BIO 214 Exam 2


Terms in this set (...)

a trait that has arisen via natural selection;
a trait that increases the ability of an individual to survive and reproduce compared to different traits of others
Life History
aspects of the organism's biology such as the number of offspring it produces, survival, size, age of reproduction; affected by environmental changes, characteristic of organism, and interaction with other species
If an organism uses energy for one function (growth/migrate), there is less energy available for other functions (reproduction)--> trade-off between function
short life span, reproduce quickly;
individuals have a single, distinct period of reproductive output in their lives
Longer adult survival, invests more in growth than reproduction;
normally experiences several reproductive events, during each event continuing to invest in growth
Density-independent factors
Disturbance, environmental changes, extreme weather; nothing to do with organism itself
Density-dependent factors
interspecific competition (food, space), intraspecific competition, contagious disease, waste production
Intraspecific Competition
within species (food, space)
ex: self thinning in plants
Interspecific Competition
between species
live in intimate, continual contact between two species
1) mutualism (sometimes): lichen fungi & algae are only found together
2)parasitic (sometimes): parasitic tapeworms can only grow/reproduce in the gut of vertebrate
Interference Competition
occurs DIRECTLY between individuals via aggression;
interfere with foraging, survival, reproduction of others, prevent physical establishment, territorial species
Exploitation Competition
occurs INDIRECTLY through common LIMITING RESOURCES that act as an intermediate
Neutral Interaction
Neither species is benefited or harmed
Doesn't affect one organism, the other is harmed
Doesn't affect one species, benefits the other
ex: small fish that eat sharks scraps, shark is not affected
one species benefits, the other is harmed
ex: parasite take nutrients from host
Mutualism (2 types)
both species benefit; benefits > costs
-doesn't have to be symmetric (one can be obligatory and the partner facultative)

1) Obligatory: organism cannot survive in the absence of the other partner
ex: algae & lichens- symbiotic

2) Facultative: organisms can live an independent existence
ex: flowers & bees- not symbiotic
Realized Niche
how the organism grows with competition;
narrower niche resulting from competition
Fundamental Niche
uses removal experiments to remove each species and see where the other grows & NO competition;
niche of the competitively-inferior species EXPANDS in the absence of competition
a niche of a species may contract in the presence of a competitor species leading to...
1) Resource (niche) partitioning- similar species exploit the limited resources in an ecological area without one species driving the others into extinction
2) Coexistence among similar species
plant eaters, including algae
meat eaters
eating one's own species- a specialized form of predation
usually insects lay their eggs on the other insects as hosts. The larvae complete development on the host, usually killing the host as a result
ex: wasps laying eggs on moth
feeding on another organism's parts without killing the organism
ex: mosquitoes spend little time on their host- not symbiotic; tapeworm lives inside gut of host- symbiotic
Obligatory Mutualism
organism cannot survive without the other partner
Facultative Mutualism
organism can live on independent existance
plants gets pollen transfer and pollinator gets food
cleaner shrimp eat ectoparasites off fish
one gets food/shelter, the other gets protection
ex: ants & acacia system, plants & nitrogen fixing bacteria, bacteria-aphids & lichens, plants & mycorrhizae (facultative)
association of interacting different species inhabiting the same area
Structure: number of species, species abundance, species diversity, biotic and abiotic factors
Group of organisms that all make their living in the same fashion
ex: all seed eating animals
Controls Number of Species and Relative Abundance:
1)Species Richness: # of species in a community
-problem: number of species depends on sample size; corrected with rarefaction

How to measure Diversity:
1) Richness: # of species
2) Evenness: how equal are the species in terms of abundance
3)Simpson's Index
4) Shannon-Weiner's Index

if two communities have the same patterns/levels of diversity then break them down into guilds and find diversity of each guild
Food Webs
summarize feeding relations in a community (direct or after food is dead)
Community is based on...?
but habitat formation, competition, amensalism, commensalism, pollination also affect relationships between organisms
Indirect Interactions
one species affects another through a third intermediary species
ex: beaver cuts down tree, nutritious leaves grow, beetle benefits from eating them (commensalism)
Apparent Interactions
Occurs indirectly between two species which are
differentially affected by the same natural enemy. For example, species A and
species B are both prey of predator C. The increase of species A will cause
the decrease of species B because the increase of As would increase the
number of predator Cs which in turn will hunt more of species B
What is a Keystone Species? How does it impact a community?
Species that has a disproportionate effect on its environment relative to its abundance

