chapter 7: biological diversity

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Chapter 7: Biological Diversity

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Chapter 7: Biological Diversity. What is Biological Diversity. Bio diversity refers to the variety of life forms in an area. Expressed as # of species in an area Or # of genetic types in an area. Biodiversity Definition: Variety of different species. Species Diversity : - PowerPoint PPT Presentation

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Page 1: Chapter 7: Biological Diversity

Chapter 7: Biological Diversity

Page 2: Chapter 7: Biological Diversity

What is Biological Diversity

Bio diversity refers to the variety of life forms in an area.– Expressed as # of species in an area – Or # of genetic types in an area

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Biodiversity Definition: Variety of

different species.

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Species Diversity:Number of different species and their relative abundances in a given area.

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Genetic Diversity: Variety in the genetic makeup of organisms of a species that allow the species to reproduce and gain a competitive advantage

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Ecosystem Diversity: The variety of forests, deserts, grasslands, oceans, lakes, etc.

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Why Should We Care About Biodiversity?

Use Value: For the usefulness in terms of economic and ecological services.

Nonuse Value: existence, aesthetics, bequest for future generations.

Figure 10-3

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Importance of Diversity Stability- stable environment Genetic reserves- genetic diversity Medicinal- medicines Agricultural- food Industrial- building homes; things we use Scientific- experimental; new technology Aesthetic- beautiful Ethical- what should we do regarding the

environment Religious- religious beliefs regarding

environment

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Biological Evolution New species arise as a result

– of competition for resources – the difference among individuals in

their adaptations to environmental conditions

Four processes lead to evolution– Mutation, natural selection,

migration and genetic drift

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Mutation Genes are inherited from one

generation to the next– Genes made up of DNA– DNA made up bases A,C,G,T

How these letters are combined determines the massage passed to a cell

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Mutation When cells divide

– DNA is reproduced – Each cell gets a copy

If an error occurs in the reproduction of DNA it gets passed to new cells

DNA change = Mutation

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Mutation

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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.

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Natural Selection Four primary characteristics

– Genetic variability– Environmental variability– Differential reproduction that varied

with the environment– Influence of the environment on

survival and reproduction

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Natural Selection The accumulation of changes may

lead to reproductive isolation– Resulting in a new species

Species = a group of individuals that can reproduce with each other.

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Migration and Geographic Isolation

Two populations become geographically isolated for a long time– Enough change accumulates so that

they no longer reproduce– Two new species have formed– Migration important evo process

(e.g. Hawaii honey creeper and Darwin’s finches)

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Adaptive Radiation Galapagos Islands

– Darwin observed numerous finches related to a single finch elsewhere

– Each with a different niche– Process called adaptive radiation

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Founder Effect and Genetic Drift

Founder effect– Small # of individuals are isolated

from larger pop. Less genetic variation than original pop Which characteristics present affected

by chance Genetic drift is changes in freq of

a gene simply by chance Ind may NOT be better adapted

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10 species; 100 ind, 87 elephants, 9 sp w/ 2 ind each

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10 species; 100 ind, 10 ind each species

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Species Diversity

Merely counting the number of species is not enough to describe biological diversity.

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The Evolution of Life on Earth

Earliest fossils 3.5 billion years old– Photosynthetic relative of bacteria– Released large amounts of oxygen

into the atmosphere

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The Evolution of Life on Earth

Cambrian Period 600 million years- 500 my

– Earliest multicellular organisms – Shells, gills, filters, efficient guts and

circulatory system.– Life remained in oceans

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The Evolution of Life on Earth

Innovations for life on land– Structural support– Internal aquatic environment– Means for exchanging gases with air– A moist environment for

reproduction system

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The Evolution of Life on Earth

Devonian Period– 420–360 million years ago– First animals on land =

crossopterygian– Gave rise to the amphibians

Still tied to water for reproduction Modern species include frogs, toads,

newts, limbless water “snakes”

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Early Life on Land

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The Evolution of Life on Earth

Reptiles– Freed from water by evolving a

watertight egg– Originate in the Carboniferous (375

mya)– Wide spread by the Jurassic (185

mya)– Two orders of dinosaurs that gave

rise to mammal and birds.

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The Evolution of Life on Earth

Mammals– More capable

brain and faster metabolism

– Placental uterus one key to mammalian success

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