Exam 2 Lecture 9 Life History Evolution Flashcards
Phenotypic plasticity
= the ability of a single genotype to produce different phenotypes across environments
•Number vs size of offspring
Intrinsic tradeoff (negative correlation)
Semelparous
is characterized by a single reproductive episode before death
Number of eggs laid per Darter clutch is _________ with egg size
negatively correlated
The cost of current reproduction i
s the decrease that current reproduction causes in future reproduction This cost typically decreases with age
•Number vs size of offspring
Intrinsic tradeoff (negative correlation)
r v k: Competitive ability
r v k:
Reproductive effort
the allocation of energy, time, and other resources to the production and care of offspring
Explain Number vs size of offspring
In any given reproductive event, there is a tradeoff between the number of offspring produced and the size of those offspring–Invest in egg yolk, blood supply, provisions
__selection: Characteristic high population growth rate
R selection
—parous: Adult survival is high
Iteroparous
Non-linearity model
If most of the costs of reproduction are realized, even at low levels of reproductive effort, then individuals that invest in a single, massive reproductive event are likely to have a fitness advantage over those that invest in multiple reproductive events
MacArthur and Wilson: r selection
per capita rate of increase
Across many different types of plants, number of seeds per plant
is negatively correlated with average seed size
Define Intrinsic tradeoffs:
- Increase in one life-history trait is linked to a decrease in another life-history trait
- The fitness gains that would have been made by the former are counteracted by the fitness loss caused by the latter •These are usually caused by genetic or phenotypic correlations between life history traits among individuals in a population
Intrinsic tradeoff (negative correlation)
- •Reproduction vs survival
- •Current vs future reproduction
- •Current reproduction vs parental growth
- •Current reproduction vs parental condition
- •Number vs size of offspring
__selection: Most prominent in species whose populations are near the carrying capacity much of the time
K selection
Live Fast Die Young & Neanderthals
‘slow growth’ gave complex brains more time to ‘cook,’ so to speak, and then learn all those things a fancy brain could learn.” “The team noted that the child’s brain had reached only about 87% of an average adult Neanderthal’s brain size, whereas modern human brains reach 90% of their adult size by age 5.
—parity is favored when the ratio of adult:juvenile survival is — or —-
Iteroparity, high or variable
__selection: Strongest in species colonizing new or disturbed habitats.
R selection
•Current reproduction vs parental condition
Intrinsic tradeoff (negative correlation)
—parous: Evolved independently several times
Semelparous
Gene flow between populations of each species
is negatively correlated with egg size
Number of eggs laid per Darter clutch is ________with female size
positively correlated
our models assume
a tradeoff between survival and reproduction!Reproductive strategies & lifespan
Positively correlated traits
•Age at reproductive maturity & adult survival •Development time & body size
•Development time & body size
Positively correlated traits
•Current reproduction vs parental growth
Intrinsic tradeoff (negative correlation)
Life Fast Die Young Hyp. (nonspec)
The theory that a higher metabolism means a shorter lifespan. Aging is the inevitable byproduct of energy expenditure. The faster you expend energy, the faster you age, and the sooner you die
r v k: Intrinsic rate of increase, rmax
r v k:
•Reproduction vs survival
Intrinsic tradeoff (negative correlation)
Life History Traits that are fitness components
- Size at birth
- •Growth pattern
- •Age and size at maturity
- •Number, size, and sex of offspring
- •Age-, stage- or size-specific reproductive effort
- •Age-, stage- or size-specific rates of survival
- •Lifespan
•Age at reproductive maturity and adult survival
Positively correlated traits
Most of our grain crops are______
Semelparous
__selection: Characteristic efficient resource use.
K selection
Fecundity
number of eggs or seeds produced by an organism
Why don’t all organisms just reproduce as soon as they are born, produce an infinite number of offspring, and live forever?
- Environmental limitations
- Intrinsic limitations & tradeoffs!
Demographic model
If adult survival is very low, then individuals that put a lot of investment into reproduction early in life will have a fitness advantage over those that spread their reproductive investment over time
—parous: Adult fecundity is low
Iteroparous
—parous: Typically have higher reproductive effort
Semelparous
Principle of allocation
Resources that are used towards survival cannot be simultaneously available to an organism for reproduction. The pie represents the total energy and resources that organisms can access
seed size is positively correlated
with rapid growth
r v k: Reproduction
r v k:
MacArthur and Wilson: k selection
carrying capacity)
r v k: Reproduction
r v k:
Reaction norm
describes the pattern of phenotypic expression of a single genotype across a range of environments. One use of reaction norms is in describing how different species—especially related species—respond to varying environments.
Iteroparous
multiple reproductive cycles over the course of its lifetime
What kind of relationship do you expect for gene flow and clutch size?
.Positive correlation
•Current vs future reproduction
Intrinsic tradeoff (negative correlation)
r v k: Development
r v k:
Gene flow
a measure of shared genetic material
Variation in life history traits are influencing the_______ ____ _______ ____ _________through ______, which is mediated by ____ ______!
distribution and abundance of populations, dispersal, reproductive strategies
Bet-hedging model
If adult survival is highly variable, then individuals that spread out their investment over multiple reproductive events will have a fitness advantage over those that invest all of their reproductive resources in a single event
r v k: Offspring
r v k:
r v k: Body size
r v k:
