Sensing and responding to the enviroment Flashcards
ideas about defining characteristics of life.
- Paul Davis: life meter, a device that use input data to estimate how close life is to evolution. How lifing thing process and store information
- Schrodiger : concept of entropy -> tendency of thing to become disorder due to random atom movement
- there are two aspect which keep them in-check:
- take in food (negative entropy), high level of order to combat disorder
- Build their body based on information form aperiodic crystal ( a stable place to store information) and pass on to the next generation. DNA
Biological maxwell demon
- help to maintain order
- channels and protein
Energy
-The ability to do work
Matter
anything that occupies space and has mass
information
-how data is store, express and pass on
Combating enthropy
-homeostasis ->pass on information
What is life
- exchange of energy, matter and information between individaul and their enviroment
- individuals are special – goal-directed
Scale in biology
- molecular (nanometer)
- molecular/cellular (micrometer)
- individual (micrometer to metre)
- population (mm to km)
- community (mm to km)
- ecosystem (mm to km)
Individual thermodynamic system
- thermodynamic is the study of heat exchange and how heat is converted
- the individual receive heat from its environment ( from the sun, air, etc)
- the individual receive energy from food
- the individual loses energy (heat) due to the environment or activity
- heat loss due to evaporation (water regulation)
Measuring metabolic rate
- direct ‘calorimetry’ = heat measurement
* indirect ‘calorimetry’ = gas measurement
• basal metabolic rate
is not moving is not digesting is in its thermoneutral zone (it isn’t feeling cold) is in its inactive phase is an adult is not reproducing
• standard metabolic rate
is not moving is not digesting is at a known temperature is in its inactive phase is an adult is not reproducing
• resting
is not moving
is not digesting
is in its thermoneutral zone (it isn’t feeling cold)
• mesuring field metabolic rate
doubly labelled water
-inject organism with “heavy water”, H2o with isotopes, measure the amount of heavy water remain after a set period of time
Animal body temperature
homeothermic(constant temperature)
endotherm( generates heat to raise body temperature above ambient)
heterothermic (variable temperature)
ectotherm (body temperature varies with ambient temperature)
Body size and metabolic rate
M = aW2/3. M= metabolic rate, W = weight
The metabolic web
• feeding • assimilation (digestion) • growth • maintenance • development (maturation) • reproduction either ontogeny (Grow and development) or life cycle (different stage of development) or life-history(organism grow affect population grow)
Growth Curves
- von-berg growth curve show gradually decrease in growth before reaching a stop M ≈ W2/3
- exponetial rise before a stop (insect) M ≈ W1
- The in between M ≈ W3/4
Temperature Tolerance
- different species have different range of temperature that they can be tolerate to.
- Endotherm have a narrower range compare to ecthoderm
Temperature Tolerance in cain toad
Survival: 5-40 ⁰C
Breed: water temp 25-30⁰C
Na+/K+ pump action is 0.8% optimum at 5⁰C
Behavioural Thermoregulation
- these are behavior that assisst animal in regulation of their body heat
- there is a wide range of beviour
Temperature response curves
- Each species have an upper and lower limit. Pass the limit mean death
- the metabolic rate would rise with the temperature (Q10) before slowing down after reaching the optimum temperature
- After the optimum tempereature, it would rapidly decrease
Topor
-A process which an organism lower their body temperature to lower their metabolism rate
different animal heat tolerant
- Generalist that have a wide range
- Specialist that is adapted to a smaller optimal range
An organism’s environment is changing constantly
Abiotic changes
• temperature, humidity, sunlight (and altitude, longitude, and substrate for mobile organisms)
Biotic changes
• temporal and spatial variation in the abundance of food, competitors, natural enemies (predators, parasites, pathogens) and reproductive partners
Cues for predators
Niko Tinbergen’s classic field experiment, in which the broken shell from a newly hatched
black-headed gull was placed at different distances from an intact egg, showed that the inside of the eggshell is conspicuous
Black-headed gull parents remove the broken egg shell immediately after their chick has hatched
A signal or cue must be recognizable
Selection must favour the evolution of the sensory mechanisms that allow the signal or cue to be detected
Six senses Sensory modalities (or channels)
- chemical
- electricity
- light
- magnetic
- mechanical
- sound
Chemical modality (olfaction)
- The oldest and taxonomically most widespread sensory channel
- require a cell to produce and distribute pheromone
- and a receptor which is activated by the pheremone
Electrical modality
Works well in aquatic environments because electricity more easily transported through water than air
Visual modalities (light)
- Visual acuity (the ability to see) varies across species, and may depend upon eye size
- The ability to detect a signal (a natural decoration on a spider’s web) varies with distance and species
Magnetoreception
Bacteria and many animals detect and respond to the magnetic field, allowing them to orient over long (i.e., migration) and short (i.e., homing) distances
Mechanical
Web building spiders use vibrations, transmitted along the flexible silk, to detect the location and size of prey that are arrested by the web
Sound frequency
Bat sonar operates at frequencies of 20-200 kHz (which is called the ultrasonic because humans can’t hear sounds above 20 kHz. Humpback whale ‘songs’ are in the range 20-24 kHz
Echolocation
• objects in space are located by directing sounds at them and detecting the echoes
• the longer the time interval until the echo is detected, the further away the object
Signals and cues
Signal – any act or structure that influences the behaviour of other organisms (receivers), and which evolved specifically because of that effect
Cue – an incidental source of information that may influence the behaviour of a receiver, despite not having evolved under selection for that function
Signal or cue?
