BOT 330 Exam 1
Today, suitable habitat reduced & fragmented • To survive, need to
- Acclimate & adapt OR - Move to cryptic refugia within dispersal range
What species use agamospermy
- Dandelions - Rosaceae - Buttercups - Nettles - Grasses - Citruses
Sibling-competition - the elbow room hypothesis
- If exactly like brothers & sisters (i.e. asexually-produced clones), have exact same requirements for food, light, nutrients etc. - If vary somewhat, overall competition may be less intense, increasing overall survival
When Northern Hemisphere points away from sun in summer, what happens?
- Less plant growth - Cooler winters less decomposition less CH4
The clean egg hypothesis
- Meiosis tends to weed out bad gametes - Plant viruses generally don't survive meiosis - Infected parent might be able to produce uninfected offspring
Candidates for assisted migration, species with
- Poor dispersal - Long life cycle - Low competitive ability
Quaking aspen(in terms of sexual reproduction)
- Stands of genetically identical ramets - Genet or clone = clonal colony of ramets - Suckers can get as far as 40 m away! - Pando ("I spread"): one male
Apomixis - Why Not Have Sex?
1. Cost of making flowers 2. Cost of attracting pollinators 3. Safety net: what if there are no nearby mates or pollinators? 4. Local adaptation
How to tease apart these potential mechanisms of change in the same plant
1. Environmental differences Clones 2. Genetic differences Common gardens
Trystyly characteristics
1. Long styles w/ med & short stamens (pin) 2. Medium styles w/ short & long stamens 3. Short styles w/ med & long stamens (thrum)
What are the two common O isotopes (oxygen stable isotopes) and weight differences
16O, abundant, light atomic weight • 18O, rare, heavy atomic weight Ratio = O18/O16
Heterostyly
2 or 3 Flower morphs in one population • On each plant, only one morph • Morphs genetically self-incompatible
Tristyly
3 Flower morphologies on one population
What drives the difference between the same plant in a different environment
3 Possible mechanisms 1. Environmental differences 2. Genetic differences 3. Environmental & genetic differences
What's a cryptic refugium?
??? high dispersal?
Interspecific Interactions
A relationship between individuals of two or more species in a community.
What are plants' options to deal with climate change?
Acclimate/adapt (or lack of impact), Move, Perish
Local Adaptation example
Allium vineale (non-native wild garlic) • Sexual reproduction via seeds • Asexual reproduction via bulbils - Aboveground vegetative bulb-like organs - More common - Fitness advantage of local adaptation?
Palynology Downsides?
Can't completely capture community composition • Not as effective in arid environments
Dobrowski and Parks 2016 main point
Climate change velocity underestimates climate change exposure in mountainous regions
The temperature in the pleistocene was
Colder temperatures
Oxygen Stable Isotopes during the ice age
Cooler equatorial temps • Cooler air holds less water vapor • Heavy isotopes precipitate out at lower latitudes • Precip at poles distinctively "depleted" in 18O
Acorn woodpecker description with regard to plants
Depend almost entirely on acorns for food - Store thousands of acorns in storage trees, "granaries" - Breed in fall of mast years
Spatially separate male & female parts lead to what
Dioecy - Seed & pollen cones - Unisexual flowers - Heterostyly
Ruddiman's major findings?
Earth should be in time of global cooling • We started altering climate earlier than previously thought • Our activities may have increased greenhouse gasses enough to prevent a glaciation
Yarrow Study What does this mean?
Ecotypic variation
Generate variability
Environment changes and varies - Increase population variation, increase • Likelihood that plants are adapted to environment • Resilience to broad scale environmental changes
how do Oxygen Stable Isotopes work
Equatorial air cools & moves towards poles • Water vapor precipitates as rain • "Heavy" isotopes precipitate out of vapor first • Air mass arriving at poles relatively "light"
Cone Arrangement
Female cones above male cones
many plants DO use sexual reproduction, why
Generate variability, Sibling-competition - the elbow room hypothesis, The clean egg hypothesis
Yarrow Study Common garden experiment
Grow seeds from different elevations at sea level • Simple & elegant way to test for genetic differences
Yarrow (Achillea millefolium) Study
Grows in many environments • Morphology varies with elevation - Taller plants at low elevations - Shorter plants at high elevations
Masting
Huge resource pulse in ecosystem • Big influence on bird & small mammal populations
Acclimate
Individual plants respond
Seed Germination
Initiation of seed growth
Local Adaptation Possibly advantageous due to
Interactions w/ mycorrhizal fungi, rhizosphere bacteria, and/or soil pathogens • Light, nutrients, and/or water availability
What can Ice Cores be used for
Learn about • Temperature variation • Atmospheric CO2 concentration
Yarrow Study - Results
Low- & mid-elevation plants grew great • High-elevation plants did not flourish; grew as tall as they normally would
Dioecy
Male & female gametes produced on separate plants
Apomixis (Asexual Reproduction)
Many species don't use sexual reproduction or use combo of sexual & asexual reproduction • e.g. Corms (undifferentiated stem tissue) & stolons
Sun leaves have higher
Max photosynthetic rate • Light saturation point • Light compensation point
De Frenne et al. 2013
Microclimate moderates plant responses to macroclimate warming - Forest canopy closure modulates understory thermophilization
How does the paleo record suggest plants will respond to climate change?
More likely to move than adapt to climate change
When Northern Hemisphere points toward sun in summer, what happens?
