Sexual reproduction:

 new individual is formed through the union of two sex cell: gametes

Haploid gametes formed by meiosis in sex organs (gonads)

Asexual reproduction:

genetically identical cells are produced by mitosis

asexual and sexual reproduction:

summer: asexual reproduction

fall: sexual reproduction produces overwintering eggs containing winged dispersing aphids.

sexually and asexually

poor conditions trigger sexual reproduction

sexual offspring overwinter

each female produces 2 offspring

sexual population maintains constant size

asexual population grows exponentially.

hermaphrodite

mate as both males and females

Protogynous(female first, then male) blue head wrasse

Protandrous( male first, then female) anemonefish, clownfish

in testes

occurs throughout life

in ovaries

stops early in life

Males make many small gametes

Females make few large gametes

Females also bear resource cost of producing offspring

Female reproduction is resource limited:

females should be choosy (few, high quality offspring)

Male reproduction is mate limited:

sire as many offspring as possible.

sexual dimorphism

female

females larger than males

larger female can better provision offspring, or larger female produce more eggs.

in extreme cases, male is little more than a parasite

sexual dimorphism

male

males produce elaborate displays

females chose between males

elaborate display may act as an honest signal of male quality

Sexual selection: Female choice.

sexual dimorphism

male (continued)

Males produce weapons, armor

males contests for access to females

Sexual selection: Male - male aggression

females often mate with more than one male

traits in males to increase sperm success:

More sperm, larger sperm

larger testes

accessory proteins to inhibit other sperm

modified genitals

Sperm competition often exhibits last male advantage

sperm competition

sperm swimming speeds

extreme sperm competition

drosophila bifurca

largest sperm per body size

males - 1.5 mm, each sperm cell = 6 cm

blocks sperm from subsequent males

females have extremely long reproductive tract:

cryptic female choice

Alternative mating strategies:

other forms of male-male competition for matings

bluegill sunfish have 3 male mating morphs:

parental

sneaker

satellite (female mimic)

Males are not always mate limited:

sexual cannibalism in redback spiders

females eat their mates

males 'sacrifice' themselves during mating

cannibalized males transfer more sperm

External: gametes released into environment

need many more gametes than internal fertilization

not feasible in terrestrial environments

Oviparity

eggs are fertilized internally

deposited outside mother's body

ovoviviparity

viviparity

Reproduction in mammals

Monotremes are ____________?

 oviparous:

duck-billed platypus and echidna lay eggs

milk secreted from mammary glands lacking nipples

Reproduction in Mammals

Marsupials

give birth to incompletely developed fetuses.

remainder of development takes place in pouch

Reproduction in mammals

placental mammals

Hormonal control of reproduction

Hypothalamus

Hormonal control of reproduction

Pituitary gland

LH-(Luteinizing hormone)

FSH(Follicle-stimulating hormone)

Hormonal control of reproduction

Gonads

Testosterone or estradiol

target tissues

breast in females

larynx in males, etc

Induced production of LH:

Induced ovulators: rabbits and cats

copulation results in reflex stimulation of LH(luteinizing hormone) production

high fecundity

how an organism responds to stimuli in its environment

proximate causation:

How it works

nervous control

physiology

ultimate causation:

why did it evolve?

benefits in terms of survival and/or reproductive success

Nature vs. Nurture

Behaviors may be innate, and inherited via genes

other behaviors are learned in a social context

Ethology: the descriptive study of innate behaviors

Innnate behaviors

fixed action patterns(fap)

highly stereotyped behaviors (always the same)

once started, usually must progress to completion

species specific

Triggered by:

sign stimulus

"releaser"

egg retrieval in greyiag geese

sign stimulus:

egg out of nest

Released behavior:

roll egg with beak

behavior continues even if egg is removed

during breeding, males have red bellies

aggressive response to other red bellied males

sign stmulus:

red coloration more important than size, shape

chicks learn to identify mother shortly after hatching

learning only occurs during brief "sensitive period"

imprint is permanent

complex learning: birdsong

learning correct song also has a "sensitive period"

complex learning: birdsong

some bird's song is innate: simple song

other birds have complex songs:

learning early in life

Practice needed by some species

some species sing many songs

reperoire size may be sexually selected

learning based on associations between different stimuli, or between stimulus and response

classical (Paviovian) conditioning:

two different stimuli become associated together

Pavlov's dogs

operant conditioning:

behavioral response associated with reward or punishment

associative learning

Classical (Pviovian) conditioning: association between stimuli

Pavlov's dogs:

present food: dog salivates

ring bell: no response

after repeated presentation of food and bell together:

dog salivates for bell only

Associative learning

Operant conditioning:

behavioral response is associated with reward or punishment

Reward: behavior repeated

punishment: behavior avoided

Mimicry works because of associative learning

predators learn that certain species of butterflies are toxic or unpalatable

Mullerian mimicry:

unrelated toxic species adopted same color pattern

Predators learn more quickly

avoid all species with this coloration

Palatable species mimics coloration of toxic species

fools predators into avoiding a palatable food source

animal cognition: observational learning

central question in animal behavior is whether animals show cognitive (thinking) behavior

