Exam 2 Flashcards
What is Speciation
a splitting event that creates two or more distinct species from an ancestral species
What are the two steps that result in speciation
genetic isolation and genetic divergence
what is a species
an evolutionarily independent population or group of populations
what does the biological species concept say
species are groups of actually or potentially interbreeding populations in nature that are reproductively isolated from other such groups
what is the main criterion of the biological species concept
reproductive isolation
what is prezygotic isolation
individuals of different species are prevented from mating successfully
what is postzygotic isolation
the hybrid offspring do not survive or reproduce
what are the types of prezygotic isolation
habitat isolation, behavioral isolation, temporal isolation, mechanical isolation, gametic isolation
what is habitat isolation
populations are isolated because they breed in different habitats
what is temporal isolation
populations are isolated because they breed at different times
what is behavioral isolation
populations do not interbreed because they have different courtship displays
what is mechanical isolation
mating fails because males and female reproductive structures are incompatible
What is gametic barrier isolation
mating fails because eggs and sperm are incompatible
what are the types of postzygotic isolation
hybrid inviability and hybrid sterility
what is hybrid inviability
hybrid offspring do not develop normally and die at some point during early development
what is hybrid sterility
hybrid offspring mature but are sterile as adults
what are the disadvantages of the biological species concept
reproductive isolation cannot be evaluated in fossils and species that reproduce asexually and it cannot be applied to populations that do not overlap geographically
how does the morphospecies concept work?
it uses difference in morphological characters to distinguish species
according to the morphospecies concept, individual lineages differ in…
size, shape or other morphological features
according to the morphospecies concept, distinguishing features most likely arise if…
populations are independent and isolated from gene flow
the morphospecies concept equally applicable to what types of species
sexual, asexual and fossil species
the morphospecies concept is useful when there is no data on…
extent of gene flow
what are the disadvantages of the morphospecies concept
one polymorphic species may be classified as more than one species (they may have different phenotypes), it cannot identify cryptic species that differ in non-morphological traits and the features used to distinguish species under this concept are subjective
how does the phylogenetic species concept identify species
evolutionary history, it is based on the rationale that all species are related by common ancestry
what is a monophyletic group
an ancestral population plus all of its descendants (clade or lineage)
what is synapomorphy
a trait unique to a monophyletic group
what are the disadvantages of the phylogenetic species concept
phylogenies are currently available for only a tiny subset of populations on the tree of life, difficult to identify species in the field, can lead to recognition of many more species than either of the other species concepts: but may actually reflect the extent of life’s diversity
when does speciation begin
when gene flow between populations is reduced or eliminated, causing genetic isolation
what is allopatric speciation
when populations of the same species become geographically isolated
what is sympatric speciation
divergence of populations living within the same geographical area into different species
what are the types of allopatric speciation
dispersal and vicariance
what is allopatric speciation by dispersal
movement of individuals from one place to another (founder effect)
what is allopatric speciation by vicariance
a physical barrier splits populations into subgroups that are physically isolated from each other (through geographic isolation, genetic isolation and genetic divergence)
what is biogeography
study of how species and populations are distributed geographically and can tell us how dispersal and vicariance effects occur
what does it mean when populations livein sympatry
populations or species that live in the same geographic and are close enough to interbreed
what is sympatric speciation
speciation that occurs among populations within the same geographical area (can be initiated by 2 events- internal and external)
what is an external (extrinsic) event
ecological speciation or mate prefernces
what is an internal (intrinsic) event
polyploidy
when does reproductive/genetic isolation occur
when mating becomes increasingly nonrandom
when does genetic divergence occur
as mutation, genetic drift and selection increase the differences between populations over time
what is polyploidy
condition of possessing more than two complete sets of chromosomes caused by massive error in meiosis or mitosis
what is autopolyploidy
individuals are produced when a mutation results in a doubling of the chromosome number; chromosomes are all from the same species (create tetraploids)
what is allopolyploidy
individuals are created when parents of different species mate and an error in mitosis occurs, resulting in a viable, nonsterile offspring; produces offspring with 2 different sets of chromosomes (allopolyploid offspring have 2 copies of each of the 2 sets of chromosomes)
what type of polyploidy forms new species
allopolyploidy
if divergence and prezygotic isolation exists…
mating between populations is rare, gene flow is minimal and populations continue to diverge
what is a hybrid zone
a geographic area where interbreeding between 2 populations occurs and hybrid offspring are common
if two populations have diverged extensively and are genetically distinct…
the fitness of hybrid offspring will be lower than the parents fitness
when postzygotic isolation occurs…
there is strong natural selection against interbreeding
what natural selection for traits that prevent interbreeding among populations called
reinforcement (permanent separation of gene pools)
what is homology
the state of having the same or similar relation, relative position, or structure.
