1. Biodiversity, and Community Processes

2. Biodiversity

4. Biodiversity Biodiversity
increases with speciation
decreases with extinction
Give-and-take between speciation and extinction  changes in biodiversity
Extinction creates evolutionary opportunities for adaptive radiation of surviving species

5. Loss of Biodiversity
Habitat destruction leads to a loss of many species starting with the plants
exact # of species lost is unknown because not all species are identified
% of all prescription drugs from natural resources
Wild species keep domestic species vigorous
Aesthetics

6. Biodiversity Latitude: Biodiversity is High near equator
Depth:  to 2000 m then …. High at bottom
Pollution:  Biodiversity
Terrestrial Biomes: Biodiversity is affected by:
Sunlight -  Biodiversity
Precipitation  Biodiversity
Elevation -  Biodiversity
Seasons – Biodiversity varies

7. The effect of latitude on Species Diversity As a rule species diversity is highest at the equator
1,000
100 10
Latitude
80ºN 60 40 20
200
90ºN 30
30ºS

8. The Effect of Depth on Biodiversity
Species diversity typically peaks ~ 2000 m 25 25
Snails
Tube worms 20 20 15 15
Species diversity 10 10 5 5
Coast
Deep Sea
Coast
Deep Sea
2,000
4,000
6,000
2,000
4,000
6,000
Depth (meters)
Depth (meters)

9. Number of diatom species Number of individuals per diatom species
Effect of Pollution on Biodiversity
Pollution frequently impacts reproductivity, causing biodiversity to decline
Unpolluted
stream
Number of diatom species
Figure 8-5 Page 168
Polluted
stream
Number of individuals per diatom species

10. Equilibrium Theory of Biodiversity
Diversity is a balance of factors that increase diversity and factors that decrease diversity
Production of new species (speciation), and influx can increase diversity
Competitive exclusion, efficient predators, catastrophic events (extinction) can decrease diversity
Physical conditions
variety of resources
Predators
environmental variability

11. Comparison of Two Communities
Richness
Relative abundance
How do we describe these differences?

12. Biogeographical Changes
Richness declines from equator to pole
Due to:
Evolutionary history
Climate
Generally tropical communities are older than temperate than polar communities
Organisms have a richer evolutionary history in an area where they are adapted to the climate.
Energy input (solar) and water availability factor into this phenomenon.
Fig Bird species numbers

13. Geographic (Sample) Size
Species-area curve
The larger the geographic area, the greater the number of species
Note that both scales are logarithmic
Fig North American Birds

14. Species Richness on Islands
Depends on:
Rate of immigration to island
Rate of extinction on island
These in turn depend on:
Island size
Distance from mainland
Because of their size and isolation, islands provide great opportunities for studying some of the biogeographic factors that affect the species diversity of communities.
Imagine a newly formed island some distance from the mainland.
Robert MacArthur and E. O. Wilson developed a hypothesis of island biogeography to identify the determinants of species diversity on an island.

15. How do species move? Humans (accidental and intended)
Animals (sticky seeds and scat)
Wind and ocean currents (+ or -)
Land bridges
Stepping stone islands
affected by climactic changes (glaciation)
ocean levels
short-term weather patterns
Aerial dispersal cause by wind, birds, flying insects. Dependent on long-term viableility of seeds, spores, etc.
Decreasing ocean levels may allow flow of organisms between land masses normally isolated. This allows for genetic mixing.
Coconuts are a good example of well adapted marine dispersed organism.
Long-lasting climactic changes such as glaciation may allow for the expansion and subsequent reduction of range, but during that expansion, gene-flow will occur.

16. What allowed colonization?
Niche opening
No competition
Endemics not utilizing resources
Accessibility to colonists
Colonization of young islands is especially rapid compared to older islands and especially the mainland
4 - Of course, if there is no access to colonists, there will be no colonization.

17. Theory of Island Biogeography
Immigration rate decreases as island diversity increases
Extinction increases as island diversity increases
Species equilibrium on islands is a balance of immigration and local extinction

18. Theory of Island Biogeography
Smaller islands have lower total populations
Probability of extinction increases with lower population
Smaller islands have lower species diversity

19. Theory of Island Biogeography
Islands further from mainland have lower immigration rates
More distant islands have lower species diversity

20. Types of Species Generalist Specialist large niches
tolerate wide range of environmental variations
do better during changing environmental conditions
Specialist
narrow niches
more likely to become endangered
do better under consistent environmental conditions

21. r and k strategists
Depending upon the characteristics of the organism, organisms will follow a biotic potential or carrying capacity type reproductive strategy
The r-strategists (Generalist)
High biotic potential – reproduce very fast
Are adapted to live in a variable climate
Produce many small, quickly maturing offspring = early reproductive maturity
“Opportunistic” organisms
The K-strategists (Specialist)
Adaptations allow them to maintain population values around the carrying capacity
They live long lives
Reproduce late
Produce few, large, offspring

22. Types of Species
Native species normally live and thrive in a particular ecosystem
Nonnative species are introduced - can be called exotic or alien
Indicator species serve as early warnings of danger to ecosystem- birds & amphibians
Keystone species are considered of most importance in maintaining their ecosystem

23. Nonnative Species
Nonnative plant species are invading the nation's parks at an alarming rate, displacing native vegetation and threatening the wildlife that depend on them
At some, such as Sleeping Bear Dunes National Lakeshore in Michigan, as much as 23 percent of the ground is covered with alien species, and the rate of expansion is increasing dramatically.

