Final Exam part 2 Flashcards
What is a species?
Groups of organisms that exchange genes within the group but cannot do so with other groups.
Is the degree of isolation higher in species or populations?
species
How is a species isolated from other species?
reproductively
What is the biological species concept?
Species are defined by reproductive isolation
What are the key components of the biological species concept?
Individuals do not interbreed, do not produce viable and fertile offspring, and there is no gene flow
What are the disadvantages of the biological species concept?
It cannot be observed in fossils or species that reproduce asexually, difficult to apply id species do not overlap, reproductive isolation can be a gradient
What is the morphological species concept?
Identifies evolutionarily distinct lineages by differences in size, shape, or other morphological traits.
What species can the morphological species concept be applied to?
sexual, asexual, and fossil species
What are the disadvantages of the morphological species concept?
Polymorphic species with different phenotypes get named as two different species, cannot identify cryptic species (identify in traits other than morphologically), and picking distinguishing features can be subjective
What is the phylogenetic species concept?
Identifies species based on evolutionary history where species are monophyletic groups
What is a monophyletic group?
An ancestral population and all of its descendants
What is a synapomorphy?
A trait found in certain groups of organisms and their common ancestor, but is missing in more distant ancestors
What are the disadvantages of the phylogenetic species concept?
Careful identified phylogenies are only available for a small subset of species, leads to recognition of more species than other concepts
What is speciation?
the formation of a new species
How can mutations cause speciation?
Different populations will have different, random mutations
How can natural selection cause speciation?
Different populations will have different selection pressure since the environment may be different
How can genetic drift cause speciation?
Different alleles may be mixed in different populations
Speciation occurs when ______ is reduced or eliminated.
gene flow
Reduced gene flow drives speciation because it ____________.
allows for divergence
What is allopatric speciation?
speciation due to geographic isolation
What is dispersal?
Movement of individuals from one place to another
What is vicariance?
Physical splitting of a habitat
What is sympatric speciation?
Speciation occurs between populations in the same geographic area
What is sympatry?
Living in close relation
What are the requirements of sympatric speciation?
- no geographic isolation
- genetic isolation
- genetic divergence
What kind of factors can cause non-random mating?
extrinsic factors, intrinsic factors
What are extrinsic factors?
Disruptive selection due to environmental difference or mate preferences (outside the organism)
What are intrinsic factors?
Chromosomal mutations (inside the organism)
______________ can drive sympatric speciation.
Changes in chromosome number
What is polyploidy?
Condition of possessing more than two complete sets of chromosomes
What is autopolyploidy?
Mutation results in the doubling of chromosome number and all chromosome come from the same species
What is allopolyploidy?
Parents of different species mate and then an error in mitosis occurs
________ often leads to speciation in plants.
Polyploidy
What is a phylogeny?
The branching evolutionary history of related species
What is a phylogenetic tree?
A graph that allows us to visualize phylogeny
What are systematics?
Discipline of biology that characterizes and classifies the relationships among all organisms on earth
What is a branch?
A line representing a species or other taxon through time
What is a root?
The most ancestral branch of a tree
What is a tip?
Endpoint of a branch; represents a living or extinct species or taxon
What is an outgroup?
A taxon that diverge before the taxa that are the focus of the study; helps to root the tree
What is a node/fork?
A point within the tree where a branch splits into two or more branches
What does the node represent?
the most recent common ancestor of the descendant groups
What is a polytomy?
A node that depicts an ancestral branch dividing into three or more descendant branches; usually indicates that insufficient data were available to resolve which taxa are more closely related
What is a paraphyletic group?
An ancestral population and some, but not all, of its descendants
What is a polyphyletic group?
Share similar traits but does not include the most recent common ancestor
What is an ancestral trait?
A trait that existed in an ancestor
What is a derived trait?
A trait that is a modified form of an ancestral trait, found in its descendant
What is a homology?
When two organism share a trait due to common ancestry
What is a homoplasy?
When similar traits evolved independently in two or more lineages and thus are similar for reasons other than lineage
What is convergent evolution?
Independant evolution of similar traits in different species due to adaptation to similar environmental conditions or ways of life
There is ________ along the branches of phylogenetic trees.
evolution
What is anagenesis?
When an original species is transformed into a different species over many generations
What is cladogenesis?
A pattern of branching in which an ancestral species gives rise to two or more species
_______ are a hypothesis of the inferred relationships subject to further refinement.
Phylogenies
More data within the trait matrix = ________
more accurate estimate of phylogenetic trees
What is parsimony?
The most likely explanation is the one that requires the fewest steps
What is the fossil record?
