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ecology and conservation > biogeography & biodiversity > Flashcards

biogeography & biodiversity Flashcards

& parasitism, herbivory

1
Q

key factors shaping diversity

A
  • location / isolation (for island sp)
  • habitat size / area
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2
Q

effects of location/geography on biodiversity

A

grad in biodiversity associated with latitude -> these shaped by climate (water & sunlight)

examples:

  • tree diversity:
    -> ~100 sp in 1 Ha of Malaysian forest
    -> ~50 sp in all of W. Europe (2 million km²)
  • ant diversity:
    -> over 200 sp in Brazil
    -> 73 sp in Iowa
    -> 7 sp in Alaska
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3
Q

Climate is likely the key driver of latitudinal diversity gradients…

A
  • ACTUAL EVAPOTRANSPIRATION
    -> determined by solar radiation & water
  • POTENTIAL EVAPOTRANSPIRATION
    -> measure of solar radiation independent of water availability)
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4
Q

One of the 1st general patterns of biodiversity described?

A

SPECIES-AREA relationship

-> lots of potential reasons

e.g. larger areas contain…

  • ↑ habitat diversity
  • support larger pops
  • ↓ likelihood of local extinction
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5
Q

island equilib model

A

describes diversity as resulting from…

equilib between rates of sp gain (via immigration) & sp loss (via extinction)

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6
Q

herbivory (and herbivores)

A
  • exploitative interaction: +/-
  • +ve outcome for herbivore: food
  • -ve outcome for plant/alga – loss of reproductive organs, food synthesis
  • key diff from predation is that herbivory is usually not lethal -> eats part of a plant/alga
  • diff herbivores generate diff effects
  • herbivores are 1º consumers
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7
Q

herbivory: effects on plants

A
  • depends on timing of attack relative to development (e.g. Plant age or leaf age)
    -> if young more likely to be fatal
  • plant usually remains alive in short term
  • effects dependent on response of plant
  • catastrophic grazing is rare (unless plants attacked early in development)
    -> opportunity for plants to respond / plant defences to act
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8
Q

types of effects on plants that suffer herbivory

A
  • UNDERCOMPENSATION
    -> grazed plants have lower fitness than ungrazed plants
  • OVERCOMPENSATION
    -> some grazed plants have GREATER fitness than their ungrazed: e.g. ↑ fruit & seed production
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9
Q

plant compensation

A

degree to which plants can tolerate grazing

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10
Q

fitness

A

organism’s ability to pass its genetic material to its offspring

-> can be measured in various ways, inc…

  • no. fruits or seeds
  • probability of survival
  • growth rate
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11
Q

in overcompensation in grazed plants, how can they have a greater fitness than ungrazed?

A
  • may evolve in plants where there is predictable amount of herbivory e.g. in path of herbivore migration
  • keep dormant tips in reserve to be used after herbivory has occurred
  • tradeoff: the cost is that…
    -> plants have ↓ flowers
    -> ↓ reproduction in absence of herbivory

COULD ALSO BE DUAL STRATEGIES…

  • with low herbivory: plants are ↑ competitive and grow small no. of shoots rapidly
  • with high herbivory: rapid growth
    is less of an adv     and it’s better to overcompensate and have lots of branching and flowering for higher fitness
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12
Q

defensive adaptations of plants

A
  • toxins & secretions
    -> morphine & other alkaloids, digitoxin, agrostemmic acid
  • spines & stings
    -> num-num plant thorns occur at ↑ densities at heights where herbivores graze
  • abscission (dropping) of leaves
    -> leaf miner mortality much ↑ in leaves that have been shed
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13
Q

Some toxins are bad for herbivores but not toxic to humans.

give examples

A

valuable crops eg…

  • curry
  • rosemary
  • cannabis
  • tobacco
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14
Q

Constitutive defences

of plant

A

present before a herbivore attack (e.g. thorns)

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15
Q

Induced defences

of plant

A

take place only when attacks occur

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16
Q

example of mutualism against herbivores

A

acacias & ants

  • plants provide refugia (hollow thorns) for ants
  • ants attack & kill small herbivores & discourage large grazers (e.g. elephants)

BUT…

  • in absence of herbivores: acacia stopped producing ant houses in hollow thorns & stopped excreting sweet nectar that bodyguard ants eat
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17
Q

adaptations of herbivores

A

Chemosensory apparatus
- chemical sensors on feet to identify toxic & most nutritious plants.
-> sense of smell e.g. goats

Digestive systems
- mutualists with cellulase activity
- multiple chambered stomachs
- coprophagy (eating faeces)
- grinding teeth, trunks, tongues, stylets (piercing mouth part)

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18
Q

symbiosis

A
  • when 2+ sp live in direct & intimate contact
  • interactions may be harmful, beneficial or neutral
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19
Q

parasitism

A
  • where symbiont derives benefit from another organism (host)…
  • to that organisms cost
  • each parasite attacks few individs (rarely more than 2) during its life
  • this intimacy distinguishes parasitism from true predators & grazers
20
Q

parasites are starting to be conserved (conservation plans).

why?

