10/25 quiz Flashcards
what are the two modes of reproduction?
sexual and asexual
sexual is far more common
what is sexual reproduction?
gametes are formed in meiosis and each contains 1/2 of parent’s genetic material -> one full set of chromosomes = haploid
sperm + egg = zygote, which is diploid
new individual develops from zygote
why is sexual reproduction costly?
energy consumption
- find mate (physically searching)
- get mate (courtship, elaborate appearance, etc)
cost of meiosis
vulnerability of predation while attracting mate
what is the cost of meiosis?
each offspring only carries one half of a given parent’s genes
why is asexual reproduction technically more productive than sexual reproduction?
fitness is measured by amount of genes passed down to next generation
asexual passes down 100%, sexual only passes down 50%
AS should be favored by NS
why doesn’t NS select for asexual reproduction?
sexual allows for genetic variability of offspring, can better survive changing conditions
genetic variation is a form of “___ ___”
bet hedging
not putting all their “genetic eggs into one basket”
can organisms reproduce both sexually and asexually?
yes, a planarian changes based on times of environmental stress
how is genetic variability related to parasitic virulence?
GV is needed to deal with continuously changing virulence
parasites often have large populations and short generations time, allowing them to evolve rapidly
what is the Red Queen Hypothesis?
how organisms are in a constant “evolutionary arms race” to simply persist in the presence of continuously evolving parasites/disease
what are the different types of sex changes?
simple life cycle -> develop sex early in life and remain constant
sequential hermaphroditism -> sex changes during life span
what does protandrous mean?
an individual is first male and then female
what does protogynous mean?
an individual is first female and then male
when is protandry favored?
when fecundity is higher in older females
good for if resources are scarce early in life, males typically need fewer
save energy and be a small male until large enough to be a female and invest energy into egg production
when is protogyny favored?
when fecundity is higher in older males
can start small as a female and be inconspicuous to predators and then, once big, avoid predators better and compete for access to females more effectively
what is an example of protandry?
clownfish
next biggest female takes over if dominant one dies
want to invest in being a growing male at the beginning and then switch to female later
example of protogyny
bluestreak wrasse - one male has multiple females, but when one dies the next largest female steps up to be the male
male gets to protect territory and mate with all females
what is senescence?
an increase in mortality and decline in fecundity
why do organisms senesce?
accumulation of physical/molecular defects
evolution of repair mechanisms in old age could have costs to earlier survival
selection on changes in survival and fecundity at old age are weak - not a super strong advantage to survive past peak fecundity age
what are the costs and benefits of earlier age of first reproduction?
B: increased reproductive output
C: lower parental survivorship
what are the costs and benefits to reproductive effort?
B: more effort -> more offspring
C: lower survivorship of parent and offspring if too much energy put in
think of european magpies with optimal 7 eggs
there is a ___ relationship between offspring size and number
negative
how does reproducing later in life help in organisms with indeterminate growth?
investing in growth earlier in life allows you to make more eggs when you become reproductively active
what is one issue with reproducing later in life?
if you die before then, your fitness is 0
what does resource allocation for growth and reproduction depend on?
predation risk of the environment
what does semelparous mean?
organism reproduces once when conditions are appropriate
will die after reproducing
when is semelparous reproduction favored?
when the cost of reproduction is high or when reproduction can be timed to occur at favorable times
what does iteroparous mean?
an organism reproduces many times
what is an example of a semelparous organism?
cicada or salmon
what is the fast-slow continuum?
concept to describe life history strategies based on growth, reproduction, and survival
what is the fast portion of the f-s continuum?
r-selected: constantly growing
rapid growth and early reproduction
shorter life span and often many offspring
little to no parental care
what is the slow portion of f-s continuum?
k-selected: have to live within carrying capacity
slower growth and delayed reproduction
longer lifespan and often fewer offspring
high parental care investment
what do K-selection life history species prioritize?
traits that increase competitive abilities - want to fit within carrying capacity
what do r-selective species prioritize?
traits that increase r
what is r-selection mainly used by?
pioneering species in habitats with high disturbance
what is K-selection mainly used by?
climax communities with species near carrying capacity
in reality, most species are … r and K selection
in between extremes of
when is r-selection favored?
unpredictable environments
when is K-selection favored?
