Selfincompatible mating systems in plants

1
Negative Frequency Dependence

• Self-incompatible mating systems in plants
• (two individuals with same mating allele will
  not produce fertile offspring)
• Plant and herbivores-
• Herbivore eats the plant that is most common

2
Positive Frequency Dependence

• Plant-Pollinators - bees learn to gather nectar
  from the common genotype, giving the common one
  an advantage

Eventually only one genotype remains
3
Mosaic Environment

• Selective forces may operate in different
  directions within different patches
• Example Erigeron canadensis, planted known
  genotypes out into a homogeneous field site,
  genotypes performed differently even when planted
  very close together

4

• We have seen how the environment influences the
  genetic composition of populations, but how does
  the genetic composition influence the ecological
  abundance and distribution of species?

5
To what extent does a species range depend upon
its genetic diversity?

• Polyploids are often more widely distributed than
  diploids
• Hybridization between a native and an introduced
  species of Spartina
• Hybrid spread throughout the British Isles
• Many invasive plant species may be hybrids

6
Population- a collection of individuals in a
location
What causes a species to be common or rare? Why
do certain populations fluctuate over time and
others are stable?Why do populations vary in
their size or age structure?
7
Plants occur in varying densities
Density number of individuals per unit area
Three patterns random, regular or clumped
8
Patterns of plant distribution
Random
x
x
x
x
x
x
Regular
x
xx
xx
x
Clumped
x
9
Patterns may tell you about mechanism
What processes are likely to generate 1.
Regular 2. Clumped
10
Quantitative samples of plant populations
Quadrat a shape of fixed areas that allows one
to estimate the number of plants per area, the
vegetation cover, or the species diversity of a
known area
11
Sampling Often populations are too large to
sample all individuals in an area
Grid the area to be sampled 1. Randomly select
quadrats 2. Select quadrats in a regular
pattern 3. Stratified Random sample
12
May also use Transects
13
Invasive Species

• A species that invades a habitat where it
  previously did not exist before and grows without
  limit causing changes in the community and
  ecosystem

14
Invasive Species vs. Alien Species

• Alien species- a non-native species
• Invasive species- alien species that causes harm
  to the community and ecosystem

15
 
By the authority vested in me as President by
the Constitution and
the laws of the United States of America,
including the National
Invasive Species Executive Order Issued by
President Clinton February 1999
Environmental Policy Act of 1969, as amended (42
U.S.C. 4321 et seq.),
Nonindigenous Aquatic Nuisance Prevention and
Control Act of 1990, as
amended (16 U.S.C. 4701 et seq.), Lacey Act, as
amended (18 U.S.C. 42),
Federal Plant Pest Act (7 U.S.C. 150aa et seq.),
Federal Noxious Weed
Act of 1974, as amended (7 U.S.C. 2801 et seq.),
Endangered Species Act
of 1973, as amended (16 U.S.C. 1531 et seq.), and
other pertinent
statutes, to prevent the introduction of invasive
species and provide
for their control and to minimize the economic,
ecological, and human
health impacts that invasive species cause, it is
ordered as follows
 
Section 1. Definitions.
 
(a) "Alien species" means, with respect to a
particular ecosystem,
any species, including its seeds, eggs, spores,
or other biological
material capable of propagating that species,
that is not native to that ecosystem.
 
(b) "Control" means, as appropriate,
eradicating, suppressing,
reducing, or managing invasive species
populations, preventing spread of invasive
species from areas where they are present, and
taking steps
such as restoration of native species and
habitats to reduce the effects of invasive
species and to prevent further invasions.
 
(c) "Ecosystem" means the complex of a
community of organisms and it senvironment.
 
(d) "Federal agency" means an executive
department or agency, but
does not include independent establishments as
defined by 5 U.S.C. 104.
 
(e) "Introduction" means the intentional or
unintentional escape,
release, dissemination, or placement of a species
into an ecosystem as a result of human activity.
 
(f) "Invasive species" means an alien species
whose introduction does or is likely to cause
economic or environmental harm or harm to human
health.
 
(g) "Native species" means, with respect to a
particular ecosystem, a species that, other than
as a result of an introduction, historically
occurred or currently occurs in that ecosystem.
 
16
Invasive Species are Everywhere!

• Australia 1,500 invasive plants
• United States 1,500 invasive plants
• Florida and California each have 1,000
• Canada 1,500 invasive plant
• Europe 800
• South Africa 800

17
In general, there are more invasive plants than
animals

• Purposefully introduced as ornamental
• Seeds can be dispersed a long distance
• Humans can act as long-distance dispersal agents

18
Characteristics of invasive species

• Reproduce sexually and asexually
• Rapid growth from seedling to maturity
• Tolerance to environmental heterogeneity
• Good competitive ability

19
Four stages necessary for a successful invasion

• Dispersal to new habitat
• Initial colonization
• Establishment
• Secondary spread

20
Stages of Invasion

• Most invasive species are not discovered until
  they reach the secondary spread phase
• In order to control invasive species we need to
  identify potential invasive species before they
  begin to spread

21
2. Initial Colonization

• Isolated individuals self-fertilize
• Plants can be sexual (hermaphrodites)
• Asexual (clonal)
• Insects and some vertebrates can store sperm
• 2. Multiple reproductive strategies
• 3. Cope with environmental heterogeneity

22
3. Establishment
Traits associated with establishment Small seed
size Short juvenile period Short interval between
seed crops
23
3. Establishment
Excellent Competitive ability Most organisms have
a trade-off between fast reproductive rate and
competitive ability BUT this may not be true for
invasive species!!
24

3. Establishment
Purple Loosestrife
Competitive ability Very high fecundity 3.5
million seeds per plant. Capable of suppressing
the biomass of 3 wetland species when grown in
competition
     
25
WORST PLANT INVADERS
Primarily aquatic or semi-aquatic Grasses Nitrogen
fixers Climbers Clonal trees
26
Examples of Invasive Plant Species
27
Local Examples of Introduced Species

• Zebra Mussel
• Double crested Cormorant
• Plant Examples
• Purple Loosestrife
• Water Chestnut
• Reed Canary Grass

28
How to control exotic or invading species

• 1. Physical control (garlic mustard, water
  chestnut)
• 2. Prevention (check borders)
• 3. Pesticides (selectively kill invading species)
• 4. Biological Control (introduce another organism
  that will naturally prey on the invasive species
• Purple loosestrife