Demonstrate understanding of the responses of plants and animals to their external environment
So what should you be able to demonstrate understanding of by the time we have finished learning together.
Describing plant and animal responses to their external environment.
· the process(es) within each response and/or the adaptive advantage provided for the organism in relation to its ecological niche.
You will be able to use using biological ideas to explain:
· how the responses occur
· why the responses provide an adaptive advantage for the organism in relation to its ecological niche.
Responses are selected from those relating to:
· orientation in space (tropisms, nastic responses, taxes, kineses, homing, migration)
· orientation in time (annual, daily, lunar, tidal rhythms)
· interspecific relationships (competition for resources, mutualism, exploitation including herbivory, predation, and parasitism)
· intraspecific relationships (competition for resources, territoriality, hierarchical behaviour, cooperative interactions, reproductive behaviours).
REMEMBER:
If you are writing comprehensively to show indepth understanding, you will be able to:
· link biological ideas to explain why the responses provide an adaptive advantage for the organism in relation to its ecological niche. The linking of ideas may involve justifying, relating, evaluating, comparing and contrasting, and analysing.
Describing plant and animal responses to their external environment.
· the process(es) within each response and/or the adaptive advantage provided for the organism in relation to its ecological niche.
You will be able to use using biological ideas to explain:
· how the responses occur
· why the responses provide an adaptive advantage for the organism in relation to its ecological niche.
Responses are selected from those relating to:
· orientation in space (tropisms, nastic responses, taxes, kineses, homing, migration)
· orientation in time (annual, daily, lunar, tidal rhythms)
· interspecific relationships (competition for resources, mutualism, exploitation including herbivory, predation, and parasitism)
· intraspecific relationships (competition for resources, territoriality, hierarchical behaviour, cooperative interactions, reproductive behaviours).
REMEMBER:
If you are writing comprehensively to show indepth understanding, you will be able to:
· link biological ideas to explain why the responses provide an adaptive advantage for the organism in relation to its ecological niche. The linking of ideas may involve justifying, relating, evaluating, comparing and contrasting, and analysing.
useful links
learn your term definitions:
introducing BEHAVIOR in nature
To be a successful, organisms (plant, animal, bacteria, fungi) must be able to survive AND reproduce. To sense the surrounding environment (abiotic and biotic) and respond to it is critical.....otherwise your reproductive success will be limited. An organism must be able to:
- find favourable conditions OR avoid unfavourable conditions
- ensure they have all their neccessary raw materials for survival
- reduce competition (interspecific and intraspecific)
- avoid being eaten
- find a suitable mate
Below is a little recap:
- find favourable conditions OR avoid unfavourable conditions
- ensure they have all their neccessary raw materials for survival
- reduce competition (interspecific and intraspecific)
- avoid being eaten
- find a suitable mate
Below is a little recap:
The Niche
The ecological niche describes how an organism or population responds to the distribution of resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another and the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts".
This is super important to learn as this may be a major focus in questions this year!
Organisms occupy ecological niches. The niche of an organism is the way it is adapted in response to the habitat in which it lives. It is a combination of WHERE it lives and HOW it lives. The niche reflects the ROLE that the organism performs in the biological community.
The ecological niche describes how an organism or population responds to the distribution of resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another and the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts".
This is super important to learn as this may be a major focus in questions this year!
- Its habitat (abiotic and biotic factors, including any if it's requirements)
- Its adaptations (any structural, physiological or behavioural traits that enable to survive in its habitat)
- Its role (e.g. producer, how it fits into a food web or interacts with other species
Organisms occupy ecological niches. The niche of an organism is the way it is adapted in response to the habitat in which it lives. It is a combination of WHERE it lives and HOW it lives. The niche reflects the ROLE that the organism performs in the biological community.
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Timing responses and internal clocks
Before we look at how plant and animals respond to their immediate environments, lets look what drives many of these cyclical changes (seasons, tides, night/day etc) in the environment and how these are linked to many biorhythms in plants AND animals.
The timing of day and night, the rise and fall of tides and the onset of seasons is reliable, why do organisms need their own clocks?
The fact that all organisms from all taxonomic groups have internal clocks suggest that internal clocks must offer great advantages.
- How do birds know when to migrate? Did they have to pack and be orgnised well before then?
- Why do you wake at 7:03 am every morning without an alarm clock?
- How do apple trees of the same species synchronise to all blossom all at the same time as each other?
- Why does leaf fall in autumn occur?
- What controls daily body rhythms such as sleep, blood pressure, temperature, blood cell count, alertness, urine composition, metabolic rate and sex drive.
- What synchronises spawning behaviour of mussels to ensures that eggs and sperms will be released at the same time?
