Transcript Animal Behaviour and Plant Responses.

Animal Behaviour and
Plant Responses.
Year 13 Biology
Overview
• Orientation
– Tropisms
– Nastic responses
– Plant hormones
– Taxes and Kineses
– Migration and Dispersal
– Homing
Overview
• Timing
– Environmental Cycles
– Biological clocks
– Biological rhythms
Revision
• The environment
– The environment includes all the factors, both
living (biotic) and non-living (abiotic), that
affect the lives of organisms.
• Abiotic – The physical factors in an
environment (non-living)
• Biotic – The living factors in an
environment.
Revision
• Main Abiotic factors
– Light (photo-)
– Gravity (geo- or gravi-)
– Temperature (thermo-)
– Water (hydro-)
– Chemicals (chemo-)
– Touch (thigmo-)
– Current (rheo-)
Revision
• Abiotic Factors
– are the physical parts of the environment to
which organisms respond. For most
organisms, the physical factors must be kept
within quite a narrow optimum range that fits
the tolerance for that species.
– If the factor is extreme in either direction the
organism suffers from physiological stress,
and if the factor becomes too extreme it leads
to death. (recall the zones of tolerance)
Niche
• Niche - You could say that the habitat is an
organism’s address, and that the ecological
niche is its profession. The ecological niche is a
description of;
– the opportunities provided by the habitat; and
– The adaptations of the organism that enable it
to take advantage of those opportunities.
Adaptations
• Most organisms are a combination of
many adaptations that allow them to fit into
their environment easily. Adaptations are
grouped into three types;
– Structural
– Behavioural
– Physiological
Detecting a stimulus
• A stimulus is a change in the environment
(external or internal) that causes a
response in an organism.
• A receptor is any cell or group of cells that
can detect this change
• A effector is a cell or group of cells that
can respond to the change.
Detecting a stimulus
Environmental stimulus
Receptor detects
Communicating system
Coordinating system
Effector responds
Other information
Orientation responses
of plants
• Plants respond to light, gravity, water,
chemicals and touch. They do this by a
growth curve towards or away from a
stimulus.
• If the growth is towards the stimulus we
say it is positive; if it is away from the
stimulus we say it is negative.
• The prefixes you learnt before tell us the
type of stimulus e.g. photo = light.
Tropisms
• A tropism is a GROWTH response
towards or away from an environmental
stimulus coming from one direction.
• For example
– If the shoot of a plant grows towards the light,
we say it is positively phototropic
– If the root of a seedling grows down, then we
say it is positively geotropic
Nastic Responses
• The response of plants to diffuse stimuli
that do not come from any particular
direction, such as the temperature,
humidity and light that surround a plant,
are called nastic responses.
• For example
– the opening and closing of flowers in
response to different light intensities.
Nastic Responses
• Nastic movements are classified according
to the nature of the stimulus
• For example
– Photonasty is the response to alterations in
the light intensity
– Thermonasty is the response to changes in
the temperature
Plant structure
Plant structure
Plant structure
Plant Hormones
• Plants use hormones to regulate their
growth and development.
• Plant hormones (or phytohormones) are
organic compounds produced in one part
of the plant and transported to another
part, where they produce a growth
response.
Plant Hormones
• There are 5 groups of plant hormones;
– Auxins (indolacetic acid or IAA)
– Cytokinins
– Gibberellins
– Ethene
– Abscisic acid (ABA)
• Together they control growth and
development on the plant at various
stages.
Auxin – indolacetic acid IAA
• The effect of auxin on roots and shoots
– The effect of auxin is different on the shoot,
lateral buds (side buds found in the axis of the
leaves where the leaf joins the stem), and the
root.
– It all depends on the concentration of the
auxin
The effect of auxin on plant
growth
Auxin Concentrations
• Low auxin concentrations stimulate root
growth, and high concentrations inhibit
root growth.
• Low auxin concentrations stimulate growth
of lateral buds; high concentrations inhibit
this.
• Low auxin concentrations do not stimulate
the growth of shoots, but high
concentrations do.