what is homoplasy
the development of organs or other bodily structures within different species, which resemble each other and have the same functions, but did not have a common ancestral origin (convergent evolution)
what are the two tools for studying life’s history
phylogenetic tree and the fossil record
what is phylogeny
the branching evolutionary history of a group of organisms
what is a phylogenetic tree
a simplified diagram of the evolutionary history of a group of organisms (the most universal tree is the tree of life)
how are phylogenetic trees used in taxonomy
they describe, name and classify species and taxa (higher-level groups)
how are phylogenetic trees used in medicine
to study the spread of disease
phylogenetic trees can aid in identifying species that are a…
conservation policy
what is an outgroup
a species that diverged before the other taxon
what do nodes represent
speciation events
what are closely related taxa depicted as
sister groups that share a common ancestor
are phylogentic trees true or a hypothesis that can be tested
a hypothesis that can be tested
what is a fossil
the physical evidence from an organism that lived in the past
what is the fossil record
the total collection of fossils that have been found throughout the world, it provides direct evidence about what organisms from the past looked like, where they lived and when they existed
what is fossilization
the physical, chemical, biological processes that lead to the preservation of plant and animal remains over time
what are the ideal conditions in which fossils form under
they must be buried rapidly and they must decompose slowly
what are the 5 types of fossils
intact fossils, compression fossils, cast fossils, demineralized fossils, trace fossils (ichnology)
what are intact fossils
fossils that form when decomposition does not occur and the organic remains are preserved intact (pollen and bones)
what are compression fossils
fossils that form when sediments accumulate on top of the organism and become cemented into rocks such as mudstone or shale, the sediments’ weight compress the organic material below into a thin, carbonaceous fil, (mostly in leaves)
what are cast fossils
fossils that form when a buried organism decomposes, leaving an empty cavity in the sediments that fills with dissolved minerals and hardens into an accurate cast of the remains (ammonite, trilobites, snails)
what are demineralized fossils
fossils that forms when organisms decompose extremely slowly, dissolved minerals gradually infiltrate the interior of the cells and harden into stone (petrified wood, bones)
what are trace fossils
fossils that form when sedimentation and mineralization preserve indirect evidence of an organism in the environment; including footprints, tracks, burrow, feeding marks and feces
what are the limitations of the fossil record
habitat bias, taxonomic and tissue bias, temporal bias and abundance bias
what is habitat bias
organisms that live where sediment is actively being deposited are more likely to fossilize; in these habitats, burrowing organisms are more likely to fossilize compared to organisms living above ground
what is taxonomic and tissue bias
when organism with hard parts are more likely to leave fossil evidence because tissues with a tough outer coat that resists decay (pollen grains) fossilize more readily
what is temporal bias
recent fossils are more common than ancient fossils; the older the fossil is, the longer it has been exposed to potentially destructive forces in deep layers of rocks
what is abundance bias
organisms that are abundant, widespread, and present for a long time leave evidence much more often than do species that are rare, local or ephemeral
what is ecology (broad)
the study of how organisms interact with each other and their environment
what is the scientific definition of ecology
the scientific study of processes influencing the distribution and abundance of organisms, the interactions among organisms, and the interactions between organism and the transformation and flux of energy and matter
what are the levels of ecological study
organisms, populations, communities, ecosystems and biosphere
what do organismal ecologists explore
morphological, physiological and behavioral adaptations
what are adaptations
heritable traits that increase fitness of an individual in a particular area
what is a population
a group of individuals of the same species that lives in the same area at the same time
what do population ecologists study
how the number and distribution of individuals in a population change over time
what does a biological community consist of
the species that interact with one another within a particular area
what do community ecologists study
the nature and consequences of the interactions (predation, parasitism, competition) between species
what is an ecosystem
all the organisms in a particular region, along with nonliving (abiotic) components
what do ecosystem ecologists study
how nutrients and energy move among organisms, through the surrounding atmosphere and soil or water
what is the biosphere
the thin zone surrounding the earth where all life exists
what do global ecologists study
the effects of human impacts on the biosphere
what is conservation biology
the effort to study, preserve and restore threatened populations, communities and ecosystems
what is a niche
the range of conditions a species can tolerate and resources it can use (a product of abiotic and biotic factors that affect where a particular species lives)
what is a fitness trade-off
evolutionary compromises between traits that cannot be optimized simultaneously
what is dispersal
organism movement from place of origin to the location where it lives and breeds as an adult
what is weather
short-term atmospheric conditions of temperature, precipitation, sunlight and wind
what is climate
long-term weather conditions found in an area
what is specific heat
capacity for storing heat energy
what are biomes
regions characterized by distinct abiotic characteristics and dominant vegetation types
what is net primary productivity
total amount of biomass generated by the carbon that is fixed per year minus the amount of oxidized during cellular respiration
what is biomass
the total mass of organisms, primary producers in this case
what does NPP represent
organic matter available as food for other organisms
how is NPP estimated in terrestrial environments
measuring aboveground biomass
the artic tundra has what NPP
low npp (low temp)
the boreal forest has what NPP
low npp but higher than the arctic (low temp, moderate precipitation)
the temperate forest has what NPP
medium npp (moderate temp, moderate precipitation)
the temperate grassland has what NPP
medium npp (moderate temp, moderate precipitation)
the desert/dry shrubland has what NPP
low NPP (low precipitation, high temperature)
the tropical wet forest has what NPP
high NPP (high precipitation, high temp)
what are anthropogenic biomes (anthromes)
globally significant ecological patterns created by sustained interactions between humans and ecosystems
what is the anthropocene
the name for the new epoch of history scientists came up with due to the explosion of human populations creating significant impacts
what are the two broad types of aquatic biomes
freshwater/streams and oceans
what are the four abiotic factors that distinguish streams from oceans
salinity, water depth and sunlight availability, water flow, nutrient availability
what is salinity
the proportion of solutes dissolved in water measures parts per thousand
why is salinity a major determinant of species distributions
it has dramatic effects on osmosis and water balance in organisms because species are adapted to specific ranges of salinity (physiological adaptation)
why is water depth and sunlight availability important
water absorbs and scatters light, so the amount and types of wavelengths available to organisms change dramatically as water depth increase
what are the ocean zones defined by
water depth and light availability
what is the intertidal zone
submerged at high tide and exposed at low tide
what is the neritic zone
from the intertidal zone to about 200m, defined by the continental shelf
what is the continental shelf
gently sloping, submerged portion of a continental plate
where are coral reefs foudn
the neritic zone
what is the oceanic zone
the “open-ocean,” deep water region beyond the continental shelf
what is the benthic zone
the bottom of the ocean at all depths
what is the photic zone
regions that are sunlit, include the intertidal and portions of the neritic, oceanic and benthic zones
what is the aphotic zone
areas that do not receive sunlight
what are lake zones defined by
water depth and sunlight availability
what are the two lake zones
littoral (seashore) zone and limnetic zone
what is the littoral zone
shallow waters along the shore, where plants can take root
what is the limnetic zone
offshore, comprises water that receives enough light to support photosynthesis, too deep for plants to take root
what are the causes of turbidity
erosion of river sediments or coastal sediments and runoff from agriculture and algal blooms/nutrient pollution
why is water flow important
it affects avaiability of oxygen, light and nutrienst
what are the factors of rapid flowing water
high oxygen, clear water, low in nutrients
what are the factors of stagnant water (estuaries)
less oxygen, murky water, high nutrients
how does water flow present a physical challenge
organisms in areas with fast flow need beneficial body shapes and behavioral adaptations to help them cope with fast flow- organisms in the intertidal zone need adaptations to deal with violent waves (hold foot)
how is nutrient availability important
nutrients (nitrogen and phosphates) limit growth rates in photosyntehtic organisms that provide food for other species
how does the photic zone get nutrients
coastal runoff, ocean upwelling, lake turnover
what is coastal runoff
as water rushes down mountains and streams get wider and slow, nutrients gather sink and collect at the bottom as debris; in estuaries where freshwater rivers meet the ocean, nutrients are plentiful
what is ocean upwelling
nutrients that have fallen into the benthic regions are brought to the surface by currents that cause upwellings; as the surface water moves away from the coast, it is steadily replaced by nutrient rich water moving up form the ocean bottom
what is lake turnover
each year, glacially formed lakes undergo spring and fall turnovers in response to air temp changes
what happens without spring and fall turnovers
most freshwater nutrients would remain on the bottom of lakes (and there would be less productivity)