An internal clock enables an organism to anticipate the environmental changes, but it is external changes that trigger these responses making it possible for organisms to prepare for activity.
Internally driven, or endogenous rhythms will operate independent of external changes (although resetting of this clock requires an environmental cue) and externally driven, or exogenous rhythms are solely driven by external events. (not many examples of these)
Apart from inhabitants of the ocean depths and deep underground caves, most organisms show rhythmic activities. Biorythms can be classified into:
- daily rhythms are linked to day-night cycles.
- annual or seasonal rhythms are linked to length of day (photoperiod) as the year progresses.
- tidal rhythms are linked to the piling of water toward and away from the moon twice a day. (tidal rhythms are distinct from lunar rhythms.
- lunar rhythms are linked to the rotation of the moon around the Earth.
Biological clocks are under genetic control, with several genes having been identified in a wide range of organisms.
Here are some great examples:
The timing of day and night, the rise and fall of tides and the onset of seasons is reliable, why do organisms need their own clocks?
The fact that all organisms from all taxonomic groups have internal clocks suggest that internal clocks must offer great advantages.
- How do birds know when to migrate? Did they have to pack and be orgnised well before then?
- Why do you wake at 7:03 am every morning without an alarm clock?
- How do apple trees of the same species synchronise to all blossom all at the same time as each other?
- Why does leaf fall in autumn occur?
- What controls daily body rhythms such as sleep, blood pressure, temperature, blood cell count, alertness, urine composition, metabolic rate and sex drive.
- What synchronises spawning behaviour of mussels to ensures that eggs and sperms will be released at the same time?
An internal clock enables an organism to anticipate the environmental changes, but it is external changes that trigger these responses making it possible for organisms to prepare for activity.
Internally driven, or endogenous rhythms will operate independent of external changes (although resetting of this clock requires an environmental cue) and externally driven, or exogenous rhythms are solely driven by external events. (not many examples of these)
Apart from inhabitants of the ocean depths and deep underground caves, most organisms show rhythmic activities. Biorythms can be classified into:
- daily rhythms are linked to day-night cycles.
- annual or seasonal rhythms are linked to length of day (photoperiod) as the year progresses.
- tidal rhythms are linked to the piling of water toward and away from the moon twice a day. (tidal rhythms are distinct from lunar rhythms.
- lunar rhythms are linked to the rotation of the moon around the Earth.
Biological clocks are under genetic control, with several genes having been identified in a wide range of organisms.
Here are some great examples:
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How Can we Study these Endogenous Rhythms
An actogram is a diagram showing the periods of activity and rest in an organism over a number of 24 hour periods so that trends in activity can be identified. A period (length of the cycle) is usually determined from the time between successive peaks of activity. These are never usually exact with the period of the environmental rhythm.
When a rhythm continues in constant environmental conditions, it is said to be free running, as it is unaffected by the absence of external cues, however, free running rhythms gradually drift out of sync with the external environmental cues. This illustrates that these rhythms are in fact endogenous.
Because the free running period of endogenous rhythms is never quite 24 hours they are said to be circadian. (circa-about, dian-day). Similarly, the free running periods of tidal, lunar, annual rhythms are also not quite the same as environmental rhythms so:
Circatidal – Tidal period about (12.4hrs)
Circasemilunar – spring/neap tide about (14.7 days)
Circalunar – monthly activity about (29 days)
Circannual – yearly activity about (365 days)
To say an organisms rhythm is "daily" just describes the rhythms period and does not imply it is in fact endogenous or not.
So endogenous rhythms do not exactly coincide with the environment, but they must be reset or entrained by an environmental cue. This is called the zeitgeber. Entrainment allows organisms to adjust to seasonal changes and fully maximise feeding times etc.
Entrainment involves a process called phase shifting, in which the endogenous rhythm is 'trained' to sync with changing light regime etc.
This might help:
Because the free running period of endogenous rhythms is never quite 24 hours they are said to be circadian. (circa-about, dian-day). Similarly, the free running periods of tidal, lunar, annual rhythms are also not quite the same as environmental rhythms so:
Circatidal – Tidal period about (12.4hrs)
Circasemilunar – spring/neap tide about (14.7 days)
Circalunar – monthly activity about (29 days)
Circannual – yearly activity about (365 days)
To say an organisms rhythm is "daily" just describes the rhythms period and does not imply it is in fact endogenous or not.
So endogenous rhythms do not exactly coincide with the environment, but they must be reset or entrained by an environmental cue. This is called the zeitgeber. Entrainment allows organisms to adjust to seasonal changes and fully maximise feeding times etc.
Entrainment involves a process called phase shifting, in which the endogenous rhythm is 'trained' to sync with changing light regime etc.
