Module 2: Evolution and Adaptive Significance Flashcards
what is the distinction between psychology and biology?
proximate and ultimate causality
what is proximate causality?
the how questions in life sciences
what is ultimate causality?
the why questions in life sciences
questions of function search for what
the function or purpose of something
what is an important mechanism of evolution?
natural selection
what is natural selection?
refers to the differential reproductive fitness resulting from differential adaptation features of the environment
what are examples of local features?
temperature, precipitation, topography
local features drive speciation by …
favoring animals that have adaptations specific to these features
what are the 3 characteristics of global features?
endurable
stable
nontrivial
most obvious features are associated with …?
the solar day
circadian clocks represent a _____-specified internal representation
genetically
what must be established to formulate hypotheses about circadian clock origins?
range of life forms that can possess circadian clocks
what makes a daily rhythm circadian?
it persists in a constant environment with a 24hr periodicity
what are the 3 domains in life?
eukaryote
bacteria (prokaryote)
archaea
true or false: true circadian clocks are within all 3 domains of life
true
are circadian clocks present in all kingdoms in life? examples are plants, animals, and fungi
yes
multicellular eukaryotic organisms have ___ circadian rhythms and unicellular eukaryotic organisms have ___ circadian rhythms
multi: true
uni: bone fide
prokaryotic organisms lack ____ but have ___ circadian rhythms
cell nuclei/membrane-bound organelles
true
based on eukaryotic and prokaryotic organisms, what can we conclude about circadian clocks?
- they are ancient and widely conserved
- they likely appeared in the history of life on Earth
- clocks have evolved many times according to operational analyses of clock genes
- life forms must make important contributions towards survival if most life forms have them
true or false: bacteria, plants, and animals have the same clock genes
false: they do not share the same clock genes
what are assumed to be the biological challenges faced by early life that led to the evolution of circadian clocks (2)?
external and internal coordination challenges
describe the external coordination challenge
challenge of needing to coodrinate biochemistry with solar radiation/temperature daily cycles
describe the internal coordination challenge
challenge of coordinating biochemical processes with each other so they occur in the correct order and so incompatible processes occur at different times of day
sunlight serves as a ____ but also a ____
potential energy source
danger
explain why sunlight can pose a danger to species
high energy can strip electrons and damage biomolecules to disrupt cellular processes
true or false: sunlight can pose as a danger to DNA replication
true
what were the 2 solutions for organisms that did not have physical barriers to block UV light?
restrict critical cellular activities to nighttime
hide from daylight
when species were proposed to hide from daylight or restrict their critical cellular processes to nighttime, what was this hypothesis called?
escape from light hypothesis
about 2.5 billion years ago, what event did the Earth experience?
the great oxidation event
what caused the great oxidation event?
the rapid increase of atmospheric oxygen by the means of reproductive fitness of cyanobacteria
cyanobacteria contributed to the great oxidation event by…
making metabolic fuel via photosynthesis from light
what is the issue with aerobic metabolism?
it generates toxic reactive oxygen molecules (H2O2/free radicals) that can damage cells
the evolution of aerobic metabolism depended on what?
the co-evolution of antioxidant biomolecules for scavenging oxygen radicals
describe how circadian rhythms may have evolved to resolve the effects of aerobic metabolism
controlled the production of antioxidants to be available for daytime when photosynthesis occurs
how do circadian rhythms work in terms of producing antioxidants for reactive oxygen molecules?
turn on production in anticipation of day when the reactive oxygen molecules would be accumulating
the hypothesis that turns on the production of antioxidants for H2O2/free radical oxygen molecules in the daytime is called..
escape from oxygen radicals hypothesis
true or false: biochemical processes are vital to cell/organ function but can be incompatible with other vital processes
true
what is nitrogen fixation?
when cells convert environmental nitrogen to ammonia for cell use
what is nitrogenase?
the enzyme needed to drive nitrogen fixation
what can destroy nitrogenase?
oxygen from photosynthesis
can nitrogen fixation and photosynthesis occur at the same time, in the same space?
no
how does the circadian clock account for the issue that nitrogen fixation and photosynthesis are not compatible?
gating the production of nitrogenase to make it available at night thus limiting nitrogen fixation to night
what is an example of mammalian clock-controlled temporal segregation of internal processes?
regulation of glucose storage in the liver
how is glucose stored and taken up?
stored as glycogen and taken up by hepatocytes
what enzyme contributes to glycogen synthesis?
glycogen synthase
what enzyme contributes to glycogen breakdown/degradation?
glycogen phosphorylase
how does the circadian clock regulate glycogen
- synthesis and
- degradation
- favors glycogen synthesis during the active-feeding phase of the rest-activity cycle
- favours glycogen phosphorylation in the rest/fasting phase of the rest-activity cycle
how many times have circadian clocks been suggested to evolve?