All fossils that have been found on Earth and described within scientific literature
What is a fossil?
Any trace of an organism that lived in the past
What does the fossil record support?
Descent with modification
What is an extant species?
A species living today
What is the geologic time scale?
A sequence o named intervals that represent the major events of Earth’s history
What is a transitional feature?
A trait in a fossil species that is intermediate between ancestral and derived species
What is the evidence that species change through time?
- Vastness of geologic time
- Species have gone extinct over time
- Transitional features link older and younger species
- Vestigial traits demonstrate that species evolve from ancestors
- Species are observed changing today
What is genetic homology?
Similarity in RNA, DNA, or amino acid sequences due to inheritance from a common ancestor
What is developmental homology?
similarity in embryonic from or due to developmental processes due to inheritance from a common ancestor
What is structural homology?
Similarity in an adult organismal structures due to inheritance from a common ancestor
What is evidence that species are related through common ancestry?
- Related species share homologies
- Similar species are found in the same geographic area
- Observations of speciation occurring in modern times
What is ecology?
The study of organisms interact with each other and their environment
What levels are ecology studied at?
- Organisms
- Populations
- Communities
- Ecosystems
- The biosphere
What is organismal ecology?
The study of how morphological, psychological, and behavioral adaptations increase fitness in a particular environment.
What is population ecology?
How the number and distribution of individuals in a population change over time
What is community ecology?
Asks questions about the nature of and consequences of species interactions
What is ecosystem ecology?
Study of how nutrients and energy move among organisms and through the surrounding atmosphere, soil, and water
What is the biosphere?
A thin zone surrounding the Earth where all life exists (5km below land surface, 10km above)
What is global ecology?
Studies the effects of human impacts on the biosphere
What is climate?
Prevailing long term weather conditions in an area
What is weather?
Short term weather conditions of temperature, precipitation, sunlight, and wind
The global climate system is powered by _______.
solar radiation
What are the steps of the solar radiation cycle?
- High energy radiation comes to Earth from the sun
- 30% of solar radiation that reaches earth’s atmosphere is reflected back into space
- The other 70% is absorbed by the Earth’s surface and atmosphere
- The earth radiates that back as lower energy longwave radiation
- Green house gases trap some of the outgoing longwave radiation, reflecting some back to Earth, warming the system
What are the main greenhouse gases?
Ozone (O3), Nitrous Oxide (N2O), carbon dioxide (CO2), water (H2O), and Methane (CH4)
How many atoms should green house gases at LEAST have?
3
What percentage of the atmosphere do greenhouse gases make up?
1%
What percentage of the atmosphere does nitrogen make up?
78%
What percentage of the atmosphere does oxygen make up?
21%
Incoming solar radiation is _________ across the globe.
not constant
Regions near the equator receive ______ sunlight per unit area than regions closer to the poles.
more
Where do deserts tend to occur?
30 degrees north and south of the equator
What is the Hadley cell?
The area between the equator and 30 degrees north and south of it
How does the Hadley cell work?
- Air is heated by solar radiation at the equator
- Heating causes the air to lose pressure
- Warm, moist air begins to rise
- As it rises, it begins to cool, increasing its pressure and causing rain at the equator
- The cool air is pushed poleward, becomes denser, and begins to fall
- Warm, dry air results in bands of deserts
What is the cell above/below the Hadley cell?
The mid-latitude cell
What is the cell closest to the poles?
The polar cell
what is the definition of a season?
regular, annual fluctuations pf temperature, precipitation, or both
What is the tilt of Earth’s axis?
23.5 degrees
How do mountain ranges influence regional climate?
As moist air blows from the ocean towards mountain ranges , it rises, and rain falls. Dry air continues over the mountain, creating desert-like conditions (called a rain shadow)
Why do oceans have a high influence on regional climate?
Water has a high specific heat
What are gyres?
Cyclical ocean currents that move warm water to northern latitudes and cold water to tropical latitudes
What are biomes?
Regions characterized by similar abiotic characteristics and dominant types of vegetation
What are terrestrial biomes characterized by?
- Average Temperature
- Average Precipitation
- Sunlight
- Wind
- Annual fluctuation of temperature and precipitation
Warmer, wetter biomes have ________.
higher NPP
What are the type of biomes?
- Arctic tundra
- Boreal forest
- Temperate forest
- Temperate grassland
- Desert and dry shrubland
- Tropical wet forest (rainforest)
What are aquatic biomes characterized by?
- Salinity
- Water depth
- Water flow
- Nutrient availability
Why is the ocean salty?
Because of dissolved, negatively charged solutes
What percentage of Earth’s water is salt water?