This might help:
Why do we suffer jetlag?
Why do we feel tired or awake at the wrong times when we go on holiday to a different timezone? We find out how your body clock works, how it is disrupted by long distance travel and if there's any way around getting jetlag. What if our eyes are damaged...how would that influence our biological clocks?
READ THIS ARTICLE HERE
READ THIS ARTICLE HERE
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LECTURE COMING TO YOU
Rasmus Gabrielsson a freshwater ecologist is coming to talk about:
His research into salmonid migration and recruitment patterns in the Clutha River system to illustrate some of the general ecological concepts, mechanisms and drivers behind fish migration found here in NZ, and show how these can influence population dynamics on both a local and regional/metapopulation scale.
He will include examples in NZ fishes of how “exogenous factors” influence and stimulates migration away from the natal habitat (i.e. density dependence, low summer flows, high water temp, predation pressure etc), and then link these to how “endogenous factors” (i.e. sexual maturity, age etc) stimulates the return migration and completion of the life cycle?
He will also focus more on how variations in migratory behaviour (and life history strategies) influence population dynamics, and how human use of water resources can create ecological traps (by altering the cues fish use or fragmenting the riverine landscape).
Feel free to do some background on this or just go with the flow!
Rasmus Gabrielsson a freshwater ecologist is coming to talk about:
His research into salmonid migration and recruitment patterns in the Clutha River system to illustrate some of the general ecological concepts, mechanisms and drivers behind fish migration found here in NZ, and show how these can influence population dynamics on both a local and regional/metapopulation scale.
He will include examples in NZ fishes of how “exogenous factors” influence and stimulates migration away from the natal habitat (i.e. density dependence, low summer flows, high water temp, predation pressure etc), and then link these to how “endogenous factors” (i.e. sexual maturity, age etc) stimulates the return migration and completion of the life cycle?
He will also focus more on how variations in migratory behaviour (and life history strategies) influence population dynamics, and how human use of water resources can create ecological traps (by altering the cues fish use or fragmenting the riverine landscape).
Feel free to do some background on this or just go with the flow!
PLANTS are COOL
Plants differ fundamentally from animals in their organisation and way of life. You should have a pretty good understanding of this from last year. They do not involve the action of specialised receptors and effector cells.
The presence of a cellulose wall in plant cells prevents them undergoing the rapid changes of shape characteristic of muscle fibers of animals. Plant movements are achieved in two ways:
- Growth responses: slow, permenant changes in cell size.
-Turgor responses: usually fast, reversible and are brought about by changes in cell water content.
Plants differ fundamentally from animals in their organisation and way of life. You should have a pretty good understanding of this from last year. They do not involve the action of specialised receptors and effector cells.
The presence of a cellulose wall in plant cells prevents them undergoing the rapid changes of shape characteristic of muscle fibers of animals. Plant movements are achieved in two ways:
- Growth responses: slow, permenant changes in cell size.
-Turgor responses: usually fast, reversible and are brought about by changes in cell water content.
plants are Amazing....Hug a plant now! seriously, do it!
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Orientation responses in pLants
- Tropisms
How is gravity detected?
Little starch-storing plastids called amyloplasts are denser than the surrounding cytoplasm and tend to sink onto cytoplasmic membranes. This must generate some kind of signal!! Experiments suggest that, in roots bending is due to a build up of auxin concentration which builds up on the lower side and inhibits cell elongation. |
These are growth responses by parts of the plant to abiotic factors such as: -Temperature thermo - Water hydro - Gravity geo or gravi - Touch thigmo - Light photo - Chemicals chemo This directional growth response is either positive or negative. Take a look at Darwin and Wents' historical research into how Auxins work. It is a great animated workshop here. |
Darwins historical experiments
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So how does this provide an adaptive advantage: Excellent reading here
- nastic responses
Interesting to make comparisons between Tropisms and Nastic responses. For both think about the adaptive advantage of the response. BE THE PLANT!
I'll say it again these responses remove a plant or parts of a plant from unfavourable conditions, placing it in more favourable....
I'll say it again these responses remove a plant or parts of a plant from unfavourable conditions, placing it in more favourable....
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photoperiodism in plants
- Long-day plants (LDPs) only flower when the photoperiod exceeds a certain value, known as the critical day length (CDL). Long-day plants are characteristic of higher latitudes, where seasonal variation in daylength is greater. LDPs are induced to flower when the days are lengthening, in spring and early summer. If transplanted to the tropics, an LDP may not flower, because the days are not long enough for its CDL to be reached. Examples include most temperate grasses, snapdragon, radish and lettuce.
