BIO-111: Exam 1

Lectures 1-5

Science

An approach to understanding natural world; Based in observations, testable hypotheses, and experimentation/testing

Scientific Method

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Research

Hypothesis

Experiment

Analysis

Conclusion

Hypothesis

Testable and falsifiable statement accounting for a fact

Why must a hypothesis be falsifiable?

Not every hypothesis is correct

Conclusion

Scientist’s opinion of what the results mean; Must be supported by data and results of study

What does science produce?

Facts

Data

Explanations

Technology & Innovations

Fact

Info/data of the natural world

Scientific Theory

Well-tested and supported hypothesis; General enough to develop further over hypotheses

Data

Observations and measurements

Qualitative Data

Non-numerical; Defining and explaining the data

Quantitative Data

Numerical; Easily graphed and analyzed

Independent Variable

Factor being manipulated/changed (ex: mouse color)

Dependent Variable

Factor being measured; Results of the study (ex: predation rate)

Control

Variable that isn’t being tested on; Serves as a comparison group

Experiment

Variable that is being tested on; Used to find results

Mouse Experiment Observation

Same species of mice were found in different habitats with different color coats

Mouse Experiment Research

Learned that the natural predators of the mice are visual hunters

Mouse Experiment Hypothesis

The coloration evolved as adaptations that camouflage mice in their native environments, protecting them from predation.

Mouse Experiment Experimentation

Put inland mice in beach population and beach mice in inland population (controlled experiment)

Mouse Experiment Results

In the beach habitat, 26% of beach mice were predated upon & 74% of inland mice were predated upon. In the inland habitat, 76% of beach mice were predated upon & 24% of inland mice were predated upon

Mouse Experiment Conclusion

Mice that were camouflaged were predated upon less

Darwinism

Descent with modification

Occurs through natural selection

Happens over generation (individuals don’t evolve, populations do)

5 Theories within Darwinism

Perpetual change

Common descent

Multiplication of species

Gradualism

Natural Selection

Theory #1: Perpetual Change

Living world is neither constant nor perpetually cycling, it’s always changing

Modifications occur over generations throughout time

Is the underlying theory of the 5 theories

Evidence of Perpetual Change

Fossil record; Perpetual change is so well documented in the fossil record that it’s considered scientific fact

Theory #2: Common Descent

All forms of life descended from a common ancestor through a branching of lineages

Living things have ancestors and leave descendants

Phylogeny

Living things have ancestors and leave descendants

Evidence of Common Descent

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Comparative studies of living things

Using patterns of similarities and dissimilarities

Similar organisms have a more recent common ancestor than dissimilar organisms

Homology

Homology

Similarity in characteristics resulting from common ancestry; Allows us to classify organisms

Theory #3: Multiplication of Species

Speciation (occurs over hundreds of generations)

Speciation

A single (ancestral) population can split to produce two or more populations that become different from each other (and the ancestral population) with time

Geographic Speciation

Members of the same species that are unable to reproduce due to separation by a geographical barrier (ex: mountains, rivers)

Reproductive Speciation

Biological factors/barriers that impede two species from producing viable, fertile offspring

Example of Reproductive Isolation

Prezygotic barriers & postzygotic barriers

Prezygotic Barriers

Stops egg from being fertilized by sperm

Postzygotic Barriers

Is fertilized but isn’t viable or fertile

Evidence of Multiplication of Species

Diversification of animals on islands

Environments with different ecological opportunities

Darwin’s finches

Theory #4: Gradualism

Populations accumulate small changes over long periods of time

An accumulation of small changes may eventually lead to a large change

Origin of new species

An accumulation of small changes may eventually lead to a large change

Evidence of Gradualism

Should be able to find intermediate species in the fossil record (very rare)

Theory #5: Natural Selection

Individuals with some traits tend to survive and reproduce at higher rates than others due to those traits

Mechanism that explains why organisms appear to be designed to meet the demands of their environment

Populations accumulate favorable characteristics over long periods of time

Is a natural process

Produces adaptations

Adaptation

Populations accumulate favorable characteristics over long periods of time

Inherited characteristic

Enhances survival and reproduction in specific environments

Aren’t perfect, represent a compromise between traits

Organisms adapt to the environment in which they originated

Evolution is always one generation behind their environment

Fitness

An organisms ability to survive and reproduce

Artificial Selection

Process humans use to select for desired traits in crops, domesticated animals, and livestock

Done over generations

Darwin’s Postulates/Principles

Variation

Overproduction

Adaptation

Descent with modification

What must be true for natural selection to occur?

