1st semester Ecology

The study of the interactions between an organism and its biological and physical environment.

Ecology

Darwin Evolution: levels of biological sphere for ecologist

Organism. Population, Community, Ecosystem, Biosphere.

Levels of Biological organism

Atoms/Molecules, Cells/Organelles, Organs/Systems,

All life has…

DNA

Energy flow

A unidirectional and noncyclic pathway. All energy comes
from the sun, and some energy is lost in each transfer.

Nutrient cycle

The movement of inorganic and organic matter back
into the production of other matter. The movement is cyclic.

“Nothing in Biology makes
sense except in light of…

Evolution’’

How do we organize the Diversity of Life ?

Two big groups are prokaryotes versus eukaryotes.

Accounts for the
Unity and Diversity of Life

Evolution

Paramecium are ________ in the SAR clade

Eukaryotes

An Example of Unity Underlying the Diversity of
Life:

The Architecture of Cilia in Eukaryotes

What is adaptive radiation?

A Group of related organisms form many new species whose adaptations allow them to fill different ecological roles.

For the ancestral state: ___ digits at terminus of limb, similar between insects and humans.

5

What is the nature of science?

• Scientists study nature.

• Scientists make observations and form and test hypotheses.

Scientific Method

Observation, Question, Testable Hypothesis, Experiment, Data Collection/Analysis, Interpretation, Final Hypothesis Supported and Theory.

A tentative answer to a well framed question.

Hypothesis

‘‘A bottom-up approach’’ Takes a number of specific observation and forms generalizations.

Inductive reasoning

Inductive reasoning examples

‘‘A fire ant stung me’’ it is a hymenopteran

‘‘This wasp stung me’’, It is a hymenopteran

(All hymenopterans have stingers)

Uses available information to make valid conclusion

Deductive reasoning

Example of Deductive reasoning

‘‘This bee is hymenopteran’’, it could sting me

‘‘This wasp is a hymenopteran’’, it could sting me

‘‘If it is raining the ground will be wet’’

Inductive or Deductive reasoning ‘‘I have trouble sleeping at night’’

Inductive

Inductive or Deductive reasoning ‘‘Therefore, I should avoid stimulants close to bedtime.

Deductive

Manipulate one factor, see effect of changing it

Experimental Study

Record observations. Analyze data for correlations. Infer causation.

Observation Study

Theories in Science

A theory is broader in scope than a hypothesis, it can lead to new testbale hypotheses and supported by a large body of evidence in comparison to a hypothesis.

What are some important Theories?

Evolution Theory, Germ theory of disease and Cell theory.

What level of inquiry would look at the number of Hemlock Woolly Adelgid and the timing of their hatch?

Population Ecology

What level of inquiry would assess hemlock mortality across the northeastern U.S.?

Landscape Ecology

What level of inquiry would look at how Hemlock Woolly Adelgid impact the growth of an eastern hemlock tree?

Community Ecology

The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

Evolution

(Every biological entity, from cell membrane to
ecosystem, is a product of evolution)

(Most important unifying principle in Biology)

GGC (DNA) —→ RNA—→ Proline (an amino acid)

Universal genetic code

Theory of Natural Selections

More individuals are produced than can survive

Following a prolonged drought on the Galapagos island of Daphne Major, the finch population was found to have a higher frequency of individuals with deep, strong beaks than before the drought. Which statement about the beak size of finches on the island of Daphne Major during the drought is true?

• A. Each bird evolved a deeper, stronger beak as the drought persisted.

• B. Each bird’s survival was strongly influenced by the depth and strength of its beak as the drought persisted.

• C. Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation.

• D. The frequency of the strong-beak genes increased in each bird as the drought persisted

B. Each bird’s survival was strongly influenced by the depth and strength of its beak as the drought persisted.

What Darwin Did Not Know

The underlying source of variation

Source of variation

Rules of inheritance

Mendel: believed in blending inheritance

Which of the following examples of an ecological effect leading to an evolutionary effect (natural selection) is most correct?

• A. When seeds are not plentiful, trees produce more seeds. • B. A few individuals with denser fur survive the coldest days of an ice age, and the reproducing survivors of the ice age will likely have more dense fur.

• C. Fish that swim the fastest in running water catch the most prey and more easily escape predation.

• D. The insects that spend the most time exposed to sunlight have the most mutations.

B. A few individuals with denser fur survive the coldest days of an
ice age, and the reproducing survivors of the ice age will likely have
more dense fur.

384-322 BC: Aristotle (Greek) – scala naturae

• Arranged life forms on ‘ladder’ of increasing complexity with humans on top

• Consistent with Old Testament account of creation

1707-1778: Carolus Linnaeus (Swedish)

Nested classification and
naming system (binomial: Homo sapiens)

1726-1797: James Hutton (Scottish

Geologist, proposed theory of uniformitarianism or gradualism

1744-1829: Jean-Baptiste de Lamarck (French

Proposes theory of evolution: Inheritance of acquired characteristics; use and disuse (giraffe)

1769-1832: Georges Cuvier (French)

Studied patterns in vertebrate fossils, described extinctions, founded paleontology

1797-1875: Charles Lyell (British)

Geologist; same geologic processes are operating today as in the past; wrote Principles of Geology