- Short-day plants (SDPs) only flower when the photoperiod is less than the CDL . Many species native to the tropics are SDPs, even though at such latitudes daylength may not vary more than two hours during the year (e.g. maize, sugar cane). In temperate countries, SDPs flower in the autumn (e.g. Chrysanthemum) or spring (e.g. strawberry).
- Day-neutral plants are insensitive to photoperiod (e.g. ephemerals, whose life cycles are too short for seasonal factors to be important), and the dandelion, tomato and garden pea.
Photperiodic responses involve Phytochrome
Phytochrome can exist in two inter-convertible states:
- Pr primarily absorbs red light (at a wavelength of 660 nm)
- Pfr absorbs far-red light (at a wavelength of about 725 nm, just visible to the human eye)
Sunlight contains both red and far-red light, so both the above reactions would be expected to occur at the same time. However, since sunlight contains more red than far-red, the effect of red light predominates.
If phytochrome is involved in flowering, the effect of red light should be reversed if it is immediately followed by far-red, and reversed again by red, and so on. This turns out to be the case.
FLOWERING:
•This is the response of a plant to the relative lengths of daylight and darkness.
•It is based on a system that monitors the day/night cycle.
•The photoreceptor involved in this is a blue-green pigment called phytochrome.
•Phytochrome has 2 forms, one active and one inactive.
Have a little look at this
What if you toy with the lights. Check out the results.
Advantages of regulating responses include:
Plants also use the phytochrome system to adjust growth according to the seasons. Photoperiodism is a biological response to the timing and duration of dark and light periods. Since unfiltered sunlight is rich in red light, but deficient in far-red light, at dawn, all the phytochrome molecules in a leaf convert to the active Pfr form and remain in that form until sunset. Since Pfr reverts to Pr during darkness, there will be no Pfr remaining at sunrise if the night is long (winter) and some Pfr remaining if the night is short (summer). The amount of Pfr present stimulates flowering, setting of winter buds, and vegetative growth according to the seasons.
In addition, the phytochrome system enables plants to compare the length of dark periods over several days. Shortening nights indicate springtime to the plant; lengthening nights indicate autumn. This information, along with sensing temperature and water availability, allows plants to determine the time of the year and adjust their physiology accordingly. Short-day (long-night) plants use this information to flower in the late summer and early fall when nights exceed a critical length (often eight or fewer hours). Long-day (short-night) plants flower during the spring when darkness is less than a critical length (often 8 to 15 hours). However, day-neutral plants do not regulate flowering by day length.
By ensuring activities happen at a certain time of year species can maximise the resources available, eg flowering when pollinators are available or germination when climatic conditions are suitable. OR By ensuring activities are synchronised species can ensure successful reproduction by having all individuals cross pollinating at the same time which will ensure greater variation in future generations. The is beneficial......
For you BRONTE.
•This is the response of a plant to the relative lengths of daylight and darkness.
•It is based on a system that monitors the day/night cycle.
•The photoreceptor involved in this is a blue-green pigment called phytochrome.
•Phytochrome has 2 forms, one active and one inactive.
Have a little look at this
What if you toy with the lights. Check out the results.
Advantages of regulating responses include:
Plants also use the phytochrome system to adjust growth according to the seasons. Photoperiodism is a biological response to the timing and duration of dark and light periods. Since unfiltered sunlight is rich in red light, but deficient in far-red light, at dawn, all the phytochrome molecules in a leaf convert to the active Pfr form and remain in that form until sunset. Since Pfr reverts to Pr during darkness, there will be no Pfr remaining at sunrise if the night is long (winter) and some Pfr remaining if the night is short (summer). The amount of Pfr present stimulates flowering, setting of winter buds, and vegetative growth according to the seasons.
In addition, the phytochrome system enables plants to compare the length of dark periods over several days. Shortening nights indicate springtime to the plant; lengthening nights indicate autumn. This information, along with sensing temperature and water availability, allows plants to determine the time of the year and adjust their physiology accordingly. Short-day (long-night) plants use this information to flower in the late summer and early fall when nights exceed a critical length (often eight or fewer hours). Long-day (short-night) plants flower during the spring when darkness is less than a critical length (often 8 to 15 hours). However, day-neutral plants do not regulate flowering by day length.
By ensuring activities happen at a certain time of year species can maximise the resources available, eg flowering when pollinators are available or germination when climatic conditions are suitable. OR By ensuring activities are synchronised species can ensure successful reproduction by having all individuals cross pollinating at the same time which will ensure greater variation in future generations. The is beneficial......
For you BRONTE.
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Introducing the Animal Kingdom-they are cool too!
Before we start, lets just get our heads back around an organisms "ecological niche"
Animal Behaviour
simple orientation responses- I HEART slaters
complex Orientation responses
Migration: A mass movement for which animals move from their breeding ground to another location to obtain food supply and over-winter.
