College aantekeningen
PSYC 306A ANIMAL BEHAVIOUR MIDTERM 2 NOTES
- Vak
- Instelling
PSYC 306A ANIMAL BEHAVIOUR MIDTERM 2 NOTES WITH Kiran K. Soma AT UBC
[Meer zien]Voorbeeld 3 van de 20 pagina's
Voorbeeld 3 van de 20 pagina's
In winkelwagen
In winkelwagen
gesponsord bericht van onze partner
Verkoper
Volgen
areenashrestha
Voorbeeld van de inhoud
Lecture 13: Feb 12 Predators and foraging PT.1What is an adaptation?
● A heritable trait/ phenotype that:
○ Spread in the past because of natural selection and has been maintained by
selection to the present OR
○ Is currently spreading relative to alternative traits because of natural selection
● Benefits> needs to outweigh cost for traits to be adaptation
● Better than existing alternative traits/ phenotypes
Descent with Modification
● Any 2 species can be traced back to a common ancestor
● Differences & similarities between them are the result of adaptation
● The more recent their common ancestor, the more similar they are
● The more similar their environment, the more similar they are
Homology vs. Analogy
● Homology = similarities due to common ancestry
○ Bat with a wing, whale with slipper = same bone structure
○ seal & penguin = have flippers , serve similar function
● Analogy = similarities due to similar environment/ function
Not all Traits are Adaptive
● Genetic mutation are randomly
○ N. Selection can only work with the genes that exist = cannot create certain
genes or traits (evolution is not a directed process )
● Environmental change, so some traits that are used to adaptive may no long be so
○ Become ‘neutral’ that will be selected against
● Some are costly but are genetically linked to other traits that provide benefits
○ ‘By products’
Mobbing behaviour of Colonial, ground-nesting Gulls
● Many birds will ‘mob’ predators - harass predators to drive them away
● Can protect eggs and chichs (reproductive success)
● While mobbing is often effective, takes time and energy , can lead to death of the
‘mobber’
STUDY: Black headed gulls in Netherlands
● Hypothesis: mobbing behaviour distracts predators, reducing the chance that predators
will find the mobber’s offspring
● Experiment: placed 10 chicken eggs, one every 10 meters, from inside of colon to
outside of colony (did this multiple times in different colonies)
● Is Mobbing an adaptation?
○ Result: data partially supported hypothesis
, ○ Invokes N. selection which produces a change in gene frequency within
population overtime
○ He did not measure whether mobbing affects gene frequency
○ Fitness (or reproductive success) isn’t just making eggs.
■ A fitness benefit is not realized until an animal’s offspring reproduce
Measuring fitness
● Scientist accept certain fitness-related ‘proxies’ (correlates of fitness) without measuring
fitness directly
● Researchers will often look at variables that are prob correlated to fitness - number of
surviving young, success in territory defense, amount of food procured
● Measures are imperfect correlation
The Comparative Method
● Another way to determine whether a trait is adaptive is to look at species that face
different or similar selection pressures
● Closely-related species with different selection pressures = might reveal divergent
evolution
● distantly -related species with similar selected pressure = convergent evolution (exp.
Independent evolution of the same trait )
○ Increase the prob that the behavior is adaptive
● Currently: 50 species of gulls ( ground nesting vs. cliff-nesting )
● Genetic techniques allow is to construct evolutionary trees based on DNA similarities
● Phylogeny: the simplest is usually correct , parsimony explanation
Prediction: if mobbing by ground-nesting gulls is an adaptation to predation, then gull species
whose eggs are at low risk of predation should show less mobbing behaviour
Cliff-nesting Gulls
● Fewer nest predators
○ Small mammals, predatory birds
○ Fewer benefits of mobbing
● Size of adults is reduced
○ More vulnerable to predator attack
○ Increased costs of mobbing
● Little mobbing behaviour = divergent evolution - suggest that mobbing is adaptive
(support the hypothesis)
● Benefits: predators like mice can’t reach them , predation is reduced , mobbing
behaviour = reduced
○ Cost higher than benefits
Convergent Evolution in Mobbing
● Many species that breed in groups (colonies) face the problem of having many nests and
young visible to predators
, ● Many such birds (exp. Colonial swallows) show mobbing behaviour
● So do colonial ground squirrels
Lecture 14: Feb 22 Predators & Foraging pt.2
Camouflaged Moths
● Peppered moth
○ Melanic form was once rare, then became common and then became less
common
● Classic Study: PLaced both forms on dark trees trucks and light trees trunks to see
which one gets eaten more quickly
○ Species does not sit on trunks . Sits below limb joints - it is a behavioural
adaptation
○ Another factor: pinned or limb joint , pollution or not
○ Have strong selection pressure vs. not
○ interaction : 3 variation , the answer depends on the morph, pollution or perch
site
Aposematism - Darwinian Puzzle
● Monarch Butterflies = emerges as a butterfly but before was a caterpillar eats a certain
milkweed that is poisonous = coloration prevents others from eating them, warning
coloration
Stotting by Gazelles
● Thomson’s gazelle: jump when they see a cheetah, when cased they leap several feet
into air and flare white rump patch at the predatory= stotting
● HYPOTHESIS:
○ tried to avoid being ambushed by other cheetah (isn’t supported)
○ It is an alarm Signal to warn others
○ Social Cohesion = group together in protection in large numbers =
communicating
○ Attack Deterrence = jumping around confuses the cheetah and doesn’t know
which one to follow/chase (supported)
● Cheetahs abandon hunts more often when gazelles stot
● Honest Signal - resistant to cheating , higher they can jump = shows that it is healthy
○ Trusted by cheetahs (they don’t waste their time and energy)
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper areenashrestha. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €8,07. Je zit daarna nergens aan vast.
Is Stuvia te vertrouwen?
4,6 sterren op Google & Trustpilot (+1000 reviews)
Afgelopen 30 dagen zijn er 78998 samenvattingen verkocht
Opgericht in 2010, al 14 jaar dé plek om samenvattingen te kopen
Laatst bekeken door jou