Can impact community by:
1) Competition- reduce competitive exclusion, increasing the number of species that could coexist
2) Predation or Herbivory: keystones can be predator or prey; removal of predator may allow its competitor to expand
3) Structure: can alter environment that creates opportunity for other species ex: coral reefs, beaver cutting trees & building damn
Patterns that increase Diversity
complex environments & intermediate levels of disturbance
Patterns that increase Species Richness
larger area, nearer source to colonizer, middle to high latitudes to equator
Why does species richness increase near the equator?
-Time since perturbation: topics are older and have less distribution
-Productivity high
-Environmental Heterogeneity- more intermediate disturbances thus more potential habitats
-Favorableness: climate determines energy
-Interspecific interactions
-Rosenzweig found strong positive correlation between species diversity & area
Food Chain
Simple interactions
Evolution (name mechanisms)
changes in allele _frequencies_ over time

1) Natural Selection
2) Mutation
3) Genetic Drift
4) Gene Flow
5) Nonrandom Mating
Natural Selection
acts on the individual, but its consequences occur in population; theory proposed by Charles Darwin
-individuals do not change, but _traits_ allowed them to better survive
-acts on _phenotype_ (if phenotype is not heritable then evolution will not occur)
-population change observed in offspring is a consequence of selection on their /parent/.
-organisms do NOT adapt to future conditions
-natural selection acts on _existing_ traits
- NOT progressive & is nonrandom
Artificial Selection
Form of natural selection; Human domestication on specific trait was selected

ex: breeding big tomatoes to produce more big tomatoes; trait selected was size
Charles Darwin
Studied for the clergy at Christ's College, Cambrian University; purposed theory of natural selection
Published Origin of Species
"the fittest would survive"
Alfred Wallace
Elements of Evolution by Natural Selection
1) phenotypic variation- populations are variable
2) heritability- passed from parent to offspring
3) competition- some individuals are more successful at surviving and reproducing
4) fitness- survival and reproduction are not random
ability of individual to survive and reproduce
proportion of total phenotypic variation that is due to variation in genes (any values from 0 to 1).
0- heritability doesn't exist; variation is all due to environmental changes
1- variations due all to genetic heritability
What can confound the analysis of the finch's beak graph?
1) Misidentified paternity- multiple fathers for 1 nest= underestimate heredity
2) Nest Parasitism- unrelated offspring in nest= underestimate heritability
3) Shared environments- similar conditions may result in similar phenotypes =overestimate heritability
4) Maternal Effects- overestimate if you look like mom
Galapagos Finches
studied variation in beak size
1) is there phenotypic variation? yes
2) is variation heritable? yes, necessary for population to evolve
3) do individuals vary in their survival/ reproduction? yes, finches population declines after drought & birds with bigger beaks survive until a new species invades, then more small beak birds remain
4) is survival/reproduction nonrandom with respect to the trait? smaller mean beak depth before drought, selection event (drought), adults surviving with bigger beaks & mean increases beak depth
Did other traits evolve over time in the Finch's experiment?
Yes, different traits were selected in different ways & have different evolutionary histories therefore they have different patterns compared to beak size. Not all traits evolved via natural selection
How do new traits evolve via natural selection?
Natural selection acts on the existing traits of an individual:
- must be variation for selection to act on
-genetic material is NOT static
-traits that evolved for one function may continue to evolve and acquire a new function= preadaptation & exaptation
-historical constraints
an effect
What is missing from Darwin's theory?
1) how variation was generated
2) how variation was passed to offspring
changes in allele frequencies within populations; observed _within our lifetime_.
ex: soapberry bugs
large evolutionary changes; on a time scale _beyond_ our lifetime.
study extinct and extant taxa, use fossil record and transitional forms
Vestigial Organs
a basic version of a body part that has an important function in another species--> shows common ancestry
ex: tail bone in humans & tail in monkeys
any similarity between characteristics due to their shared ancestry --> shows common ancestry
Same bones/structure, different function

ex: human arm, dolphin fin, bat wing
a product of the organism; defined by the species