• Physical evidence did not support the traditional view that Earth was only a few thousand years old (one of the first to believe Earth is >300 million years old

1809: Charles Darwin is born

English

1831-1836: Darwin travels around the world on

HMS Beagle

1844: Darwin writes essay on

descent with modification

1858: Alfred Russel Wallace (British

Sends Darwin his hypothesis of natural selection

1859: Darwin publishes On the

Origin of Species

Charles Robert Darwin
(1809 – 1882)

• 22 yrs old

- 5 year voyage on Beagle

• 1844 (35 yrs old)

- 1st essay on natural selection

• 1858 (49 yrs old) - letter from Alfred Wallace

Key observations from Darwin

1. Many shared characteristics of life

2. Rich diversity of life

3. Striking ways in which organisms are suited for life in their environments

Earth’s many species are descendants of ancestral species, and that species are modified, or change, through time

Descent with modification

Inherited characteristics of organisms that enhance their survival and reproduction in specific environments

Adaptation

As observed by many scientists prior to Darwin

• Biology, geology, physics, and chemistry

The pattern of evolution

The ideas of Darwin and Wallace were revolutionary because they proposed a mechanism for change over time

Process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits; descent with modification

Natural Selection

What Darwin proposed in “The Origin”

1. Historical Evolution - Species evolve, share common ancestry - Now accepted as fact

2. Mechanism - Natural Selection - a “theory” - What is a theory?

In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to increasingly colder temperatures throughout their life span, would eventually give rise to more cold-tolerant winter wheat. Lysenko’s attempts in this regard were most in agreement with the ideas of:

• A. Cuvier

• B. Lamarck

• C. Darwin

• D. Lyell

B. Lamarck

The figure shows an outcrop of sedimentary rock whose strata are labeled A-D. If x indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum? •A.

•B.

•C.

•D.

C

Change in the genetic composition of a population from generation to generation

Evolution

“descent with modification”

Charles Darwin

Natural selection is the mechanism of change

Charles Darwin and Alfred Russel Wallace

How does natural selection work?

Heritable variation exists among individuals in a population

Individuals make many more offspring than the environment can support

Individuals that are well suited to their environment tend to survive better and produce more offspring

Over time favorable traits accumulate in the population

• Evolution leads to adaptation within a population or species

Nature selects which individuals will survive and
breed (This is not a chance event)

Natural selection

After the drought of 1977, researchers hypothesized that on the Galapagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?

•A. Evolution of yet larger, deeper beaks over time, until all birds have relatively large, deep beaks.

•B. Evolution of smaller, pointier beaks over time, until all birds have relatively small, pointy beaks.

•C. Increased variation in beak size and shape over time.

•D. No change in beak size and shape over time

After the drought of 1977, researchers hypothesized that on the Galapagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?

• A. Deeper beaks C. Increased variation in beaks

• B. Pointier beaks D. No change in beaks

C. incresed variation in beaks

Evidence for Evolution

1. Direct observations of Evolutionary Change

1. Recently introduced species exhibit selection

2. Drug resistant bacteria

3. Artificial Selection: Vegetable breeding, Dog breeding

2. Homology

1. Anatomy

2. Embryos

3. Vestigial Structures

4. Genetic Code: DNA, RNA

5. Genes

3.Fossil record

4.Biogeography

Evolution of drug resistant bacteria

• Natural selection does not create resistant pathogens, it selects for resistant individuals that are already present in the population

• MRSA = methicillin-resistant bacteria, causes “flesh-eating disease” caused by Staphylococcus aureus.

Artificial Selection

Humans select which individuals will survive and breed. Just have to consistently pick criteria.

The cow Bos primigenius (which is bred for meat and milk) has a smaller brain and larger eyes than closely related wild species of ungulates. These traits most likely arose by

A. natural selection, because these traits evolved in the population over time.

B. natural selection, because these traits were not consciously selected by humans.

C. artificial selection, because changes in these traits co- occurred with human selection for high milk output and high muscle content.

D. artificial selection, because these animals differ from their close relatives and common ancestor.

C. artificial selection, because changes in these traits co- occurred with human selection for high milk output and high muscle content.

Homology

Similarities resulting to common ancestries

Human limbs vs whale flukes

Seen in embryos

Convergent Evolution

Similarities with animals who are different species

Biogeography

The study of the geographic distribution of species

You are raising a stock of Drosophila flies, and when each individual hatches out you clip off its wings. Assume this treatment does not disrupt their later mating success and they go on to produce new generations, in each of which you continue the clipping process. By the end of 50 generations, what would you most expect to observe in the last generation of flies as they were hatched out?

A. All flies would be born without wings.

B. All flies would be born with wings.

C. Many flies would be born without wings.

D. The size of the wings would decrease from the first to the 50th generation.

B. All flies would be born with wings

Microevolution

A change in allele frequencies in a population over generations

Gene

Unit of heredity that is transfered from a parent to offspring

Locus

The location of a gene(or a significant DNA sequence) on a chromosome

Allele

Any one of two or more genes that may occur alternatively at a given site (locus) on a chromosome.

Genotype

A combination of alleles situated on corresponding chromosomes that determines a specific trait

Phenotype

The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment

Genetic Variation

Makes evolution possible,