Chapter 24 and 25 Flashcards
Species
Defined as an evolutionarily independent population or group of populations
Biological species concept
members of populations that actually or potentially interbreed in nature, not according to similarity of appearance
Prezygotic isolation
mechanisms of separation of different species to keep them from creating offspring by preventing the gametes from forming a zygote.
Postzygotic isolation
Reproductive isolation in which the hybrid offspring does not survive or reproduce
Morphospecies concept
Researches identify evolutionarily independent lineages by differences in size, shape, or other morphological features
Polymorphic species
A species that over 2 distinct phenotypes in the same interbreeding population
Cryptic species
Differ in tratis other than morphology
Phylogenetic species concept
Identifies species based on evolutionary history of populations
Definition that species are the smallest monophyletic group in a phylogenetic tree
Monophyletic group (lineage, clade)
include a single common ancestor and all of its descendants
Synapomorphy
Trait that is found in certain groups of organisms and their common ancestor but is missing more distant ancestors
These are what identifies monophyletic groups
Three common species concepts
Biological species
Morphospecies
Phylogenetic species
Allopatry
describes a population or species that is physically isolated from other similar groups by an extrinsic barrier to dispersal
Allopatric speciation
Speciation occurs when populations of the same species become geographically isolated
Starts in two ways called dispersal and vicariance
Dispersal
Movement of individuals from one place to another from place of origin to place of living and breeding
Vicariance
The physical splitting of a habitat by a geographic barrier
Biogeography
Study of how species and populations are distributed geographically
Sympatry
Condition in which two or more populations live in the same geographical area or close enough to permit interbreeding
Sympatric speciation
Speciation that occurs even though populations live within the same geographical area
Niche
Range of resources that a species can use and the range of conditions that it can tolerate
Polyploidy
Condition of possessing more than two complete sets of chromosomes, is caused by a massive error in mitosis or meiosis
Two types of polyploids
Autopolyploid
Allopolyploid
Autopolyploid
Individuals are produced when a mutation results in a doubling of chromosome number and the chromosomes all come from the same species
Allopolyploid
Individuals are created when parents of different species mate and then an error in mitosis occurs and it results in viable offspring with two full sets of chromosomes
Reinforcement
The natural selection for traits that prevent interbreeding among recently diverged species
Sympathic
2 species live in the same area
Allopatric
2 species live in different areas
Hybrid zone
Geographic area where interbreeding occurs and hybrid offspring is common
Hybrid sterility
Postzygotic mechanism occurs when the offspring of two different species are sterile or have reduced fertility
Unable to produce viable offspring themselves
Habitat isolation
Prezygotic mechanism that refers to species being isolated by differences in their habitats or ecological niches, reducing the chance of encountering and mating with each other
Mechanical isolation
Prezygotic mechanism involves structural differences in reproductive organs that prevent successful mating between different species
Temporal isolation
Prezygotic mechanism that involves differences of reproductive activates such as breeding seasons, flowering times, or mating rituals, preventing the interbreeding of different species.
Phylogeny
Evolutionary history of a group of organisms
Phylogenetic tree
Branching diagram that depicts the evolutionary relationships among species or other taxa
Systematics
Discipline of biology that characterizes and classifes relationships among all organisms on earth
tree of life
phylogenetic tree that includes all organisms
taxa
Any named group of organisms at any level of a classification system
branches
part of phylogenetic tree that represents populations through time
Sister groups
Two lineages that are each other’s closes relatives, represented by two branches emerging from a node in a phylogenetic tree
polytomy
Node in a phylogenetic tree that depicts an ancestral branch dividing into three or more descendant branches
Trait
Any observable characteristic at any level of observation of an individual
Outgroup
taxon that is not part of the taxonomic group being studied but is closely related
Added to establish direction of change of each character
Ancestral trait
Trait that existed as an ancestor
Derived trait
Modified form of an ancestral trait, found in a descendant
Synapomorphy
Trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors
Allow biologists to recognize monophyletic groups
homology
Similarity among organisms of different species due to shared ancestry
Homoplasy
Similarity among organisms of different species due to reasons other than common ancestry
Parsimony
The principle that most likely explanation for a phenomenon is the one that implies the least amount of change
bioinformatics
A discipline at the intersection of biology, computer science, and statistics, concerned with the storage, analysis, and presentation of biological data
Fossil record
Total collection of fossils that paleontologists and amateur collectors have found throughout the world and archived in thousands of private collections
Intact fossil
Forms when decomposition does not occur and the organic remains are preserved intact
Compression fossil
Forms when sediments accumulate on top of the organism
Cast fossil
Organism decomposes after buried and hole is replaced with minerals
Permineralized fossil
Forms when organisms decompose extremely slowly
Dissolved minerals gradually infiltrate cells
Trace fossils
Forms when sedimentation and mineralization preserve indirect evidence of an organism such as footprints, tracks, burrows, feeding marks and feces
Conditions in which fossils form
buried rapidly
decompose quick
Habitat bias in fossilization
Organisms that live in areas where sediments are actively being deposited, like beaches, mudflats, and swamps are more likely to form fossils than are organisms that live in other habitats.
