how do we get biodiversity?
DESCRIPTION
How do we get Biodiversity?. 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. - PowerPoint PPT PresentationTRANSCRIPT
1
How do we get How do we get Biodiversity?Biodiversity?
2
3
BiodiversityBiodiversity• 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
Interpretations of SpeciationInterpretations of Speciation
Two theories:Two theories:1.1. Gradualist Model (Neo-Gradualist Model (Neo-
Darwinian):Darwinian):
Slow changes in species Slow changes in species overtimeovertime
2.2. Punctuated Equilibrium:Punctuated Equilibrium:
Evolution occurs in spurts of Evolution occurs in spurts of relatively rapid changerelatively rapid change
5
Adaptive Adaptive RadiationRadiation
Emergence of Emergence of numerous species numerous species from a common from a common ancestor introduced ancestor introduced to new and diverse to new and diverse environmentsenvironmentsExample::Hawaiian Hawaiian Honeycreepers Honeycreepers
Convergent EvolutionConvergent Evolution
Species from different evolutionary Species from different evolutionary branches may come to resemble one branches may come to resemble one another if they live in very similar another if they live in very similar
environmentsenvironments
Example:Example:
1. Ostrich (Africa) and Emu (Australia).1. Ostrich (Africa) and Emu (Australia).
2. Sidewinder (Mojave Desert) and2. Sidewinder (Mojave Desert) and
Horned Viper (Middle East Desert)Horned Viper (Middle East Desert)
8
CoevolutionCoevolution• Evolutionary changeEvolutionary change
– One species acts as a selective force on a One species acts as a selective force on a second speciessecond species
– Inducing adaptations Inducing adaptations – that act as selective force on the first that act as selective force on the first
speciesspecies Example:Example:1.1. Wolf and MooseWolf and Moose2.2. Acacia ants and Acacia treesAcacia ants and Acacia trees2.2. Yucca Plants and Yucca mothsYucca Plants and Yucca moths3.3. LichenLichen
10
11
1. Diversity is a balance of factors that increase diversity and factors that decrease diversity
2. Production of new species (speciation), and influx can increase diversity
3. Competitive exclusion, efficient predators, catastrophic events (extinction) can decrease diversity
4. Physical conditions a. variety of resourcesb. Predatorsc. environmental variability
Equilibrium Theory of BiodiversityEquilibrium Theory of Biodiversity
12
Species DiversityDef: the variety of species in an area
Two subcomponents: species richness species evenness
13
Species Richness vs. EvennessSpecies Richness: measurement of the
number of species in a given area
Species Evenness: measurement of how evenly distributed organisms are among species
Community A Community B
species 1 25 1species 2 0 1species 3 25 1species 4 25 1species 5 25 96
14
Determining Species Diversity
Scientists may want to:
* get an estimate of # of species in an area
* compare species diversity of two communities
To be accurate, need to:
* take both species evenness and species richness into account
15
Species Diversity IndicesShannon-Weiner (Shannon-Weaver) Index
Diversity =
(p spp 1 - ln(p spp 1)) + (p spp 2 - ln(p spp. 2) + …
(p spp N - ln(p spp. N)
Simpson Index
Diversity = 1
(pspp1)2 + (pspp2)2 + … (psppN)2
16
Why should we care about measuring
biodiversity(species diversity)?
17
Biodiversity Factoids
~ 2,000,000 spp. have been described ~ 10-30,000,000 species actually exist (est.)
~ 8,000,000 – 22,000,000 spp. unidentified
~ 40 – 60% of all spp. occur in two areas:
* tropical rainforests* coral reefs
18
• Richness (number of species)
• Relative abundance
• How do we describe these differences?
Comparison of Two Comparison of Two CommunitiesCommunities
19
Biogeographical ChangesBiogeographical Changes
• Richness declines from equator to pole
• Due to:
–Evolutionary history
–ClimateFig 53.23 Bird species numbers
20
• Species-area curve
• The larger the geographic area, the greaterthe numberof species
Geographic (Sample) SizeGeographic (Sample) Size
Fig. 23.25 North American Birds
21
Species Richness on IslandsSpecies Richness on Islands• Depends on:Depends on:
–Rate of immigration to islandRate of immigration to island–Rate of extinction on islandRate of extinction on island
• These in turn depend on:These in turn depend on:–Island sizeIsland size–Distance from mainlandDistance from mainland
22
How do species move?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
23
What allowed colonization?What allowed colonization?