97.5%
What percentage of Earth’s water is trapped in glaciers and ice caps?
2%
What percentage of Earth’s water is in rivers, groundwater, ponds, and lakes?
0.5%
What is the littoral zone?
Water along the shore shallow enough for plants to take root
What is the limnetic one?
Water that receive enough light to support photosynthesis but is too deep for plants to take root
In temperate regions ________ cycles nutrients.
turnover
What are the aquatic biomes?
- Lakes and ponds
- Freshwater wetlands
- Streams
- Estuaries
- Oceans
What is distribution?
How organisms are arranged over space
What is species distribution?
Where that species can be found geographically
How are species limited in their distribution through abiotic conditions?
- No species can survive all conditions on earth
- Species are adapted to a limited set of abiotic conditions
- Enzymes can only function in a narrow band of temperatures
What is performance?
Any trait that impacts fitness
What does T0 mean?
Optimum temperature for survival
What does CTmin mean?
Minimum temperature for survival
What does CTmax mean?
Maximum temperature for survival
What is a tolerance breadth?
All the temperatures in which an organism can survive
How are organisms limited in their dispersal through biotic conditions?
Not all organisms can reach other environments with suitable conditions (dispersal ability) and interactions between organisms of different species can effect distribution.
How are organisms limited through past conditions?
Past conditions on Earth have shaped the evolutionary trajectories of species living today
What is a niche?
An organism’s place in the environment
What determines distribution?
An organism’s niche
What is an ecological/fundamental niche?
The limits for all important environmental features in which individuals of a species can survive, grow, and reproduce
What is a realized niche?
The portion of a fundamental niche actually occupied by the species
Species ranges are determine by ________________.
The distribution of populations over space
Usually species consist of __________________.
Independent populations connected through dispersal
What is a metapopulation?
A population of populations connected by dispersal
What are the types of spacial distribution?
random, clumped, and uniform
Populations are dynamic, meaning?
Distribution and abundance can change over time and space
What is demography?
The study of factors that determine the size and structure of populations through time.
What is immigration?
organisms moving into a population
What is emigration?
organisms leaving a population
How do populations gain individuals?
Through birth and immigration
How do populations lose individuals?
Through death and emigration
To determine changes in population size over time use a _______ to track the individuals in a population over time.
life table
What does a life table do?
Summarizes the probability that an individual will survive and reproduce at any given interval of their life
What is a cohort?
A group of individuals of the same age
What is a type 1 survivorship curve?
Survivorship throughout life is high and then drops drastically in old age
What does a type 1 curve demonstrate?
Parental care, small number of offspring, and slow development
What is a type two survivorship curve?
Individuals have the same probability of dying each year of life
What are/is the trait(s) of a type 2 curve?
Some parental care early on in life
What is a type 3 survivorship curve?
Extremely high death rates in early life stages but high survivorship for individuals that make it past this stage
What are the traits of a type 3 curve?
Little to no parental care, common in insects and fish
What is fecundity?
The number of female offspring produced by each female within a population
What is net reproductive rate?
Survivorship x fecundity
If net reproductive rate = 1, the population is _______.
stable
If net reproductive rate is >1, the population is ________.
growing
If net reproductive rate is < 1, the population is _______.
decreasing
An organisms life history strategies influence ________________.
survivorship and reproductive rates
What is life history?
How an individual allocates resources to reproduction, growth, and survival.
What are life history traits?
Traits that affect the amount of reproduction or the development of offspring
Life history traits are the result of _________.
fitness trade-offs
Every individual has a limited amount of _____________.
time and resources at its disposal
Growth curves predict _________.
how population size changes over time
Change in N/ Change in T = _______________
Births - deaths + immigrants - emigrants
N= ________
Population size
t= ___________
time
Population growth curves only measure __________.
births and deaths
What are two types of population growth curves?
Logistic and exponential
What are the characteristics of an exponential growth curve?
Resources are not limiting, growth is density-independent
Birth rate - death rate = __
r
r=_________
per capita rate of increase
r= 0, the population is ___________
not changing
r > 0, the population is ___________
increasing
r < 0, the population is __________
decreasing
R= __________
net reproductive rate
g= ___________
generation time
To know if population size is changing in the number of individuals _________________.
multiply the per capita rate of increase by the population size
What is an intrinsic rate of increase?
When birth rates are as high as possible, or as low as possible
Nt= ________
population size at the end of time
N0= ___________
population size at time 0
When is exponential growth common?
colonization of a new habitat, recovery after a natural disaster
What are the characteristics of logistic growth?
