variation at all levels of biological organization
General definition of Biodiversity
variation in the genetic make-up between individuals within a population and between populations
Genetic Diversity
the variation in a particular level of the taxonomic hierarchy (species, genera, and beyond)
Organismal Diversity
the number of species within a given sampling area
Species richness
how abundant each species is relative to the total number of individuals
Species evenness
ecological differences between habitats and biomes
Ecological Diversity
diversity within a particular area or ecosystem
Alpha Diversity
differences in alpha diversity between ecosystems
Beta Diversity
overall diversity for the different ecosystems in a broad region
Gamma Diversity
- Low oxygen environment
- First life arises
- cyanobacteria begin photosynthesizing
Achaen Eon
- Great oxygenation even
- Eukaryotes evolve
- Life dominated by small, small-bodied eukaryotes
Proterozoic Eon
- “Snowball Earth”
- Massive ice ages
- Possibly leads to more diversity in Ediacaran
Crynogenian Period
-Proliferation of multicellular, soft-bodied organisms
Ediacaran Period
- Nearly all invertebrate phyla appear
- Life begins in oceans and moves to land
Paleozoic Era
- Cambrian Explosion
- Most major animal phyla appear
- marine life still dominant
- origin of general body plan for metazoans
Cambrian Period
major diversification of form and function
Cambrian Explosion
- first vertebrates with true bones appear
- first life on land
- mass extinction at the end
Ordovician Period
- life on land progresses
- first appearance of vascular plants
- major diversification of fish
Silurian Period
- significant radiation of life on land
- tetrapods and anthropoids colonize land
- mass extinction near end of period
Devonian Period
- warm and humid
- Extensive forests generate massive coal reserves
- reptiles appear
Carboniferous Period
- supercontinent pangea
- starts with ice age and ends with mass extinction event
Permian Period
- “Age of the Dinosaurs”
- fragmentation of Pangea leads to much specification
Mesozoic Era
- warm and dry climate
- slow recovery from Permian extinction
- mammals and dinosaurs evolve
Triassic Period
- first birds appear
- largest land animals of all time present
- cycads dominate plant world
Jurassic Period
Mammals dominant on land
Cenozoic Era
last major ice age
Pleistocene Epoch
after ice age, allows for species radiation
Holocene Epoch
What Epoch are we said to be in?
Anthropocene
- short events resulting in massive species loss
- random
- open up niches for adaptive radiation and greater diversity
Mass extinction events
What was the largest mass extinction event
Permian Extinction (95% of all species lost) -prob due to gradual environmental changes and a catastrophic event
What was the dinosaur extinction
Cretaceous-Tertiary
Fossil record shoes a______
erratic but relentless increase in biological diversity
Why are viruses said to be alive
- Posses genes and evolve by natural selection
- Replicate by generation multiple copies of their genetic makeup
Why are viruses said not to be alive
- no oxygen intake
- no nutrition required
- no definite lifespan
population of morphologically similar, interfertile organisms that are reproductively isolated from other such groups
Biological species
a polythetic class of viruses that constitute a replicating lineage and occupy a particular niche.
Viral Species
The viral protein coat is removed to expose the viral NA to the cytoplasm of the cell
Uncoating
Naked viral NA acts as template for production of viral mRNA, or is the mRNA itself
Transcription
Viral mRNA is translated by host ribosomes and tRNAs into viral proteins.
Translation
Parental viral NA is copied for progeny virions. Process catalyzed by the viral replicase enzyme.
Replication
Viral coat protein and NA assemble to form complete virions.
Assembly
The progeny virions are released from the cell to infect other cells and other susceptible individuals
Release
cell death as end result of infection
Cytocidal infections
Noncytocidal infections are _________
acute or persistent
viruses flushed out of body quickly by various defense mechanisms
Actue infections
the infected cells continually produce irons
Chronic infections
the infected cells do not continually produce irons. Virus becomes dormant for a time before becoming active again
Latent infections
Persistent infections often are ________
lysogenic
blending of Darwinism & Mendelism. Evolution arises exclusively from gradual accumulation of mutations & sex recombo of genes under control of natural selection
Neodarwinism
life forms join genomes honed by evolution, & such fusions often lead to major saltations. This mechanism is not random, but a creative force.
Symbiogenesis
How many viral elements constitute the human genome
50%
up to ____ of some plant genomes is viral
90%
the science of naming, describing, and classifying living things; one aspect of systematics
Taxonomy
a group of organisms at a particular level of a classification system
Taxon
Who were the first to organize like organisms in GENERA
Greeks and Romans
Who developed binomial system
Carolus Linnaeus
began in the middle ages
a series of descriptive terms added to the name of a genus to refer to a particular order
Polynomial system
any recognizable trait, feature, or property of an organism (eye color, leaf shape)
Character
a discrete condition within a character
Character State
organism on which species description is based
Holotype
collected at same place and time as holotype
Isotype or isotope
collected at different place or time than holotype
Paratype
the study of the diversity of organisms and their evolutionary relationships
Systematics
the evolutionary history of a taxon
Phylogeny
show inferred evolutionary relationships hypothesized by particular investigators
Phylogenic trees
a simplified visualization of a taxon evolutionary history
Cladogram
character states are used to
group related organisms
includes the most recent common ancestor and all of its descendants (clade)
Monophyletic group
includes the most recent common ancestor but not all of its descendants
Paraphyletic group
grouping derived from more than one ancestor
Polyphyletic group
a taxon that serves as a reference group for other taxa in a cladogram
Outgroup
- establish protected areas
- promote sustainable development
- restore degraded ecosystems
- control invasive species
In situ conservation
- seed banks and zoos
- culture collections
- captive breeding
Ex situ conservation
- increases with area
- increases from poles to equator
- decreases with elevation
Trends in biodiversity
species found only in a single, limited area
Endemic Species
- peaks on large
- increases from poles to equator
Trends in endemism
There are ____ hotspot regions
25
Criteria for hotspots
- at least 1500 species of endemic vascular plants
- lost at least 70% of its original habitat
- (irreplaceable and threatened)
Biodiversity hotspots cover _____ of Earth’s land surface, constitute ____ of all extant plant species, and ______ of all extant vertebrates
1.4%
45%
35%