BIOL 3010 exam 1

evolution

any change in the inherited traits of a population that occurs over a time period longer than the lifetime of an individual (over a generation)

fossil

preserved evidence of life from a past geological age, including impressions and mineralized remains of organisms embedded in rocks

genetic drift

a mechanism that can lead to evolution, due to random changes in the genetic composition of a population from one generation to the next

genus

a grouping that includes multiple species

homology

a characteristic that is similar in two or more groups of organisms because it is inherited from a common ancestor

lineage

a chain of ancestors and their descendants.

mutation

any change to the genetic sequence of an organism

natural selection

a mechanism that can lead to evolution, whereby differential survival and reproduction of individuals cause some genetic types to replace (outcompete) others

phenotype

an observable and/or measurable aspect of organisms, such as physical structure, physiology, and behavior

morphology

referring to the form and structure of organisms

phylogeny

a visual representation of the evolutionary history and relationship among biological entities (can be genes, organisms, populations, species, larger groups)

synapomorphy

a form of a trait that is shared by a group of related species (that is, one that evolved in the immediate common ancestor of the group and was inherited by all its descendants)

branch

a lineage evolving through time that connects successive speciation or other branching events

character

a heritable aspect of organisms that can be compared across taxa

clade

a branch or groups of branches representing an organism and all of tis descendants

convergent evolution

the independent origin of similar traits in separate evolutionary lineages

evolutionary reversal

the reversion of a derived character state to a form resembling its ancestral state

exaptation

a trait that initially carries out one function and is later co-opted for a new function; the original function may or may not be retained

homoplasy

a character state similarly not due to shared descent

monophyletic

describing a group of organisms that form a clade

node

a point in a phylogeny where a lineage spits (a speciation event or other branching event, such as the formation of subspecies)

outgroup

a group of organisms (for example, a species) that is outside of the monophyletic group being considered

paraphyletic

describing a group of organisms that share a common ancestor, although the group does not include all the descendants of that common ancestor

parsimony

a principle that guides the selection of the most compelling hypothesis among several choices; that requiring the fewest assumptions or steps is usually (but not always) best

phylogeny

a visual representation of the evolutionary history of populations, genes, or species

polyphyletic

describing a taxonomic group that does not share an immediate common ancestor and therefore does not form a clade

polytomy

an internal node of phylogeny with more than two branches (that is, the order in which the branchings occurred is not resolved)

synapomorphy

a derived form of a trait that is shared by a group of related species (that is, one that evolved in the immediate common ancestor of the group and was inherited by all its descendants)

taxon

a group of organisms that a taxonomist judges to be a cohesive unit, such as a species or order

why do mammals like whales and dolphins live in water and look like fish?

ancestors were terrestrial mammals and evolved adaptations for aquatic life

if a leaf imprints in concrete, is that a fossil?

NO, because it is not preserved evidence of life from a past geologic age

transitional fossil

a fossil of an organism that has characteristics of both its ancestors and descendants. these connect past forms with present time species

whales look like fish how?

convergent evolution giving rise to analogous structures

what are characteristics of cetaceans that are shared with fish

aquatic, body shape adapted for swimming

what are characteristics of cetaceans that are shared with mammals

lungs, live birth, placenta, mammary glands

18O/16O ratio in seawater versus freshwater

higher ratio in seawater

what is life

1. made of one or more cells

2. store, use, and transit genetic info

3. acquire, transform, and use energy and matter (metabolism)

4. sense stimuli and respond to the environment

5. adjust their internal environment to maintain a stable equilibrium (homeostasis)

6. able to grow and reproduce

7. ability to evolve

prebiotic soup

a pool of organic molecules suspended in water on the early earth that grew richer in complexity over time (including nucleic acids and proteins)

DNA or RNA first

RNA. they have the ability for self-replication

multicellularity arose independently in different lineages of eukaryotes. what are the lineages?

animals, fungi, protists, plants

what are not under the eukaryotic class

bacteria and archaea

sequence of critical evolutionary events

1. the origin of self-replicating information-carrying molecules

2. the transition from RNA as both catalyst and genetic materials, to DNA as genetic material and RNA as a messenger for the synthesis of proteins

