Unit 3 : Thermoregulation Flashcards
What is homeostasis?
A dynamic process tightly regulated by an organism which changes its behaviour in order to keep all processes and traits in a certain liveable range. (Dynamic environment that has things to counteract those changes and keep it in a range, NOT ONE SPECIFIC VALUE!)
Or: “The regulation of an internal environment in the face of changes in the external environment.”
Example of the thermostat, how does it regulate temperature? What are the three parts of the thermostat that allows it to do this?
When temperature int he house is too low, it turns on and produces heat to warm the house. Once it’s too low, it turns off to allow the house to cool.
It does this through a negative feedback circuit:
Some physiological variable increases/decreases, which a sensor / receptor notices.
This sensor sends a signal to the integrator, which compares this value to the set point.
This then sends a signal to the effector if it is too far from that set point, and the effector is what CAUSES the change. Once the physiological variable changes back to its normal state, the sensor relays this to the integrator, which then turns the effector off.
What is the ideal situation for production of a species? Is this the reality? What can be done if this is not the reality to survive?
What is the ultimate goal of an energy budget?
The ideal situation for the reproduction of a species is to have unlimited resources to support maximal growth and a long life and a continuous production of offspring, to grow that population to the maximum. But of course many other factors come into play that inhibit this, such as energy being used to find food, to reproduce and to survive, and energy is not limitless. Therefore, an energy budget must be used to balance this energy across the many different places it is needed, and hence survive.
If you survive but don’t reproduce, you are an evolutionary dead end, but if you reproduce a lot and then die, you can’t contribute to the population and help your offspring survive — both to the extreme is detrimental.
Ultimate goal of an energy budget is to have enough energy left over to allocate to reproduction.
What is a life history trait? Life history strategy? What led to the development of these strategies?
Life history trait: This is a characteristic that the organism has that affects the organisms fitness and relates to the timing and occurrence of various key life cycle stages. Specifically, their size and age at sexual maturity, age specific survival rates, growth rate and patterns of dispersal, and lifespan. These all determine its fitness and are individualized based on many factors.
Life history strategy: This is the set of strategies outlined above which define how an organism allocates its resources and experiences throughout its life — so how it utilizes the above traits to survive most efficiently. This was shaped by natural selection — based on what type of lifestyle kept that specific species alive the longest or producing the most offspring.
What in the past shapes what in the future?
What things may change these factors in the present?
Success in the past shapes the life history strategies of the future. This is because by trying out different patterns of growth, development and reproduction, natural selection was able to chose specific traits for each species, which allowed it to be the most “fit” in its environment. So whatever traits allowed previous generations to survive and reproduce were clearly effective and hence were passed onto the next generation and hence determine the life history strategies that are used to be fit.
The environment can change the life history traits due to changing resources available, and hence those organisms may need to shift their patterns in order to survive in the changing environment.
What are tradeoffs and why are they essential?
Tradeoffs are when the energy put into one trait is taken away to be put into another trait. These are essential because energy budgets are fixed due to competition in the environment, and hence each species much chose where they want to allocate their energy in order to be the most successful and “fit”. As well, selective pressures in the environment can shape how these tradeoffs occur, especially if an organism is being continuously hunted, it cannot spend energy on reproduction as the young will die. It must spend energy on survival until the predator population decreases and then it can go back to reproduction.
Overall, if you spend energy on one factor, you will lose the energy available to spend on another factor.
Spend more money on growth — you might be eaten because you are not protected.
Spend more money on defence — you wont grow as well and have as much energy saved to reproduce as much.
If 2 _______ ________ __________ compete for a share of _________ _______, then its is impossible to __________ __________ __________ simultaneously.
If 2 life history traits compete for a share of limited resources, then its is impossible to maximize both traits simultaneously. One has to give up some energy reservoir for another, and this is all based on natural selection and current selective pressures in the environment.
ANY GAINS BY ONE TRAIT WILL RESULT IN A LOSS BY THE OTHER.
THIS IS BECAUSE BOTH TRAITS CANNOT BE MAXIMIZED SIMULTANEOUSLY!!!
What does a graph of fitness V.S. Number of seeds produced look like? Why? What about fitness V.S. Size of seeds produced? Why? What about seed size v.s. Number of seeds produced? Why?
Graph of fitness V.S. Number of seeds is a linear upwards line, where as the number of seeds increases, the fitness of the plant will greatly increase, as it is increasing the probability of one of those seeds planting in the ground and growing a new plant.
Graph of fitness v.s. Seed size will also be a linear upwards line, because as seed size increases, they will have more energy in each seed and hence will be able to more easily burrow into harder ground. So each seed has a higher chance of growing into a new plant.
Lastly, number of seeds vs seed size: As the seed size increases, number of seeds produced has to decrease, because the plant is putting energy into producing more seeds, and hence there is not enough energy to increase their size. The same happens in the opposite direction. Therefore, this graph is a linear downwards line, so that as one trait is maximized, the other is minimized, and only if both traits are at a medium amount will they both be able to be optimized.