It is innate, genetically programmed (biological clock) which is initiated by zeitgebers. This allows for physiological preparation for….it is carefully planned for!! Survival depends on this preparation and accuracy of their navigation.
Triggers: Drop in temperature, length of day, life cycle maturity
Benefits:
· Animals remain in favourable temperature because….. therefore…less energy expenditure to maintain stable body temperature, increase survival of chicks/calves.
· Better genetic mixing because……therefore…genetic variation....
· Have a constant rich supply of food because… therefore grow larger, maintin condition therefore produce more offspring.
· Enable to exploit quite different niches in two locations because…. thus reducing intra-specific competition.
· It reduces predation/parasitism/disease moving from fresh to salt water or moving locations….
Most birds are diurnal, yet many are nocturnal migrants. There are several advantages:
- decreased vulnerability to predators, daytime allows some aquisition of food, reduced dehydration and overheating and stable winds in the evening.
Costs:
· increased energy consumption therefore….
· high risk of predation/injury therefore….
· increased stress to individual due to changes in environment therefore….
REMEMBER advantages outweigh the disadvantages…..
YOUR CASE STUDY
To help you understand migration in animals, check out this link. Use the following links and videos to build a case study for at least one animal. You will be sharing your animal next lesson.
Choose from: Longfin eels, Salmon, Humpback whales, Shining cucko, Monach butterflies and Bar tailed godwit.
Case study: Destinations, triggers, navigation methods, advantages and disadvantages to that particular species.
Check out the DOC site
It is innate, genetically programmed (biological clock) which is initiated by zeitgebers. This allows for physiological preparation for….it is carefully planned for!! Survival depends on this preparation and accuracy of their navigation.
Triggers: Drop in temperature, length of day, life cycle maturity
Benefits:
· Animals remain in favourable temperature because….. therefore…less energy expenditure to maintain stable body temperature, increase survival of chicks/calves.
· Better genetic mixing because……therefore…genetic variation....
· Have a constant rich supply of food because… therefore grow larger, maintin condition therefore produce more offspring.
· Enable to exploit quite different niches in two locations because…. thus reducing intra-specific competition.
· It reduces predation/parasitism/disease moving from fresh to salt water or moving locations….
Most birds are diurnal, yet many are nocturnal migrants. There are several advantages:
- decreased vulnerability to predators, daytime allows some aquisition of food, reduced dehydration and overheating and stable winds in the evening.
Costs:
· increased energy consumption therefore….
· high risk of predation/injury therefore….
· increased stress to individual due to changes in environment therefore….
REMEMBER advantages outweigh the disadvantages…..
YOUR CASE STUDY
To help you understand migration in animals, check out this link. Use the following links and videos to build a case study for at least one animal. You will be sharing your animal next lesson.
Choose from: Longfin eels, Salmon, Humpback whales, Shining cucko, Monach butterflies and Bar tailed godwit.
Case study: Destinations, triggers, navigation methods, advantages and disadvantages to that particular species.
Check out the DOC site
Have look at NZ Research into the Migration of NZ Bar tailed Godwits. Here.
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Amazing Migration of Monach Butterflies.
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how animals find their way- navigation of course!
Most of the early experiments into navigation involved homing pigeons and small migratory birds. Some of these were ineffective because most birds use more than one navigation cue. Why would that be?
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Remembered landmarks: Animals including mammals, birds and insects such as bees and wasps are capable of learning ,landmarks in their environment, and of using these in navigation.
Orientation by the sun: (solar compass)The sandhopper, uses the sun and its internal clock to determine direction.
There is evidence that some animals can navigate using celestial cues such as the position of the sun. Since the sun moves in the sky, navigation by this means also requires an internal clock.
eg.An experiments with Manx shearwaters showed that when released "under a clear sky" far from their nests (in Skokholm), the seabirds first oriented themselves and then "flew off in a direct line for Skokholm", making the journey rapidly. For example, one of the birds, released at Boston airport, arrived in Skokholm 12½ days later; It was calculated that if the birds flew for 12 hours per day, they must have traveled at 20 miles per hour, their full normal speed, so they could not have deviated significantly from a straight line course or searched at random for their destination.
BUT if the sky was overcast at the time of release, the shearwaters flew around in circles "as if lost" and returned slowly or not at all. It was concluded that it was essential for the birds that "at the moment of release the sun was visible by day, or the stars by night".
Orientation by the night sky: eg Warblers placed in a planetarium showing the night sky oriented themselves towards the south; when the planetarium sky was then very slowly rotated, the birds maintained their orientation with respect to the displayed stars.
