Test 2 Flashcards
Water moves in the hydrolytic cycle via
fluxes between major pools
Abiotic factors such as ___ are important in shaping aquatic communities
- temperature
- salinity
- light
- pressure
- oxygen content
What are lotic systems?
streams and rivers
The most valuable marine communities occur
near shore
Broad sense heritability
the proportion of the total variation in a phenotypic trait that is due to the genetic differences among individuals
-ranges from 0-1
Narrow sense heritability
the proportion of the total phenotypic variance that is due to additive genetic variance, Va
-ranges from 0-1
Stimulus response
a specific behavior elicited by a specific stimulus
ex: courtship displays
Communication
any action by one individual that alters the probability of a behavior of another
Natural selection
fitness refers to both an organism’s ability to survive and reproduce
Sexual selection
some traits may improve reproductive success while reducing survival
How can you tell if an organism is male or female?
females produce larger gametes than males
Monogamy
when a male mates with a single female
What is serial monogamy?
a monogamous relationship that lasts for a single breeding season
Polygyny
when a male mates with more than one female during a breeding season
Polyandry
females mate with more than one male during a breeding season
Inclusive fitness
the relative ability to transfer one’s genes, or copies of them, into the next generation
What are the equations for broad sense heritability?
H^2 = Vg/Vp Vp = Vg + Ve -Vg: genetic variation among indiv. -Ve: environmental variation -Vp: total phenotypic variation
What are the equations for narrow sense sense heritability?
1) h^2 = Va/Va+Vd+Ve
-Va: variation due to additive genetic differences between indiv.
-Vd: the effect of dominance (the masking of recessive genes by dominant ones)
-Ve: environmental variation
2) “the breeder’s equation”
R = h^2s
-s: selection coefficient
-R: change in the trait over time
-h^2: heritability
Behaviors are a result of ___ as well as ___
genetic makeup; environment and experience as an individual
Traits with high heritability respond to natural selection ___ than traits with low heritability
more rapidly
If h^2 is high, the rate of evolution is ___
greater
Females are limited by ___ and ___, but not ___
- number of eggs they can make and other investments
- NOT MATES
Female fitness increases as a function of the quality of the progeny, making ___ more important
mate choice
Males are limited by ___, not ___
- number of mates
- NOT SPERM
Male fitness increases with ___
number of females he inseminates
When there is competition for mates, sexual selection will be
stronger
Which sex is normally competitive?
males
Which sex is normally choosy?
females
What does Bateman’s principle say?
- because males compete, they experience greater variation in reproductive success than females
- leads to a strong selection on males
- sexual selection and asexual dimorphism are tightly related
What are the 3 ways that males compete?
- combat
- post copulatory competition
- infanticide
What is combat?
direct male to male competition; females may be oblivious
What is post copulatory competition?
When females mate with more than one male
- make lots of sperm
- males guard their mates
- add pheromones to make females less attractive
- prolonged copulation
- block next guy’s sperm
- remove previous sperm
What is infanticide?
killing another male’s offspring to make females receptive to mating sooner and avoids investment in non-related offspring
-mostly in mammals
What is the balance hypothesis?
states that male traits are exaggerated by female choice until their overall fitness cost is too high
What is the “truth in advertising” hypothesis?
states that elaborate phenotypic traits of males are an indicator of overall fitness
-helps females choose a superior male, thereby increasing the quality of her progeny
The mating system involves
- the number of mates an individual copulates with during mating season
- the relative contribution of males and females to parental care
- how long the relationship between males and females lasts
What is characteristic of social monogamy?
- female bonds with 1 male
- male and female share in parental care
What is characteristic of genetic monogamy?
- all progeny of a socially monogamous pair is produced by the male and female of that pair
- rare
What are the ecological determinants of monogamy?
- if successful rearing of the young requires both parents, monogamy is advantageous for both sexes
- if reproduction is highly synchronous
- most common type of mating system in passerine birds
What are ecological determinants of polygyny?
-spatial distribution of females
spatial distribution of other critical resources
What are behavioral determinants of polygyny?
- lek-mating species
- males display together on traditional sites known as leks
- females choose their mate based on these displays
- a few males obtain the majority of copulations
What are the ecological determinants for polyandry?
- fitness benefit to females
- nuptial gifts from male to female
- reduces the probability of mating with a poor quality male
What are the fundamental components of social systems?
- group size/composition
- degree of cooperation b/w individuals
- mating system
Group size and distribution depend on
- abundance
- distribution
- types of resources
Cooperation among individuals includes
- cooperative hunting in wolves
- shared care of the young
- altruistic behaviors
What is Hamilton’s rule?
states that genes for altruism can increase in frequency if rB - C > 0
- r: coefficient of the relationship of the altruist
- B: fitness benefit to the recipient
- C: fitness cost to the altruist
What is a stimulus-response?
specific behavior elicited by a specific stimulus
-behavioral response is invariant
What is an example of a stimulus-response?