ant pheromone • a signal for other ants • a cue for adult butterflies [for mating and oviposition] • a cue for spiders [to locate webs where butterflies search]
Signals are effective only if they are detected
Signals, and the information they provide, may not reach their intended receiver because they ‘attenuate’ as they travel through the environment (it is more difficult to discern colour patterns or hear sounds the further from the source)
Background noise — Signals are only effective if they can be detected, and this can be a problem is there is ‘background noise’ (try having a quiet conversation in a noisy room)
Signals are strategic and efficacious
a) Signaling strategy [bright colouration reveals toxicity and thus reduces likelihood of predation]
b) Signaling efficacy [same information, different impact]
Distinguishing between signals and cues
- A signal has evolved as a vehicle for information because it benefits both the individual that produced the signal and the receiver that detected it. Selection will favour greater distinctiveness in the signal and greater ability of the receiver to detect it
- A cue has not evolved as a vehicle for information, but rather it inadvertently provides useful information to the receiver. Selection may favour greater detection abilities in the receiver, but will not act on the cue, unless it disadvantages the source of the cue
How does an animal ‘know’ what is a signal or cue and how does it know how to
respond?
The source of ‘information’ that allows animals to behave:
Innate a behaviour that is performed the first time an animal encounters the cue or signal appropriate for that behaviour
Learned a behaviour that is modified as a result of the animal’s experience of its environment
Costs to signaling
Physiological
• drain on resources during growth (often the case for visual signals, like feathers or organs for
bioluminescence), or during immediate production of signal (movement or making sounds and vibrations)
Exploitation
• signals (or cues) may be intercepted by an untended receiver (predator or parasite)
Eavesdropping
Eavesdropper
• an unintended receiver that detects and uses the signals of others for its own benefit
• may be a competitor or natural enemy (predators or parasites)
Example of eavesdropping
-‘Playback’ experiments showed that the calls of white-browed scrubwren chicks attracts predators (currawongs). Chicks make fewer begging calls when predators are nearby
-Parasitoid flies eavesdrop on the courtship calls of bush-crickets – males that are more attractive to females are more likely to be parasitised
Meat ants
• numerous workers are deployed to display grounds, located mid-way between the nests, where workers engage in ritualised displays
• displaying ants release an alarm pheromone that recruits other ants
Habronestes spider cannot capture foraging ants
• found where ants are displaying
• easily captures displaying ants
Eavesdropping inter-specific cues
Most eavesdropping is of an intra-specific signal – released and detected by members of the same species
Eavesdropping by the web building spider of the odours from the lycaenid butterfly tending ant is unusual because the ant social signal is also a cue for both a mutualist and a predator
Camouflage
Camouflage reduces the likelihood that an organism will be detected or recognized
Masquerade
A type of camouflage that prevents recognition by resembling an uninteresting or unimportant object, like a leaf or stick
Motion masquerade
• movement improves crypsis and thus reduces likelihood of predation
Prediction
• individuals will start swaying when they detect changes in wind pressure
n Batesian mimic
- benign Batesian mimic resembles a noxious or dangerous model
- predators avoid eating both the model and mimic
Aggressive mimicry
Many predators have evolved aggressive mimicry strategies to lure prey
Frogfish: have a ‘lure’ that attracts prey (fish, crustaceans) by mimicking worms, small shrimps or fish.
