BIOL 2Q04 Lecture Notes - Lecture 15: Lek Mating, Mate Choice, Circadian Clock
14 Dec 2016
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BIOL 2Q04 | November 9th, 2016
Behavioural Ecology Cot’d
Exploitation of Patches
− Food not evenly distributed in space and time
− Pre aailailit ithi a path dereases as a result of the predators foragig atiit eause of:
o Depletion of prey
o Evasive action by prey
− To aiize the rate of gai of a resoure, predators should follo the argial alue theore
o Looks at over time, how much time should a predator spend at one location to maximize
resource gain?
Marginal Value Theorem
− To maximize gain/time, a predator should leave at the point (maximum net gain) that gives the
greatest gain or food/unit time (steepest slope of the line)
− If travel time increases (i.e. patches further apart), the optimal time to stay in a patch also increases
Migration
− A regular long-distance change in location
− Animals use environmental stimuli to provide cues to trigger migration behaviour
o Some animals track their position relative to the sun, moon or stars
o Adjust to sun, stars, etc. by circadian clock, others use magnetic fields (pigeons, fish)
o Can also be an innate response
Mating Behaviour/Mate Choice
− Mating behaviour and mate choice are critical for reproductive success
− Includes:
o Seeking and attracting mates
o Choosing among potential mates
o Competing for mates (agonistic behaviour)
o Caring for offspring – needs of young greatly influence mating systems
▪ Young require a lot of investment, having a mom = greater chance of survival
▪ I.e. highly variable environment with lots of disturbance → high young mortality causes
an increase in maternal investment to care for their young and allow for parental
genes to pass onto next generation
Why Sex?
− Basil orgaiss = aseual = life origiated ithout se! “o se had to eole BUT…
− A lot of costs are associated with sex:
o Cost of males
▪ Asexual organism can produce many females
o Passing on genes is like tossing a coin
▪ 2 copies of a gene – doest esure that the gees ou at passed o ill e passed
onto offspring
o Cost of mating
▪ A lot of time/energy into finding mates, injury, competition, etc.
• Competition = risk of injury for males
o Increased predation
o STIs
Sex = Variation
− Aseual orgaiss dot last!
find more resources at oneclass.com
find more resources at oneclass.com
o Most mutations are detrimental thus mutation acquisition is a one-way process in the genome
of asexual organisms
▪ Mullers rathet – accumulation of irreversible deleterious mutations
− More variation = natural selection operates faster
o Variable environment = quicker adaptations – parasite arms race
− Sex evolved within the lineage of life because the benefits outweigh the costs
Mating Systems
− Consequence of different reproductive strategies of males and females
o Vary in length and # of relationships
− Monogamy – mates stay together for long periods of time
o Ensures their genes are being put forth to the next generation
o Shares load of caring for offspring
− Polygyny – males mate with more than one female
− Polyandry – Each female mates more than once
− Lek mating system – sedutio arket
Lek Mating System
− Gathering of males, engage in:
o Competitive displays
o Males guard a territory and females choose male based on what she sees
o Advantages/disadvantages?
▪ Advantage
• Less energy cost searching
▪ Disadvantage
• Easy for predators to find them – grouped together
Sexual Dimorphism
− Extent to which males and females differ in appearance
− Varies with the mating system
o Monogamous – males and females the same
o Polygamous – males such shower than females
▪ I.e. Peacocks
Batea’s Priciple
− Sexes differ due to fundamental differences in their reproductive strategies:
o Females bear the direct physical, physiological and energetic cost of reproduction
▪ Point where female fitness cannot increase by producing more young = fitness
increases as a function of quality
• In her best interest to pick the strongest, and most beautiful male in order for
her to receive good genes for their offspring
o Male reproduction is not limited in this way, so male fitness increases by more copulation
▪ Males eperiee greater ariatio i reprodutie suess tha feales = Bateas
principle
− Selection on males for traits to increase copulation AND strong selective force from females on males
for preferred traits = higher reproductive success = sexual selection
Sexual Selection
− Influences the degree of sexual dimorphism – any trait or behaviour that confers an advantage
o Intersexual selection (mate choice) – 1 sex chooses mate based on some characteristics
▪ I.e. best song, dance, voice, territory, coloration, etc.
Handicap Principle
− Exaggerated traits hadiap come at a great cost
− Benefits > costs – for feales hoest sigals are a HUGE eefit
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
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