Exam 1

What are the 3 types of diversity?

1. Genetic — variation w/ in a spp

2. Species — types of organisms

3. Ecosystem — different types of habitats, biotic communities, or ecological processes

What are two methods for measuring biodiversity?

1. Species richness

2. Species abundance

Define species richness

Rich in number of species / Number of diff. species in habitat

Presence / absence

From image: C represents best richness

Define species abundance (evenness)

How evenly distributed a species is / Relative number of each type in a particular habitat

From image: A represents best evenness

Define Alpha diversity

local diversity, or species diversity at a site

• estimated by spp richness or by one of the alpha diversity indices

Define Beta diversity

spatial differentiation, or the variation in species composition among sites within a region of interest

Define Gamma biodiversity

regional diversity, or species diversity in a region of interest

• estimated by pooling observations from a large number of sites in the area and computing an alpha diversity index

Why is biodiversity calculated based on genus or phyla, instead of species?

It can depend on your research question. As a scientist, you decide what is meaningful

Does marine biodiversity generally increase or decrease after a mass extinction?

increases

• 90% of all marine spp may have gone extinct, now twice as many marine invertebrates since 200 mya

What are the 10 factors that correlate with biodiversity species richness? (BIG 10)

1. sample size and sampling effort

2. body size

3. depth

4. lat and long

5. habitat size

6. habitat complexity

7. disturbance

8. productivity

9. grazing and predation

10. genetics and dispersal

BIG 10: Sampling size and effort

• how many samples taken

• how much info is in each sample

• how large is each sample

BIG 10: Body size

• small size tends to be more abundant

• sampling and sorting size are selective

  • difficult to compare spp richness between samples collected using different methods

Within a habitat, is there a greater number of large or small individuals?

small

BIG 10: Depth

• species richness tends to decrease with depth (deeper = harder to survive) - lower temps, productivity, and habitat heterogeneity

• Rappaport’s rule — zones with higher species richness should also contain spp with smaller depth ranges, species diversity, and spread out into different depth niches

What is Rappaport’s Rule?

zones in the sea with higher spp richness should also contain spp with smaller depth ranges

BIG 10: Latitude and Longitude

• generally higher diversity and richness in low latitude tropics, higher richness on western side of oceans

longitude: is there greater spp richness on the western or eastern side of the ocean? why?

western

• more upwelling occurring creating more productivity

latitude: is there greater spp richness at the poles or the equator? and exceptions to this?

the equator

• sharks, tuna, and swordfish have hotspots near mid-latitudes which are good hunting grounds for them

• pycnogonids are diverse in antarctic waters

• brachiopods are not found north of equator in Pacific, and have typical latitudinal gradient in Atlantic

why are there more species in the tropics?

still debated in literature

• different reasons for different organisms

a few compelling hypotheses:

1. longer evolutionary history

2. higher productivity (can support more species)

3. shorter generation times and faster rates of evolution

BIG 10: Habitat size

• larger habitats support higher number of species and more niches for species to diversify into

• primarily through decreased extinction

depth or latitude ranges are not considered habitats

BIG 10: Habitat complexity

• large areas of homogenous habitat are unlikely to support large number of species

BIG 10: disturbance

• the greatest biodiversity in found in intermediate areas of disturbance

• intermediate disturbance hypothesis

BIG 10: Productivity

• high nutrient levels and higher productivity can cause higher OR lower species diversity (depends on habitat or species)

• coral reefs more diverse in lower nutrient concentrations

• bivalve mollusks more species rich in high nutrients

• eutrophication can be an issue with excessive nutrient concentrations

Define: Eutrophication

when a body of water receives an excessive nutrient load, resulting in an overgrowth of algae

• algae dies and decomposes, depleting oxygen from water and causing mass death

BIG 10: Grazing and predation

• higher trophic levels affect lower trophic levels

  • top-down forcing

  • trophic cascades

  • keystone predators

  • regime shifts / phase shifts

BIG 10: Genetics and dispersal

• how far apart populations are and how far species can spread genetic information (species moving, spores traveling, etc.)

• spatial genetic variability is linked to geographic distances between populations and the ability of species to disperse

You will have more species in a habitat when…

• the environment is productive and has favorable conditions to support life

• increase in colonization

• decrease in extinction

• a dominant competitor is suppressed

What is dispersal vs. migration?

Dispersal — movement of members of a spp or population from one place to another (one-time)

Migration — daily, seasonal, annual and multi-annual movement - OFTEN repeated

What are the three stages of dispersal?

1. departure (emigration)

2. vagrant (traveling)

3. settling (immigration)

Why disperse?

Chance of survival

• spread biological material

• seek out more resources

• avoid predators

• avoid competition and resource limitation

• increase genetic diversity (reduce inbreeding)

• escape stressful area or conditions

• reduce risk of disturbance (disease, parasites, etc.)

Departure: what are brooders?

Spp that:

• care for young

• generally few offspring at once

• internal fertilization (shelled eggs or live birth)

• quality over quantity

Departure: what are broadcast spawners?

Spp that:

• release hatched larvae, fertilized eggs, or sperm and unfertilized eggs (fertilization away from adults)

• larvae mature and travel in water before settling

• quantity over quality

Departure: Eggs (two locations)

• Demersal (near bottom):

  • laid close or attached to substrate

  • female lays eggs, male then fertilizes

  • larger and fewer eggs (energy)

  • limited dispersal

• Pelagic (open ocean)

  • broadcast spawning

  • large dispersal

Departure: Larvae (two types)

1. Planktotrophs — feed for themselves, longer development time

2. Lecithotrophs — limited or no feeding, relies on energy stores supplied by adult, development success depends on egg size

What are advantages of planktonic life stages?

• water or longer dispersal

• can stay in water column longer since they feed

• moving away helps avoid resource competition and reduces inbreeding

• lower energy investment for parents, more can be released

• higher genetic diversity with larger numbers

• short lifespan, faster evolution

• reduce benthic mortality by predation

What are disadvantages of planktonic life stages?

• vulnerable to predation in open water

• need to seek out food

• reliant on environment for survival

• risky to disperse away from home habitat

• different needs between larval and juvenile life stages

• larvae need a cue signal to signal metamorphosis and settlement

Departure: spawning and hatching

• timing is important

  • determined by env. cues (moon, tidal height, temp.)

  • spawning aggregations

  • sessile spp (release of gametes usually determined by temp._

What is the “mismatch hypothesis”?

implies that variability in timing of phytoplankton production leads to variability in larval mortality and hence possible fish year class strength

Dispersal stage: traveling

• Planktonic Larval Duration (PLD)

• higher temp, higher metabolism and development, shorter PLD

• PLD affects dispersal distances and genetic structures of populations

Traveling: Connectivity

release frequency affects population networks

Traveling: Currents

• affects dispersal distances and direction

• adjust release timing

• selective tidal stream transport (go to surface on flood tides and sink to bottom on ebb tides to get back to shore)

Traveling: Retention

• never leave home

• wander planktonically, return

Which species lacks a planktonic stage?

A

What mechanisms are in place to guide settlement success?

• ecological / biological — presense of predators or competitors

• physical — wind, tides, currents

• chemical — water or substrate chemistry

• combination of all

What are some cues and stimuli to aid settlement?

• biological / ecological — biofilms, conspecifics

• physical — temperature, current flow, tidal height, substrate preference

• chemical — scents and smells

Why migrate?

• food availability

• avoid predation

• breeding / spawning grounds

• avoid physical stress

what are the two types of fish migration? what do they mean?

1. Anadromy — freshwater to saltwater (salmon)

2. Catadromy — saltwater to freshwater (eels)

During migration, how do you know where to go?

• olfactory cues

• the sun

• geomagnetic / electrical signals (turtles, sharks)

How do benthic invertebrates migrate?

they have a seasonal migration of inshore and offshore

Why are there vertical zones, with dominance often of a single sessile species within a zone?

possible explanations:

1. differences in tolerance of env conditions across species at different tidal heights

2. competitive interspecific interactions

3. predation changes with tidal level

is the upper or lower intertidal more exposed in the rocky intertidal?

the upper intertidal is more exposed

what are some stresses in zonation in the rocky intertidal?

Physical —

• desiccation

• wave action

• temperature

Biological —

• predation

• competition

in what rocky intertidal zone is physical stress the greatest? why?

the upper intertidal

• more variation in salinity, moisture, and temperature, but less species living there so less competition

in what rocky intertidal zone is biological stress the greatest? why?

lower intertidal

• more marine organisms and you must be able to compete with them and defend yourself

in a salt marsh, where is physical and biological stress the greatest?

Biological — upper intertidal

Physical — lower intertidal

• It is the opposite of the rocky intertidal

What are adaptations to intertidal challenges (biological and physical)

• Desiccation - shells, behavior changes

• Salinity - euryhaline (adapted to wide range of salt) vs. stenohaline (adapted to narrow level of salt)

  • just know some species more adapted to salt than others

• oxygen consumption - breathe in air and water, some close in shell

• wave action - attachment and body shape adaptations

three phases of salt pan disturbance?

1. killing of grass by wrack (salt accumulation on blades)

2. wrack carried away - high salt prevents seed germination plant growth

3. (possible) rain dissolve salts, recolonization by runners of grasses, germination by some seeds in sediment

soft sediments: vertical stratification

• dominant species found at different levels below sediment-water interface

• experimentally reduce density of deep-dwelling clams, remaining individuals grow faster; demonstrates effect of density

• removal of shallow dwelling species of bivalves has no effect on growth of deeper-dwelling species

what are angiosperms?

flowering plants, mostly living on land

• salt is stressful and few can withstand, so angiosperms want to get away from it, where most comp. will be with herbivore / terrestrial wildlife

Types of coral growth forms zonation: vertical gradient

-       Flatter forms tend to be more common in deeper areas of the reef, probably to help with capturing all possible light available

-       Taller, more branching colonies tend to be more common in the shallower areas of the reef, due to intense competition for space and light

what are two strategies to deal with desiccation?

1. hiding - moving to a tide pool with more moisture (motile organisms) or only living in areas where moisture remains when tide is out (shallow rocks / crevices)

2. clamming up - closing shells in attempt to conserve moisture

what is the trade-off or risk when “clammed up”?

they’re not foraging

challenges with oxygen consumption in the intertidal?

• usually cannot respire at time of low tide

• respiratory organs (gills) must be moist to acquire oxygen and so are usually withdrawn at low tide

  • some animals reduce rate at time of low tide

    • some high intertidal animals can respire from air even at low tide, as long as air is not too dry

challenges with oxygen availability in the intertidal?

• O2 can be exhausted if organism clams up during low tide

• can also be exhaused in tide pools if high density of organisms, particularly algae, at night (no photosynthesis)

• CO2 can build up

  • some organisms have evolved the ability to exchange gases in both air and water

would you expect organisms to be taller / larger in high or low wave energy?

• shorter in high wave energy

• taller in low wave energy

scientific name for the American Eel?

Anguilla rostrata

define: metapopulation

a group of populations that are separated by space but consist of the same species

• spatially separated populations interact as individual members and can move from one population to another

define: population

a group of the same species living together, that have the potential to breed

does this equation describe curve A or linear curve B?

• this equation describes curve A

• its a power function, or sigmoidal curve, because species are not uniformly distributed across the landscape

• also, habitat heterogeneity increases with area

what are habitat patches referred to in terms of metapopulations?

they’re islands

• separation can be natural OR anthropogenic

draw the Equilibrium Theory of Island Biogeography ***

• island size affects extinction rates

• island remoteness affects immigration rates

• predictions on long term trends

  • number of species reaches constant level

  • continual species turnover

what is the species-area relationship?

larger patches can hold more species

what’s a pioneer species

• 1st species to colonize a newly disturbed area

• r-selected

what are characteristics of an r-selected species

• high reproductive effort

• high growth rate

• short life span

• low competitive ability

• parental investment is all pre-fertilization (massive amt of gamete production)

what is a late successional / k-selected species?

• low reproductive output

• higher maternal investment per offspring

• high competitive availability

• long life span

• slow growth rate

• offspring nourished / protected / learn by parents

traits of intermediate r/k selected species?

• nest building, guarding

• carrying eggs in / on the body

• mouth brooding (some through early larval stage)

(some invertebrates, some fish, turtles)

disturbances are physical events that can…

• influence mortality

• affect reproduction

• influence distribution and abundance of organisms

• reduce abundance of competing species

• allow colonization of species adapted to disturbance

• allow coexistent of competitively inferior species

spatial scale of disturbance is crucial in subsequent colonization events, how? **

• a very small scale disturbance (small patch) in mussel bed might just result in them moving and sealing off opened patch

• larger patches might be colonized by other species, and patch might last many months or indefinitely

• therefore, spatial scale of disturbance might affect spatial pattern of dominance of species, creating a mosaic of long-lived patches

in terms of disturbance, why do spatial scales matter?

