Exam 1 Flashcards
Ecology
Study of the natural environment and relations of organisms to each other and their surroundings
5 propositions of Evolution
Variation: physiological or morphological
Heritable: some variations genetically based
Species have potential for unlimited population growth
Different individuals leave different numbers of
descendants
Number of descendants influenced by interaction of
offspring and environment
Adaptation
Phenotypic changes enhancing fitness
Phenotypic plasticity
organisms change the expression of traits in response to environment
Exaptation
change in the function of a trait during evolution for a purpose other than what the trait was evolved for
Non-Adaptation
physiology differences occurs later in development
Stabilizing selection
Favors average phenotype
Directional selection
Favors extreme phenotype shifting average in one direction
Disruptive selection
Favors two or more extreme phenotypes over the average
Group selection
when natural selection occurs on whole group of organisms not related to them
self sacrifice for those not related to them
Kin selection
animals engage in self-sacrificial behavior benefiting genetic fitness and increasing reproduction survival of relatives that share the same genes
Kin selection examples
Social insects, deer, lions
Lions form coalitions to secure pride even if they are not able to reproduce
Sexual selection
female chooses male based on physical features such as behavior, coloration, song
it results in differences in reproductive rates among individuals as a result of differences in their mating success
Eusociality
complex level of social behavior consisting of multiple generations living together, cooperative care of young, and the separation of sterile (nonreproductive) and reproductive castes
Inclusive fitness
An individual’s overall fitness is determined by its own survival and reproduction plus the survival and reproduction of individuals with who they share genes
favored by kin selection
Eusociality example
Naked mole rats live in a colony with one queen keeping all other females sterile
They’re all related and have distinct roles
Haplodiploidy in eusociality
All males are haploid and all females are diploid making colony very similar genetically
Clines
change in phenotype or genotype across geographical gradient
Cline population of animals and plants
animals: races
plants: ecotypes
2 ecogeographical patterns among clines
Bergmann’s rule: geographic races of animals have increased body size towards the poles
Allen’s rule: extremities of birds and mammals decrease in length towards poles
Morphological species concept
Based on difference in color, structure, proportions
Linnaeus
problems with morphological species concept
polymorphic species (change color)
sexual dimorphism
sibling species (2 species looking identical but cant reproduce)
Biological species concept
group of actually or potentially interbreeding population that produce fertile offspring
problem with biological species concept
asexual species
Phylogenetic species
evolutionary relatedness based on morphology and genetics (species that share a pattern of ancestry
allopatric speciation
when populations are geographically isolated, species can arise
- rivers, mountains, movement of species
founder effect
subset of a population founds a new colony and original diversity of genotypes can be lost
bottleneck effect
random event kills disproportionate number of genotypes and they can be lost
Sympatric speciation
production of a new species within the population within the dispersal range of the population
Exploiting underused or novel resource
introgression of allopatric speciation
If geographic barrier is gone after it has been up long enough, the species won’t be able to reproduce when mixed again
Polyploidy
abrupt or instantaneous speciation
Doubling of chromosomes prevents offspring from being able to reproduce with parent population (diploid organism)
Adaptive radiation (divergence)
evolutionary diversification of species derived from a common ancestor
Occurs after organisms colonize island group or a new environment
enough genetic variation to establish itself under selective pressures of climate in new environment
parallel evolution
adaptive changes in organisms with common evolutionary heritage in response to similar environmental conditions but different locations
convergent evolution
unreleated species develop similar haracteristics from living in similar environmental conditions
How Hawthorn and apple flies demonstrate sympatric speciation
Apple flies prefer apple scents while hawthorn flies prefer hawthorn fruit smells
2 species evolved in the same geographic region from common acnestor species.