Apical dominance
• Apical dominance
– If you take a bean shoot and leave it to grow,
the intact tip keeps the lateral buds from
growing.
– If, however you remove the apical bud (the
bud at the tip of the main growing shoot) the
two lateral buds start to grow within hours.
– If you were to place a plug onto the apical bud
that contained auxin you would find that the
growth of the lateral buds is inhibited.
Apical dominance
Other effects of auxin
• Cell elongation
• Encourages root development
• Involved in the abscission (dropping of
leaves and fruit). It appears to delay this.
• Stimulates growth of the cambium when a
tree stem is under stress
• Suppression of root elongation
• Initiations of flowering in some plants
Cytokinins
• Produced mainly in the roots
• Functions
– Promote cell division
– Slow down the process of aging (senescence)
in plants.
– If applied to leaves it can prevent the
yellowing of mature leaves in autumn and
their dropping (abscission)
Gibberellins
• Originates from a fungus Gibberella
fugikuroi . This caused a disease that
made plants grow so tall they toppled over
and rotted. Gibberellins have now been
isolated from this fungus.
Gibberellins
• Functions
– Increases the internode length
– Promotes the germination of a wide
variety of seeds that would otherwise be
hard to germinate
– Causes flowering on biennials that
normally need a period of chilling
(vernalisation)
Gibberellins
• Which plant received gibberellin treatment?
Ethene
• The saying that ‘one rotten apple will spoil
the barrel’ is actually true – a ripening
apple gives off a gas called ethylene that
ripens adjacent fruit, even a fruit of a
different type!
• Functions
– Accumulates in mature fruit to induce ripening
– Promotes leaf fall
Abscisic Acid (ABA)
• Generally abscisic acid functions as an inhibiting
hormone acting against auxin, gibberellins and
cytokinins all of which tend to promote growth
• Functions
– growth inhibitor made in the leaf chloroplasts in
response to water stress. Acts on guard cells causing
stomatal closure
– Induces leaf fall (only in a few selected species)
– Promotes seed dormancy
Biological orientation
responses in animals
• In this case the term orientations means a
behaviour by which the animals positions
itself in a certain way in relation to its
surroundings.
• These include taxes and kinesis, homing
and migration.
Taxis
• This is the movement of the whole animal,
towards or away from a stimulus which is
coming from one side only.
• As with tropisms, movement towards a
stimulus is positive and away from a
stimulus is negative.
• The stimulus is also denoted by the same
prefixes.
Taxis
• Examples
– Flatworms moving towards a pieces of
raw meat are showing positive
chemotaxis
– Moths flying to a light are positively
phototactic
– Trout will line themselves up in an
upstream direction, so they are
positively rheotactic
Taxis
• Taxes often involve moving the head (which
carries the sensory receptors) from side to side.
• If there are two sensory organs then the animal
can move directly towards or away from the
stimulus as it can constantly check the position
of the stimulus.
• If there is only one sensory organ, the animal
must move around to get information about the
stimulus. E.g. a maggot must move its head
from side to side to keep in position. It performs
a zigzag ‘direct’ line.
Taxis
•
Task
– Identify the environmental cue involved
and the adaptive value of the behaviour
1. Chemotaxis
2. Thermotaxis
3. Phototaxis
4. Thigmotaxis
5. Gravitaxis
6. Hydrotaxis
Kinesis
• This is a non-directional response to a
stimulus.
• It is the change in activity rate in response
to a change in the intensity of the stimulus.
• Example
– If woodlice are placed in a wet/dry choice
chamber, the animals in the dry side
increases their random movements and rate
of turning compared with those on the wet
side.
Kinesis
• Orthokinesis – the speed of the
movement is related to the intensity of the
stimulation
• Klinokinesis – the amount of random
turning is related to the intensity of the
stimulation.
• See diagrams for summary.
Pheromones
• A pheromone is a chemical produced by
an animal and released into the external
environment where it has an effect on the
physiology or behaviour of members of the
same species.