Resources are limiting, growth is density-dependent, early growth is rapid, growth later falls to 0
What is carrying capacity?
K. The maximum number of individuals in a population that can be supported in a particular habitat over a sustained period of time
What are some density-dependent factors?
Competition for resources, disease and parasitism, predation, toxic waste, and social behavior
Carrying capacity is not _____.
fixed
Carrying capacity can be _______.
overshot
Species interactions are characterized by _________.
their outcomes
What density-dependent factors would you measure to quantify the outcome of a species interaction?
population size, reproductive success, organismal health, death rate, and offspring survival
What is mutualism?
Interaction in which both species benefit
What is commensalism?
One species benefits while the other is unaffected
What is parasitism?
Parasite lives in or on a host and feeds off the flesh or fluid of the host
What is symbiosis?
An interaction between two organisms living in close physical association
What is predation?
One organism benefits by preying on the other, which is negatively affected
What is herbivory?
Animal species benefits from feeding on a plant species, which is negatively affected
Predation and herbivory often drives the __________.
evolution of defenses
What is competition?
An interaction between individuals in which each is harmed by their shared use of a limited source
What is intraspecific competition?
Competition among individuals of the same species
What is interspecific competition?
Competition among individuals of a different species
What is interference competition?
Direct competition in which one individual physically excludes the other from that portion of the habitat
What is exploitative competition?
Indirect comptions in which use of resources depletes the amount available to others
What is competitive exclusion?
if two species require the same resources, they cannot coexist indefinitely
What is niche partitioning?
When competing species use different resources to reduce competition
What is character displacement?
Genetically based divergence in phenotypic traits results in decreased competition between species
Species interactions can change based on __________.
environmental conditions
What is coevolution?
A pattern of evolution in which two interacting species reciprocally influence each other’s adaptations over time
In what kinds of competition does coevolution occur?
mutualism, parasitism, and predation/herbivory
A change in the trait of one species acts as a __________ on the other species.
selection pressure
What is an evolutionary arms race?
A mechanism of coevolution that occurs in t/- species interactions. Traits that increase feeding efficiency in predators, herbivore, and parasites evolve. In response, traits evolve that make prey elusive or unpalatable.
Communities are _______ and _________.
dynamic, change over time
What is a disturbance?
A strong, short-lived disruption to a community that changes the distribution of biotic and abiotic factors
What does the impact of a disturbance depend on?
- Type of disturbance
- Frequency of disturbance
- Severity
What is a disturbance regime?
Predictable frequency and severity of characteristic disturbances in a community
What is succession?
Predictable pattern of community dynamic after a disturbance where species with certain life history patterns succeed each other.
When does primary succession occur?
When a disturbance removes the soil
When does secondary succession occur?
When a disturbance removes some of the organisms in an area leaves the soil intact, including the seeds and organisms within the soil
Primary succession is a ________.
slow process
Secondary succession is a ________.
fast process
What is a pioneering species?
A species adapted for growth in disturbed soils that devote most of their energy to reproduction, not competition
What are the steps of secondary succession?
- Pioneering species
- Early successional community
- mid-successional community
- Climax community
What is a keystone species?
A species with a much greater impact on the distribution and abundance of the surrounding species than predicted by abundance
When characterizing community structure, ecologists often consider a subset of species when studying ________.
the community
What is species diversity?
The number of species and abundance of each species
What is sampling effort?
How many samples are required to characterize the community
When the sampling curve levels out ___________.
we have found almost all of the species
When a species accumulation curve levels off at a higher y-value, __________.
The community has a higher species richness
What are species indices?
A mathematical measure of diversity that takes into account species richness and evenness
H= ________
diversity index
S= _________
total number of species in a community
Pi= _________
portion of community made up of the species
What are primary producers?
Organisms that transform solar energy into chemical energy as sugars and carbohydrates (also called autotrophs)
What is gross primary productivity (GPP)?
Measure of the total amount of chemical energy produced within an area over a given period
What do primary producers use the energy they produce for?
Cellular respiration, growth, and reproduction
What does NPP represent?
The total amount of chemical energy stored in organic material in an ecosystem (biomass)
What do primary consumers eat?
Primary producers
What are trophic levels?
Organisms that obtain their energy from the same source
What do food chains represent?
The pathway of energy flow through trophic levels
Energy transfer is ________.
Inefficient
Only ___ of biomass is transferred between trophic levels.
10%
What is productivity?
Rate of biomass produced by growth and reproduction
What is efficiency?
Fraction of biomass transferred from one trophic level to the next
Pollutants become concentrated at _______.
Top trophic levels
What is biomagnification?