More plant growth - Warmer winters more decomposition more CH4
Pleistocene
Most recent period of widespread glaciation Last Glacial Maximum • Flora & fauna similar to now, but different • Mastodons, giant sloths, & saber toothed tigers
What Drives these Cycles of Glaciation & Interglaciation?
Natural variation? • Humans?
what is selfing
Not apomixis; a form of sexual reproduction • ~50% of angiosperms are self-compatible
Pack Rat (Neotoma) Middens
Pack nests w/ material from surrounding environment • Pees on it to mark territory • Sugars in urine crystallize - Preserve pile materials up to 50K years - Glue everything together
Milutin Milankovitch
Paired historical climate changes to changes in Earth's movements Quantified effect of solar radiation on Earth
• How do we know the vegetation was different way back when (18K years ago)?
Palynology and Pack rat middens
Dystyly can be what two things
Pin morph or a thrum morph
Gemmae
Plant makes little ball of itself & sets it loose • Frequently spread by rainfall • Prevalent in fungi, algae, liverworts, & mosses
De Frenne et al. 2014
Plant movements and climate warming: intraspecific variation in growth responses to nonlocal soils
Cortlett & Westcott 2013 What's the big deal?
Plant species survived periods of rapid climate change during Pleistocene glacial-interglacial periods
Ronsheim 1997 main point
Planted "home" (parent genotype) & "away" (from a different parent) bulbils in concentric rings around parent • If equal growth, no local adaptation
Methane (CH4) is tied closely to which cycle
Precession
Palynology
Quantify share of pollen "rain" in lake sediments by species • Reconstruct historical vegetation • Predict plant responses to future climate changes
Changes in these three cycles (Eccentricity, Obliquity, Precession) influence climate in what ways
Quantity of solar radiation hitting Earth • Where solar radiation hits Earth • Albedo • Temperature (land heats quicker than ocean)
Pack Rat (Neotoma) Middens can
Reconstruct past plant environments • In areas where pack rat middens present, palynology typically not used
Adapt
Selection acts on a population or species
Eccentricity
Shape of Earth's orbit • Varies from perfectly round to ovoid • 100K Year cycle
how does plant sex promote outbreeding
Spatially separate male & female parts, Temporally separate male & female parts (dichogamy) Self-incompatibility
Dichogamy
Temporally separate male & female gametes
Obliquity
The "tilt" of the Earth • Changes in plane of Earth's orbit • Changes by as much as 2.4° • 41K Year cycle
Precession
The "wobble" of the Earth • Shifts in direction Earth's axis points: towards or away from sun • 22K Year cycle
What can oxygen stable isotopes be used for
Track historical climate changes • Historical oxygen in ice cores as frozen water
Less extreme intervention
Translocate plants to edge of natural range - Reduce risk of unpredictable impacts
How can we help plants survive climate change bottleneck?
Translocation (breeding) • Restore connectivity (reduce fragmentation) • Protecting refugia
How do seeds pollinate
Usually plants rely on animals or the wind to pollinate them, they can also self pollinate
Oxygen Stable Isotopes during interglacial periods
Warmer equatorial temps • Warmer air holds more water vapor • Heavy isotopes precipitate out at higher latitudes • Precip at poles distinctively "enriched" in 18O
How Do Plants Respond to Changes?
acclimate and adapt
Reproductive Strategies
apomixis and sex or both
Agamospermy
asexually create seeds No meiosis • No fertilization • Widespread in many plant families
Mast year
bumper seed crop for plants in an area in a single year
Cortlett & Westcott 2013 discussed
climte velocity
What are good reasons for plants to disperse their seeds?
colonize new areas and escape disease
Vegetation is ___________, it moves over time
ephemeral
• In non-mast years, plants produce
few to no seeds
About 8K years ago, what human activity started increasing atmospheric CO2 levels?
humans started clearing forests, planting crops and raising livestock
About 5K years ago, what human activity started increasing atmospheric methane levels?
increased emissions from flooded rice fields, as well as burgeoning numbers of livestock
Over the past 250 thousand years, global methane levels have cycled up and down. Peaks in methane levels are thought to correlate with __________.
increased plant growth in summer, increased plant decomposition in winter increased solar radiation levels in Northern Hemisphere
As glaciers retreated, __________ moved north • Beach pine stayed behind on our _____________
lodgepole pine, beaches
CH4 & CO2 at higher levels than would be expected based on __________________ alone
natural variation
During interglaial periods deciduous trees extended
north again
Plant Sex - Promotes
outbreeding
Pre-Milankovitch: knew ________________ existed, but couldn't explain them
past ice ages
Group phenomenon:
plants coordinate quantity & timing of seed production
two main kinds of sex
self or outbreeding
Suckers
shoots arise from adventitious buds on underground root
During glacial periods, deciduous trees moved to
southern refugia
Ecotypic variation
the type of genetic variation found in a large continuous geographic populations
Why can't we use fossil records for vegetaion 18k years ago
too recent for fossils
What is the Janzen-Connell hypothesis?
widely accepted explanation for the maintenance of tree species biodiversity in tropical rainforests
Glacial Refugia Hypothesis
~12K Years ago, last major ice age ended • Climate warmed • Glaciers retreated • Sea level rose • Plants moved north from their southern refugia
Glaciers in the pleistocene did what
• Glaciers extended down through Great Plains
Pin morph
• Long styles • Short stamens
What was the sea level and water content of glaciers in the pleistocene
• Lots of water tied up in glaciers & ice caps • Sea level lower, more plant habitat
Thrum morph
• Short styles • Long stamens
