Biology Renne Exam 3

behavior

the observable response of organisms to internal or external stimuli; has adaptive value

behavioral ecology

study of behavioral responses that contribute to the survivorship and/or reproduction of organisms

proximate and ultimate causes

proximate causes - a stimulus (e.g., change in day length)

ultimate causes - effect on reproduction or survivorship

innate

behaviors that are driven by genetic programming (not learned)

humans have innate reactions/behaviors

behavior results from simple genetic influences

a single gene can have dramatic impacts on behavior

very few genes need to be involved

learning

modify behavior based on previous behavior; this has adaptive value, (all behaviors do), as does habituation

habituation

one of the simplest forms of learning

* organism ignores/responds less to repeated stimulus
* animals habituate to humans where there is no hunting
* can be modified in the future!!!!!!!!!!!!!!!!!!!!

associative learning

association develops between stimulus and response

2 main types of associative learning

classical conditioning - involuntary response becomes associated positively or negatively with a stimulus that did not originally elicit the response

operant conditioning - animals behavior reinforced by a consequence (reward or punishment)

cognitive learning!!!!!!

ability to solve problems with conscious thought and without direct environmental feedback; “assessment”

* chimpanzees stack boxes to reach banana
* ravens retrieve meat by pulling up a string

critical period

time when many animals develop species-specific patterns of behavior - in some species, once the CP is passed, they will never learn. even humans have critical periods

behavior is often a mix of innate and learned

birds are genetically programmed to learn but many will sing the correct song only if the correct songs are heard

migration

long-range seasonal movement generally linked to seasonal availability of food

* bird, mammal, and insect examples
* 3 navigation mechanisms (butterflies migrate south in the summer)!!!!!!!!!!!!!!

piloting

animal moves from one familiar landmark to the next

* features of the coastline, for example

orientation

ability to follow compass bearing and travel in straight line - cannot adjust for course

navigation

follow compass bearings but also set or adjust path

* adult starlings can adjust flight path when transported and released (juveniles cannot)

navigation - the toolkit!!!!!!!!!

birds may use three compass systems in their navigational toolkit:

* position of sun by day, stars at night (celestial objects)!!!!
* landmarks!!!!
* earths magnetic field!!!!!!

homing pigeon navigation

can navigate well on overcast days, even with frosted eye lenses, but only if they are not equipped with a magnet. !!!!!!these birds thus use the sun and geomagnetism as a compass!!!!!!!!

Eurasian Blackcaps migration

there is assortative mating, in part because they arrive at breeding ground earlier - migration differences and the lack of gene flow may result in an allopatric speciation event.

foraging

optimality theory predicts an animal should behave in a way that maximizes benefits of a behavior while minimizing costs

optimal foraging proposes that an animal seeks to obtain the most energy possible with the least expenditure of energy

defending a territory has costs and benefits

territory - fixed area in which individual or group generally excludes others

territory is expected when benefits exceed costs!!!!!!!!!!!!!!

* benefit is exclusive access to resource - food, mates, nesting sites
* costly to defend

sunbird species

saved 780 calories a day in reduced foraging activity

spent 728 calories in defending the territory

net gain of 52 calories/day…here, it is profitable to defend!

communication

use of specifically designed signals or displays to modify the behavior of others

these include: !!!!!!!!!!!!!!!!!!!!!