Pre mating reproductive isolating mechanisms
Temporal: mate at different times
Ecological isolation: live in different habitats
Behavioral isolation: different courting behaviors
Mechanical isolation: can’t mate due to incompatible reproductive structures
Pre zygotic reproductive isolation
barriers to fertilization where it can’t occur
post zygotic reproductive isolation
fertilization can occur but no viable or fertile offspring
How does glyphosate work
Glyphosate binds to epsps gene preventing shikimic acid from binding and no amino acids are made
Build up on shikimic acid prevents photosynthesis from occurring
2 mechanisms plants can evolve resistance
translocate
modification in gene
population
group of individuals of the same species living in the same place at the same time
abundance v density
abundance: number of organisms in a given area
density: number of organisms per unit area
Desert shrubs spatial distribution
Shrubs spread out with minimal overlap to compete for water and nutrients belowground
Stingless bees spatial distribution
Aggressive bee nests evenly spaced due to competition
nonaggressive bee nests randomly spaced
Random distribution
individuals have equal chance of living anywhere within an area
Individuals ignore each other
Regular/uniform distribution
individuals are uniformly spaced
individuals repel each other
competition
Clumped/contagious distribution
individuals have a much higher probability of being found in some areas than others
individuals attract each other
Coefficient of dispersion
Variance/Mean
S^2/x̄
Coefficient of dispersion in distributional patterns
random =1
regular < 1
Clumped >1
Calculating population size
Nt+1= Nt + B - D + I - E
Number at some time in the future= Number currently + births- deaths + immigration- emigration
Cohort life table
identify large number of individuals born at about the same time an keep records on them from birth to death
Age structure diagram
population pyramid showing distribution of age and sex in population
Rapid growth: many young people, little older people; inward curve pyramid
slow growth: more even old and young people
stable growth: dome shaped
negative growth: more middle age less young people
Diagram life table
Transitions in lif cycle
Iteroparous organisms reproduce many times
semelparous reproduce once in life
Tabular life table
Net basic reproductive rate R0: average number of offspring per individual female per lifetime
>1 pop increase
=1 female replaces self
< 1 pop decline
Generation time: average length between birth of individual and birth of its offspring
Intrinsic rate of pop growth r: per capita rate of increase
close to 0= stable pop
Survivorship curves
Type I: little mortality early in life
Type II : Linear decline in survivors, constant rate regardless of age
Type III: high mortality early on in life followed by high rate of survival
Static Life table
record age at death of large number of individuals born at different times
snapshot of survival within population during short time interval
Geometric/discrete growth
Nt= N0 (R0)^t
Number at time t= number at initial time X avg offspring left by individual raised to t
Continous growth/exponential
dN/dt= rN
rate of pop growth= per capita rate of increase X pop size
r=ln(R0)/ Tc
Logistics growth curve
growth model incorporating environmental limitation
carrying capacity: max population that environment can support
Problems with logistic growth curve
Assume effect of density of rate of increase is instantaneous
Deterministic
carrying capacity constant
Logistic equation
dN/dt= rN (K-N/K)
= per capita growth rate X pop size X carrying capacity-pop size/ carrying capacity
Intraspecific competition
within species
effect decreases contribution of individuals to next generation
resource competed for must be in limited supply
density dependent competitoin- larger effect with more competitors
Density dependent v density independent competition
density independent: resources do not regulate population size
Density dependent: resources available affect pop size
Types of Intraspecific Competition
Resource competition (scramble, exploitative): organisms compete for resource without directly interacting with each other
- resource must be limited
interference competition (contest): Organisms compete for resources while directly interacting
Life history
pattern of survival and reproduction of organisms and traits influencing this pattern
Life history patterns and principle of allocation
C= (R+A) + (F+U) + (B+G)
Consumption= metabolic needs + waste + gain
Principle of Allocation: if an organism uses energy for one function, it reduces the amount of energy available for other functions
Cost of reproduction
Reproduction decreases chance of future reproduction and decreases growth
decreased growth decreases survival
Life history trends- body size
Within a species, larger organisms produce more young
organisms producing larger offspring produce fewer
R selected species
unpredictable ephemeral environment
- Early maturity
- Small size at maturity
- Many small young
- Large reproductive effort
- Shorter life span
- Semelparous
- Minimal parental care
K selected species
stable, predictable environment
- Delayed maturity
- Larger size at maturity
- Fewer but larger young
- Smaller reproductive effort
- Longer life span
- Iteroparous
- Substantial parental care
r v K selection trends
Body size v gen time
Instanteous rate of increase v weigh
Metabolism v weight
Body size v gen time : positive correlation
Instanteous rate of increase v weight: negative correlation
Metabolism v weight: negative correlation
Selective pressures on plants
Intensity of disturbance (physical environment)
intensity of stress (abiotic factors)
Plants’ strategies must match requirements of their environment
Interspecific competition
-/- interaction
can be between closely or not related species
Doesn’t always lead to exclusion
Characteristics can change in competitive environment over generations
competitive exclusion principle
complete competitors (using same limited resource in same way) cannot coexist
competitve release
removal of organism releases another from competition
character displacement
change in morphology in response to competitors
DeWit replacement series
Compare inter and intraspecific competition
Increase density increased effect intraspecifically and interspecifically between 2 species
fundamental niche
largest ecological niche an organism or species can occupy in absence of interspecific competition and predation
Lotka- Volterra model for interspecific competition
Logistic growth
competition coefficient a >1 affected more by interspecific
a< 1 affected more by intraspecific
2 ways to tell if there is competition
add superabundance of resources
remove one competitor
How 2 closely related species coexist at different location of same environment
Competition, competitve exclusion, resource partitioning
each species adapted to different locations because of competition in past
2 different species with no competition past or present
Isocline
line linking points each giving rise to the same rate of population increase
dn/dt=0
cap to what pop can grow to
zero isocline
line where there is neither increase or decrease in rate of population growth
rate=0
Drawing and reading zero isoclines
assuming 0 pop growth look at when N1=0 and N2=0
If Lines do not cross, line on top is winner
Unstable v stable equilibrium on zero isocline
Unstable equilibrium: if lines cross and arrows point away from intersection
stable equilibrium: if lines cross and arrows point towards intersection
Type of animals looked at in static life table
long lived
Barnacles competition
interspecific
Theoretical logistic model when r>0
N<K
Flour beetles niche
identical fundamental niche