Courtship displays
-if each individual does not perform the prescribed behavior, courtship breaks down and mating doesn’t occur
What are commonly used forms of communication?
- visual
- auditory
- olfactory
- tactile signals
What determines the choice of what type of signal to use?
the nature of the communication and the physical properties of the environment
What is sexual dimorphism?
differences in size, coloration, or morphology between males and females
Sexual dimorphism suggest that
different selective forces operate on males and females
How do females bear direct anatomical, physiological, and energetic costs of reproduction?
- lay and incubate eggs or carry them to term internally
- there is a point at which female fitness can’t increase by producing more young
- her fitness increases as a function of the quality of young she produces
Male contribution, sperm, can be produced in great numbers so male fitness increases with
the number of females he inseminates
What does Bateman’s principle suggest?
males experience greater variance in reproductive success than females
Opportunity for selection to affect one sex increases the degree of
sexual dimorphism
What is female choice?
a mechanism of sexual selection in which females choose mates on the basis of their physical or behavioral characteristics
What is male to male competition?
a form of sexual selection in which males compete with one another directly or indirectly for access to females
What is the balance hypothesis?
states that male traits are exaggerated by female choice until their overall fitness cost is too high
-natural and sexual selection gradually come to a balance
What is the “truth in advertising” hypothesis?
suggests that elaborate physical traits of males are an indicator of overall fitness
-explains the elaboration of the traits important to females that don’t contribute to male fitness
What is a mating system?
the length of the relationships between males and females, the relative contributions of males and females to parental care, and the number of mates an individual copulates with
What are the advantages of female promiscuity?
- increases genetic diversity of offspring
- ensure the female has opportunity to mate with a number of males with high fitness or to increase the probability that at least one male is fertile
What is the most common relationship between males and females?
polygyny
What is female defense polygyny?
a form of polygyny that occurs when groups of females are guarded by males
What does resource defense polygyny suggest?
if critical resources are distributed such that males can defend them, the males may obtain a territory that attracts multiple females
Which is the rarest mating system?
polyandry
What are the direct benefits of polyandry to females?
- nuptial gifts provided by males
* energy or nutrient rich resources that increase the female’s reproductive success
What are the indirect benefits of polyandry to females?
superior male genes
What is outcrossing?
a plant mating system in which mating occurs between different individuals
What is autogamy?
a plant mating system in which individuals self fertilize
What is apomixis?
a plant mating system in which individuals reproduce asexually
What is degree of self-incompatibility?
a phenomenon in plants in which individuals can’t self-fertilize
What is protogynous development?
a pattern of development in plants in which female parts of the flower develop before male parts
What is protandry?
a developmental phenomenon in which the male parts of the flow mature before the female parts
What is a habitat?
the abiotic and biotic characteristics of the place where an organism lives
What is a microhabitat?
the subset of the habitat that differs in important abiotic and biotic characteristics
-ex: caribou choose different microhabitats within the tundra during different seasons
What is a home range?
the portion of the habitat used by an individual on a daily or seasonal basis
What is territoriality?
exclusive use of a portion of the home range
What determines the size of a territory?
resources of importance and their spatial distribution
What is dispersal?
the one-way movement of an individual from the natal area
What is the natal area of an individual?
the place where the individual was born
When an organism is described as philopatric, what does that mean?
it means they do not disperse
What is saturation dispersal?
dispersal of individuals that occurs when the habitat is filled or resources are limiting
What is pre-saturation dispersal?
dispersal of individuals that occurs before the habitat is filled or resources are limiting
What is inbreeding depression?
a decrease in fitness due to mating among related individuals
What is altruistic behaviors?
any behavior that increases fitness of others at the expense of the altruist’s fitness
What is an example of an altruistic behavior?
alarm calling behavior of Belding’s ground squirrels
Mating systems are shaped by
pattern of resource distribution
What is eusocial?
describes a complex social system in which there is divisions of labor or castes, a high level of cooperation, and sometimes altruism
Coarse-grained environmental variation
patch size is larger than the organism’s mobility (an organism experiences few environments over its lifetime)
Fine-grained environmental variation
patch size is smaller than the organism’s mobility range, an organism is exposed to many environments
Biological species
in sexually reproducing organisms, a species is a group of populations that can interbreed and produce fertile offspring
Ecotype
genetically distinct populations adapted to local environment via natural selection
Subspecies/race
a local, distinct form that is distinctly different in phenotypes (may rarely interbreed)
Phenotypic plasticity
development of different phenotypes in different environments by the same genotype
Common garden experiments
individuals with different phenotypes in the field are grown under similar conditions
Muller’s ratchet
process by which the genomes of an asexual population accumulate deleterious mutations in an irreversible manner
Population bottlenecks
persistence of drift and inbreeding AFTER population re-expansion, caused by burden of ongoing homozygosity and expression of deleterious alleles
Effective population size
the size of “an ideal population” of organisms (ideal refers to a hypothetical population in a Hardy-Weinberg sense with constant population size, equal sex ratio, and no immigration, emigration, mutation, or selection) that would experience the effects of drift or inbreeding to the same degree as the population we are studying
Ecological effects of temporal variation depend on
- amplitude of the change
- speed of the change
- predictability
What give rise to ecotypes?
genetically determined differences between populations inhabiting different environments
What give rise to phenotypic plasticity?
non-genetic changes
What are the factors that favor the evolution of ecotypes?
- existence of genetic variation in the trait
- intensity of natural selection
- geographical barriers to gene flow
What does Fischer’s fundamental theorem suggest?
the rate at which the mean fitness of a population increases by natural selection is equal to the additive genetic variation in fitness (i.e., the combined effects of all the different genes that affect fitness)
What is a reaction norm?
the range of all possible phenotypes that one genotype can produce
Spatially (and temporally) fine-grained environments favor ___ ___ because it is the optimal response under variable ecological conditions
phenotypic plasticity
Coarse-grained environments lead to more predictable selective pressures that favor
fixed genetic adaptations
In common garden experiments, if the field phenotypes persist in the common garden
the differences among populations are likely genetically controlled
If the phenotypes in the common garden are similar, the variation in the field is due to
phenotypic plasticity
What is the ultimate source of all genetic mutation?
mutations
Once mutations arise, their frequencies and combinations change due to
- meiosis
- natural selection
- genetic drift
- breeding system
What are mechanisms that decrease genetic variation?
- stabilizing selection
- directional selection
- inbreeding
- genetic drift
What are mechanisms that increase or maintain genetic variation?
- overdominant selection (when a heterozygotes’ phenotype different than either homozygous phenotype and heterozygotes have higher fitness)
- disruptive selection
- negative frequency-dependent selection (fitness depends on whether genotype is rare/common, highest fitness when your genotype is rare)
- outcrossing (breeding with distantly related individuals)
- migration/gene flow
What is the two fold cost of sex?
asexual individuals pass on twice as many genes to their offspring as sexual individuals
What is an evolutionary stable strategy?
an adaptation that increases in frequency when rare
Is sex an evolutionary stable strategy?
no
Red Queen Hypothesis
selection in a constantly changing environment favors sex
Wright’s F-statistic
F(IT) = F(IS) + F(ST)
- F(IT): genetic variation
- F(IS): variation within populations
- F(ST): variation between populations
The higher the value of F(ST), the larger the proportion of the total genetic variation is due to
the differences among populations
Spatial variation in the environment is the result of
discontinuities in physical and biological factors from place to place
Infraspecific variation
genetic or phenotypic variation within a species
Magnitude of the differences between patches determines
the selective pressure exerted on the organism
What are ecotones?
boundaries between habitat types
The degree to which patches are isolated determines
the potential adaptive response of the organism
Temporal change occurs
over many time scales
Unpredictability poses a ___ than a constant environment
greater challenge
What is an essential feature of infraspecific variation?
that the phenotype varies with the patterns of environmental variation
What are ecotypes?
genetically distinct populations adapted to the local environmental conditions
The amount of genetic variation in the population may limit
the adaptive process
Fischer’s Fundamental Theorem
the principle that the rate of change in fitness by natural selection is equal to the additive genetic variance in the population
Additive genetic variation
the combined effects of all the different genes that affect a trait
Ecotypic differentiation is more likely to occur if the spatial variation in the environment also includes
barriers to gene flow among populations
What is the difference between phenotypic difference and phenotypic plasticity?
phenotypic difference: arise due to the direct detrimental effect of the environment
phenotypic plasticity: when the phenotype shifts in adaptive ways in different environments
Adaptive phenotypic plasticity requires a mechanism that not only detects ___ but also alters the ___ so as to produce the optimal phenotype
environmental change; developmental pathways
Why is phenotypic plasticity both advantageous and disadvantageous?
the organism can respond to its environment, but the developmental complexity and energetic requirements for phenotypic changes may be a burden
What determines whether the adaptive response to the environment is genetic or phenotypic?
temporal and spatial pattern of variation in the environment
Plasticity is advantageous if the pattern of temporal variation includes
rapid shifts or highly unpredictable conditions for which a genetic response would be too slow
How does disruptive selection maintain genetic variation in the population?
more than one phenotype is adaptive and selection ensures that each persists
How does frequency-dependent selection maintain variation?
by favoring rare genes
How does stabilizing selection decrease variation?
by eliminating extreme phenotypes and their genotypes
How does directional selection decrease variation?
