Life histories (Lecture 10) Flashcards
iteroparity
multiple reproductive cycles over the course of a life time
semelparity
a single reproductive episode before death
Disadvantage of sexual reproduction
- Waste of time and energy finding a mate
- exposes parent to predators
- exposure to STDs
- cut genetic contribution to offspring in half
__________ drive the evolution of a species
Fitness.
Those who survive and mate pass on traits to next generation.
David Lack
One of the first people to combine ecology and evolution
???
Stuctch
Believed that the reason for different clutch sizes was that parents spent time on increasing the survival of a few offspring so they are robust (limiting deaths).
The problem with this thinking was that it requires the notion of group thinking and doesn’t account for selfishness or individuals benefits.
Ashmole
emphasized density dependency. Mortality is the driver, seasonal impacts seasonality.
George Williams
To understand why there is different clutch sizes at different latitudes, one needs to look at the average clutch size over the entire life time of an organism (Breeding over many years).
It is probably due to trade offs in life histories.
Sexual Selection
Selection for traits that promote an increase in number of copulations
Focus on mating success
Intrasexual Competition
winner gets to mate
Intersexual competition , leads to what type of choice
female choice
monecious
male and female parts on the same plant
an example of an organism that is sequential hermapridites
clown fish
Lek System
sexual selection
example organism bird of paradise
operational sex ratio
number of individuals of opposite sex that are available to you (limited by pregnancies, rearing clutch).
Mating systems are defined on basis of
- number of mates
- length of association between mates
- degree of parental care
What are the types of mating systems?
- Monogamy
- Polygamy
- Promiscuity
polygyny
polygamy, male takes multiple females
polyandry
polygamy, female takes multiple males
Life history
a set of co-adapted traits “designed” by natural selection to solve particular ecological problems
Mortality in r selected vs K-selected
In r selected organisms mortality is often castrophic, density independent.
In K selected organisms it is more directed and density dependent.
Bet- hedging is…
how individuals should optimize fitness in varying and unpredictable environments by sacrificing mean fitness to decrease variation in fitness
