chapter 3: Biological Systematics and the Diversity of Life

Biological systematics

science of organizing life: describing, naming, and categorizing all the different kinds of living things.

taxonomy

which is the describing and naming of living things

classification

organizing of living things into different groups

phylogeny

ancestry of living things

taxon

the name assigned to a particular grouping of living things, of whatever inclusiveness

monophyletic group or clade

all of the species that descended from the same common ancestor

what year did Aristotle publish Historia animalia

350 BCE

what year did Carl von Linné establish the formal framework of our current taxonomic system in his great work Systema Naturae

1735

what year did Charles Darwin lay out the theory of evolution in On the Origin of Species

1858

what year was discovery of the structure of DNA by James Watson and Frances Crick

1953

what year was Robert Whittaker’s wildly successful Five Kingdoms of Life model published

1969

what year did Neil Armstrong walk on the moon

1969

Plantae

the land plants

Animalia

animals

Protista

all the other eukaryotes, including various algae & almost all the single-celled forms

Monera

all the prokaryotes

monerans actually contain

two entire domains of life, with dozens of proper kingdoms in each

protists include..

numerous monophyletic kingdoms, all as different from each other as animals are from plants and fungi

the world had atomic bombs before

the structure of DNA

Magellan-Elcano expedition successfully sailed around the world nearly 150 years before

Robert Hooke’s discovery of the cell

pocket watches and electrical batteries were both invented before

Darwin conceived of the theory of evolution

The members of all three of these domains (eucarya, archaea, bacteria) share certain basic features like

utilizing a lipid bilayer for their cell membranes and storing information via the same nucleotide code in their DNA

Archaea and Bacteria are prokaryotic or eukaryotic?

prokaryotic

Eukarya are prokaryotic or eukaryotic?

eukaryotic

protists are prokaryotic or eukaryotic?

eukaryotic

what are protists

organisms that do have nuclei, includes a great diversity of both single-celled and simple multicellular organisms

What type of life dominated Earth for the first two billion years?

tiny, single-celled prokaryotes

what was the specific that led to the creation of the eukaryotic branch

About two billion years ago, a bacterial cell began living symbiotically within an archaeal host cell

What modern organelle is descended from that original bacterial endosymbiont?

mitochondria, which function as the energy factories for today's eukaryotic cells

How did photosynthesis first enter the eukaryotic domain?

Through a separate endosymbiotic event where a eukaryotic cell co-opted a cyanobacterium, which evolved into chloroplasts

What are three pieces of evidence that mitochondria and chloroplasts were once free-living bacteria?

similar in size and shape to bacteria, divide independently via binary fission, contain their own circular DNA

theory of endosymbiosis

organelles may have derived from once free-living cells that somehow became incorporated into eukaryotic cells

In what year did Ernst Haeckel first speculate that organelles might be derived from once free-living cells?

1866

What year did Lynn Margulis resurrect the endosymbiotic hypothesis after it had been largely forgotten?

1967

How many times has complex multicellularity evolved independently across the eukaryotic domain

25

primary endosymbiosis

a eukaryotic cell directly engulfs a cyanobacterium, which eventually becomes a chloroplast.

secondary endosymbiosis

when a eukaryotic cell engulfs another eukaryotic cell that already contains a chloroplast.

acquired phototrophy

A temporary condition where a non-photosynthetic organism obtains photosynthetic abilities by taking in a photosynthetic organism or its chloroplasts.

What happened in Paulinella?

amoeba engulfed a cyanobacterium that became permanently integrated as a photosynthetic organelle.

What is a nitroplast?

A nitrogen-fixing organelle that evolved from an engulfed cyanobacterium

Where was the cyanobacterium that eventually became a nitroplast discovered?

marine unicellular alga

diazotrophs or nitrogen fixers

all of the organisms that are able to convert atmospheric nitrogen gas N2 to the ammonia NH3 or other nitrogenous compounds that other living things can use

pathogens

any organisms (or even viruses) that cause disease

Primary producers

able to take up carbon dioxide and convert it to sugar

trophic strategy

how they obtain their carbon and energy

Autotrophs

able to use inorganic carbon (CO₂) to manufacture sugar (carbon fixation)

Heterotrophs

must acquire carbon from an already fixed organic source, which usually means another living thing.

Chemotrophs

can only use energy from chemicals.

Phototrophs

can use energy from light, in addition to chemicals.

species accumulation curve

graph showing the total number of species discovered in a group over time or sampling effort, used to estimate how completely the group has been surveyed.