Observational learning:

Learning by observing others perform a behavior

blue tits & milk bottles

chimpanzee termite hunting

animal cognition: problem solving

cognitive behavior: multi - step problem solving

some problem-solving examples are compelling:

chimpanzees

ravens, cows

many animals migrate, using several methods of navigation

Piloting: using familiar landmarks

compass naviagation: following a specific bearing

many birds do both

also learn roules from experienced migrators

Migration & navigation

monarch butterflies:

complex multi-generation migrations

end up in precise locations, even though migrants have never made the journey before

scrub jays cache food

maintain constant mental map of their food caches

will steal from other caches

known to move food if they were watched by other scrub jays while storing food

animals juse many modes of communication:

visual, sound, smell, pheromones & many others

behaviors may depend on multiple modes

honeybee "waggle" dance

indicates direction and distance of food source

a true symbolic language

ground squirrels & prairie dogs live in social groups

one member will give alarm call to warn others of predators

altrustic behavior

can not evolve" for the good of the species"

cheater strategy wins over altrustic strategy

altrustic acts must benefit the actor, directly or indirectly

alarm calling benefits close genetic relatives:

increases reproductive success of relatives

compensates for the reductions of own fitness

benefit of altruism depends of level of relatedness

altruism- cooperative breeding

Nest helpers:

young are relatives(kin selection)

gain parenting experience

may inherit the territory

mutual exchanges of altrustic acts occur

reciprocal grooming in primates

feeding in vampire bats

behavior is given more if it has been received in the past

organismal ecology

population ecology

community ecology

ecosystem ecology

species interactions

food webs

organismal ecology

how do individuals interact with each other and their physical environment?

population ecology

how and why does population size change over time?

community ecology

how do species interact, and what are the consequences?

ecosystem Ecology

how do energy and nutrients cycle through the environment?

nutrients move upstream

bears move salmon inland

trees near salmon streams grow larger

distribution of different ecosystems results from:

amount & distribution of solar radiation and precipitation

seasonal variations

global atmospheric and oceanic circulation

seasonal variation in sunlight

march 20

seasonal variation in sunlight

june 21

seasonal variation in sunlight

september 22

seasonal variation in sunlight

december 21

there are _____ cells of circulation in each hemisphere

major atmospheric circulation patterns

most of the world's deserts:

west moisture-laden air blows onshore from pacific ocean

air rises over mountains and cools; rain falls

east of mountain dry air creates desert conditions

this area is in the rain shadow.

influenced by atmospheric circulation and land masses

important influence on both terrestrial and squatic habitats

temperature decreases as you move:

away from the equator

towards higher elevation

6 degrees celsius per 1000m up or 500 miles toward pole

major biomes

tropical wet forest

contain over half of all plants and animals

very productive

average temp 25 degrees celceus

very high rainfall

major biomes

subtropical deserts

low productivity

plants and animals adaptedto water scarcity

average temp 40 degrees celcius

very low rainfall

major biomes

temperate grasslands (prairies)

dryness, fires prevent invasion by woody plants

herds of grazing mammals

average temp 22 degrees celcius

rainfall low

major biomes

temperate forest

seasonal growth

moderate productivity and diversity

average temp 22 degrees celcius

moderate rainfall

major biomes

boreal forest

long freezing winter

forests dominated by a few species of cold-tolerant conifers

average temp 15 degrees celcius

major biomes

arctic tundra

long freezing winter, very short growing season

treeless

permafrost(permanently frozen ground) near surface

average temperature 5 degrees celcius

average rainfall very low

intertidal zone:

between high and low tide lines

neritic zone:

<200m deep

coral reefs

both are diverse, productive

less productive tan intertidal & neritic zones

plankton near surface account for 40% of all photosynthesis on earth

few species in the deep aphotic zone

freshwater ecosystems

inland takes:1.85 of earth's surface

running water: 0.3% of surface

marshes, swamps: highly productive

provide key ecosystem services: filtering water

bogs: stagnant, acidic: low productivity, slow decay

where rivers join ocean

brackish (partly saline)

constant flow of nutrients from up-river

high diversity of species

among the most productive habitats

history

colonization

dispersal

what else controls where species occur?

