SPECIES RICHNESS

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SPECIES RICHNESS

• READINGSFREEMAN, 2005
• Chapter 54Pages 1265-1277

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CONSERVATION BIOLOGY

• Conservation biology is a new science that has
  developed in response to concerns about
  decreasing biodiversity.
• It seeks to understand the effects of human
  activities on populations, species, communities
  and ecosystems.
• It intends to develop practical approaches to
  preventing declines in biodiversity and to
  restore species into functioning ecosystems.

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What is Biodiversity?

• Biodiversity is the full range of living things
  on earth and their surroundings and their
  heritage (genes).
• Everything from genes to ecosystems
• The millions of plants, animals, fungi and
  microbes that inhabit earth the genes they
  contain and the ecosystems they help build.

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Biodiversity Is Reflected In

• Ecosystem (Community) Diversity as described by
  community composition and environmental
  conditions.
• Species Diversity as measured by species richness
  (number of species) and relative abundance of
  each species (species evenness).
• Genetic (Populational) Diversity as determined by
  morphological traits and DNA comparisons.

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ECOSYSTEM DIVERSITY

• The diversity of life within the biosphere can be
  seen at global, regional and local scales
• Biomes (Global) -- marine, freshwater,
  terrestrial
• Life Zones (Regional) -- marine littoral
  (shore), pelagic (open water), benthic (bottom),
  abyssal (dark), reef (shallow)
• Habitats (Local) -- prairie wet, mesic, dry.

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ECOSYSTEM DIVERSITY

• Preserved as National Parks.
• Natural areas owned by the Federal Government.
• Preserved for scientific, educational and
  recreational activities.
• Showcases of nature including a wide spectrum of
  ecosystems.

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NATIONAL PARKS
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NATIONAL PARKS
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NATIONAL PARKS
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GENETIC DIVERSITY

• The diversity of life is fundamentally genetic. A
  variety of genetic methods have been used to
  investigate diversity both within and between
  species. Here are a few
• Morphological variation -- a good clue, but does
  not correlate perfectly with genetics
• Chromosomal variation -- inversions,
  translocations and polyploidy
• Soluble proteins -- blood groups, soluble enzyme
  polymorphisms
• DNA markers -- microsatellites, fingerprint
  loci.

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Morphological Variation

• Morphology (appearance or phenotype) provides
  clues to the genetic diversity that underlies
  species differences.
• But, looks can be deceiving. The wolf and coyote
  show distinct mussel lengths. The red wolf is in
  fact a hybrid between these two species thus,
  has an intermediate mussel length

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Chromosomal Variation

• This ideogram (arrangement of chromosome photos)
  shows variation in genetic material from a
  species of Brazillian fish species.
• This is a striking example of genetic variation
  within a morphological species.

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Soluble Protein Variation

• The human ABO blood groups are an example of
  soluble proteins that demonstrate genetic
  variation.
• Prior to DNA technology, soluble proteins
  provided some of the first material for studying
  heterozygosity, a measure of genetic variation.

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SPECIES DIVERSITY

• Species Richness is a measure of the total number
  of species in an area or taxonomic group. A
  simple count of number of species.
• Species Evenness is a measure that indicates how
  evenly the total number (abundance) of
  individuals is apportioned among species. The
  Simpson Index and Shannon-Weaver Index are
  measures of evenness.
• Species Difference (Taxonomic Diversity) is a
  measure of phenotypic differences among species.
  A rough over-view of this concept is seen in
  classification schemes.

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SPECIES DIFFERENCE (TAXONOMIC DIVERSITY)

• Classification system of Domains, Kingdoms, Phyla
  or Divisions, Classes, Orders, Families, Genera,
  Species.
• Two Domains - Prokaryotes Eukaryotes.
• Six Kingdoms - Archaebacteria, Eubacteria,
  Protista, Plantae, Fungi, Animalia.

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SPECIES RICHNESS

• How many species on earth?
• Only 1.5 million have been classified.
• Best estimate places number of species at 10
  million.
• Birds, mammals and butterflies are mostly named
  and described by science.

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Global Distribution of Species Richness

• Highest species richness is found in tropical
  forests.
• Mammals and butterflies are often used as
  indicators of species richness.
• Endemic species is found only in the local or
  regional area. Numbers for Richness (Endemic).

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SPECIES EVENNESS

• The Simpson Index (or Diversity Index) gives a
  simple measure of evenness.
• It addresses the question What is the
  probability that two individuals encountered at
  random in a community will belong to the same
  species?
• D 1 - sum(pi)2
• where D is the Diversity Index with values
  that vary from 0 (all of same species) to 1
  (myriads of species, all equal in number)
• sum over all species in community
• pi is the proportion of species i
  in the
• community.

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Simpson Index (or Diversity Index)

• For example, consider two communities (1 and 2),
  each of which has 3 species, A, B and C.

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Simpson Index (or Diversity Index)
D 1 - sum(pi)2 1 - (0.98)2 (0.01)2
(0.01)2 1 - (0.96) 0.04
Community 1 has very low species evenness.
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Simpson Index (or Diversity Index)
D 1 - sum(pi)2 1 - (0.35)2 (0.32)2
(0.33)2 1 - (0.33) 0.66
Community 2 has very high species evenness.
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Diversity Increases Productivity (I)

• Hypothesis More species result in higher
  community productivity.
• Method Plots with the same number of plants, but
  with different numbers of species were created.
  In the second year of growth, the area of each
  plot covered by plants was measured.