Orientation by polarised light: The sun is not always visible, but providing some part of the sky is clear birds, insects and underwater fish and whales can detect the plane of polarisation of the sun's rays.
Some animals, notably insects such as the honey bee, are sensitive to the polarisation of light. A worker bee returns to the hive and signals to other workers the range and direction relative to the sun of the food source by means of a waggle dance. The observing bees are then able to locate the food by flying the implied distance in the given direction, though other biologists have questioned whether they necessarily do so, or are simply stimulated to go and search for food. However, bees are certainly able to remember the location of food, and to navigate back to it accurately, whether the weather is sunny (in which case navigation may be by the sun or remembered visual landmarks) or largely overcast (when polarised light may be used).
Magnetoception: Magnetic receptors contain magnetite (iron oxide)crystals in the olfactory organs. A wide variety of of animals use the Earth's magnetic field, including mice, bats, sea turtles, sharks, crayfish and bees. The angle of which the "lines force" make with the earth's surface change with lattitude. So that at the equator lines are horizontal and at the poles they are vertical.
eg. The Homing pigeon can quickly return to its home, using cues such as the earth's magnetic field to orient itself.
Olfaction: Returning salmon may use olfaction to identify the river in which they developed.
Olfactory navigation has been suggested as a possible mechanism in pigeons.
eg Olfactory cues may be important in salmon, which are known to return to the exact river where they hatched. Salmon may use their magnetic sense to navigate to within reach of their river, and then use olfaction to identify the river at close range.
So what is the role of experience?
Although some animals can navigate unfamiliar territory to a predetermined location, experience is also important. Experiments suggest that experienced animals reach destinations more effectively than less experienced animals.
Orientation by the sun: (solar compass)The sandhopper, uses the sun and its internal clock to determine direction.
There is evidence that some animals can navigate using celestial cues such as the position of the sun. Since the sun moves in the sky, navigation by this means also requires an internal clock.
eg.An experiments with Manx shearwaters showed that when released "under a clear sky" far from their nests (in Skokholm), the seabirds first oriented themselves and then "flew off in a direct line for Skokholm", making the journey rapidly. For example, one of the birds, released at Boston airport, arrived in Skokholm 12½ days later; It was calculated that if the birds flew for 12 hours per day, they must have traveled at 20 miles per hour, their full normal speed, so they could not have deviated significantly from a straight line course or searched at random for their destination.
BUT if the sky was overcast at the time of release, the shearwaters flew around in circles "as if lost" and returned slowly or not at all. It was concluded that it was essential for the birds that "at the moment of release the sun was visible by day, or the stars by night".
Orientation by the night sky: eg Warblers placed in a planetarium showing the night sky oriented themselves towards the south; when the planetarium sky was then very slowly rotated, the birds maintained their orientation with respect to the displayed stars.
Orientation by polarised light: The sun is not always visible, but providing some part of the sky is clear birds, insects and underwater fish and whales can detect the plane of polarisation of the sun's rays.
Some animals, notably insects such as the honey bee, are sensitive to the polarisation of light. A worker bee returns to the hive and signals to other workers the range and direction relative to the sun of the food source by means of a waggle dance. The observing bees are then able to locate the food by flying the implied distance in the given direction, though other biologists have questioned whether they necessarily do so, or are simply stimulated to go and search for food. However, bees are certainly able to remember the location of food, and to navigate back to it accurately, whether the weather is sunny (in which case navigation may be by the sun or remembered visual landmarks) or largely overcast (when polarised light may be used).
Magnetoception: Magnetic receptors contain magnetite (iron oxide)crystals in the olfactory organs. A wide variety of of animals use the Earth's magnetic field, including mice, bats, sea turtles, sharks, crayfish and bees. The angle of which the "lines force" make with the earth's surface change with lattitude. So that at the equator lines are horizontal and at the poles they are vertical.
eg. The Homing pigeon can quickly return to its home, using cues such as the earth's magnetic field to orient itself.
Olfaction: Returning salmon may use olfaction to identify the river in which they developed.
Olfactory navigation has been suggested as a possible mechanism in pigeons.
eg Olfactory cues may be important in salmon, which are known to return to the exact river where they hatched. Salmon may use their magnetic sense to navigate to within reach of their river, and then use olfaction to identify the river at close range.
So what is the role of experience?
Although some animals can navigate unfamiliar territory to a predetermined location, experience is also important. Experiments suggest that experienced animals reach destinations more effectively than less experienced animals.
Here is an excellent scholarship reading.
BEST MOVIE EVER- Click and sign into Clickview with NCG sign in:
Intra-Specific Relationships
A with plants, animals must obtain resources from the environment, grow to sexual maturity and reproduce successfully. In doing so animals must either compete with or cooperate with other biotic factors in the environment.