by favoring phenotypes in one tail of the bell curve and eliminating those at the other extreme
What is genetic similarity?
the measure of the proportion of alleles shared by two
Demography
the quantitative description of the structure of populations
-includes size, age structure, sex ratios, and growth rate
Ecological population
a group of individuals of a species that occupy a particular area, its boundaries are determined by an ecologically relevant change in the environment
Evolutionary population
a local group of individuals that mate at random (a deme), its boundaries are determined by the barriers to mating and gene flow
Connectivity
the link between 2 or more populations by dispersal of individuals
Abundance, N(t)
number of individuals in a population (NOT number of species in a community)
Density
number of individuals per unit area or volume
Genet
a genetically distinct individual or clonal colony in a plant population
Ramet
a physiologically distinct individual within a plant genet
Unitary organism
exist as separate and distinct individuals
Modular organisms
develop repetitive patterns of growth of body parts
Cohort life table
follows a group of individuals over time
Static life table
based on a sample of the population at one moment in time
Survivorship curve
graphically represents the pattern of age-specific survival
Life expectancy (Ex)
the mean expectation for further life of an individual of age x
Life span
the max number of years and individual in the population could potentially live
Net reproductive rate (r0)
the average number of offspring produced by an individual during their lifetime
Lincoln (mark-recapture) method
N=N1*N2/Nm
N: total population size
N1: number of individuals marked and released in the population at time T1
N2: number of individuals captured in the population at time T2
Nm: number of marked individuals at time T2
Poisson distribution
Px=a^xe^-a/X!
x: number of occurrences
a: mean number of occurrences per grid square
e: base of the natural log
X!: x factorial; this means we multiply the value of x times the values of x-1,x-2,x-3 and so on until the remaining term is 1
Life expectancy
Lx=n(x)+n(x+1)/2
Tx=L(x)+L(x+1)+L(x+2)+…+L(infinity)
e(x)=Tx/n(x)
Net reproductive rate (R0)
- b(x):expected reproductive output for an individual of age x
- l(x)b(x): realized population determined by probability an individual will live to age x
- R(0): sum l(x)b(x)
For exponentially growing populations with discrete generations
N(t)=R(0)+N(0)
-N(0): number of individuals at time 0 (now)
For exponentially growing populations with overlapping generations
r: instantaneous growth rate, or intrinsic rate of increase
-r=b(0)-d(0)
N(t)=N(0)e^rt
Population boundaries determined by
- number of individuals
- spatial distribution
- reproductive rate
- isolation vs connectivity
What are ways to quantify population size?
- total census
- for large animals, trees, humans
- lincoln (mark-recapture) methods
- for small, mobile organisms
- Quadrat or transect methods
- for sessile or relatively immobile organisms
- indirect, relative measure of the abundance, but can be scaled up
What is random distribution?
individuals distributed without regard to others
-neutral or little interaction between individuals and between individuals and local environment
What is clumped distribution?
individuals in discrete groups, positive interactions
-attraction between individuals or to a common reassurance or little dispersal far from parent
What is regular distribution?
individuals maintain min distance between themselves and their neighbors
-antagonistic interactions between individuals or local depletion of resources
Poisson distribution is a
random distribution
Type 1 survivorship
low survival in young ages, then high survival until old age, when mortality increases rapidly
-many mammals, including humans
Type 2 survivorship
survivorship is constant across all ages
-common in small mammals, lizards, birds
Type 3 survivorship
early mortality is very high, but decreases with older ages
-many marine fishes, invertebrates, and plants
If R(0) > 1,
the population is increasing
If R(0)=1,
the population size is stable
If R(0) < 1,
the population is decreasing
1 degree sex ratio
sex ratio at fertilization
2 degree sex ratio
sex ration at birth or hatching
3 degree sex ratio
sex ratio at sexual maturity
4 degree sex ratio
sex ratio of the adult population
Populations change in time and space by
- immigration to the population (I)
- emigration from the population (E)
- additions to the population via births (B)
- losses from the population via deaths (D)
For exponentially growing populations with overlapping generations, if r > 0,
population declines
For exponentially growing populations with overlapping generations, if r = 0,
population is stable
For exponentially growing populations with overlapping generations, if r < 0,
population grows
A transition matrix tracks
- the probabilities of transition from one age to another
- the corresponding reproductive output that accumulates in the process
Which of the following is not characteristic of interspecific competition?
The limiting resource does not change over time
According to the competitive exclusion principle
Two species can’t exist on the same limiting resource
Character displacement
Is the result of selection to decrease niche overlap
Which survivorship curve best fits a population with a large number of offspring per parent living close to carrying capacity?
Type 3
In Lotka- Volterra state-space plots an isocline
Determines where population growth is 0
A niche describes
The environmental requirements of a species