A
  • essential for healthy functioning communities
  • major contributor to mortality and can impact abundance of organisms
  • 5-10% of 450 parasite sp studied are committed to extinction by 2070 from climate-driven habitat loss
  • up to 30% of parasitic worms committed to extinction
21
Q

endoparasites

A

live within host’s body

eg. hookworm, tapeworm, liver fluke

22
Q

ectoparasites

A

feed on external surface of
the host

eg. copepods, lice, ticks, fleas

23
Q

parasitoids

one type of paratism

A
  • Insects (usually small wasps) lay eggs inside host
  • larvae develop inside living host, feeding on it & eventually killing it
  • numerous eg.s, some developed as biological controls
24
Q

parasitic plants

A

E.g. Rafflesia sp. (corpse flower, no stems, leaves or roots), and many Orchids

  • plant that derives some / all nutritional requirements from another plant (holoparasitic)
  • Rafflesia are holoparasitic
    -> obligate parasite -> cannot complete life cycle without host
25
Q

parasite life cycles are often complex.

give example and describe

5 steps

A

eg. blood fluke -> 2 free-living stages & 2 hosts
-> causes schistosomiasis

  1. mature flukes live in blood vessels of human intestine -> female fluke lives on males larger body
  2. flukes reproduce sexually in human host. Fertilised eggs exist host via faeces / urine
  3. if faeces / urine reaches water source: eggs develop into ciliated larvae -> larvae infect snails (intermed. host)
  4. asexual reproduction in snail => motile larva -> escapes snail
  5. larvae penetrate skin & blood vessels of humans exposed to water contaminated with fluke larvae
26
Q

schistosomiasis

A

blood fluke causes this

caused by parasitic flatworms (schistosomes)

  • urinary tract / intestines may be infected
  • symptoms inc abdominal pain, diarrhea, bloody stool / blood in urine
27
Q

with every required transmission to new host, parasite risks not infecting the next host & dying before reproducing.

why do parasites often have complex life cycles?

A

experiement done with 973 parasite sp

  • found that parasite growth & reproduction highest in large hosts – parasite fecundity (fertility) higher as they can grow bigger
  • but large hosts typically only accessible via small intermed. hosts
    -> small hosts facilitate transmission as more abundant
  • so complex life cycles arise because best hosts for growth & transmission are not the same

(to get to big host: need to go to small host first for improved transmission)

28
Q

Parasites can alter behaviour of hosts.

example?

A

Succinea snails & Leucochloridium paradoxum (parasite)

  • L. paradoxum is endoparasitic flatworm of both Succinea snails & various birds, inc crows, sparrows & finches
  • when on snail host: it needs to get to bird host. To do this…
    -> causes drastic deformity in its intermed. host, (Succinea snail)
    -> also provokes behavioral changes that ↑ suicidal tendencies in snail
  • parasite causes both snail’s tentacles to be occupied by a broodsac -> mimics appearance of insect larva e.g. caterpillar, ↑ likelihood snail will be eaten by parasite’s next host: birds
29
Q

what are the suicidal tendencies shown by Succinea snail after parasite?

A
  • snail more likely to stay in well lit places
  • sits on higher vegetation
  • more mobile
30
Q

mutualism

A

interaction that benefits both parties

eg…

  • Mycorrhizae & plants (nutrient exchange)
  • Cellulose digesting microbes
  • Leguminous plants
31
Q

mutualism in Microbes

A
  • in hindgut of a termite
  • break down cellulose into more easily digested sugars & short-chain fatty acids
32
Q

mutualism in Mycorrhizas

^beneficial fungi growing in association with plant roots

A

exist by taking sugars from plants ‘in exchange’ for moisture & nutrients gathered from soil by fungal strands

33
Q

mutualism in Rhizobium

^genus of Gram-negative soil bacteria that fix nitrogen

A
  • form endosymbiotic nitrogen-fixing association with roots of legumes & other flowering plants
  • these bacteria colonise roots of leguminous plants that in response produce set of new organs called ‘nodules’ on their roots
34
Q

key processes driving community dynamics

A
  • competition
  • predation
  • herbivory
  • symbiosis
  • facilitation
35
Q

most important ecological relationships on earth

A

Plants: nitrogen fixing, nutrient uptake
Corals: largest biological structures on earth

36
Q

Madagascar Orchid sp & Hawk
moths mutualism

A
  • moths enormous tongue can uniquely reach bottom of nectar tubes of Madagascan star orchid
  • +ve for moth:
    -> if insect is only one that can access nectar it is guaranteed food others are denied
  • +ve for orchid:
    -> further ↓ risk of misdelivered pollen and can cut back on its investments
37
Q

Cnidaria & algae
mutualism

A
  • host coral gets energy from algal p/s
  • algae get nutrients (N / a.a) from host
38
Q

Mutualisms are susceptible to exploitation – each sp could gain more & give less.

give examples

A
  • moths can chew into nectaries and gain food without pollinating Orchid - ‘nectar robbers’
  • Cnidarians enslave their algae massively ↓ growth & ‘grabbing’ up to 95% of photosynthetic production
39
Q

commensalism

A
  • interaction that benefits 1 sp
  • but neither harms nor helps other
40
Q

commenalism example

A

Atlantic puffin

-> these puffins use burrows for nesting that were made by rabbits

41
Q

facilitation

A

Like mutualism (but without direct contact) & typically involves plants

eg. Chondrus crispus:

  • suffers desiccation at low tide
  • survival ↑ in presence of fucoids, since canopy provides shelter
42
Q

3 levels of biological diversity

A
  • within sp
  • within community/ecosystem
  • within landscape – how diff are communities in sp composition?
43
Q

landscape diversity

A
  • ⍺ diversity – sp diversity in location / habitat patch
  • β diversity -> how diff sp composition is among locations
  • ɣ – species diversity at landscape level
44
Q

Biophilia / love of nature

what does it lead to?

A
  • biased towards ‘charismatic’ sp
  • might be seen as a luxury, not necessity
45
Q

why preserve biodiversity?

utilitarian

A

utilitarian: useful to humans, now / in future

  • sources of genetic diversity for crop breeding
  • new medicines
  • ecosystem services in agriculture
    -> e.g. pollination, pest control
  • carbon sequestration (capture and storage)

-> ecosystem functioning: we depend on local & global ecosystem processes
^more diverse ecosystems function better

ecology and conservation (9 decks)

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