• Task
– Outline the many ways animals use
pheromones.
Migration
• Refers to regular, annual or seasonal
mass movements made by animals from
their breeding area to another area.
Advantages of Migration
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Animals remain in a favourable temperature
They grow larger
They leave more offspring
They have a constant supply of food
It may lead to the colonisation of a new area
Reduces predation/parasitism disease
Greater genetic mixing
Better breeding conditions
Disadvantages of Migration
• They may get lost or caught in a storm
• They may get eaten by a predator
• The may use up too much energy in the
migration, leading to exhaustion
• They may starve
• It is a huge investment in energy
Trigger to migration
• The behavioural trigger that sets off migratory
behaviour varies.
• Some trigger include
– Maturation – some animals migrate as the sex
organs mature and there is a need or desire to
reproduce
– Environmental cues – such as drop in temperature,
shortening of the length of the day e.g. migratory
birds (migratory restlessness)
– Genetic Drive – The trigger may be inbuilt (innate)
e.g star patterns for navigation are learned, but how
to learn then is innate
– Endogenous circadian rhythm – internal biological
clock.
Methods of Migration
• Piloting – An animal moves from one
landmark that it is familiar with to another
landmark, until it reaches its destination
– Generally used over short distances and uses
visual cues.
Methods of Migration
• Compass Orientation – an animal can
detect a compass direction, and travels in
a straight-line path until it reaches its
destination. This can be accomplished
using the magnetic field lines of the earth,
chemical cues and sound.
Methods of Migration
• Navigation – is the process by which an
animal uses various cues to determine its
position in reference to a particular goal.
Methods of Navigation
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Visual
Solar
Magnetic fields
Stellar (stars)
Chemical
Sonar (sound)
Homing
• This is the ability of an individual to return
to the home site after it has been away to
look for food, sometimes over
considerable distances.
Timing Responses
• Timing
– Environmental Cycles
– Biological clocks
– Biological rhythms
Environmental Cycles
• The astronomical cycles
– The motions of the Earth, moon and
sun result in complex and
interdependent cycles.
– These create environmental changes
that range from short term to long term.
Biological Rhythms
• Environmental cues such as daylength,
timing and the height of tides, and phase
of the moon are often used by plants and
animals to establish and maintain a
pattern of activity.
• They synchronize important events in the
life cycle of an organism.
Biological Rhythms
• Biological rhythms in direct response to
environmental stimuli are said to be
exogenous – the rhythm is controlled by
an environmental stimulus that is external
to the organism
• Those rhythms that continue in the
absence of external cues are said to be
endogenous
The Biological Clock
• Biological clock – an internal timing system
which continues without external time clues, and
controls the timing of activities of plants and
animals.
• Uses of biological clocks
– Control of the daily rhythms of the body e.g. sleep,
pulse, metabolic rate, sex drive
– Reproductive timing
– Preparing for migration by eating a lot of food
– Preparing for winter by storing a lot of food
– Navigating by the sun or the stars.
Some Biological Rhythms
• Circadian – daily activity period, approximately
24 hours (circa=about, dies=day)
• Circatidal – tidal activity period, approximately
12.4 hours
• Circasemilunar – spring/neap tidal period,
approximately 14.7 days (semilunar=half moon)
• Circalunar – monthly activity period, 29 days
(circa=about, lunar=moon)
• Circannual – yearly activity period,
approximately 360 days (circa=about,
annual=year)
Daily Cycles in Animals
(circadian rhythms)
• Animals are active at different times of the
day:
– Diurnal – active during the day, inactive at
night
– Nocturnal – active at night, inactive during
the day
– Crepuscular – active at dawn and dusk
– Arrhythmic – no regular pattern
Other Important Terms
• Free running period – when the biological clock
is running without any clues for the environment,
so is ‘running free’
• Entrainment – the resetting of the biological
clock on a regular basis, forcing it to take up the
period of the environment. This is done with a
Zeitgeber.
