Natural Slection and Fitness Flashcards
Why is it difficult to find evidence for the evolution of behaviour?
Cannot go back in time but comparisons can be made of animals alive today
Helpful when species are closely related so differences are slight and the changes are easier to reconstruct
Can be difficult as behaviours may be found in one population but not in another (cultural transmission, Japanese macaques)
Name and describe an example of 2 closely related species in which behaviour can be seen to be different
Colobus monkeys
Red colobus and black and white colobus
both live in E.Africa with overlapping ranges
diet consists of foliage
Red Colobus - lives in wet forests, eats flowers, shoots, fruits and leaves, has 40+ in a troop and has a range of around 1km squared
B&W colobus - lives in dry forests, eats mature leaves of few species, has less than 10 in a troop and has a much smaller range
What is the difference between homologous and analogous?
Homologous - derived from a common ancestor (wings of birds, limbs of humans, fins of fish)
Analogous - Solution to a common problem (wings of birds and insects - no common structure)
Why have behaviours evolved through time?
Natural selection
- individuals within a species differ from each other (show variation)
- Variation, to some extent, is inherited
- Species individuals produce more offspring that can ever survive
How does natural selection favour beneficial behaviours?
Favours foraging behaviours that maximise the amount of energy gained
Favours behaviours that maximise the reproductive success (finding mates with superior qualities)
What conditions must change to drive evolutionary change?
Environment must change
Difference must be inheritied
What 2 aspects determine wither a trait will be successful or not?
Give an example of this
Costs to the animal
Benefit to the animal
Incubation - benefits - keeps eggs warm, maximises hatching success, increased reproductive success
- costs - no time to forage, immobility of incubating bird
Define the term reproductive value and who coined the term
Ronald Fisher 1930
fitness value varies with an individuals age
depends on the ability to reproduce and the ability to survive
Name and describe the terms associated with reproductive cycles
Semelparity - single reproductive episode before death
Iterparous - multiple reproductive cycles over a lifetime
What is the driving force in life?
Maximising fitness - ensuring the passing on of genetic material from one generation to the next
What is inclusive fitness?
Can be maximised at the expense of individual fitness
parents often sacrifice themselves for offspring
important as it explains behaviours impossible to account for
What is eusociality?
Different animals have different jobs to do. There is a division of labour. Some castes may be sterile
Animal generations overlap. different generations in the hive or nest
Animals cooperate to care for young
What are the 2 ways a behaviour can affect an individuals fitness?
Directly enhacing or inhibiting
Indirectly precluding another behaviour
In what ways can fitness be measured?
attempt to specify costs and benefits
measure changes in reproductive output associated
What are the 4 aspects that contribute to the variation in fitness of a species?
Ability to survive to reproductive age
success in mating
number of young produced
offspring survival to reproduction
Give an example of genetic behaviours and an example of learned behaviour (cultural transmission)
genetic - cricket song (Shaw, 1996) same genus different species different song when bred the hybrid has an intermediate song
leaned - sweet potato washing in Japanese macaques and termite fishing in chimps
Give examples of how the benefit of a behaviour outweighs the cost
infanticide in lions
migration in birds
Examples of altruism?
killdeer bird
groove-billed ani
meerkats
What is altruistic behaviour?
Any behaviour that decreases an individuals fitness but increases the fitness of another individual
What is Hamilton’s rule?
rB>C
r = coefficient of relatedness
B= benefit = average number of extra offspring recipient produces
C= How many fewer offspring altruist has as a result
If rB>C natural selection favours altruism
What are the temporal and spatial scale?
Temporal: Species can appear fixed at human lifetime scale
Spatial: Species can appear distinct but when compared around the world can be seen to change
Describe a study that debates the seemingly altruistic behaviours of meerkats
Tatalovic - 2010
Uses four models of analysing meerkat behaviour to better understand if it is beneficial to the individual or to the group
Found that despite appearing that being a sentinal for the group may be more dangerous that these meerkats were often predated upon least due to the loud noises and position of the meerkats. The behaviour though must have been evolved to fit an altruistic purpose though in that the meerkat puts itself in danger to warn the other members of the group to danger.
