6th extension mod 1
How many currently known species
2.3 million
Almost all primates including humans show up just before
3 to 4 MYA
Formation of earth
4.6 BYA
First organisms recognizable to us, multicellular fossils, so not appear until
400 to 500 MYA
How many mass extinctions have there been?
5
Devonian 340 MYA
70%, caused by asteroid impact, rapid climate change (global cooling)
Triassic 200 MYA
75%, caused by increase in greenhouse gases, rapid climate change
About how many species
8.7 million
Cretatious / Tertiary 65 MYA
80% ext rate. Caused by asteroid or comet impact, volcanic activity, climate change
Mass extinction at end of Ordovician period caused loss of
85% species in planet
Ordovician 445 MYA
85%, caused by rapid climate change (global cooling), falling sea levels
Permian 250 MYA
95%, caused by volcanic activity, increase greenhouse gases, rapid climate change
Systematics
A scientific discipline focused on classifying organisms and determining their evolutionary relationships.
Family Hominidae
Ability to walk erectly
Order primates
Adapted to climb trees
Geographic separation with lungless salamanders is called
Allopathic speciation
Adaptive radiation
An evolutionary pattern in which many species evolve from a single ancestral species, adaptations to allow them to survive in different environmental conditions
Bacteria is the most
Ancient domain
Biodiversity hotspots
Areas of the world that contain more types of life than others. Account for over 50% of all plant species and 42% of all animal species
Prokaryotes
Bacteria and Archaea, no nucleus
General background extinction rate level
Btwn 0.1 and 2.0 species lost per million species per year
Domain Eukarya
Cells contain a nucleus and membrane bound organelles
post-zygotic isolation mechanisms
Different species can mate but there are reproductive issues in the offspring. Result in sterile hybrid between the parent species or offspring that lacks fitness to survive
Most general classification
Domain
3 major life groups
Eukarya, bacteria, archaea
Eukaryotes
Eukarya, have nucleus
Mass extinctions are more
Global in nature
Over one million species are in danger of
Going extinct in next few decades
Number one factor of sixth extinction crisis
Human induced climate change caused by increase of greenhouse gases in atmosphere
Genus homo
Large brain, tool use
sympatric speciation
Less common, species become isolated by other factors when territories overlap
Species
Level of biological classification that represents populations that are reproductively compatible
mass extinction
Loss of large number of plant and animal species from many different taxonomic categories in a relatively short period of time
Extinction
Loss of species from the planet
Biological species concept
Most commonly used. Defines a species as one that is sexually reproductively isolated from other species
Ex of post zygotic isolation mechanisms
Mules that come from horse and donkey
Kingdom Animalia
Multicellular organisms that are mobile and ingest food
To be considered as 2 separate species,
Organisms in a population need to be reproductively isolated from each other
punctuated equilibrium model of speciation
Periods of no change are interrupted by events that promote rapid speciation. Species arise regularly over time
Extinction is not just species but can be of an entire
Phyla or class
Class mammalian
Posses hair and mammary glands
Phyla Chordata
Possess a dorsal supporting rod (spine) and nerve cord
Supergroup Opisthokonts
Possessive cells with flagella
prezygotic isolating mechanisms
Present barriers to 2 pops of similar organisms, preventing mating
Major biodiversity on our planet lies in the
Prokaryotic domains
Phylogenetic trees
Provide indication of relatedness of organisms
Speciation
Rate at which new species are formed
Morphological species concept
Separates species based on differences in physical traits, or morphology (form). Difficult to apply to animals that don't meager fossil records
Speciation is a _______ process
Slow
Gradualistic Model of Speciation
Small changes occur periodically in a population until reproductive isolation occurs, supported by Darwin, unsupported by fossil record
Levels of org small to big
Species-populations-biological communities-ecosystem
Lungless salamanders
Start in N California, slowly migrated south and divided into 3 groups and couldn't mate together, south versions changed color and form
Species
Sum of all the populations of similar organisms that are reproductively compatible of interbreeding and producing living offspring
Biodiversity
The number of different species in an area
Taxonomy
The scientific study of how living things are classified
If the rate of species loss exceeds the rate of new speciation,
There's a general loss of biodiversity
Phylogenetic species concept
Traces evolutionary history of organism and its relatedness to other species through its traits. In this model, the study of an organisms traits and location on the evolutionary tree is a better indication of whether it is a unique species than the biological species concept
BYA
billion years ago
Archaea are more closely related to
eukarya than bacteria
MYA
million years ago
Gene flow
movement of alleles from one population to another via mating between populations
Extinction is a _____ process
natural
background extinction rate
normal extinction of various species as a result of changes in local environmental conditions, typically don't result in a large loss of species.