24. Introduced Species Zebra Mussels Kudzu Argentine Ants Cane Toads
Starlings, house sparrows
Brown Tree Snake
Lionfish
Nutria
Asian Snakehead

25. Indicator Species
a species whose status provides information on the overall condition of the ecosystem and of other species in that ecosystem
reflect the quality and changes in environmental conditions as well as aspects of community composition

26. Keystone Species
A keystone is the stone at the top of an arch that supports the other stones and keeps the whole arch from falling
a species on which the persistence of a large number of other species in the ecosystem depends.
If a keystone species is removed from a system
the species it supported will also disappear
other dependent species will also disappear
Examples
top carnivores that keep prey in check
large herbivores that shape the habitat in which other species live
important plants that support particular insect species that are prey for birds
bats that disperse the seeds of plants

27. Figure 8-1 Page 165
Flying Foxes – a keystone species

28. Species Interaction

29. Competition
Any interaction between two or more species for a resource that causes a decrease in the population growth or distribution of one of the species

30. Species Interactions: Competition
Intraspecific competition – secretion
of chemicals, dispersal of seeds, territoriality
Interspecific competition –
for limited resources  fundamental niches overlap
 Migration, shift of habits (natural selection),
pop decline, extinction
Interference competition –
regardless of resource availability – competition is
between differing species

31. Species Interactions: Competition
Exploitation competition – competing
species have equal access to a resource but differ in their ability
to exploit it
Competitive exclusion principle –
One species eliminates another through competition for limited
resources. (Paramecium experiment)
Resource partitioning – allows different
species to co-exist in the same habitat – ex. Warblers in spruce
trees – p. 173

32. Competition

33. Competition

34. PREDATION

35. Species Interactions: Predation
Predator - doesn’t live on/in prey
Prey - individual may or may not die
Prey population may benefit!
Prey acquisition - pursuit & ambush using
speed, eyesight or cooperation OR hide & ambush
Predator Avoidance - speed, sight, smell,
protective shells, thick bark, spines, thorns,
camouflage, chem warfare – see fig 8-11

36. Predation: Predator Adaptations
Prey detection and recognition
sensory adaptations
distinguish prey from non-prey
Prey capture
passive vs. active
individuals vs. cooperative
Eating prey
teeth, claws etc.

41. Predation: prey adaptations
Avoid detection
camouflage, mimics,
diurnal/nocturnal
Avoid capture
flee
resist
escape
Disrupt handling (prevent being eaten)
struggle?
protection, toxins

42. Ways prey species avoid their predators
See fig 8-11, p. 177
Span worm
Bombardier beetle
Viceroy butterfly mimics
monarch butterfly
Foul-tasting monarch
butterfly
Poison dart frog
When touched, the
snake caterpillar
changes shape to look
like the head of a snake
Wandering leaf insect
Hind wings of io moth
resemble eyes of a
much larger animal

46. Herbivory Herbivore needs to find most nutritious
circumvent plant defenses
Herbivory strong selective pressure on plants
structural adaptations for defense
chemical adaptations for defense

49. Symbiosis: Mutualists, Commensalists and Parasites

50. Symbiosis and symbiotic relationship are two commonly misused terms
Translation of symbiosis from the Greek literally means “living together”
Any relationship between two species of animals is symbiosis and includes both positive and negative interactions

51. Mutualism DEFINITION:
An interaction between two individuals of different species that benefits both partners in this interaction

52. Raise the carrying capacity
Mutualism
Increase birth rates
Decrease death rates
Increase equilibrium population densities,
Raise the carrying capacity

53. Symbiotic Species Interactions: Mutualism
Reproductive mutualism: pollination
Nutritional mutualism – lichen, coral
Nutritional/protection mutualism
Fig p. 179

54. Pollination (hummingbird/bee and flowering plants)
animals visit flowers to collect nectar and incidentally carry pollen from one flower to another
animals get food and the plant get a pollination service

55. Yucca moth and yucca
Yucca’s only pollinator is the yucca moth. Hence entirely dependent on it for dispersal.
Yucca moth caterpillar’s only food is yucca seeds.
Yucca moth lives in yucca and receives shelter from plant.