• Niche opening
• No competition
• Endemics not utilizing resources
• Accessibility to colonists
24
Theory of Island BiogeographyTheory of Island Biogeography
1. Immigration rate decreases as island diversity increases
2. Extinction increases as island diversity increases
3. Species equilibrium on islands is a balance of immigration and local extinction
25
26
1.Smaller islands have lower total populations
2.Probability of extinction increases with lower population
3.Smaller islands have lower species diversity
Theory of Island BiogeographyTheory of Island Biogeography
27
28
1.Islands further from mainland have lower immigration rates
2.More distant islands have lower species diversity
Theory of Island BiogeographyTheory of Island Biogeography
29
30
Community Community RelationshipsRelationships
31
Niche isthe species’ occupation
and its
Habitat location of species
(its address)
32
NicheNicheA species’ functional role in its ecosystem; includes anything affecting species survival and reproduction
1. Range of tolerance for various physical and chemical conditions
2. Types of resources used
3. Interactions with living and nonliving components of ecosystems
4. Role played in flow of energy and matter cycling
33
NicheNiche
Realized niche:Realized niche: more restricted more restricted set of conditions under which set of conditions under which the species actually exists due to the species actually exists due to interactions with other speciesinteractions with other species
Fundamental niche:Fundamental niche: set of set of conditions under which a conditions under which a species might exist in the species might exist in the absence of interactions with absence of interactions with other speciesother species
34
Types of SpeciesTypes of Species•Generalist
–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
35
Types of SpeciesTypes of Species• Native speciesNative species normally live and thrive in a
particular ecosystem• Nonnative speciesNonnative species are introduced - can be
called exotic or alien• Indicator speciesIndicator species serve as early warnings of
danger to ecosystem- birds & amphibians• Keystone speciesKeystone species are considered of most
importance in maintaining their ecosystem
36
Nonnative Nonnative SpeciesSpecies• Nonnative plant species are invading the Nonnative plant species are invading the
nation's parks at an alarming rate, nation's parks at an alarming rate, displacing native vegetation and displacing native vegetation and threatening the wildlife that depend on threatening the wildlife that depend on themthem
• At some, such as Sleeping Bear Dunes At some, such as Sleeping Bear Dunes National Lakeshore in Michigan, as much National Lakeshore in Michigan, as much as 23 percent of the ground is covered with as 23 percent of the ground is covered with alien species, and the rate of expansion is alien species, and the rate of expansion is increasing dramatically.increasing dramatically.
37
Indicator Indicator SpeciesSpecies
• 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
38
Keystone SpeciesKeystone 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
39
Species Species InteractionInteraction
40
CompetitionCompetitionAny interaction between two or more
species for a resource that causes a decrease in the population growth or
distribution of one of the species
1. Resource competition
41
CompetitionCompetition
42
Resource CompetitionResource Competition
43
CompetitionCompetitionAny interaction between two or more
species for a resource that causes a decrease in the population growth or
distribution of one of the species
1. Resource competition
2. Preemptive competition
44
45
CompetitionCompetitionAny interaction between two or more
species for a resource that causes a decrease in the population growth or
distribution of one of the species
1. Resource competition
2. Preemptive competition
3. Competitive exclusion
46
Competitive ExclusionCompetitive Exclusion
47
CompetitionCompetitionAny interaction between two or more
species for a resource that causes a decrease in the population growth or
distribution of one of the species1. Resource competition2. Preemptive competition3. Competition exclusion 4. Interference competition
48
CompetitionCompetition
Resource PartitioningResource Partitioning• Division of resources in
an ecosystem so that species with similar needs (overlapping ecological
niches) use the same scarce resources at different times, in different ways, or in different places.
49
50
PREDATION
51
Predator AdaptationsPredator Adaptations• Prey detection and recognition
–sensory adaptations
–distinguish prey from non-prey
52
53
54
55
Predator AdaptationsPredator Adaptations• Prey detection and recognition
–sensory adaptations
–distinguish prey from non-prey
• Prey capture–passive vs. active
–individuals vs. cooperative
56
57
58
59
60
Predator AdaptationsPredator 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.