What percentage of mammal, bird, and vascular plant species have likely already been cataloged?

Greater than 90%

How many mammal species are likely on Earth?

5000-6000

How many bird species are likely on Earth?

9000-10000

How many vascular plant species are likely on Earth?

300,000

What percentage of vascular plants are flowering plants?

95%

How many insect species have been described so far?

About 1–1.5 million species

Which group will probably account for most future species discoveries?

prokaryotes

what year was discovery of cells by Robert Hooke

1665

Earth’s biogeochemical cycling

the various transformations of chemical compounds from one form to another across the face of the planet

microbiome

The community of microorganisms, mainly prokaryotes, that live in and on an organism's body.

A certain organism takes up chemicals from the environment for energy, and then uses that energy to fix its own carbon (combine molecules of CO₂ into sugar). This organism is best described as what?

Chemoautotrophic

Animals and fungi are consumers who cannot use energy from light. Animals and fungi are properly classified as what?

Chemoheterotrophs

Plants are photosynthetic. What is another term for photosynthesis?

Photoautotrophy

The heliobacteria are bacteria that are able to use energy from light, but are not able to use the energy to fix their own carbon (so they must get it from an outside organic source). Heliobacteria are best described as what?

Photoheterotrophic

Mariprofundis ferrooxydans is a bacterium that grows in the dark environment of deep sea hydrothermal vents. Like many prokaryotes in this ecosystem, M. ferrooxydans is able to extract energy from chemicals spewed out of the vent and use it to fix carbon dioxide into sugar. How should M. ferrooxydans be classified?

Chemoautotrophic

What is quorum sensing?

A communication system where bacteria detect their population density and change their behavior when enough cells are present.

What are myxobacteria?

Single-celled bacteria that can come together and coordinate their activities in swarms.

Multicellular organisms

an organism that is made of multiple cells throughout its life once fully developed.

genetic program of development

The set of genetic instructions that controls how, when, and where cells divide and differentiate during development.

Cell division

process by which cells divide to increase their number

Cell differentiation

process by which cells become specialized into different types and forms

simple multicellular or colonial organisms

Organisms that are made up of a fairly low number (perhaps dozens to thousands) of mainly very similar and largely self-sufficient cells

complex multicellular organisms

composed of trillions or even quadrillions of cells, representing hundreds or thousands of highly differentiated (specialized) cell types, each of which is fully interdependent on all of the others.

Heterocyst

specialized cyanobacterial cell adapted for nitrogen fixation

Akinete

tough, specialized cyanobacterial cell that functions as a survival spore during harsh conditions

What is the upper limit (“ceiling”) of prokaryotic multicellularity?

Cyanobacteria

How do some cyanobacteria become multicellular?

Cells repeatedly divide but remain connected, forming long chains called filaments.

What can multiple cyanobacterial filaments form?

Large globules or spheres held together by a secretion produced by the cells.

When did complex multicellularity first emerge among eukaryotes?

A little less than 1 billion years ago

How many times has complex multicellularity evolved among eukaryotes?

At least 25 separate times

Phylogenetically, plants include

red algae, green algae, and land plants

cell walls are made of

cellulose

Plant colonization of land began around

500 million years ago

The earliest fossils we have of organisms that can properly be called animals, or

metazoans

Where did the earliest animals live?

in the ocean about 650 million years ago

What major evolutionary event occurred about 100 million years after the earliest animal fossils?

Cambrian Explosion

What is the Cambrian Explosion?

A massive burst of evolutionary radiation in which animal diversity exploded. most of the phyla and basic body plans present in animals today emerged over a period of only about 10 million years

Tens of thousands of these fossils were discovered in a Canadian Rocky Mountain formation called

Burgess Shale in 1909

When does the first fossil evidence of terrestrial animals date to?

About 100 million years after the Cambrian Explosion.

collagen

Animals produce this structural protein

What larger clade contains both animals and fungi?

Opisthokonts

What are fungi?

Filamentous or single-celled heterotrophs with cell walls made of chitin

Are fungi always multicellular?

no

How do fungi obtain nutrients from food?

They secrete digestive enzymes outside their bodies, digest the matter externally, and absorb the resulting nutrients

hyphae

Fine, hair-like chains of fungal cells

What do hyphae form?

body/mycelium of a multicellular fungus

What is mycelium?

body/network of a fungus formed by hyphae

What is a fruiting body?

spore-producing reproductive structure of a fungus

What can layered hyphae produce?

Three-dimensional structures such as fruiting bodies