Exam 2 Flashcards
Life History Strategy
how an organism obtains evolutionary fitness through its lifetime
Life history decisions are driven by
resource availability
external cues (seasons, temperature, precipitation)
r-selected characteristics
“live fast, die young”
rapid reproduction and high growth rates (exponential growth)
short life-span, quick to develop, low parental investment
k-selected characteristics
“slow and steady”
slower reproduction and gets slower as population approaches carrying capacity
long life span, slow development, late maturation, high parental investment
Life history trade-offs
foraging vs. vigilance
size vs. number of offspring
Semelparous species
reproduce once and die
salmon and pineapple
Iteroparous species
reproduce many times
bunnies
How is evolutionary success determined?
reproductive success
Vegetative reproduction
asexual reproduction
offspring produced from non-sexual tissues of parent
cloning and binary fission
Parthenogenesis
asexual reproduction
offspring produced without fertilization
Sexual reproduction
requires 2 types of gametes
results in genetic recombination
Characteristics of asexual reproduction
quick
direct copy of your genome
slow reaction time to changing environment (pathogens could wipe them out quickly)
Characteristics of sexual reproduction
genetic recombination
changing conditions have less of an effect
lost 1/2 genetic information each time
takes longer than asexual reproduction
Hermaphrodites
possess both male and female parts
Sequential hermaphrodites
change once (nemo)
Simultaneous hermaphrodites
can change back and forth multiple times
Characteristics of social monogamy
biparental care
occurs when care by both parents is important to survival
occurs when it is difficult to monopolize multiple females
birds, beach mouse
Characteristics of polygyny
female sociality
male control of resources coupled with defending one’s own habitat
occurs when females are clumped
pipefish
Characteristics of polyandry
very rare
male-biased sex ratio (no choice for males)
rich in resources
Characteristics of promiscuity and polygynandry
multiple mating by males and females
presence/absence of social ties
plural breeding
Intrasexual selection
mate competition (MvM or FvF)
intense fighting/ competition
Intersexual selection
choosier sex picks mate
mates are picked based on preferred characteristics
Characteristics of anisogamy
females produce small amounts of large eggs
males produce large amount of small sperm
Why choose your mate?
material benefits like fertility and survival
genetic benefits to give more offspring
Handicap principle
females prefer a trait that reduces male survival
“honest signal” of fitness
Sex role reversal
if males invest more per offspring that females
access to males is limiting resource
choosy males
Benefits to group living
protection
group hunting
care of offspring
thermoregulation
Costs to group living
attracts predators
spread of disease
competition
conspecific aggression
Cooperation
joint activity among animals to achieve a shared goal
Altruism
behavior that increases direct fitness of recipient but lowers direct fitness of donor
Kin selection
animals help relatives reproduce, and so pass on shared alleles
A relative will help when…
the benefits x relatedness outweighs the cost
Br>c (Hamilton’s rule)
Characteristics of eusocial species
adults live in a group
overlapping generations
cooperative brood care
reproductive dominance by one or a few individuals
haploiddiploid
honeybees (queen, worker, drone)
Conflict and cooperation in eusocial species
workers cooperate more with relatives
workers behave less favorability toward less related animals
To increase a population, there needs to be…
more reproduction or movement into the group than deaths or movement out of the group
Geometric growth assumptions
deaths are constant
1 birthing event
unlimited resources
equal individuals
no immigration or emmigration
Lamda is…
geometric population growth rate
Exponential growth assumptions
unlimited resources
all individuals are equal
no movement in or out of a population
births and deaths are constant
r is…
intrinsic growth rate (for exponential)
Lamda values for:
decrease pop
steady pop
increase pop
lamda<1
lamda=1
lamda>1
r values for:
decrease pop
steady pop
increase pop
r<0
r=0
r>0
Density-dependent factors
cause birth/death rate ect. to change as population density changed
Density-independent factors
no relationship with density
natural disasters
Logistic model assumptions
k is constant
unlimited resources
all individuals are equal
no movement in or out of a population
births and deaths are constant
Age structure
the proportion of individuals in a population in different age classes
Incorporating age structure relaxes the assumptions that…
all individuals are the same
birth and death rates are constant
What do the age structures for the following look like?
Stable
Growing
Shrinking
constant all the way up with a lil hat on top
think like a pyramid
larger in the middle with a small bottom layer
Type 1 survival curve
survival to old age like bears and humans
half of an upsidedown parabola
Type 2 survival curve
constant dying like squirrels
negative liner line
Type 3 survival curve
most die young like dandelions
negative exponential graph
Survivorship
proportion surviving from birth to age x
can vary within and between populations
can be affected by habitat and social factors
Fecundity
average number of offspring produced by a female of age x
Does age structure change from year to year?
No, it does not
proportion in each age class remains the same
Population fluctuations
unpredictable changes through time
Population cycles
nearly constant intervals
alternate high and low abundance
