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Chapter 8: Biological Diversity and Biological Invasions

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1 Chapter 8: Biological Diversity and Biological Invasions

2 Overview What is Biological Diversity? Biological Diversity Basics
Biological Evolution Competitive and Ecological Niches Symbiosis Predation and Parasitism How Geography and Geology Affect Biodiversity Invasions, Invasive Species and Island Biogeography

3 What is Biological Diversity
Bio diversity refers to the variety of life forms in an area. Expressed 2 ways Number of species in an area Number of genetic types in an area

4 Why Do People Value Nature?
Eight Reasons Utilitarian Public service Moral Theological Aesthetics Recreational Spiritual Creative

5 Biological Diversity Basics
Genetic Diversity Total number of genetic characteristics of a specific species, subspecies, or group of species Habitat Diversity The different kinds of habitats in a given unit area Species Diversity Species richness - total number of species Species evenness - relative abundance of species Species dominance - the most abundant species

6 Species Diversity Counting the number of species is not enough to describe biological diversity Left = 10 species; 100 individuals, 87 elephants, 9 species with 2 individuals each Right = 10 species; 100 individuals, 10 individuals each species Which has greater species richness? Species evenness?

7 Number of Species on Earth
1.5 million species have been identified Estimated that almost 3 million different species currently exist All living things categorized into taxa Kingdom Phylum Class Order Family Genus Species

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9 Biological Evolution How did biological diversity come about?
Too amazing to have come about by chance Many believed that it must have been created by God “everything in the world is marvelously ordered by divine providence and wisdom for the safety and protection of us all” -Cicero

10 Biological Evolution Charles Darwin Biological Evolution Ninth century
Explanation of diversity known as biological evolution Biological Evolution Change in inherited characteristics of a population from generation to generation

11 Biological Evolution New species arise as a result of:
Competition for resources Difference among individuals in their adaptations to environmental conditions Four processes lead to evolution Mutation Natural selection Migration Genetic drift

12 Mutation Genes are inherited from one generation to the next
Contained in the chromosomes of each cell Genes made up of DNA DNA made up bases A,C,G,T How these letters are combined determines the “message” interpreted by a cell

13 Mutation When cells divide
DNA is reproduced Each new cell gets a copy Mutation - when an error occurs in the reproduction of DNA as it gets passed to new cells Possible causes: radiation or a viruses

14 Mutation In some cases offspring with a mutation cannot survive
In some cases a mutation simply adds to genetic variability in the species In some cases mutation changes the offspring drastically and a new species is created

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16 5 big factors that decrease biodiversity - HIPPO
H = Habitat Destruction I = Introduced Species P = Pollution P = Population Growth O = Over-consumption

17 Natural Selection Some individuals may be better suited to the environment than others Those better able to survive and reproduce leave more offspring Their descendants form a larger proportion of the next generation The accumulation of changes may lead to reproductive isolation Resulting in a new species

18 Natural Selection Four primary characteristics Genetic variability
Environmental variability Differential reproduction that varied with the environment Influence of the environment on survival and reproduction

19 Migration and Geographic Isolation
Two populations become geographically isolated for a long time Differences accumulates so that they no longer reproduce Two new species have formed Migration important evolutionary process (Adaptive Radiation) Ex: Hawaii honey creeper and Darwin’s finches

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21 Genetic Drift Genetic drift Founder effect
Changes in frequency of a gene in a population simply by chance Founder effect Small number of individuals are isolated from larger population Less genetic variation than original population Characteristics present are affected by chance Individuals may NOT be better adapted

22 Interaction between Species
Competition The outcome is negative for both groups Symbiosis Benefits both participants Predation and parasitism The outcome benefits one and is detrimental to the other.

