

principles of geology

-charles lyell
-<b>fundamental concepts that form basis of understanding geological history and processes</b>

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

1st fossils in argentina

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

galapagos observations

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

origin of species

1859
-Charles Darwin's book explained how various species evolve over time and only those with advantages can survive and reproduce

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

louis pasteur

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

alfred russel wallace

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

genotypes

-genetic composition of an individual organisms DNA

phenotypes

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

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

heritable trait

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

phenotype differences

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

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

evolutionary fitness

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

physical fitness

-physically fit but not evolutionary fit if no children produced

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

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

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

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

2 ways sexual selection can occur

-intersexual selection
-intrasexual selection

intersexual selection

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

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

direct benefit

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

indirect benefits

-benefits that affect the genetic quality of the female offspring

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

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

synapomorphies

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

what is the most currently widely used evidence in creating phylogenies

DNA sequences

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

fossils

what provides evidence of ancestor/descendant relationships

-comparative anatomy and embryology

cladistics

-seires of principles that define a clade

clade

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

monophyletic group

-common ancestor and all known descendants

cladogram

-evolutionary tree

homology

-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

homoplasy

-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

morphological species concept

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

-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

biological species concept

-<b>define species based on their ability to interbreed and produce viable fertile offspring</b>
-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

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
-<b>define species based on evolutionary relationships and genetic divergence</b>
-<b>focuses on evolutionary history</b>
-<b>applicable for both sexual and asexual organisms</b>
-usually based on fossils and especially DNA differences

classical speciation models

-allopatric speciation
-sympatric speciation

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)

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

2 types of breeding barriers

-prezygotic barrier
-posyzygotic barriers

pre zygotic barrier

-prevent sperm and egg from meeting and producing a zygote

-ex. gametic isolation

post zygotic barrier

-follow successful fertilization but reduce hybrid viability or fitness

-hybrids have reduced viability or sterility

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)

ancestral trait

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

character state

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

convergent evolution

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

derived trait

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

divergent evolution

-pattern of evolution which closely related species evolve different traits

in-group

-specific group that are the primary focus to study

outgroup

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

sister taxa

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

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

genetic divergence

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

hybrids

-show mixtures of traits from crossing of 2 different species

niche

-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

allopolyploid speciation

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

allopolyploid

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

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

hybridization

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

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

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

gene pool

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

null hypothesis

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

alternate hypothesis

-statement that the factor being investigated will have an effect

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