* chemical
* auditory
* visual
* tactile

chemical communication

* common among canines and felines
* scent trails laid by social insects
* pheromones produced by female moths to attract males
* queen bee releases pheromones to suppress reproductive system workers

auditory communication

* sounds travel farther in air
* air at dawn and dusk less turbulent
* many males use auditory communication to attract females
* sound production can also lure predators

visual communication

* competition among males, or female choice for most impressive displays leads to elaborate coloration and extensive ornamentation (part of sexual selection)
* male fireflies flash species-specific number and duration of flashes
* predator uses flashes to lure males in to eat them

tactile communication

* used to establish bonds between group members
* round dance or waggle dance of honeybee scout conveys food location

living in groups

* group living can reduce predation through increased vigilance and protection in numbers
* group living has consequences as well. aggression tends to increase and competition (e.g., for food) is high

many-eye hypothesis

by living in groups, individuals may decrease the amount of time scanning for predators and increase time feeding

altruism

an act that benefits a non-relative at the expense of oneself

behavior that benefits others at a cost to the actor

most “altruistic” acts serve to benefit the individuals close relatives

individuals selection is much more likely because

* mutant individuals that use more resources have an advantage over those that use fewer resources
* individuals with a genetic-based selfishness can immigrate and spread to other areas
* also, selfish non-sharers should displace altruistic sharers
* individual selfish behavior is much more likely!!!!!!!!!

group selection

a group containing altruists would have a survival advantage over a group composed of selfish individuals

kin selection

behavior/act that lowers an individuals own fitness but enhances the reproductive success and/or survivorship of relatives!!!!!!!!!!!!!!!!!!!

coefficient of relatedness - probably that any 2 individuals will share a copy of a particular gene is a quantity r

an organism can not only pass on its genes by having offspring, but also by ensuring that relatives survive

Hamiltons rule

* a kin-selected gene is favored by natural selection when rB>C
* r is the coefficient of relatedness of donor “altruist” to recipient
* B is benefit to recipient
* C is cost incurred by donor
* evolution of bright coloration to advertise distastefulness!!!!!!!!!!!!!!!!!!!

sexual conflicts among men and women

* sexual conflict abounds throughout all biota
* the mean number of offspring os obviously the same for each sex (it has to be) but depending on the mating system, the variance in offspring # can be much higher in males…some men produce many offspring, many produce none! The higher the variance in offspring production, the greater the degree of sexual dimorphism

sexual selection

* the combination of women investing more than men ( and their resulting choosiness) and the potentially high payoff for men leads to male traits that are solely concerned with increasing mating success.
* this is sexual selection and may be driven by intrasexual competition (e.g., male-male competition) and/or intersexual choice (e.g., women’s choice for particular traits)

intersexual choice

member of one sex chooses mate based on particular characteristics

female mate choice

* female hangingflies demand a nuptial gift - allows female to produce more eggs and allows male to copulate longer
* choices based on plumage color or courtship displays - widowbird with experimentally lengthened tails attracted more females and fathered more clutches

intrasexual competition

* members of one sex compete over partners w/the winner performing most of the matings
* male-male competition produces males substantially larger than females (strong sexual dimorphism)

mating systems - types

natural selection favors production of the rarer sex so that the sex ratio is kept balanced at \~ 1:1

monogamy

1:1 necessary conditions include: neither sex has an opportunity to monopolize resources, including more members of the opposite sex, and shared parental care also maximizes the reproductive success of males and females

polygyny

one male: more than one female

males may defend women’s resources that attract women. success raising young not greatly reduced by one parent only

polyandry

more than one male: one female

relatively rare avian system (

polygamy

more than one man: more than one woman

uncommon

mating system structure is primarily driven by

* ability to defend resources (food, breeding space, mates)
* opportunity to defect after mating (if one parent can successfully raise offspring, abandonment is common)
* opportunity to get/prevent extra pair copulations

all of these are driven by ecological conditions!!!!!!!

population

a group of interbreeding individuals that occupy the same habitat at the same time!!!!!!!!!!!!!!!!!!!!!!