The surface odour of a salNcid spider resembles that of green tree ants, allowing the spider to gain access to the nest, where it feeds on the ant larvae
Müllerian mimicry
Müllerian mimicry, named for the
German naturalist Fritz Müller, where two or more species have similarly antipredator traits (for example, they are distasteful) and similar ‘warning’ signals,
but do not share an immediate common ancestor
Coevolution and arms race
Coevolution is a process involving pairs of species (orlineages) whereby changes in the traits of individuals of one species (or lineage) causes reciprocal changes in the other species (or lineage) over evolutionary time
Antagonistic interactions may lead to reciprocal evolutionary change and ‘arms races’: while both predator and prey improve their offensive and defensive adaptations, there is little change in their net advantage
Some coevolution interactions
Prey defense adaptations Predator counter-adaptations
Camouflage (prevent
detection)
Improve sensory acuity (learning, sensory
organs)
Mimicry (prevent recognition) Improve sensory acuity (learning, sensory
organs)
Early detection of predator Camouflage, faster or more secretive
approach
Active defense (chemical,
physical)
Capacity to ‘de-activate’ or detoxify the
chemical defense; greater armaments
Bats vs moth
Bats use echolocation as a means of detecting the location of their prey Ears, with auditory receptors: A1 and A2 cells Having two receptor cells can reveal the location of the bat
Brood parasitism
- where a female of one species lays her eggs in the nests of other species, who raise the ‘parasitic’ chick
- brood parasite avoids the ‘costs’ of raising chicks, while the cost to the host includes an energetically costly loss of reproductive output
- classic example of coevolution in the context of sensory information
- not very common (1% of bird species)
European cuckoos
Cuckoo signals
• visual resemblance to raptors – encourages the host to leave nest, allowing the cuckoo to fly onto the nest, remove an egg and lay her own, all in <10s
Host response
• hosts that detect a cuckoo near their nest and/or a non-matching egg in the nest will abandon the nest and start again
Selection on improved egg mimicry
Across species, the degree of egg mimicry is higher in species with with higher host rejection rates
Egg mimicry reduces the risk of host rejection of cuckoo eggs, but this selects for better discrimination by hosts
Australian cuckoos take it to the next level
Horsfield’s bronze cuckoo (left) has evolved a mimetic egg that fairy-wrens (right) are unable to distinguish from their own
In response, fairy-wrens have acquired the ability to recognise and reject cuckoo chicks
Prediction: over evolutionary time, cuckoo chicks will be visual mimics of fairy wren chicks
Reproduction: information transmission
For asexual organisms, information is transmitted directly and perfectly from female to
female, whereas sexual reproduction results in the ‘transfer’ of slightly different
information because it derives from females and males
reproduction methods and environmental variation
Asexual species are more common in agricultural habitats that are typically homogenous
-sexual reproduction provides advantages in spatially and temporally variable environments
Challenges of bringing sexes together
Signals, indicating location and receptivity, are required to bring the sexes (or gametes) together
That can also act as cues to alert natural enemies
Modes of reproduction that remove the hassle
with sex
Facultative parthenogenesis
females are able to produce viable eggs irrespective of whether mating has taken place
Hermaphroditism
organisms have complete or partial reproductive organs and produces gametes normally associated with both male and female sexes
Sexual selection
- Differences between the sexes (sexual dimorphism) are not easily explained by natural selection
- Charles Darwin proposed sexual selection, in which there is competition between members of one sex (typically males) for reproductive opportunities with the other sex (typically females)
- Mate choice and male-male competition are the underlying mechanisms of sexual selection; both involve signaling.
Male male competition
Males have armaments that are used in contests (and may also signal fighting ability)
Pheromone detection and receptor organ
morphology expiriment
Theory Two females
• by releasing small quantities of sex- pheromone, females attract males with larger antennae (and of higher quality)
Experiment
• place either one or two female Gum-leaf skeletoniser moths Uraba lugens in Delta traps
• measure size of trapped males -male with longer attena are more effective
Reproduction – a paradox
Although males and females have a mutual ‘evolutionary’ interest, namely ensuring their genetic information is passed onto the next generation, sexual reproduction creates evolutionary conflicts of interest
Females
Reproductive success can be improved by mating with more than one male (polyandry) within their reproductive cycle
Males
Reproductive success is compromised by polyandry, and sexual selection favours mechanisms to prevent it
Male counter-adaptations to polyandry
Preventing polyandry
• physically preventing her from mating
• interfering with female signaling
Reproductive conflict in dunnocks
Males and females form territories independently, and the pattern of overlap determines the ‘mating system’
polyandry and polygyny
Polyandry is the ‘best’ outcome for females, while
Polygyny is the ‘best’ outcome for the a male, but not the b male
Parental care
-Providing protection doesn’t always mean the brood
must stay in the same place
-foraging food for young
- provisioning: provide food for young before they hatch, does not return
Negative of parental care
The net benefit for the female is maximized at PIm, but this is not the best outcome for the offspring (perhaps closer to PIo
Female Diaea spiders lay a single clutch of eggs, but subsequently accumulate more weight: the more weight they gain the more more soma available to their matricidal offspring
Cooperative breeding in birds and mammals
The dependent young receive parental care (food defense) from their parents and other individuals in the group
Eusocial insects
–
extraordinarily
cooperative care
Major defining features
i) Cooperative care of young, involving more individuals than just the mother
ii) Sterile castes that help in nest maintenance and raising offspring, but cannot themselves reproduce
iii) Overlapping generations, such that mother, adult offspring and larval offspring are alive at the same time
And complex societies require the exchange and acquisition of lots of information