in predictable environments
annual plants
produce many seeds at once, hold nothing back
but must grow quickly to complete lifecycle in one growing season
risk of not growing in a bad season
perennial plants
can grow and store energy over multiple seasons
must survive winter and can’t allocate as much energy to seed production
what is an ecological community?
a group of interacting species that
co-occur in a particular place
what are important factors to an ecological community?
species richness (how many), evenness (how common) and composition (what are they doing and how are they interacting)
what determines the species composition of a community?
climate/abiotic factors (environmental tolerance)
environmental complexity (niche space)
competition and biotic interactions
chance events
(also long-term events, but not focusing on these)
what does greater environmental complexity allow for?
greater complexity of inhabiting species
thinkl-l invertebrates and trees
how can the physical environment impact community composition?
directly -> environmental tolerances
indirectly -> biotic interactions
what is an example of an indirect biotic interaction related to the effects of the physical environment on community composition?
the presence of flowers impacting the presence of bees
w/o flowers, bees won’t live there
what are the types of interactions between species?
mutualism
communsalism/facilitation
predation/herbivory/parasitism/disease
ammensalism
competition
no interactions
what is mutualism?
when both organisms benefit from the interaction
what is commensalism/facilitation?
when one organism benefits and the other is indifferent
one species increases the probability that another is occurring in the community
what are predatory/herbivory/parasitic/disease interactions?
when one organism benefits and the other is harmed
what is no interaction?
neither organism is effected, both are indifferent
what is ammensalism?
when one organism is indifferent but the other is harmed
what is competition?
when both organisms are harmed by the interaction
what is an example of mutualism?
hummingbirds receive nectar from flowers (energy) and the flowers being pollinated by the hummingbirds’ movement
what is an example of facilitation?
kelp forests
kelp just grows, but it provides a habitat for other species at the same time
what are keystone species and ecosystem engineers?
examples of facilitation - species with a significant role in determining community structure
we typically notice the importance of their presence after they’re gone
what is an example of a keystone species?
wolves in Yellowstone national park (helped with species maintenance, especially with elk)
what is an example of an ecosystem engineer?
beavers - build dams that help prevent flooding and establish habitats for fish
what does symbiosis mean?
umbrella term for species interactions
what is neutral symbiosis?
commensalism - some partners benefit but none suffer
what is beneficial commensalism?
mutualism - all partners benefit; obligate or facultative
what is exploitative symbiosis?
one partner benefits and other suffers
what are obligate mutualisms?
the interaction is required by both species
orchids with a particular pollinator
what are facultative mutualisms?
occur in moments of opportunity but can survive w/o
honey bees w/ flowers
what is an example of a predatory/herbivory/parasitism/disease interaction?
pathogens in host
what is an example on ammensalism?
stepping on a bug
what is an example of a competition interaction?
seals fighting over access to females, expends energy for both individuals
what are the two types of herbivory?
predator and parasite
what is predator herbivory?
eating the whole plant
what is parasite herbivory?
only eating part of a plant
what do carnivores do?
consume whole individual (or more)
what do parasitoids do?
consume whole individual (or more)
what do parasites do in species interactions?
consume part of host
one parasite won’t consume the whole host
what are the three types of mutualism?
trophic, defensive, and dispersive
what is trophic mutualism?
partners in obtaining energy
ex: bacteria in gut, get energy from breaking down cellulose that the host otherwise couldn’t digest
what are defensive mutualisms?
food/shelter in return for defense
ex: ant defending aphid bc aphid feeds ant
what are dispersive mutualisms?
food in return for dispersal - pollination or seed dispersal
ex: bees or seed-eating birds
how are the plants in the salt marsh an example of facilitation and ecosystem “engineers”
species that can grow in the salty water block/buffer further back species from the tides and salinity, making conditions more favorable for them
mutualism in aquatic environment
corals have high productivity due to mutualism btwn polyp and unicellular algae
algae provide carbohydrates through photosynthesis and secrete 90-99% of fixed carbon to coral
polyps shelter algae and produce ammonium as a waste product, which is a nutrient to the algae
parasites play a role in …
maintenance of genetic diversity
sexual reproduction
female mate choice
regulation of host populations
how is disease different from predation?
is doesn’t necessarily kill its victim
after infection, victim often becomes immune
disease is much smaller than victim, opposite w/ predators
disease organisms aren’t often independently mobile
what are important characteristics of disease population dynamics?