• Zeitgeber – (‘time giver’ – the German word is
the most commonly used) – the environmental
agent that resets the biological clock. This could
be light, temperature etc.
Plant Rhythms
• Plants are capable of responding to
environmental variables in a variety of
ways.
• Some activities follow daily rhythms, while
others are seasonal.
Photoperiodism in Plants
• Photoperiodism is the response to the
relative length of daylight and darkness.
• Photoperiodic activities are controlled by a
pigment called phytochrome. It acts as a
signal for some biological clocks in plants
and is also involved in other light initiated
responses such as germination, shoot
growth and chlorophyll synthesis.
The flowering of Plants
• A photoperiodic response of plants
depends on the critical night length
• Plants can be divided into 3 types:
– Short-day plants
– Long-day plants
– Day-neutral plants
The flowering of plants
• Short-day plants
– Require a short day and long night
– Will flower if the photoperiod is less than a
certain critical length
• Long-day plants
– Require a long day and short night
– Will flower if the photoperiod is greater than a
certain critical length
The flowering of plants
• Day-neutral plants
– Flowering is unaffected by the amount of
daylight per day.
– See page 197 biozone
The Phytochrome System
• Photoperiod of plants controlled by
pigment phytochrome
• There are two forms of this pigment
– P665 (Pr) – inactive form that absorbs red
light
– P725 (Pfr) – active form that absorbs far-red
light
The Phytochrome System
• So how does it all work?
– During the day P665 absorbs red light
(present during the day) and as a result is
quickly converted to the active form, P725.
– This P725 then accumulates.
– During the night P725 absorbs far-red light
(present during the night) and slowly converts
back to the inactive form, P665.
The Phytochrome System
• What is the link between this system and
flowering?
– If the day is long enough P725 accumulates
and long-day plants flower
– If the night is long enough P665 accumulates
and short-day plants flower (it is thought that
this may be due to the low concentration of
P725 rather than high concentrations of P665)
Plant Responses to the
Biotic Environment
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Plant-plant relationships
Plant-fungi relationships
Plant-animal relationships
Plant defences (aggressive)
Co-operative relationships
Plant-plant relationships
• Relationships between plants is more
complex than you might think.
• Examples
– Allelopathy – this is when a plant may
secrete a toxic substance from their roots or
leaves that inhibits plants growing near them.
• E.g. Chaparral bush, black walnut
– Seed dispersal mechanisms – ensures
spread of offspring over a wide area
Plant-plant relationships
– Growing larger leaves to capture available
light when it is reduced
– Plants arranging in layers (stratification) in
response to differing environmental conditions
(will have adaptations enabling them to
survive in certain layers)
– Epiphytes – grow on other trees to gain
access to better conditions
– Lianas – plant climb up trees
– These are just some examples –
Plant-fungi relationships
• Many plants will form relationships with Fungi
– Mycorrhizal fungi form mutualistic relations with
many plant roots. The fungi help the plant roots
absorb water and minerals and in return get organic
molecules (nutrients) made by the plant by
photosynthesis
– Obligate mutualistic relationships – lichen (made
up of algae and fungi) that are obliged to live together.
Fungi absorbs water and nutrients and keeps the
algae wet and the algae carries out photosynthesis
and provides sugars and food for the fungus.
Plant-animal relationships
• Herbivores eat plants by
– Grazing
– Browsing
– Suck sap
– Feed on nectar, pollen, fruit and seeds
– Chew roots
– Eat gum
Plant defences
• Plants must have strategies to defend
themselves against herbivory.
– Examples
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Thorns
Divarication
Chemicals
Low growing point
Seed masting
Hiding etc
Co-operation in plants
• Co-operative interactions between plants
and other plants, and plant and animals
can include
– Pollination – animal pollinators (insects/birds)
are attracted by rewards or advertisements
– Guarding plants by animals
– Animals gaining protection from thorns
– Eating fruits and seeds pass through digestive
track and are dispersed
Overview
• Species Interactions
– Behaviour and communication
– Social Organisation
– Courtship and pair bonding
– Aggressive behaviour
– Interspecific interactions
– Intraspecific interactions
Animal Responses to the
Biotic Environment
• Intraspecific responses – aggressive and
co-operative
• Interspecific responses – aggressive and
co-operative
• Complete pages 208 Biozone
Intraspecific aggressive
responses
• Agonistic behaviour
– Is aggressive
– Towards members of the same species
– Involves threats or fighting
– Determines which competitor gains access to
resources.