Plants will exists on a continuum along this line, and where they place on this continuum all depends on the environment they live in.
What is indeterminate growth? What about determinate growth?
Indeterminate growth: Growth of an organism continues throughout its lifespan, so never reaches an “adult size/ maturatity”. Therefore, it spends a little energy throughout its entire lifespan on growth.
Ex: Ectotherm — reptiles, fish, plants, etc.
Determinate growth: Growth stops once an adult size is reached, and so it spends a lot of energy on growth at the beginning, but then spends none later on in its life to focus on reproduction and other strategies.
Ex: Endotherms such as birds and mammals and humans (only spend energy on maintenance growth).
What is asexual reduction? Sexual reproduction? Advantages and disadvantages of each?
Asexual reproduction: When they produce clones (exact copies) of themselves by only reproducing within that organism. So this involves budding, mitosis, binary fission, vegetative propagation (grows roots underground which sprout into a new plant) and fragmentation (parent plant breaks into fragments and each fragment turns into a new organism).
Advantages: doesn’t rely on finding a mate and so can replicate at any time, population can increase rapidly in favourable conditions, more time and energy efficient because don’t have to spend energy on finding a mate, and it is much faster.
Disadvantages: Limited genetic diversity, so if something changes in the environment it will wipe out the entire species. Harmful mutations in the parent are ALWAYS passed onto he offspring and this can accumulate over generations rather then being phased out (due to natural selection in sexual reproduction when different traits can be chosen from). Inability to adapt due to lack of variance in traits, short lifespans, and disease is easier to transfer between parent and offspring. Evolution cannot have as much of an effect.
Sexual reproduction: When they produce recombinant of the two parents, and hence requires two mates whose traits are mixed and chosen for by natural selection, hence evolving to produce the most efficient offspring over time. In this case, replicated genomes are halved into gametes and then these are shared between the two parents to produce a zygote.
Advantages: There is genetic variation which allows for different genes to be shown and hence the best traits to be selected for. Disease will not affect the entire species as it is not necessarily one of the genes passed down, and so natural selection will also phase out organisms with that gene so it is not passed down. It can also combine mutations into beneficial ones that can increase the organism’s fitness. Also allows for selective breeding, so based on traits that will help an organisms fitness, various mates will be chosen. Allows for evolution to chose certain traits and create more fit individuals!
What is the main tradeoff that is very important to all organisms? Why can’t both be maximized?
The main tradeoff that is very important to all organisms is the energy put into growth of that organism VS the energy put into reproduction. As one increases, the other must decrease because there is a total amount of energy present and you can’t have a lot of both. Therefore depending on the environment, different species will maximize different things. Therefore, growth rate and reproduction are inversely proportional.
How does parental investment in offspring and amount of offspring produced relate? Is there a tradeoff here?
Here, as parental investment in each offspring increases, the number of offspring produced total will increase, because you can not have so much energy that both can be maximized. If you put a lot of energy into taking care of offspring once they are born, then you can only have a few offspring that are larger, as that energy cannot be both concentrated and dispersed at the same time.
Then if you put a lot of energy into producing a bunch of offspring, you won’t have enough energy left to take care of your offspring once they are born. SO in this case you put a lot of energy into making many, to increase the chances of more offspring surviving.
What is another tradeoff that relates just to the parent alone?
Well the more energy you put into offspring, the less energy you put into yourself. Therefore, more of the food you collect goes into your babies development, and less into your own. plus when you are out collecting food and are powered by less food, then you will be weaker and less likely to survive yourself.
So it is a balance between living long enough to help your offspring grow up, and also giving your offspring enough energy to grow up. So the longer you live, the less energy that is going into your offspring, but the shorter you live, the more energy initially going into offspring, it’s just they may not survive as long.
Of course we want to live as long as possible, but this would result in us being an evolutionary dead end which is not desirable.
Semelparity is…
Iteroparity is…
“Parity” means…
Semelparity are individuals of the same species that can breed only once in their lifetime, and hence they spend a LOT of energy into that breeding. A lot of the time this leads to death of that organism once they reproduce. For example, salmon that do one long migration, give birth, and then die.
Iteroparity is when individuals of the same species can breed many times in its lifespan (has nothing to do with how many times they ACTUALLY BREED). So they may not spend as much energy in each birth but they can have more births overall.
So this does include humans, even if that human has only had one offspring, because they could have had more if they wanted. For example also, salmon that make a short trip to have offspring and then come back — they don’t expend all there energy into getting somewhere far away to breed.
Does evolution favour larger organisms with respect to offspring production?
Yes it does, because larger organisms can take in more energy total, and they don’t need as much energy per gram body weight and therefore they have more energy to allocate to each egg or offspring.
therefore, organisms that wait to a later age when they are larger to produce offspring will produce the most eggs, and this will increase those egg’s chances of survival.
