lecture 19- strategies for survival: carnivores & ant plants

carnivory

plant that attracts, captures, and digests animal prey

carnivory is restricted mainly to plants of what type of site

sunny, moist, nutrient-poor

how many times has carnivory evolved

8-12 different origins

what plant organs are modified to make traps

bog

environment that is low in nutrients and inhospitable to nitrogen-fixing microbes

what environments are nutrient-poor, high-light

bogs, shallow tropic soils, tropical heathlands, acidic soils on sandstone

are availibility of water and solar energy limiting to photosynthesis

no

what is limiting to photosynthesis

lack of nutrients

sticky traps

specialized trichomes (ex- traps of sundews)

sticky leaves

contain two types of gland on leaf surface- stalked trichomes and sessile glands.

stalked trichomes

contain glands that secrete mucilage

sessile glands

secrete digestive enzymes

pitchers

trap insects and organisms in pitcher-shaped leaves. contain tube with liquid and digestive enzymes. modified leaves

three families with adaptations to make pitchers

sarraceniaceae (north america), nepenthaceae (australia, oceana), cephalotaceae (sw western australia)

pitcher plants produce

pitchers and photosynthetic leaves

phenotypically plastic production of pitchers

plant can change how many pitchers it makes or how large they are depending on the environment

pitcher production nitrogen hypothesis

it is adventageous to invest in pitcher production when nitrogen levels are low

• supported by fertilization experiments where high N leads to few pitchers, more leaves and the opposite

suction trap that springs open

trap is normally closed and opens when animal touches trigger hair then quickly shuts (ex lentibulariaceae, bladderworts)

suction trap that springs shut

trap is open then springs shut after being triggered (ex- venus flytrap, droseraceae). modification of the root

Droseraceae

one of the two plants worldwide that cpature their pray in traps that spring shut, north and south carolina only. (venus flytrap)

animals that feed plants without being eaten

some pitcher plants have evolved mutualistic relationships with animals that provide nutrition via their excretions

myrmecotrophs

plants fed by ants

domatia

small structures (like pockets, stems, pits) that provide shelter for ants

how do plants with domatia absorb nutrients

from waste materials accumulated in ant colonies

ant domatia in swollen tubers

ant colonies in smooth-walled chambers, ant wastes in warty chambers, plant absorb nutrient ions from waste

types of ant domatia

tubers, stem domatia, leaves (pouches from swollen petioles), stipules, tufts of hairs (like on the underside of oak leaves)

ant gardens

ants build a carton nest, worker ants plant seeds inside the carton, plant roots stabilize the nest, some plants provide rewards like extra floral nectar

acacias & ants

acacias are a type of tree/shrub that have a mutualistic relationship with ants. they provide domatia (modified stipule spines) and food from extrafloal nectaries (EFNs)

obligate mutualism in ants

once ants have had their first meal they can no longer feed on anything but the host nectar, nectar in extrafloral nectary inhibits the ability of ants to digest sucrose

most limiting nutrients for plant growth

nitrogen, phosphorus, potassium (N, P, K)

what happens when prey lands on venus flytrap

insect touches the sensory hairs and if the hairs are touched twice within a short time (20s) the trap is triggered

what happens immediatley after the venus flytrap is triggerend

the trap shuts quicky, in about 0.1 second, trapping the insect inside

what happens after the venus flytrap closes around the prey

the edge seals tightly to form a stomach and the plant secretes digestive enzymes

what happens during the final stage of venus flytrap prey processing

the insect is digested over 12 hours to 5 days and the plant absorbs the nutrients. after digestion the trap reopens about a week later

extrafloral nectaries

nectaries that appear on the outside of the plant, usually provide nectar reward for mutualistic ants

food bodies

provide rewards rich in lipids, proteins, sugars for ants. white or yellow little bodies on plants