COMPETITION: because members of the same species resemble each other more closely than members of other species, intra-specific competition for resources and mate is most intense.
aggressive behaviour towards another member of the same species involving threats, submissions, chases and physical combat. Agonistic behaviour is a contest to determine who gains access to a resource. (Does not include predatory aggression for obtaining food)
•Conflicts between members of the same species are usually resolved with ritualistic behaviour. This prevents serious injury to the combatants.
•Fighting to the death is non-adaptive to most animals. Only occurs when eliminating a stranger from another group.
•The more scarce the resource the more intense the fighting.
Agressiveness
•Belligerent behaviour by an animal that threatens to harm or kill another animal with which it is competing.
•Combat is more likely to be physical if it is essential to the survival and reproductive success of the competitors.
•Natural selection favours a quick end to combat to prevent the winner from becoming too injured, to be able to take advantage of the resources won.
•Fighting between males for mates is common. Winner mates with female and passes on genes for successful fighting. Selection may cause males to become larger than females (sexual dimorphism).
Territory
In territorial species, holding a territory is an advantage. If the territory is pourely for breeding, only those with a territory can reproduce!
•A territory is an area defended against other members of the same species.
•It provides food, water supplies, nesting areas, and refuges from danger.
•Ownership of a territory is signaled by vocalisations, scent marking, visual displays.
•Boundary marking warns against accidental intrusion by others of its species.
•Another animal is only likely to attempt to dislodge the owner of the territory if it has a chance of being successful.
•Territorial behaviour is reinforced by natural selection where the benefits to the species outweigh the risks and the energy costs of defending the territory.
•Territories help to regulate the population to a size that can be supported by the available resources.
•Territorial behaviour varies widely. Most animals have a definite home. The area the animal covers regularly in search of food and mates is the home range. This area is not defended.
•The part of the home range defended against others of the same species is the territory.
•Aggressive behaviour is used to hold on territories.
Marking and Defending
Vocalisations – e.g. birds singing on boundaries of their areas at dawn and dusk
Scent – e.g. marking with urine (dogs and cats) or faeces
Scent glands – special glands produce chemo markers.
e.g.: on rump, between horns (deer), wrists (lemur), behind ears (cats)
Physical gesturing – crabs wave claws at edge of territory
Social Dominance
Another behavioural mechanism that regulates access to resources such as food and mates is a social hierarchy. Highest ranking animals gain greater access over lower ranking individuals.
Rank is usually determined by by skirmishes and then once established conflict is reduced and usually just occurs between individuals who are closer in rank and they use ritualized displays of dominance and subordination to maintain order . This is for the good of the population:
safety in numbers, superior quality gene only passed on, resources unevenly distributed in habitat.
COOPERATION: As we discussed briefly yesterday animals cooperate with members of the same species for the following reasons
Advantages of group behaviour :
Hunting - work as a team to kill prey. E.g. wolves, lions, wild, dogs.
Defence – form defensive circles or post guards to watch for danger whilst rest of group feeds. E.g. Himalayan yaks (circles), baboons (guards).
Protection – Dolphins protect mothers during birth process and help carry baby to surface until it has learned to breathe. Baboons, mother and young in safest position in the pack (centre).
Insect societies – organisms specialised to carry out aspects of maintenance of nest or hive. Centred around a queen who co-ordinates group with pheromones.
Defence– confuses predators, difficult to pick out individuals. E.g. shoals of fish, flocks of birds
Breeding – Many groups from for breeding purposes. Safest breeding sites are in the centre of the group.
Aero/hydrodynamics- Fish swim faster in schools than as individuals, similarly birds take advantage of flying in a V which allows them to conserve 25% energy than if they were to fly solo.
Behavioural adaptations of individuals within a species is selected for because it enhances survival of that individual and therefore reproductive success. This means those genes will be inherited in future generations.
Today we will look at how animals of the same species cooperate during courtship, pare bonding and parental care.
Courtship
Gametes have 2 important limitations. Sperm can't swim very far and eggs don't survive for very long. Therefore it is vital that eggs and sperm are released together as close as possible (both distance and time wise). This would mean reproductive activities would need to be synchronised! For some animals animals environmental cues are critical to stimulate this. (remember the Palolo worms) and others rely on chemical cues. (Mussels) Courtship are signals and actions exchanged between male and female which leads to mating. check out some examples below:
Advantages of courtship are:
-ensures partners are the same species to reduce wastage of gametes. (remember poor ducky!)
-Reduce or supresses aggression between individuals so they can physically mate. It actually allows female to be in a receptive state. eg. supressing her urge to fly away etc.
- triggers physiological readiness of partners which maximizes chances of successful fertilisation.