23 Competitive Exclusion Principle
Two species that have exactly the same requirements cannot coexist in exactly the same habitat. Ex- British Red Squirrel and American Grey Squirrel

24 Niches: How Species Coexist
Ecological Niche Concept Explains how so many species can coexists Example: Flour beetles (Tribolium) Specific # of beetles of two species placed in flour Containers maintained at various temp and moisture levels Periodically beetles counted One species always wins but which one depends on conditions

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27 Niches: How Species Coexist
All flour beetles have the same ecological functional niche Same “profession” – eating flour Different Flour beetles can live in different habitats

28 Measuring Niches Describe the niche Measured Niche
the set of all environmental conditions under which a species can persist and carry out its life functions Measured Niche Fundamental niche Realized niche Ex- flatworms in streams

29 Fundamental temperature niche
The occurrence of freshwater flatworms in cold water streams in Great Britain. When A and B occur alone niche is larger than where they occur together. Realized temperature niche

30 Symbiosis Describes a relationship between two organisms
beneficial to both enhances each organism’s chance of persisting Each partner called a symbiont Ex- reindeer and gut bacteria Food for reindeer Home for bacteria

31 Predation and Parasitism
Relationship is beneficial for predator or parasite and negative for prey or host Predation One organism (predator) feeds on other live organisms (prey) Parasitism One organism (the parasite) lives on, in, or within another (the host)

32 How Geology and Geography Affect Biologic Diversity
Species are not uniformly distributed over the earth’s surface They are not uniformly distributed locally, either Species change with soil type and topography: slope, aspect (the direction the slope faces), elevation, and nearness to a drainage basin

33 Interrelationships among climate, geology , soil, vegetation and animals.

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35 Biotic Provinces In 1876 Wallace suggested that the world could be divided into six biogeographic regions Referred to as realms Neartic, Neotropical, Palaeartic, Ethiopian, Oriental, and Australian

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37 Biotic Provinces In each major biogeographic area certain families of animals are dominant and fill ecological niches For example large herbivores North America - bison and pronghorn South America - capybara Australia - kangaroo Africa - giraffes and antelope

38 Biotic Provinces Wallace’s realms still valid and extend to all life forms A biotic province is a region inhabited by a characteristic set of taxa, bounded by barriers that prevent emigration and immigration.

39 Biotic Provinces W/in a realm
Species more likely to be related Evolved and adapted in the same place for a long time When a species introduced may be unrelated or distantly related to native species. Ecological and evolutionary adjustments are yet to take place. Introduced species may be superior competitor

40 Biomes Similar environments provide similar opportunities and similar constraints Leads to evolution of organisms similar in form and function Rule of climatic similarity

41 Biotic Province vs. Biome
A biotic province is based on who is related to whom An evolutionary unit A biome is based on niches and habitat If we know the climate we can make predictions about the biome

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43 Saguaro from North America
Example of Convergent Evolution- given sufficient time and similar climates species similar in shape and form will tend to occur Joshua Tree Saguaro from North America Euphorbia of East Africa

44 Ostrich from Africa Rhea from South America Emu from Australia Divergent evolution - population is divided and each evolves separately

45 Invasions, Invasive Species and Island Biogeography
Fewer species than continents Two new sources of species is migration and evolution Smaller the island the fewer the species The farther away from a continent the fewer the species

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47 Island Biogeography Small islands tend to have fewer habitat types
A small population easily wiped out by a storm, flood, catastrophe or disturbance The smaller the population the greater the risk of extinction The farther an island is from the mainland the harder it is to reach

48 Island Biogeography Islands tend to maintain consistent number of species over time. Result of the rate at which species added Minus rate at which they become extinct Concept applies to ecological islands A comparatively small habitat separated from a major habitat of some kind.

49 Biogeography and People
Biogeography affects biological diversity Changes in biodiversity affect people and resources Effects extend from individuals to civilizations

50 Biogeography and People
People alter biodiversity by Direct hunting Directly disturbing habitats Introducing exotic species into new habitats Introductions of exotics have mixed results Food sources, landscaping, pets Disastrous ecological consequences

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