4 times
how are circadian clocks conserved across phylogeny?
they continue to make important contributions to a species survival
organisms with no skin and pigmentation that would help minimize penetration of UV light will have to anticipate what?
the change from day to night and back
true or false: environmental temperature and humidity are important to Nematode worms’ anticipation
true
can circadian clocks be critical in timing an event that only occurs once in a lifetime? what organism is an example with this concern?
yes
fruit flies
what is food anticipatory activity?
when memory is inferred from the emergence of activity prior to mealtime
at what times are rats active when food anticipatory activity is established?
1-2 hours before meal time
during meal time
if a meal is skipped, will the FFA pattern still occur the next day?
yes
if an FFA pattern still persists if a meal is skipped, what does that say about the animal?
it is remembering the time of day rather than responding to simple hunger
____ program behaviour but the clock system is flexible and can ____ adjustments when necessary
circadian clocks
permit
when there are 2 predictable meal times where each has a different location, what do animals use to decide where to go with the help of no external cues?
time of day
what are the 2 modes in which circadian clocks can be used conceptually?
- alarm clock mode
2. wristwatch mode
which organism uses the ideas of alarm clock and wristwatch modes when determining mealtime?
honey bees
what is the idea of a wristwatch mode?
the concept of a unitary clock that can be continuously consulted
what is the benefit of using wristwatch mode?
foraging efficiency by discriminating time of day without using external cues
what is time-place learning/association?
another term for memory time
how do animals demonstrate time-place learning?
they can discriminate the time of day by learning to go to a particular place at particular time of day
what do animals use to navigate over short or long distances as a directional tool?
the sun
how far does the sun rotate every hour?
15 degrees of arc
because the sun moves 15 degrees of arc per hour, animals have to …
continuously adjust its bearing relative to the sun
how do bees communicate time and location of food to other bees?
waggle dance
describe the honeybee dance used to communicate where other can forage for food
running in a circle on the vertical plane where each revolution it bisects the circle at a specific angle
true or false: circadian clocks help animals forage for mates
true
why is the role of circadian clocks in finding mates important to some species?
they have brief adult lives or live in a solitary lifestyle
what would enhance the chances of males and females meeting?
both sexes being active in the same time of day
how do circadian clocks achieve exposing males and females meeting?
create a rest-activity cycle that is synchronized by an environmental time cue to which both are exposed
describe how blind mole rats have true circadian rhythms that entrain light/dark cycles
small rudimentary eyes under the skin with specialized photoreceptors that communicate directly with the brain circadian clock
___ of predators is important throughout life of an organism but takes on special importance at vulnerable stages
avoidance
how do guillemot chicks reduce their chances of getting eaten when they leave their nests to find their own fish to eat? how do they do this?
fledge in large groups and only do so in the evening
controlled by circadian clocks
what is temporal niche segregation?
use of circadian clock to limit activity to day/night in order to avoid competition with other species or with dominant individuals of the same kind
what are 3 more uses for circadian rhythms?
- photoperiodism
- habitat selection
- extended physiological states
what is photoperiodism?
ability to measure the length of a day as a means to keep track of the time of the year and adjust behaviour in advance in seasonal changes
what is habitat selection?
animals that use cave/underground rely on circadian clock to control wake up time to ensure animal begins its foraging activities
explain what is meant by extended physiological states
the biological necessity to spend part of each 24 hour cycle sleeping
what did Patricia Deocoursey discover? (2)
- chipmunks with their master circadian clock removed still showed daily rhythms
- had eliminated their rest-activity rhythms which caused them to make noises when they were supposed to sleep
true or false: loss of the clock might impair any physiological system sufficiently to result in death
false
observing cave fish with regressed visual systems and lack of pigmentation showed they have weak or absent circadian rhythms but..
rhythms can become rhythmic if restricted to one meal time
what can be learned from cave fish-produced rhythms?
arrhythmic species can become circadian if food availability becomes circadian
what are the 2 conditions in which growth and survival is most successful
- there is a circadian rhythm that matches environmental cycles
- the environment is rhythmic and not constant
what can one conclude about a circadian organization as a result of the observations on tomato plants, drosophila, mutant hamsters, adrenalectomized hamsters, and cyanobacteria?
circadian organization does provide significant advantages for growth/survival but only when the environment is circadian and if there is competition for resources
mutation of clock genes or repeated shift changes of the light/dark cycle do what?
link circadian clocks with health and survival
some clock genes regulate the expression of genes that control ____
the cell division cycle
what happens when clock genes are knocked out?
dysregulation of cell division and tumor growth
