Marine Biology Exam 2

What is evolution?

a change in gene frequencies over time

What is macroevolution?

changes in allele frequency within the entire biota over long periods of time

What is phylogeny?

the evolutionary history of a group

What is a phylogenetic tree?

a graphical summary of the evolutionary history

What does the phylogenetic tree illustrate?

the sequence of speciation events, which taxa are more closely or distantly related, and sometimes the timing of branching events

What are synapomorphies?

shared, derived traits that evolved in a common ancestor and are present in all or most of its descendants

What is homoplasy?

when a trait is shared by different organisms but didn’t come from a common ancestor

What is the principle of parsimony?

the preferred tree is the one that minimizes the total amount of evolutionary change that has occured

What is the principle of parsimony used for?

when characters give conflicting information about phylogeny, it can be used to decide which tree most closely reflects evolutionary history

What are the three phylogenetic groups?

monophyletic, polyphyletic, and paraphyletic

What is a monophyletic group?

contains a common ancestor and all of its descendants

What is another name for a molophyletic group?

a clade

What is another name for a clade?

a monophyletic group

What is an example of a monophyletic group?

cnidarians (corals, jellyfish, anemones)

What is a paraphyletic group?

consists of an ancestor and some, but not all, of its desendants

What is an example of a paraphyletic group?

fish, includes sharks, rays, bony fish, but excludes tetrapods

What is a polyphyletic group?

consists of organisms that are grouped together but don’t share their most common ancestor within that group

What is an example of a polyphyletic group?

seaweeds

What are the patterns of macroevolution?

stasis, character change, lineage-splitting (speciation), and extinction

What is stasis?

lineages that don’t change much for a long time

What are organisms in stasis called?

living fossils

What are examples of stasis organisms?

coelacanths and horseshoe crabs

What is character change?

lineages can change quickly or slowly, in a single direction, or can reverse

What is an example in character change?

rib number in trilobite lineages

What is lineage-splitting (speciation)?

lineages splitting into separate species

What is extinction?

can be a frequent or rare event within a lineage, or it can occur simultaneously across many lineages

What are the mechanisms of macroevolution?

genetic drift and natural selection

What is genetic drift?

random changes in allele frequencies due to chance

What is natural selection?

non-random change in allele frequencies because some traits increase survival or reproduction

What are the active research questions in evolutionary theory?

does evolution tend to proceed slowly and steadily or in quick jumps and why are some clades very diverse and some unusually sparse

What is a gradualism model of evolution?

expectation of fossil record to preserve many traditional forms, documenting a slow, continuous transformational from ancestral to descendant species over long time

What is rapid burst evolution?

expect fossil records to show sudden morphological changes over short time periods, with relatively few transitional forms linking ancestral and descendant species

What does clade diversity depend on?

speciation rate and extinction rate

In what rate does a clade grow?

speciation higher than extinction

How does the clade move when speciation is more than evolution?

the clade grows

What is the rate when a clade shrinks?

speciation is less than extinction

How does the clade move when evolution is higher than speciation?

the clade shrinks

What rate does the clade stay stable at?

speciation equals extinction

How does the clade move when speciation equals extinction?

the clade stays stable

What traits increase speciation?

small body size and limited dispersal

What traits reduce extinction?

large geographic range/high dispersal potential and broad environmental tolerance

What is evolutionary potential?

the capacity of a population to evolve in response to environmental change

What are the levels of taxonomic classification?

domain, kingdom, phylum, class, order, family, genus, and species

What are viruses?

parasites that develop and reproduce only when infecting a living prokaryotic or eukaryotic cell

What do viruses consist of?

a small amount of DNA or RNA protected by an outer protein coat?

What is the outer protein coat in viruses?

capsid

What is capsid?

the outer protein coat in viruses

What are the smallest microbes?

viruses

How big are viruses?

20-200 nm

What are the building blocks of life?

carbon, nitrogen, and phosphorous

What is carbon?

the chemical backbone of living material

What is nitrogen?

a limiting nutrient of primary production

What is phosphorous?

an essential element of nucleic acids and lipids

Where does DOM come from?

half of all organic matter produced by primary producers

What is the microbial loop?

the major energy pathway where DOM isn’t lost from the system

What uses the dissolved organic matter?

bacteria and archaea

What eats bacteria and archaea?

tiny protozoans (protists)

What eats the protozoans?

zooplankton

What is the largest source of DOM?

virus activity

What is cell lysing?

viruses causing infected cells to burst and release the cells’ contents

What are prokaryotes?

the smallest and simplest independently living things on Earth

What do prokaryotes include?

eubacteria (bacteria and cyanobacteria) and archaea

What are prokaryotic cells enclosed by?

a protective outer cell wall

What is the cell wall in prokaryotes?

the outer protection

What do prokaryotes lack?

a nucleus and membrane bound organelles

What is photoautotrophy?

using photosynthetic pigments to trap light energy to manufacture organic compounds

What is chemoautotrophy?

deriving energy from chemical compounds to manufacture organic compounds

How big are bacteria?

about 1 micron long

What is ubiquity?

found everywhere

What is the ecological role of bacteria

important part of microbial loop, consuming DOM released when viruses lyse cells, passing energy up to protozoans

What else in cyanobacteria called?

blue-green algae

What group are cyanobacteria in?

photosynthetic bacteria

What is the most abundant photosynthetic organism in the ocean?

prochlorococcus

What is among the first photosynthetic organisms on Earth?

cyanobacteria

What are stromatolites?

calcareous mounds formed by cyanobacteria

What is the ecological role of cyanobacteria?

accumulation of oxygen in atmosphere

What is symbiotic bacteria?

bacteria evolved to live in close association with other marine organisms

What is mutualism?

interactions where both parties benefit

Where are bacteria sheltered in other organisms?

in special tissues or organs

What are archaea?

prokaryotic microorganisms once thought to be bacteria but now recognized as being more closely related to eukaryotes

What where archaea first known as?

extermophiles

What is extremophily?

living in extreme environments

What is the ecological role of archaea?

not well understood

What are eukaryotes?

cells that have membrane-bound nuclei

What are protists or protozoans?

unicellular eukaryotic organisms

What is autotrophy?

plank-like

What is heterotrophy?

animal-like

What are the plank-like protists?

diatoms, dinoflagellates, and coccolithophores

What are diatoms?

cells enclosed by cell wall of silica and form a glassy shell or frustule

What are the small holes in frustule for?

allowing water and nutrients in and out

What is the ecological role of diatoms?

important primary producers in temperate and polar zones?

What percentage of global photosynthetic fixation of carbon do diatoms account for?

20%

What are dinoflagellates?

cell wall armored with plates of cellulose with spines, pores, etc.

What do dinoflagellates have?

two flagella

Where are the flagella of dinoflagellates located?

around the groove of middle of cell and trailing

What is the purpose of the middle flagella?

forward motion and spinning

What is the purpose of the trailing flagella?

propulsion

What is the ecological role of dinoflagellates?

important primary producers in tropical and subtropical zones

What are dinoflagellates often responsible for?

harmful algal blooms

What are coccolithophores?

flagellated, spherical cells, covered with coccoliths plates made of calcium carbonate