-Increases chance of pair bonding to increase survival chances of offspring.
-Courtship allows for the selection of genetic fitness.
I love you David Attenborough. I think you will really the below video. It is a bit long so you might want to make it "date night Friday".
-ensures partners are the same species to reduce wastage of gametes. (remember poor ducky!)
-Reduce or supresses aggression between individuals so they can physically mate. It actually allows female to be in a receptive state. eg. supressing her urge to fly away etc.
- triggers physiological readiness of partners which maximizes chances of successful fertilisation.
-Increases chance of pair bonding to increase survival chances of offspring.
-Courtship allows for the selection of genetic fitness.
I love you David Attenborough. I think you will really the below video. It is a bit long so you might want to make it "date night Friday".
Pair Bonding
Most species during breeding come together briefly and then part. A long lasting stable relationship between male and female which ensure cooperation during breeding and rearing of young is pair bonding.
Parental Care
Parental care increases the chance of survival of the offspring at an energy cost (providing protection and nourishment) to the parent. There are a wide variety between species in the amount of parental care provided for offspring, producing a 'line of continuum' of parental care with extremes being: Little/no parental care and considerable care.
Most species during breeding come together briefly and then part. A long lasting stable relationship between male and female which ensure cooperation during breeding and rearing of young is pair bonding.
Parental Care
Parental care increases the chance of survival of the offspring at an energy cost (providing protection and nourishment) to the parent. There are a wide variety between species in the amount of parental care provided for offspring, producing a 'line of continuum' of parental care with extremes being: Little/no parental care and considerable care.
Organisms described as r-strategists typically live in unstable, unpredictable environments. Here the ability to reproduce rapidly (exponentially) is important. Such organisms have relatively little investment in any one progeny individual, they are typically weak and subject to predation and the challenges of their environment. The “strategic intent” is to flood the habitat with progeny so that, regardless of predation or mortality, at least some of the progeny will survive to reproduce. Organisms that are r-selected have short life spans, are generally small, quick to mature and waste a lot of energy. Typical examples of r-strategists are
What do think about this statement?
In all cases, however, the end result is the same. Though we think of the K-strategy as being more advanced (perhaps because we are K-strategists) but in actual fact the outcome is the same. Investment of reproducing is great for both but in different ways. On average the survival rate is the same.
- salmon
- corals
- insects
- bacteria
What do think about this statement?
In all cases, however, the end result is the same. Though we think of the K-strategy as being more advanced (perhaps because we are K-strategists) but in actual fact the outcome is the same. Investment of reproducing is great for both but in different ways. On average the survival rate is the same.
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Kin selection is the evolutionary strategy that favours the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction.It favours altruistic behaviour (self-sacrificing) toward a relative. |
inter-specific relationships
When you watch the video below see how many relationships + examples you can identify.....who can identify the most?
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Read 113-140 in your text book too please.
A species niche reflects its role in the biological community of which it is a member. Individuals interact with other members of the biological community in a variety of ways: commensalism, mutalism, parasitism, competition, expliotation!! Many animal species compete with each other for resources. As resources decrease, competition increases and according to the competitive exclusion principle (gause's principle) no two species can occupy the same ecological niche. When organisms occupy the same habitat and have the same or similar resource requirements (i.e. requirements overlap), competition occurs. The more similar the requirements and/or the more limited the resources, the more intense the competition. As competition harms both competing species, reducing their evolutionary fitness, strong selection pressures act on organisms to favour adaptations that reduce competition by exploiting a new resource or by eliminating the competitor |
Predation is a form of exploitation. Predators have various ways in which they can increase their effectiveness. Can you think of some ?
-Which animal uses deception?
-Which animal uses a snare?
-Which animal employs a poisonous weapon?
- Which animal uses a luminescent organ?
-What animal is super fast?
I know, I know super cool ah!! Man nature is just so amazeballs!!
Often very close relationships between predator and prey populations. One will surely influence the other. See next door this predator prey cycle. What is happening to the number of wabbits and foxes over the 40 year time span? What causes this?
-Which animal uses deception?
-Which animal uses a snare?
-Which animal employs a poisonous weapon?
- Which animal uses a luminescent organ?
-What animal is super fast?
I know, I know super cool ah!! Man nature is just so amazeballs!!
Often very close relationships between predator and prey populations. One will surely influence the other. See next door this predator prey cycle. What is happening to the number of wabbits and foxes over the 40 year time span? What causes this?
Prey employ many strategies to avoid being eaten. Make a we summary chart and describe how the following strategies (there are much more than what is below) provide a defensive mechanism and give an example.
- Living in Groups.
- Camoflage
- Mimicry (Batesian and Mullarian)
- Autotomy
- Countershading
- Chemical
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