Persistent organic pollutants (POP’s) increase at higher levels of the food chain
_________ varies across space.
Productivity
NPP is higher in the ________.
Wet tropics
NPP is lower in __________.
Dry and cool environments
Productivity varies by _______.
biome
What are decomposers?
Organisms that feed on dead animals
How are decomposers impactful on the environment?
They play a key role in nutrient cycling by breaking down dead organisms, they make nutrients available to primary producers, and without them NPP would drop.
What is detritus?
Dead animals and dead plant tissue
Community structure can be determined by _______________.
Bottom-up and top-down processes
What is bottom up control?
When the amount of nutrients, sunlight, water, and other abiotic facts determine the abundance of different trophic levels.
What is top down control?
When the presence of certain consumers (biotic factor) determine the abundance of different trophic levels.
What is a trophic cascade?
When changes in top-down control cause conspicuous effects two or three links away in the food web.
What are nutrients?
Elements that are essential for normal metabolism, growth, and reproduction
What is a biochemical cycle?
The path an element takes as it moves from abiotic systems, through trophic levels, and back again
What are the steps of nutrient cycling?
- Nutrients are taken up from the soil by plants and assimilated with plant tissue
- Nutrients pass through the consumer food web
- Decomposers feed on detritus and release nutrients back into the soil
What is soil organic matter?
Complex mixture of partially and fully decomposed detritus
What is humus?
Completely decayed detritus, rich in humid acid
What is decomposition rate influenced by?
abiotic conditions, quality of detritus, abundance and diversity of detritivores
Warmer and moisture environments have _____ decomposition rate.
higher
What are reservoirs?
Areas where elements are stored within the cycle
What is flow?
Processes that moves elements from one reservoir to another
What is groundwater?
A reservoir of freshwater stored in the ground
What are aquifers?
layers of porous substrate saturated with water
What is genetic diversity?
The total genetic information contained within all individuals of a population, species, or group of species.
What is genome sequencing?
Investigates the entire genome (complete set of genes present in an organism)
What is environmental sequencing?
Sequences all genes from a sample of water or soil
Genetic diversity is important because ____________.
it represents the ability to evolve in response to environmental change
What is species diversity?
species richness and evenness of a community
The evolutionary and ecological contexts of all species are not equal, meaning __________.
some species play a bigger role in the community than others
Species richness=________
the number of species within a community
What is phylogenetic diversity?
Evolutionary distinctiveness, measured using branch lengths among species in a phylogeny.
What is functional diversity?
Ecological distinctiveness, measured by categorizing and counting the functional traits of species.
There are often ________ in protecting functional versus phylogenetic diversity
trade-offs
Biodiversity is ________.
dynamic
Why is biodiversity dynamic?
Changes in time and changes over space
How does genetic diversity change over time
mechanisms of evolution
How does species diversity change over time?
Speciation increases it while extinction decreases it
Changes in environmental conditions impacts the distribution and abundance of species, influencing ______________.
diversity of regions across the globe
Biodiversity is ________ in the tropics and ________ with increasing latitude.
highest, decreases
Biodiversity is ______ on land than in the sea.
higher
What is an endemic species?
Species that are found in a particular area and nowhere else.
What the conditions of a biodiversity hotspot?
- contain at least 1500 endemic vascular plant species
- have lost at least 70% of their primary vegetation
How much of earth’s area do biodiversity hotspots make up?
17%
Biodiversity hotspots make up ___ of all plant species and ____ of all terrestrial species.
50%, 77%
What are ecoregions?
Regions with similar conservation concerns, biological processes, and ecosystem services
What are ecosystem services?
The direct and indirect benefits that humans derive from organisms and the ecosystems they compose.
What are provisioning services?
services that provide raw materials
What are regulating services?
part of earth’s life support system
What are cultural services?
Services that enrich quality of life
What are supporting services?
Services that enable all other ecosystem services
Biodiversity supports ______.
ecosystem functioning
Increased diversity leads to __________.
increased NPP
How does biodiversity support ecosystem functioning?
Resource use efficiency, facilitation, and chance inclusion of high productivity species
If biodiversity improves productivity and stability improves ecosystem function which in turn ________.
promotes healthy ecosystem services
When does a mass extinction occur?
When at least 60% of species are wiped out within one million years
Current extinction rates indicate __________.
a 6th mass extinction
What is background extinction?
Extinction rate when no mass extinction is occurring
What was the End-Cretaceous mass extinction?
Hypothesis: an asteroid struck earth, leading to the extinction of 60%-80% of living species
What happened because of the end of the cretaceous period?
The rise of mammalian diversity