61
62
63
64
Prey AdaptationsPrey Adaptations• Avoid detection
–camouflage, mimics,
–diurnal/nocturnal
65
66
67
68
69
Prey AdaptationsPrey Adaptations• Avoid detection
– camouflage, mimics,
– diurnal/nocturnal
• Avoid capture– flee
– resist
– escape
70
71
72
73
Prey AdaptationsPrey Adaptations• Avoid detection
– camouflage, mimics, – diurnal/nocturnal
• Avoid capture– flee– resist– escape
• Disrupt handling (prevent being eaten)– struggle?– protection, toxins
74
75
HerbivoryHerbivoryHerbivore needs to find most
nutritious–circumvent plant defenses
77
HerbivoryHerbivoryHerbivore needs to find most
nutritious–circumvent plant defenses
Herbivory strong selective pressure on plants–structural adaptations for defense–chemical adaptations for defense
78
79
80
HerbivoryHerbivory
81
HerbivoryHerbivory
82
Symbiosis: Symbiosis: Mutualists, Mutualists,
Commensalists Commensalists and Parasitesand Parasites
83
• Symbiosis and symbiotic relationship are two commonly misused terms
• Translation of symbiosis from the Greek literally means “living together”
• Both positive and negative interactions
84
MutualismMutualismDEFINITION:
An interaction between two individuals of different species that benefits both partners in this interaction
85
MutualismMutualism
• Increase birth rates
• Decrease death rates
• Increase equilibrium population densities,
Raise the carrying capacity
86
PollinationPollination
• 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
87
• 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.
Yucca and Yucca Moth Yucca and Yucca Moth
88
Lichen (Fungi-Algae)Lichen (Fungi-Algae)• Symbiotic relationship of algae and
fungae…results in very different growth formas with and without symbiont.
• What are the benefits to the fungus?
89
Nitrogen FixationNitrogen Fixation
Darkest areas are nuclei, the mid-tone areas are millions of bacteria Gram -, ciliate
90
CommensalistsCommensalists• Benefit from the
host at almost no cost to the host
• Eyelash mite and humans
• Sharks and remora
91
Parasites and ParasitoidsParasites 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-ex tarantula spider)
92
Parasitic waspsParasitic wasps
• Important parasites of larvae.
• In terms of biological control, how would this differ from predation?
ovipositor
93
Ecological Ecological ProcessesProcesses
94
Ecological SuccessionEcological Succession
Primary and Secondary SuccessionPrimary and Secondary Succession
gradual & fairly predictable change in species composition with time
•some species colonize & become more abundant;
•other species decline or even disappear.
95
Ecological SuccessionEcological SuccessionGradual changing environment in
favor of new / different species / communities
97
Primary Primary SuccessionSuccession
Glacier Glacier RetreatRetreat
99
100
DisturbanceDisturbanceEvent 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
101
Ecological StabilityEcological StabilityCarrying Capacity – maximum number of
individuals the environment can support
102
Ecological Stability - StressEcological Stability - Stress1. Drop in Primary Productivity2. Increased Nutrient Losses3. Decline or extinction of indicator
species4. Increased populations of insect
pests or disease organisms5. Decline in Species diversity6. Presence of Contaminants
103
BibliographyBibliography1. Miller 11th Edition2. http://abandoncorporel.ca/medias/evolution.jpg3. http://www.ne.jp/asahi/clinic/yfc/fetus.html4. rob.ossifrage.net/images/ 5. http://www.mun.ca/biology/scarr/Five_Kingdoms_Three_Domains.htm6. http://www.gpc.peachnet.edu/~ccarter/Millerlec5/Millerlec5.PPT7. http://www.dnr.state.md.us/education/horseshoecrab/lifecycle.html8. http://www.falcons.co.uk/mefrg/Falco/13/Species.htm9. http://www.sms.si.edu/irlspec/NamSpecies.htm10. http://www.falcons.co.uk/mefrg/Falco/13/Species.htm11. http://www.globalchange.umich.edu/globalchange1/current/lectures/complex_life/complex_life.html12. http://nsm1.nsm.iup.edu/rwinstea/oparin.shtm13. http://www.angelfire.com/on2/daviddarling/MillerUreyexp.htm14. http://exobiology.nasa.gov/ssx/biomod/origin_of_life_slideshow/origin_of_life_slideshow.html15. http://www.geo.cornell.edu/geology/classes/Geo104/HistoryofEarth.html16. http://astrobiology.arc.nasa.gov/roadmap/objectives/o2_cellular_components.html17. http://pubs.usgs.gov/gip/fossils/18. http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/halfli.html19. http://www.accessexcellence.org/AE/AEPC/WWC/1995/teach_rad.html20. http://biology.usgs.gov/s+t/SNT/noframe/pi179.htm21. http://www.npca.org/magazine/2001/march_april/nonnative_species.asp22. http://www.bagheera.com/inthewild/spot_spkey.htm23. Biology, 2003, Prentice Hall24. http://www.nearctica.com/ecology/habitats/island.htm25. http://www.valdosta.edu/~grissino/geog4900/lect_1.htm