* water lies in a particular lake
* humans in New York City

population ecology

study of the ecological factors affecting population size and how these factors change over space and time

uses the tools of demography

birth rates, death rates, age distributions, and size and growth of populations

* these tools have very high management value

clumped dispersion patterns

* most common; resources tend to be clustered in nature
* social behavior may promote this pattern

uniform dispersion patterns

* competition may cause this pattern
* may also result from social interactions

random dispersion patterns

* rarest; resources are rarely randomly spaced
* may occur where resources are common and abundant

semelparity

produce all offspring in a single reproductive event, individuals reproduce once and die (annuals, salmon, some insects)

Iteroparity

reproduce in multiple years or breeding seasons (nearly all trees, birds, mammals)

seasonal iteroparity

distinct breeding seasons

continuous iteroparity

reproduce repeatedly at any time of the year

age classes

its stricture can be resolved through demographic analysis

* expect a population increasing in size to have many young and a decreasing population to have proportionately more older individuals
* of course this assumes survivorship and reproduction are the same across populations

life tables

data on the number of individuals alive in a particular age class, and their survivorship and reproduction

demographic analysis (e.g. life history tables)

age-specific fertility rate, mx

* proportion of female offspring born to females of reproductive age
* 100 females produce 75 female offspring mx=0.75

age-specific survivorship rate, lx

* use survivorship data to find proportion of individuals alive at the start of any given age class

lxmx

contribution of each age class to overall population growth; estimates population growth

why is demographic analysis important?

not only can we estimate age structure and population growth, we can focus our management efforts on the most important age classes driving the population growth of invasive or endangered species

3 patterns of survivorship curves

* type 1 - rate of juvenile loss low and most individuals lost later in life; few, high quality young (e.g., humans, elephants, albatross)
* type 2 - fairly uniform death rate (beaver example)
* type 3 - rate of loss for juveniles high and then loss low for survivors (e.g.. many plants, invertebrates)

logistic growth

resources limiting, limits to growth

intuitively and via every observation, we know that no population can increase indefinitely.

every single species can go thru exponential growth

logistic growth equation

dN/dt = r(max)N (K-N)/K

**the (K-N)/K term is the** **density dependent term** which puts the breaks on population growth. as N approaches K, resource availability declines per individual and population growth slows

NK = -, N=K = no growth

what are populations regulated by? !!!!!!final exam!!!!!

density-dependent factors

density-independent factors

density-dependent factors !!!!final exam!!!!

* mortality factor whose influence varies with the density of the population
* parasitism, predation, and competition for limiting resources
* predators kill few prey when the prey population is low and kill more prey when the population is higher

density-independent factor !!!!final exam!!!!

* mortality factor whose influence is generally bot affected by changes in population size or density
* primarily physical factors (weather, drought, flood, fire)

life history

organismal adaptations that affect its Darwinian fitness (W), including juvenile and adult survival probability, age of reproductive maturity, and the number and size of offspring

* tremendous diversity in evolved strategies by which organisms persist
* how, when, and where to allocate limited resources in darwinian fitness is called life history strategy, or life history tradeoffs

life history evolution - r and K selection theory

the value of fitness-related traits that promote individual success vary according to ecological conditions

r selected traits

* maximize reproductive output, small body size, and short generation time
* these traits tend to spread when ecological conditions conducive to rapid growth are ephemeral
* r-selected individuals are poor competitors

k-selected traits

* maximize competitive ability and are opposite of r-selected traits
* tend to occur when resources are stably limited.

traits and strategies

population attribute: r selection: K selection:

* r(max) high low
* competitive ability not strongly fav. high fav
* development rapid. slow
* reproduction early late
* body size small large
* reproduction single, semelpar. repeat. iteropar.
* offspring many, small. few large

as populations grow… (graph)

they naturally evolve

r selection is favored

as it increases, k becomes more favorable

age structure

* relative numbers of individuals in each defined age group
* commonly displayed as population pyramid; helps predict future population growth

population inertia

when survival rates exceed death rates

(if China and India had every family only birth one child, their pop. would still grow)

intraspecific competition

between individuals of the same species; this form of competition is usually the strongest!!!!!!! because conspecifics generally share a more similar niche than heterospecifics

interspecific competition

between individuals of different species

ecological niche

all of the ecological factors that affect the survivorship and reproduction of a species

the realized niche is most often smaller than the fundamental niche (n)

competition affects species distributions

Connell demonstrated that the distribution of Chthamalus is heavily affected by Balanus but not vice versa. The upper range of Balanus is constrained by physical limitations