56. Variation on a theme: exploitation
Bee orchid flower emphasizes sexual characteristics of female bee…..offers no nectar.
Male transports pollen amorously from plant to plant.
Males prefer bee orchid flowers to female bees!

57. Seed disperser (plants and squirrels)
Many birds and mammals consume fruits and incidentally disperse the seeds contained in those fruits
Animals get food and the plant gets seed dispersal (often with fecal fertilizer)

58. Behavioral (honey guide, honey badger)
Honey badgers raid bee’s nests for honey
Guided by honeyguides that then share in the feast.

59. Nitrogen fixation (rhizobial bacteria).
Darkest areas are nuclei, the mid-tone areas are millions of bacteria Gram -, ciliate

60. Ant-tended plants
Ants live inside swollen Acacia thorns or hollow stems, e.g. Cecropia trees.
Patrol for caterpillars or leaf predators and storm out to repel intruders…including you!

61. Rewards of Mutualism Food: energy and nutrients Protection:
from other species (competition, predation)
from the physical environment (shelter)
Gamete or zygote dispersal (the most common of all)
Pollination and fruit dispersal (between plants and animals).

62. Obligatory mutualism
Obligatory: An organism can't live without the mutualism--either cannot survive or cannot reproduce.
the common pollinator systems like bees and flowering plants
protozoans in the guts of termites
the alga in the lichen partnership

63. Facultative mutualism
Facultative: This is "take it or leave it" for one or both partners
While the organism benefits when the mutualism is present, it can still survive and reproduce without it
ant mutualisms, such as ants protecting plants from predation
ants tending aphids

64. Commensalists Benefit from the host at almost no cost to the host
Eyelash mite and humans
Us and starlings or house sparrows
Sharks and remora

65. Symbiotic Species Interactions: Commensalism
Indirect: i.e., small plants growing in shade of larger plants
Direct: i.e., epiphytes, remoras
Fig p. 180

66. Parasites and parasitoids
Parasites: draw resources from host without killing the host (at least in the short term).
Parasitoids: draw resources from the host and kill them swiftly (though not necessarily consuming them).

67. Symbiotic Species Interactions: Parasitism
Parasite – smaller than host–
may weaken host over time, rarely kills host
Host – harmed by parasite, yet parasites play
an important ecological role
Endoparasites – live inside host – ex.
Tapeworms & pathogenic microbes
Ectoparasites – Live outside host –
ex. Ticks & fleas

68. Parasitic wasps Important parasites of larvae.
In terms of biological control, how would this differ from predation?
ovipositor

69. Ecological Processes

70. Ecological Succession
Primary and Secondary Succession
gradual & fairly predictable change in species composition with time
some species colonize & become more abundant;
other species decline or even disappear.

71. Ecological Succession
Gradual changing environment in favor of new / different species / communities
Tree fall gap becomes colonized by sun loving pioneer plants they eventually create less suitable conditions
will ultimately be replaced by different species that require less sunlight

72. Population and Succession
Top 6 most abundant elements in living things
(not in order) * NCHOPS
Top 8 elements in the earths crust (in order)
O, Si, Al, Fe (iron), Ca, Na (sodium), P, Mg
(Only silly apes in college study past midnight)

73. Primary Succession
Gradual establishment of biotic communities in an area where no life existed before.
No preexisting seed bank.
newly formed islands (i.e. volcanic origin)
retreat of a glacier

75. Primary Succession Glacier Retreat

76. Secondary Succession
Gradual reestablishment of biotic communities in an area where one was previously present.
Preexisting seed bank.
treefall gaps
"old field succession"
forest fire

77. Secondary Succession
Fig p. 181

80. Edge Effects Differences at boundaries and ecotones
Habitat fragmentation  Edge Effects
Some species thrive here (pheasants and deer)
Some species suffer:
Vulnerability to predators & fire
Barriers preventing migration & movement for food & mating

81. Facilitation –one species makes an area
The Rate of Succession
Facilitation –one species makes an area
suitable for the next species
Inhibition – early species hinder the
establishment of other species – ex. Toxic chem.
Tolerance – late succession plants unaffected
by earlier plants
Refer to Table 8-1 p. 182

82. Disturbance Event that disrupts an ecosystem or community;
Natural disturbance
tree falls, fires, hurricanes, tornadoes, droughts, & floods
Human–caused disturbance
deforestation, erosion, overgrazing, plowing, pollution,mining
Disturbance can initiate primary and/or secondary succession

83. Ecological Stability
Carrying Capacity – maximum number of individuals the environment can support

84. Ecological Stability - Stress
Drop in Primary Productivity
Increased Nutrient Losses
Decline or extinction of indicator species
Increased populations of insect pests or disease organisms
Decline in Species diversity
Presence of Contaminants