biotic interactions:

competition

parasitism

symbiosis

organismal ecology & animal behavior

population ecology

community ecology

ecosystem ecology

population ecology

population processes: birth, death, growth rates

all of the individuals of the same species, in one place at one time

species have a limited geographic range only occupy certain areas withing range

may be difficult to define boundaries of a "population"

depends on spatial location of individual across landscape

dispersion:

how individuals are distributed across the landscape

individuals can be dispersed:

randomly

clumped

uniformly

reflects interactions of individuals

with each other and the environment

the most common dispersion pattern:

individuals cluster around unevenly distributed resources

limited dispersal

individuals live in family/social group

shooling, herding: protection in numbers

strong intra-specific interactions

Territoriality:

animals defend patch of resources

competition:

competition for scarce resource (e.g water in desert plant)

allelopathy:

some plants secrete chemicals that inhibit the growth of others

Individuals are unpredictably dispersed

uniform availability of resources

little competition within/among species

relatively rare

tropical trees

shift over time

Populations grow and shrink over time

demography- statistical study of population size and change

4 basic demographic parameters:

birth rate

death rate

immigration from other populations

emigrations to other populations

Population size is stable when:

birth + immigration = deaths + emigration

Population growth rate (r)

with no limits to growth, population grows exponentially

rate of increase (r) = birth rate - death rate

(assuming no migration)

Carrying capacity (K) is the maximum number of individuals the resources in a given area can support

density dependence:

growth rate is a function of population size.

r-selected species:

rapid population growth

produce many, small offspring, low investment in parental care

K-selected species:

stable population size at carrying capacity

produce few, large offspring, large investment in parental care

populations are age structured

can follow a single age class from birth to death

cohort: all individuals of the same age

survivorship: proportion of individuals surviving

fecundity: offspring per individual in each time period

survival and fecundity during discrete time periods are tabulated in a life table

key parameters for population size: Survivorship and fecundity

can't have both high fecundity and high survival

natural selection favors strategy that maximizes lifetime fitness

Humans, elephants

high early survivorship

few offspring

parental care

hydra, adult songbirds

constant mortality rate

steady survivorship

fish, many plants

many offspring

high early mortality

high survival of adults

life history trade-offs: fecundity

investment per offspring:

trade-off between the number of offspring produced and resources available per offspring

offspring size often related to survival

life history trade-offs: fecundity

How many times to reproduce during lifetime?

One time vs multiple times:

finite amount of resources must be split between:

growth

survival

fecundity

semelparity - many offspring produced in a single event

iteroparity - fewer offspring at a time, spread over multiple reproductive seasons

many offspring produced in a single event

salmon

some arthropods

annual plants

benefits of producing more offspring now outweighs the cost of survival & growth for another year

r-selected species are often semelparous

Iteroparity

Iteroparity: fewer offspring at a time, spread over multiple reproductive seasons

avoids "putting all the eggs in one basket"

useful when conditions for offspring survival vary year to year

K-selected species are often iteroparous

demography:

birth rate & death rate

survival & fecundity

life history trade-offs

population dynamics are also influenced by:

density-dependent factors ( resources)

density independent factors (environment)

species interactions

population growth in a limited density

near carrying capacity, resourse limitation decreases survival & fecundity

growth rate is limited by something other than population density

external environmental conditons

species interactions and population size

predator-prey dynamics can influence population size

population cycles

predator cycle lags behind prey cycle

both, food and predators control hare population

population size of a patch influenced by:

birth rate

death rate

migration into patch

emmigration from patch

an important tool for conservation

model population growth based on field data

viable: 95% probability of surviving 100 years

historically, human population limited by food, disease, predators

improved health care

greatly reduced infant mortality

stable: rectangular

rapid growth: triangular

declining: inverted triangle

organismal ecology & animal behavior

how members of a species interact with each other and with their environment

population ecology

population size: birth, death, growth rates

community ecology

species interactions

species composition of communities

ecosystem ecology:

broad scale patterns of climate, nutrient cycles

community: all of the species in an area

individualisstic concept:

species with similar tolerances occur together

species come and go

community is in flux

hard to predict which species will be present

Holistic concept:

interactions among species are important

species are interdependent

groups of species always occur together

community structure is predictable & stable

species pool:

interactions among community members drive ecological and evolutionary processes

interactions can influence community structure

interactions can be beneficial(+), costly(-) or neutral (0)

competition (-/-)

predation, Parasitism (-/+)

mutualism (+/+)

commensalism (+/0)

no two species utilizing the same niche can coexist indefinitely:

one species wil outcompete & eliminate the other

the species will diverge into different niches

predation can have a large impact on species diversity and abundance

which species are present

population sizes of predators and prey

longer term patterns:

Selection for prey defenses

selection for predator to avoid defenses

in complex food webs:

many predator-prey interactions

complex patterns of species abundance and diversity

have a disproportionate effect on community structure

top predators are often keystone species

mutualism

commensalism

parasitism

abundace of one species is likely influenced by abundance of the other species

species richness: the number of species in a community

species evenness:The relative abundance of species

species diversity: includes both richness and evenness

diverse plots had higher productivity:

greater ground converage

Diverse plots are more stable:

lower decline in biomass after drought

why are there so many species in the tropics?

high productivity

lower extinction rate

more time for speciation in unglaciated areas.

Organismal ecology & animal behavior

how members of a species interact with each other and with their environment

Population ecology

population size: birth, death, growth, rates

Community ecology

species interactions

species composition of communities

ecosystem ecology

broad scale patterns of climate, nutrient cycles

ecosystems

an ecosystem includes all the organisms in a place, and the abiotic environment in which they interact

two main processes:

energy flow through ecosystems

biogeochemical cycles

water

carbon

nitrogen & phosphorus

total light energy converted to chemical energy by producers:

gross primary productivity(gPP)

chemical energy used for growth on few  biomass:

Net Primary Productivity (Npp)

Npp is the energy available to consumers

new biomass created by consumers

secondary productivity

usually only a small fraction of the NPP

metabolism consumes most energy from food (especially in endotherms)

energy transfer between trophic levels is only ~10% efficient

limits most food webs to 3-5 trophic levels.

total biomass decreases as you move up the food chain

fewer individuals at each successive trophic level

interactions among trophic levels

trophic cascade: events at one trophic level influence other trophic levels

top-down effects:

removal of piscivorous fish:

increase in zooplanctivorous fish

decrease in zooplankton

increase phytoplankton

bottom-up effects:

increased primary productivity(e.g. by nutrient addition):

increased numbers of primary, secondary, tertiary consumers

ecosystems also influenced by cycling of nutrients in abiotic environment

water

carbon

nitrogen

human have significantly altered each of these cycles

large impacts on biodiversity

for many aquifers, groundwater withdrawal rates exceed replenishment rates

drop in the water table

forest:90% of water taken up by plants, transpired back to atmosphere

land cleared for agriculture, housing etc.

much higher runoff

nutrients lost in runoff

increasing global temperature

rising sea levels

increase in violent storms?

Habitat destruction:

melting of permafrost

spread of deserts

Changes in timing of:

flowering

migrations

Terrestrial habitats:

increased primary productivity, but fewer species

Aquatic habitats:

increased growth of phytoplankton:

Algal blooms

as algal bloom decomposes, oxygen level crashes

anaerobic "dead zones"

most species that have ever lived are now extinct

5 mass extinctions in earth's history

current rate of extinction may be greatest yet

extinctions since 1600:

2.1% of known mammal species

1.3% of known birds

many extinctions have occurred on islands

the biodiversity crisis- future extinctions

estimates:

20% of world's biodiversity will be lost within 30 years

50% of world's biodiversity may be lost within 100 years

value of biodiversity

direct economic value:

sources of:
food

medicine

clothing, etc

value of biodiversity

indirect benefits

ecosystem services:

water purification

flood buffering

pollination

mineral cycling

value of biodiversity

Ethical & aesthetic value:

habitat destruction

habitat degradation

overexploitation

introduced species

loss of genetic variablility

disruption of ecological interactions

destruction of habitat

also has major impacts on water flow, erosion, ecosystem functions

quality of habitat decreased

pollution, removal of ground cover etc.

can support fewer native species

size of habitat decreased

connectedness of habitat decreased

increased amount of edge habitat

Decreased core habitat

competition:

native to europe

purple loosestrife displaces native wetland species in north america

native to australia, papua new guinea

brown tree snakes have eliminated many birds species in guam, hawaii

preserve genetic "uniiqueness"

conservation efforts focused on phylogenetically distinct species

preserve ecologically important species

conservation efforts focused on keystone species:

have a large impact on their ecological community

top predators

pollinators, seed dispersers

conservation strategies: Endemism

Endemism & hotspots of diversity:

endemic: a species found naturally in only one geographic area

 isolated areas such as islands, often have many endemic species.

protecting just 1.4% of the world's land surface, can preserve:

44% of the world's vascular plants

35% of its terrestrial vertebrates

protecting habitat or ecosystems likely more effective than single species approaches

however, these areas:

contain 20% of the world's population

are areas of intense commercial exploitation