• cannot extrapolate all interactions at small → large scale

• larger patches created by disturbance may be qualitatively diff than small scale - outcomes may be diff

• at habitat scale, potential for alternative stable states

what is abrasion (wave shock)?

particles (rock, sand, etc.) in suspension scrape delicate structures

define: disturbance

usually refers to physical change in environment that causes mortality or affects reproduction (storm, ice scour)

what is the intermediate disturbance hypothesis?

low levels — competitive dominant species takes over

intermediate levels — promotes coexistence, more species present

high levels — most individuals removed, reduces total number of species

what is competitive exclusion? at what level of disturbance does this occur?

whoever is most competitive, wins. they are excluding everyone else, and this happens as LOW levels of disturbance

• at high levels of disturbance, only the most successful, top dog predator wins

define: succession

predictable order of appearance and dominance of species, usually following a disturbance

some examples of disturbance and colonization?

• volcanism (surface lava flow) → coral colonization

• volcanism (hydrothermal vent) → deep-sea invertebrate colonization

• deposition of sand → colonization by burrowers

what are the 2 types of succession? examples?

Primary

• growth occurs on newly exposed surfaces where no soil exists

• example - natural events such as retreating glaciers scrape existing rock bare or new rock can form when lava cools

Secondary

• growth occurring after a disturbance changes a community without removing the soil

• example - after a forest fire, or once a cultivated field, or coral bleaching event

what are the three mechanisms of succession? (be able to look at data and state which mechanism it is)

Facilitation

• early species improve habitat (early spp. may or may not win)

• early marine colonists might provide substrate for settling of later arriving species

Inhibition

• early species take precedence (early spp. win)

• competition for space, nutrients and light or territoriality

Tolerance

• late-successional species are unaffected by earlier ones and can establish and mature in their presence because they are better at tolerating lower resource levels

• early species are less able to tolerate limited resources than late spp. or are less capable of directly competing (early spp. lose)

what is the mechanism? (succession)

facilitation

what is the mechanism? (succession)

facilitation AND tolerance

• early species are less able to tolerate limited resources than late spp. or are less capable of directly competing (early spp. lose)

what are the stages of succession? examples in different marine communities?

pioneer —> climax

example: whale fall

• mobile scavenger stage - active scavengers consume soft tissues

• enrichment opportunistic stage - warm of invertebrates move in, colonizing in the bones as they are supported by the organic matter left in carcass

• sulfophilic stage - bacteria feed on lipids; chemosynthetic bacteria dominates

• reef stage - most organisms have been broken down and it’s just the skeleton as habitat

Are climax communities common in marine benthic communities?

yes coral reefs are a prime example - high biodiversity and complex structure

what are the four different types of interactions between species (interspecific interactions)?

1. competition — two organisms mutually harm one another

2. predator-prey / parasite-host — one organisms benefits, the other is harmed

3. mutualism — both organisms’ benefit

4. commensalism — one organism benefits, the other is not affected

two types of resources that species compete for?

1. renewable - e.g., copepods exploiting diatom population

2. non-renewable - space on a rock expoilted by long-lived sessile species

three outcomes of competition?

1. competitive displacement — one species outcompetes another for a resource

2. coexistence — two species exploit different resources, some process allows two species to exploit same resource without displacement (resource partitioning, character displacement)

3. extinction — usually local, habitat shift

what is intraspecific competition?

competition between organisms of the same species

• occurs regularly and can maintain, in the long-term, populations around their carrying capacity

• density dependence

• as organisms approach K, they compete for food, space, refuge, mates

• results in reduced population growth due to increase morality / reduce fecundity due to disease, starvation, fighting, etc.

what is interspecific competition?

competition between organisms of two different species

how do individuals in a population compete? (inter- comp)

1. exploitation competition — use of a resource by one population affects how much is available to other populations (organisms interact INDIRECTLY by consuming scarce resources)

2. interference competition — one population affects another populations capability by using the resource (organisms interact DIRECTLY by fighting for scarce resources)

define: ecological niche

the sum total of an organism’s use of the biotic and abiotic resources in an environment

• includes space utilization, food consumption, temperature range, moisture requirements

what is a niche versus a habitat?

niche

• like an occupation

• what an organism does

habitat

• like an address

• where an organism lives

why can’t some species occupy their entire niche?

the presence or absence of other species

• interspecific competition

• observation of this in nature has led to concepts of fundamental and realized niche