– Especially strong between members of the
same sex e.g. males fighting over females.
• Biozone pg 213
Intraspecific aggressive
responses
• Territories
– Are established areas for feeding, mating or
rearing young, that are defended.
– Held by aggressive behaviours
– Usually consist of a lair or nest in the centre of
the territory, surrounded by a large home
range that animals cover regularly in search
of food and mates.
– Only the territory is defended
Intraspecific aggressive
responses
• Advantages of territoriality
– Ensures space for each animal
– Reduces disease
– Harder for predators to find animals if they are
spread out
– Reduces fighting
– Ensures there is enough food for everyone
– Safe breeding sights that are defended
– Best genes are handed on to offspring
Intraspecific aggressive
responses
• Disadvantages of territoriality
– Males without territories fail to breed as not
seen as attractive
– Losers must spread out to find food rather
than fight
– Biozone 217-219
Intraspecific aggressive
responses
• Marking and defending
– Singing
– Mark with urine
– Using scent glands
– Using signals
– Calling
Intraspecific aggressive
responses
• Hierarchies
– when every animal is either above or below
another (linear hierarchy).
– There are no equals
– Forms “Pecking Orders” (see pg 221-222)
– Usually established competitively
– “top dog” will usually make decisions for the
group
– Maintained by posture and display
Intraspecific co-operative
behaviour
• Includes
– Group formation
– Courtship and pair-bond formation
– Parental care
Group Formation
• When animals join together to cooperatively undertake tasks
– E.g. Hunting, defence, protection etc
Advantages of forming
groups
• Team work while hunting leads to increased
success rate.
• Less predation as can have members of the
group on “look out”
• Older members protect young or weak
individuals
• Large numbers can cause confusion for
predators
• Breeding sites are located within a boundary
that is protected by members of a group
Disadvantages of group
formation
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Competition is increased
Disease can spread faster
Parasites (e.g. fleas) spread faster
Increases conflict between members
Courtship/pair-bond
formation
• Requires co-operation, suppression of
aggressive behaviours and
communication.
• Usually females make the choice who they
mate with, but both partners need to make
sure;
– They are the same species
– Both fertile
– Both fully prepared to mate.
– See 225
Courtship
• Males usually will compete for the
attention of females by;
– Competing with other males by fighting or
ritualised combat
– Compete indirectly by attracting females by
displays and adornments
• E.g. antlers in deer, brightly coloured feathers in
peacocks, singing and dancing of many bird
species, producing pheromones.
Pair-bond relationship
• A stable relationship between animals of
the opposite sex that ensures co-operative
behaviour on mating and rearing of the
young
– E.g. turns, albatross
Parental Care
• Survival depends on successfully breeding
adequate numbers of offspring.
• Can be achieved by to possible strategies
– R-strategy – produce large numbers of
unprepared offspring with a low chance of
survival
– K-strategy – produce few, well prepared
offspring which have a high chance of survival
– See 227 Biozone.
Parental Care
• Degree of parental care depends on the
species
– E.g. eggs buried and then abandoned (many
fish species), nest constructed and defended,
offspring themselves defended
– Often those species that have a high degree
of parental care will teach their offspring how
to find food, where to find water, how to make
a home etc.
Reproductive Strategies
• Monogamy – each mating with only one
member of the opposite sex (often for life)
• Polygyny – males mate with many females thus
fathering many offspring
• Polygamy – dominant males mates with a
harem of females
• Polyandry – females mate with more than one
male
• Polygynadry (promiscuity) – both male and
female mate with more than one member of the
opposite sex.
• See 224 Biozone