virulence: how quickly the population grows within a host
transmission rate: how the disease moves between hosts
rate of spread: host movement (migration and dispersal)
how can a disease can modify host behaviors to induce transmission
sneezing/coughing
rubbing eyes/scratching pustules
induced excretion
biting (rabies)
what are factors that limit population growth?
density-independent
competition (both inter and intraspecific)
predation (herbivory, parasitism, disease)
what is coral reef bleaching?
due to environmental stress, corals expel algae even though it is harmful in the long run, they can’t maintain them anymore
two forms of competition
inter and intraspecific
two forms of interspecific competition
interference and exploitative
how did arthur tansley use the common garden experiment?
to test interactions between closely related species
what were the results of arthur tansley’s common garden experiment?
both plant species grew best in their natural soil but were able to grow a bit in the opposing one
when in combination, the native plant grew best in its own soil with few of the foreign plant succeeding
what did tansley’s experiment demonstrate?
the effect of an organism’s environment and competition
why did the gazelle population decrease after the wildebeest population grew?
the gazelle population’s carrying capacity changed
what effect can species a have on species b if they are in the same habitat?
the presence or absence of species a can determine the p/a of species b due to competition between the two
both can persist, but one may be better at it and out compete or interfere with the other
___ conditions can affect competition
environmental
how can past competition impact the present?
it can influence present species distributions
what is a resource?
anything consumed/used by organisms
what are examples of resources?
water, food, space, shelter
what is a limiting resource?
a resource that is in short enough supply that the amount available begins to impact population growth
what is a non-limiting resource?
a resource that is plentiful enough that increasing it wouldn’t increase population growth
lower availability of resources leads to…
lower population growth rates
what is the definition of competition?
any use or defense of a resource by one individual that reduces the availability of that resource to other individuals
what is intraspecific competition?
within a species
species has a negative effect on itself
what is interspecific competition?
between species
what mathematical model do we use to calculate intraspecific competition?
a rearrangement of the logistic equation
very similar to carrying capacity
what mathematical model do we use to calculate interspecific competition?
a modified version of the logistic equation that integrates intensity of competition and the population size of the other species
how are competing species related?
they are functions of each other
as species a increases, there will be a decrease in growth rate of species b, and vice versa
what happens to intraspecific competition at high population densities?
competition is strong
what does intraspecific competition do for population size?
regulates it
what does intraspecific competition do in terms of selection?
leads to evolution by natural selection and sexual selection because mates are a resource
what does interspecific competition help determine?
which species can coexist
what does interspecific competition help regulate?
each species and the ones around it
what can interspecific competition lead to?
extinction of a species
what is exploitation?
indirect interspecific competition
a reduction in growth rate due to use of a shared resource
what is interference?
direct interspecific competition
a reduction in growth rate due to active interactions between two species
in exploitative competition, one species … of a resource required by another
reduces the abundance
in interference competition, one species … to a resource required by another
denies or reduces access
what is an example of a behavior that demonstrates interference competition?
birds that eat fruit off trees attacking other fruit-eating birds that approach fruit tree but being indifferent to non-fruit-eating birds
defensive of fruit tree
what is apparent competition?
the relative ability of two species to tolerate an external pressure
competition mediated by predators/parasites/disease
what is an example of apparent competition?
tree frogs surviving poorly when all three frog species exist together in the absence of predators
with few predators: tree frogs survive a bit better
with multiple predators: tree frogs survive best
what is the competitive exclusion principle?
two species cannot coexist indefinitely on the same limiting resource
keyword: LIMITING
limiting resources can occur …
only part time/seasonally
according to body size, age, etc. (ex: only competing as juveniles)
limiting resources become more limiting with more competitors, this leads to ___ ___ effects
density dependent
when can competing species coexist?
when they have different niches
the greater the niche overlap between species, the…
stronger competition will be
what is a fundamental niche?
includes all the resources a species CAN use
neglects species interactions
what is a realized niche?
the resources a species actually uses given competition by other species
is narrower than the fundamental niche
example of fundamental and realized niches
barnacles
one species can inhabit all of the space (fundamental niche), but sticks to top bc of other species (realized niche)
other species can only survive in lower area, stays within its fundamental and realized niche
when there are limiting resources, we can model which species will win based on those species’…
carrying capacities