3. the origin of the first cells (prokaryotes: bacteria)

4. the origin of eukaryotic cells

5. the evolution of sexual reproduction

6. the evolution of complex multicellularity in eukaryotes

7. the evolution of social groups

clades aka

monophyletic group

features aka characters can have different conditions and therefore are called

character states

homology vs homoplasy

homology = derived from a common ancestor

homoplasy = common ancestors did not have these traits (aka analogous aka convergent evolution)

the principle of parsimony

choose the simplest scientific explanation. the preferred hypothesis is the one that requires the fewest evolutionary changes

why can two organisms/species have similar character states

1. the state was inherited from a common ancestor with that state

2. the state was evolved independently in each of the two groups

what are the three flavors of homoplasy

1. convergent evolution = two lineages that begin with different traits evolve a similar characteristic independently of one another

2. parallel evolution = two lineages independently evolve the same set of changes, starting from similar ancestral character states (the same set of underlying genes were involved)

3. evolutionary reversal = a lineage evolves toward one of its ancestral traits, effectively losing a more recently evolved trait

cladogram

where branch length is arbitrary, only relative info is available on when branching events occured

trees with base subsitutions per site

branch length is proportional to the extent of genetic difference; based on molecular evidence

trees with years

phylogeny based on morphology, with the addition of fossil-dating; node positions reflect estimated time of divergence

molecular phylogeny uses what evidence

DNA, RNA, protein sequences

in DNA/RNA, each nucleotide represents how many possible character states

4

in protein, each amino acid represents how many possible character states

20

maximum parsimony is supported by what statistical evidence

(favors the simplest explanation) uses bootstrapping analysis

distance matrix

clusters taxa based on genetic distance

maximum likelihood and bayesian methods

rely on given knowledge of how molecular evolution works (rates of mutation of different genomic regions)

what is the difference between maximum likelihood and bayesian methods

maximum likelihood determine the probability of the data given a hypothetical tree. Bayesian determines the probability given a particular data set

what is the molecular clock

when mutations may build up in any given stretch of DNA at reliable rates (changes per base pair per billion years)

what is adaptive radiation

exceptionally rapid diversification into a variety of lifestyles or ecological niches

when can adaptive radiation occur

in the absence of competition

key innovations

the emergence of new traits in a clade

causes of extinction

decimated by predators, natural events, environmental changes disrupting the habitat/resources

background extinction

extinction at a constant rate

mass extinction

events that caused a statistically significant loss in biodiversity in a relatively short amount of time

alleles

sequence variants of genes that arise by mutation

gene tree

a branched genealogical lineage of alleles of a gene that traces their evolution back to an ancestral allele

two limitations of molecular phylogenetics that confound results

incomplete lineage sorting and introgression

introgression

interbreeding indicating a closer relationship than in reality

incomplete lineage sorting

the average divergence time between genes may differ from the divergence time between species

how are isotopes used to estimate the age of earth

compare the concentration of a radioactive isotope to its decay product in a rock sample

identify methods a scientist could use to study a newly discovered fossil

scanning electron microscopy to inspect the fossilized tissues closely, radiometric dating of the fossil or surrounding rock using carbon-14, & CT scanning to image the interior of the cavities in the fossil

what factors promote fossilization

1. low levels of environmental oxygen

2. rapid burial

3. scavengers absent

4. aquatic environment

what factors inhibit fossilization

1. bacterial present

2. sun, wind, and rain

how have modern technologies since the 1900s helped paleontologists study fossilized specimens

X-ray spec and scanning e- microscopy show cellular structures in fossils, radiometric dating of rocks that surround a fossil establishes when a fossilized organism lived, CT scans give precise images of the interiors of fossilized skulls and other hollow structures

what are examples of biomarkers in fossil record

okenane, cardon isotopes in hominin’s teeth, DNA gragment in a dinosaur’s bone

what happens to a population when biological evolution takes place

a change takes place in the genetic traits passed from one generation of the population to the next

what are examples of evolution via natural selection

bacteria that are resistant to antibiotics increase in frequency in a population, penguins with heritable traits that improve swimming are better able to survive and reproduce