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Diversity Increases Productivity (II)

• Results Communities with higher species richness
  had a higher percentage of the area covered by
  plants. See Figures 53.24 and 55.4 in Freeman
  (2005) for description of the experiment (page
  1238) and definition of functional groups (page
  1271-1272).
• Conclusion Diverse communities are more
  productive.

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Biogeography and Species Richness

• Number of species on an island is related to its
  size.
• In general, a 10 fold larger area will have twice
  the number of species in a given taxa.
• Conservation biologists have used this
  generalization to predict species loss from
  habitat destruction and to determine optimum
  preserve size.

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Species-Area Relationships

• The observation that the number of species in a
  sample plot increases as a log-log function of
  area is well established.
• This graph indicated data for native species from
  104 sites throughout the world.

(Lonsdale, 1999)
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Species-Area Relationships

• To learn more about species-area relationships
  see the laboratory on Biodiversity and Nitrogen
  Deposition.
• Also, read section 53.3 on pages 1236-1239 and
  1275-1276 in Freeman (2005).

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Species Loss in Local Communities

• Recensus of 54 Wisconsin Prairies showed 8-60
  loss of native plant species after 32-52 years.
  Local extinction at a rate of 0.5-1.0 per year.
• Annual rate of loss elsewhere Limestone out crop
  in England (1.6) Beech-Hemlock forest in
  Pennsylvania (0.9-1.2) Calcareous grassland in
  Czech Republic (1.1) Seeps in California (1.6).

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Declining Eastern U.S. Songbird Populations

• Migratory populations of most songbird species
  declined substantially sing the 1940s those
  hardest hit are scarlet tanager, wood thrush,
  American redstart.
• Even some resident populations have declined
  song sparrow, white-breasted nuthatch.
• Others are stable northern cardinal, Carolina
  chickadee.

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Causes of Decline in Native Populations of
Plants and Animals

• Habit Destruction Conversion of natural areas
  into farms, dwellings, industries, places of
  business and corridors for transportation.
• Introduction of Exotic (Non-native) Plants and
  Animals The intentional or unintentional
  transport of a plant, animal, fungal, protozoan
  or bacterial species into areas where they did
  not previously occur.
• Overexploitation Hunting, fishing, grazing,
  cutting, gathering, collecting native plants and
  animals.
• Other Pollution (particularly aquatic species)
  Unknown.
• Decline is often due to a combination of the
  above causes, as well as demographic and other
  environmental factors.

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Major Causes of Endangerment

• Of 632 species listed as endangered in the 50
  states, the major causes of endangerment were

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HABITAT DISTRUCTION

• Habitat loss and fragmentation are the most
  pervasive threats to the conservation of
  biodiversity.
• Farming and logging prior to the 1900s were
  responsible for most habitat loss in eastern U.S.
• Residential and commercial development are the
  primary reasons for habitat loss in recent times.

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Loss of Forest Habitat

• The rate of loss of deciduous forest habitat
  between the 1850s and early 1900s is more than
  10 times faster than after.
• In fact, today forest acreage is increasing due
  to abandonment of farmland.

1620
1850
1920
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Edge Effects in Fragmented Forests

• Biologists recorded forest fragmentation by
  following the fate of 66 study plots in Manaus,
  Brazil. There were four 1-hectare fragments, 3
  10-hectare fragments and 2 100-hectare fragments.
• The graphed results indicate a decline in biomass
  in 16 study plots along forest edges.
• The loss of large trees along edges reduced the
  number of habitat layers thus, beetles, orchids
  and birds disappeared.
• See Freeman (2005) Figure 55.7 for more.

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EXOTIC SPECIES

• Exotic or invasive species are non-native plants
  and animals introduced into an area by people.
• They are able to establish populations in the
  wild.
• They lack natural predators, competitors or
  pathogens in the new place.
• They often have boom and bust population
  dynamics.
• Currently more than 4,500 exotic species in U.S.
• They are arriving at a high rate due to
  accelerated trade and travel.

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Examples of Introduced (Exotic) Animal Species

• Flathead catfish -- Introduced as a sport fish
  into rivers of the SE and SW US from the Midwest
  US.
• Asian Longhorn Beetle -- Arriving from China on
  shipping pallets into New York City and Chicago.
• Cherry Bark Tortrix -- arriving from Asia via
  Europe into ports in Washington state , currently
  spreading into Oregon.

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Examples of Introduced (Exotic) Plant Species

• Purple Loostrife -- Introduced from Europe as a
  horticultural plant.
• Tamerix -- Newly established in SW US desert as
  an escaped ornamental introduced from Eurasia.
• Old-World Climbing Fern -- A nursery escape in
  Florida from SE Asia.

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Introduction of Zebra Mussel

• The geographical distribution of the zebra mussel
  is being extended rapidly in the US.
• First reported in the St. Lawrence Seaway on 21
  November of 1991 it had spread throughout the
  Missouri and Mississippi drainage basin by the
  year 2000.

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OVERHARVESTING OF WHALES

• The whaling industry engaged in harvesting almost
  to the point of extinction of some species.
• End of commercial harvest -- Blue Whale 1969 Fin
  Whale 1975 Sei Whale 1977 Sperm Whale 1982.
• International ban on whaling.
• Resumption of harvest will call for a sustained
  yield harvest.

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OVERHARVESTING OF GINSENG

• Ginseng is used as a herbal by people throughout
  the world.
• Harvesting natural populations in eastern U.S.
  has endangered this deciduous forest plant.

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SPECIES RICHNESS

• READINGSFREEMAN, 2005
• Chapter 54Pages 1265-1277