Ecology Flashcards
what is ecology?
the study of the interactions of organisms with their environment
what kinds of ecosystems are there?
biotic and abiotic
at what levels can ecology be studied?
individual, population, communities, ecosystems
populations: groups of individual organisms that interbreed with each other
communities: populations of different species that interact with each other within a local
ecosystems: all living organisms as well as nonliving elements that interact in a particular area
what is predation?
when one organism feeds on another (community ecology)
this exerts a strong selective pressure on prey
what do animals do to avoid predation?
1) camouflage
2) warning coloration (mimicry)
3) mechanical defense
4) chemical defense
5) behavioral defense
what is coevolution?
interactions between species are strong (community ecology)
selection and evolution across species boundaries
selection driven by interaction between species –> species are engaged in a “reciprocal adaptive response”
what is an example of coevolution?
symbiosis
what is symbiosis and what are some examples of it?
close interactions between species
- parasitism
- mutualism
- commensalism
- predator-prey
what’s an example of parasitism?
european cuckoo
puts its eggs into other eggs nests so other birds will have to take care of their kids
what’s an example of commensalism?
cattle egrets
the birds eat the bugs off the cattle –> they get food and the cattle gets cleaned
what is the selective regime?
the selective regime is not set by the physical components of the environment but by the biological interactions occurring within the ecosystem
coevolution and fitness?
each participant in the coevolutionary relationship undergoes natural selection, with the highest fitness and associated with genotypes that address the partnership
other selective forces such as food availability, sexual reproduction, etc. still apply but are of lower importance and so don’t determine the direction and mode of selection the way the partnership does
how does coevolution happen?
1) mutualism
2) escalating “arms race” (predator/prey interaction)
3) cospeciation (host/parasite interactions)
what is an arms race?
predator/prey interaction
what is cospecitation?
host/parasite interactions
what are mutualistic relationships?
both partners derive some benefit from the interaction
typically fairly specific –> otherwise force of selective pressure may not be sufficient
how can you test differences in fitness in a mutualistic relationship?
fitness levels are higher when the organisms are together vs. when they’re not
the predator-prey arms race
prey are under strong selection to avoid predator
predators are under strong selection to find sufficient food
if a predator specializes upon a single kind of prey or a prey item has only one significant predator, this interaction may be the strongest selective force facing the organism –> having multiple prey/predators diffuses the effect any one interaction has on overall fitness
how do you show that two organisms are actually in coevolution with each other?
all things that are eaten have a general defense against predators
BUT
to be co-evolution the predator-prey relationship must be the primary selective force and there must be reciprocity in the response
what is the Red Queen hypothesis of the evolutionary arms race?
it takes all the running you can do to keep in the same place, if you want to get somewhere else you must run at least twice as fast as that
organisms must constantly adapt, evolve, and proliferate not just to gain reproductive advantage, but also simply to survive while pitted against ever-evolving opposing organisms in an ever-changing environment, and intends to explain two different phenomena: the constant extinction rates as observed in the paleontological record caused by co-evolution between competing species,[1] and the advantage of sexual reproduction (as opposed to asexual reproduction) at the level of individuals
does daphnia cyclomorphosis experience coevolution?
no
an abundance of predators induces metamophosis to pointier, more robust and less digestible morphology
however, this response can be induced by any one of 3/4 predators or by turbidity so there is no evidence that predators are reciprocally selected –> they may have other food sources
what are some expectations about arms races?
we expect predators to increase as prey increases initially
but then a boom in predators will decrease the number of prey
as prey becomes scarcer, predators die of starvation
as predators become scarcer prey populations rebound
**they will cycle through this until stable = equilibrium densities are reached
anti-herbivore defenses of plants
plants in the carrot family contain many noxious compounds that have been shown to deter herbivorous insects
Depressaria and parsnip
depressaria spends most of its life on a single plant and preferentially eats reproductive tissues (flowers and seeds)
in a controlled environment, more seeds are made and set compared to the wild but making furanocoumarins costs the plant in terms of energy and resource allocation
depressaria detoxifies the plants metabolically and the ability to detoxify furanocoumarins has a genetic basis –> the metabolic processes are expensive in terms of energy
there is a variation among depressor in terms of the ability to detoxify and a variation among parsnips in terms of the amount of furanocoumarins –>the most toxic genotypes co-occur with the most metabolically capable depressaria