All four principles must apply in order for natural selection to occur

Principle #1: Variation

Individuals within a population differ in their inherited traits

Principle #2: Overproduction

More offspring are produced than can survive which leads to competition

Principle #3: Adaptation

Some individuals survive longer and reproduce more than others due to advantageous traits

Principle #4: Descent with modification

The traits of individuals that survive and reproduce will become more common in a population

Differential Survival

Differential Reproduction

Differential Survival

Individuals with favorable trails will survive better than individuals with less favorable traits

Differential Reproduction

Individuals with favorable trails will reproduce more offspring than individuals with less favorable traits

Differential Survival + Differential Reproduction =

Natural Selection

On what or whom does natural selection operate?

Operates on individuals

“Survival of the fittest”

Less fit aren’t eliminated they just don’t survive and reproduce as well as the more fit

Who or what evolves?

Populations evolve

Population

Same species in the same place at the same time

Can natural selection fashion the perfect organism?

NO

Natural selection can only act on existing variations

Evolution is limited by historical constraints

Adaptations are often compromised

Chance events can affect evolutionary history of populations

When an environment changes, populations will either…

Adapt

Disperse

Go extinct

Taxonomy

The method of grouping, naming, and ordering/arranging living things

Taxonomy as a Human Characteristic

The desire and ability to name, group, and order living things is part of what makes us human; It’s important to differentiate between things

Folk Taxonomies

Various ways people of different culture and geographic regions name, group, and order living things

Based on similarities and differences

Recognizes the same groups of animals and plants

Folk taxonomy doesn’t include names for…

Really small living things (tiny insects, bacteria)

Organisms with differences too small for the human eye

Organisms not encountered (found on ocean floor)

Taxa

Hierarchy of categories

Hierarchies of Classification

Groups of organisms within groups

Shared common ancestry and traits

That distinguish from other groups

**D**ear **K**ing **P**hilip **C**ame **O**ver **F**or **G**ood **S**oup

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

Classification is…

SUBJECTIVE

Happens at all levels

“Lumpers” vs “Splitters”

People are biased

Definitions based on different species concept

Species

A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring

Niche

Sum of how a species interacts in the world with living and non-living parts of the environment

Common Names

Everyday names

Scientific Names

Derived from Latin

Why are scientific names necessary?

Common names are misleading

Many species have more than one common name

Multiple species can have the same common name

Many organisms don’t have common names

Karl Linne

Swedish physician and naturalist that created the binomial system (two word names in Latin) that we use today

Binomial Nomenclature Rule #1

Species name = genus name + specific epithet (ex: Loxodonta africana)

Binomial Nomenclature Rule #2

Genus and specific epithet are italicized if typed and underlined if handwritten

Binomial Nomenclature Rule #3

Genus is capitalized, specific epithet is not

Binomial Nomenclature Rule #4

Can use genus name alone, but not the specific epithet

Binomial Nomenclature Rule #5

Can abbreviate genus once mentioned

How is the five-kingdom system classified?

Cell structure

Cell association

Mode of nutrition

Prokaryotic Cell

No nuclei or organelles

Eukaryotic Cell

Have nucleus and other membrane bound organelles

Unicellular Cell

Composed of a single cell

Multicellular Cell

Composed of many (connected) cells

Autotroph

Make their own food (photosynthesis)

Heterotroph

Need to eat other organisms

Heterotroph by Digestion

Digest inside their body (ex: humans)

Heterotroph by Absorption

Digest outside their body (ex: fungi)

Photosynthesis

Process by which an organism uses sunlight to make food

Respiration

A metabolic process by which organisms gain energy and release waste

Three Domains System

Bacteria

Archaea

Eukarya

Phylogenetic Tree

A branching diagram that illustrates the evolutionary history of a group of organisms

Prokaryotic Cell Structure

Unicellular

No nucleus

No membrane enclosed organelles

DNA is circular

Three Common Shapes of Prokaryotic Cells

Cocci (spherical)

Bacilli (rod-shaped)

Spirilla (spiral)

Cell Colonies

Mass of individual bacteria cells

Began with a single cell

Appearance can be helpful in identification

Binary fission

Ring of DNA replicates and the cell pinches in two

Capsule

Sticky layer of protein or polysaccharide (carbohydrate) that surrounds the cell wall

Cells can adhere to one another or to a substrate

Protect against dehydration

Fimbriae

Hair-like appendages

Allow cells to stick to another or to a substrate

Endospore

Protected copy of chromosomes

Resistant to drying, heat, acids, even some disinfectants

Can survive for decades or centuries

Nutritional & Metabolic Adaptations

Aerobic

Anaerobic

Facultative

Aerobic

Needs oxygen to survive

Anaerobic

Poisoned by oxygen