Biology: Evolution and Biodiversity Concepts

Unit 1: Evolution and Biodiversity

• Evolution, phylogenetic trees, evolution of populations, origin of species, and history of life are discussed
• Biodiversity of bacteria, archaea, protists, fungi, and plants are included

Show and Tell

• A photo of a praying mantis on an orchid is shown

Today's Topic: Evolution- Descent with modification (Ch. 22)

• The topic is evolution, specifically descent with modification
• Images of ladybugs and a collage of various insects are included
• Chapter 22 is highlighted

Synopsis for today

• Understanding patterns in biodiversity
• Explaining natural and artificial selection
• Understanding evolution

Evolution: descent with modification

• The Darwinian revolution challenged traditional views of a young Earth.
• Descent with modification by natural selection explains the adaptations and unity/diversity of life.
• Evolution is supported by overwhelming evidence including the fossil record, homologies, direct observations, and molecular DNA data.

What is Biodiversity?

• Biological diversity is the variation of life at all levels of biological organization
• Biodiversity refers to the total of life forms across an area, including the range of differences between those forms
• It encompasses genetic diversity within populations and variety of ecosystems globally.

Biodiversity and Human Health

• Health is defined as complete physical, mental, and social well-being
• Biodiversity is critical to ecosystem functioning and essential to human health & well-being
• Biodiversity and human health are interlinked

Soil Biodiversity & Human Health

• Soil biodiversity is often negatively impacted by poor land management and climate change
• Important for human health via pest and pathogen control, nutritious food, and clean water/air

Observations About Biodiversity

• Rich biodiversity exists in nature with varied patterns, and shared characteristics
• Organisms are suited to local environments
• Variations in organisms, such as body size, bill size, bill shape, diet, and vocalizations, are seen

Observation About Biodiversity

• Shared characteristics among different species demonstrate the unity of life
• Different species show differing characteristics, such as size, shape, and color

What is Evolution?

• Evolution is defined as change in genetic composition (allele frequencies) of a population over generations.
• Variation in traits is associated with evolution.
• Populations are the smallest entities capable of evolving and changes occur over time

What Is Evolution?

• Evolution is viewed as pattern (& process)
• Scientific data reveals life's evolution over time
• Mechanisms cause these evolutionary changes

Evolution: Fact or Fiction?

• Natural selection causes population changes over time via allele frequency changes.
• Written and geological records have shown changes in organisms over time.
• Change in allele frequencies over time lead to changes in phenotypic frequencies.
• Mechanisms of evolution in events are still discussed and investigated

EVOLUTION

• Evolution is a fact with well-established general mechanisms
• Mechanisms are still being studied and debated with new models beyond traditional views
• Evolution and religion/spirituality are not mutually exclusive

Origins of Evolutionary Theory

• Plato and Aristotle believed in an unchanging linear ladder of life with humans at the top.
• Natural theology (1700s-1800s) sought to understand the creator's plan through nature, with Linnaeus contributing binomial nomenclature.

Origins of Evolutionary Theory

• Georges Cuvier, a paleontologist, observed extinctions and proposed catastrophism.
• James Hutton and Charles Lyell - proposed gradualism and uniformitarianism, supporting the Earth's great age

Origins of Evolutionary Theory

• Fossils of extinct taxa are found in a consistent order in strata from older to younger

Origins of Evolutionary Theory

• Darwin, influenced by geologists, recognized the Earth's vast age and slow processes of change.
• Darwin observed diverse species around the world
• Darwin developed observations related to Malthus's population growth

Origins of Evolutionary Theory: Lamarck

• Individuals match environments with acquired traits but do not pass traits to offspring
• Organisms have a drive for more complexity, which is untrue
• Traits change due to use and disuse

Voyage of the Beagle (1831-1836)

• Charles Darwin's voyage on the HMS Beagle

Galápagos Finches

• Varied beak shapes match varied food sources
• Beak shapes are inherited adaptations to promote survival and reproduction, a result of natural selection for suitable traits

What is Fitness?

• Fitness is the contribution of an individual to the gene pool of the next generation based on other individuals
• The fittest individual has the highest proportion of alleles in future generations
• Individuals who reproduce but die young can still have high fitness

Adaptations

• Inherited traits assisting individuals in survival & reproduction, enhancing fitness are adaptations.
• Examples include salt-limiting glands, oil-secreting glands, streamlined bodies, and webbed feet.

Descent With Modification

• Common ancestor for elephants and hyraxes is shown on the tree diagram.
• Extinct species are labeled.
• Extant (living) species are listed together with ages (time from common ancestor)

Natural Selection: Darwin

• Traits vary within populations
• Traits are inherited from parents
• Species commonly produce more offspring than the environment can sustain
• Limited resources lead to death among many offspring

Inferences From Darwin's Theory

• Individuals inheriting traits for higher survival/reproduction tend to have more offspring
• This unequal ability will lead to increased presence of beneficial traits within populations

Natural Selection

• Examples of canine species and their ancestral connections over millions of years illustrate natural selection.

Evolution by Natural Selection

• Traits vary within a population
• Traits are inherited from parents to offspring
• Individuals differ in reproductive output

Artificial Selection

• Artificial selection differs from natural selection
• How artificial and natural selection are similar

Natural Selection: Key Points

• Individuals do not evolve, but populations do.
• Natural selection acts on heritable traits (acquired traits are not heritable).

Natural Selection: Key Points

• Favorable traits depend on environmental context
• Natural selection is not goal-directed

Is this statement correct?

• The statement "Lions evolved big teeth in order to kill and eat big prey" is incorrect

There is no "goal"

• Natural selection works through differential survival/reproduction of individuals with suitable traits

Instead, think…

• Big teeth are a predominant trait in lion populations due to increased fitness
• Variation in teeth already existed and natural selection favored increased size

Do antibiotics cause bacteria to become resistant?

• Antibiotics do not cause antibiotic resistance but rather select for those bacteria already harboring resistance mechanisms.

Environmental Change & Evolution

• Environmental change can lead to evolution through natural selection when favorable traits are favored.
• If food sources change from balloon vine to goldenrain tree, bugs with beaks adapted to the goldenrain tree seeds will have a greater chance of survival and reproduction.

Environmental Change & Evolution (continued)

• How beak length has changed can be explained through natural selection

Theory of Evolution

• Evidence for evolution: observed patterns and hypothesized mechanisms
• Theories are rigorously tested unifying concepts; still subject to revision based on new evidence
• Evolution is the unifying theory in biology

Evolution: descent with modification

• The Darwinian revolution contested the traditional idea of a static earth with unchanging life.
• Descent with modification via natural selection explains the adaptations and diversity of life.
• Evidence supporting evolution is extensive encompassing the fossil record, homologous structures, direct observations, and molecular (DNA) data.

Next: The Evolution of Populations & Origin of Species

• Evolution involves changing allele frequencies in a population over time, as illustrated by changing mouse population distributions