Taxonomic bias
Since slow decay is essential to fossilization, organisms with hard parts such as bones or shells are most likely to leave fossil evidence
Tissue bias
Some organism’s tissues like teeth or pollen grains are encased in outer coats that resist decay, thus they can fossilize easily
Temporal bias
Recent fossils are much more common than than older fossils
Abundance bias
Organisms that are abundant, widespread, or present on earth for long periods of time leave evidence much more often than do species that are rare, local or ephemeral
Radiometric dating
Researchers used this to assign absolute dates to events in the fossil record
Based on the well studied decay rates of certain radioactive isotopes
Precambrian
The interval between the formation of the Earth, to the appearance of most animal groups about 541 million years ago
Unicellular organisms were dominant for most of this era
Oxygen was absent from the oceans and atmosphere for almost 2 billion years
Divided into Hadean, Archaean, and Proterozoic eons
Phanerozoic Eon
Interval between 541 mya and the present
Divided into 3 eras Paleozoic, Mesozoic and Cenozoic
Paleozoic (ancient life)
Origin and initial diversification of animals, land plants, and fungi
Mesozoic era (middle life)
Begins with end-Permian extinction events and ends with the extinction of dinosaurs and other groups
Gymnosperms were dominant plants and dinosaurs were dominant vertebrates
Cenozoic era (recent life)
Angiosperms were dominant plants, birds and mammals were the dominant vertabrates
Anthropocene
Proposed name of new, current epoch in the geologic time scale to reflect the dramatic physical, chemical, and biological changes that humans are causing on earth.
Adaptive radiation
Rapid evolutionary diversification of a single lineage into a wide variety of adaptive forms
Three hallmarks of adaptive radiation
Monophyletic group
Speciated rapidly
Diversified ecologically into many niches.
Two general mechanisms that can trigger adaptive radiations
Factors extrinsic to organisms, such as favorable new conditions in the environment
Factors intrinsic to organisms, such as the evolution of key morphological, physiological or behavioral traits
Ecological opportunity
Term used to describe the processes that can produce a diverse group of species from a single colonizing ancestor
Morphological, Physiological, Behavioral innovation
Allows descendants to live in new areas, exploit new sources of food or select mates in new ways, triggering diversification events in the history of life.
Cambrian explosion
Rapid diversification of animal body types and lineages that occurred during a 50-million-year-period about 541 mya at the start of the proterozoic eon
Fauna
All the animals that live in a particular region, period, or environment
First microfossils fossils
Appeared during Ediacaran and included sponges, jellyfish, and comb jellies, as well as fossilized burrows, tracks, and other traces from unidentified animals
None of them had shells, limbs, heads
Filtered or absorbed organic material from water to make a living
Cabrian macroscopic fossils
Sponges, jellyfish, combjellies were abundant with these
Species in this Cambrain fauna, slithered, swam, and crawled and had skeletons
What triggered Cambrian Explosion
Higher oxygen levels
Rise of algae
Evolution of predation
New niches beget more new niches
New genes new bodies
Higher oxygen levels
Increased oxygen levels made aerobic respiration more efficient and it supported larger bodies and more active movements
Rise of algae
The photosynthetic nutrient rich algae increase during this time lead to a higher quality food source for animals
Evolution of predation
During the Cambrian explosion, animals started to eat other animals and it resulted in natural selection for prey animals in terms of defense mechanisms
New genes New bodies
During the Cambrian explosion, gene duplication and diversification lead to
the Hox gene which signaled where cells are in the embryo. It lead for larger, more complex bodies to survive
Mass extinction
rapid extinction of a large number of diverse species around the world.
Background extinction
Refers to lower, average rate of extinction observed when a mass extinction is not occurring
Occurs when normal environmental change, emerging disease, predation pressure, or competition with other species reduces certain populations to
End Permian Extinction
“Mother of Mass Extinctions”
Flood basalts or outpouring of molten rock belched heat, CO2, and sulfur dioxide into the atmosphere.
High amounts of sulfur dioxide caused acid rain that devastated plants and organisms.
Flood basalts ignited coal fires that pumped toxic ash, including mercury, into the air
Oceans lacked oxygen and became fatal to organisms that relied on aerobic respiration
Sea level dropped dramatically, reducing habitat
Impact hypothesis
Hypothesis that a collision between Earth and asteroid caused a mass extinction that ended the Cretaceous, 66 million years ago
Description of the asterioid
Size of Mount Everest
Would have caused tsunamis, and acid rain due to sulfate-containing rock in the asteroid that reacted with water in the atmosphere to form sulfuric acid
The dust, ash, and soot would have blocked the sun and caused rapid global cooling
Paraphyletic
It includes an ancestral population and some of its decendants not all
Polyphyletic
shares similar traits but does not include the most recent common ancestor
Convergent evolution
the process whereby distantly related organisms independently evolve similar traits to adapt to similar necessities.
Self-fertilization
Most extreme form of inbreeding
Fusion of male and female gametes (sex cells) produced by the same individual
What do fossil records show
What organisms in the past looked like
Where they lived
When they existed
Artiodactyls
Any of various hoofed mammals of the order Artiodactyla, having an even number of toes on each foot. Artiodactyls include the pig, sheep, ox, deer, giraffe, and hippopotamus.