T. confusom vs T castaneum

T. confusom usually won, but note that T. castaneum does better under some conditions (not complete niche overlap; specialization is common)

Gause’s competitive exclusion principle

no two species can occupy the exact same niche and coexist

resource partitioning

differentiation of niches, both in space and time, that enables similar species to coexist in a community through reduced interspecific competition (note: interspecific competition is the main driver of character displacement)

character displacement

adaptive divergence in morphology and resource used when ecologically similar species co-occur (Darwins finches) driven by interspecific competition

this mechanism reduces competition and promotes species coexistence

antipredator strategies: chemical defense

* bombardier beetle ejects hot spray
* aposematic coloration, or warning coloration, which advertises an organisms unpalatable taste
* many tropical frogs have bright coloration to advertise their skin’s lethality

antipredator strategies: cryptic coloration

* camouflage
* stick insects mimic branches
* sea horses adopt body coloration to mimic habitat

antipredator strategies: mimicry

* resemblance of mimic to another organism (model)
* Mullerian mimicry
* batesian mimicry

antipredator strategies: displays of intimidation

* porcupine fish inflates itself
* deceive predator about ease of eating prey

antipredator strategies: fighting/mobbing

* horns/antlers used in defense; mobbing predators

Mullerian mimicry

two distasteful unrelated species converge on a particular morph, thereby increasing predator reinforcement and benefiting both. morph tends to remain stable.

* brassolinae goes to viceroy butterfly
* danainae goes to monarch butterfly

Mimicry - Batesian

palatable prey can also avoid predators by looking like a distasteful species

antipredator strategies: agility

grasshoppers powerful jumping ability

antipredator strategies: armor

* shells of turtles provide strong defense
* beetle exoskeleton

antipredator strategies: masting

* synchronous production of many progeny to satiate predators: the result is that a relatively high number of young survive
* seed predation reduced with many acorns: increases acorn population also
* periodical cicadas

plant/herbivore coevolutionary arms race

* generalist herbivores can feed on many plant species
* specialist herbivores restricted to few host plants

mutualisms

interactions between two or more species, where each species benefits, are extremely diverse.

they typically involve:

* transportation of gametes
* nutrient rewards and/or
* protection (usually only two are involved at once)

time hypothesis

* communities diversify or gain species through time via migration and in situ speciation
* temperate regions have less rich communities than tropical ones because they are younger and have only more recently recovered from glaciation
* support - many more taxa found in comparable unglaciated relative to glaciated areas
* drawback - limited applicability to marine organisms

productivity hypothesis

* greater production of plants results in greater overall species richness
* support - plants grow better where it is warm and wet and species richness in trees can be predicted by the evaporation rate
* problems - some tropical seas have low productivity but high richness, sub-antarctic ocean has high productivity but low species richness

area hypothesis

larger areas have more species because they can support larger populations and a greater range of habitats; does not explain latitudinal diversity gradients well

problem

there are not more species in Asia; taiga is largest biome but very low richness; open ocean with largest volume has fewer species than tropical surface waters; tropical rainforests \~7% of Earth but harbor \~50% of all spp.

intermediate-disturbance hypothesis!!!!!!

* highest number of species are maintained in communities with intermediate levels of disturbance
* disturbance: droughts, fires, floods, hurricanes, herbivory, predation, parasitism
* support - coral reefs are richest where hurricanes hit, tropical forests are richest where storms caused landslides and tree falls
* a few stress tolerators dominate in high disturbance areas
* a few strong competitors dominate in low disturbance areas

succession

gradual and continuous change in species composition and community structure over time