BIO 160 - Unit 1

What is Science

What is Science

pursuit and application of knowledge and understanding of the natural and social world following a systematic methodology

The Scientific Method

1. Observation/questioning

2. research

3. hypothesis

4. experiment

5. analysis

Characteristics of living

• highly ordered structure

• reproduction

• response to external environment

• growth + development

• homeostasis/regulation

• energy utilization

• evolutionary adaptation

Taxonomic Levels

Darn King Phillip Came Over For Good Sushi

• domain

• kingdom

• phylum

• class

• order

• family

• genus

• species

Evolution

Descent with modification. All present organisms are related to ancestors in the past through descent.

Changes in the population’s genetic makeup over time.

• we all have a common ancestor which is bacteria

Species

Can MATE and produce VIABLE offspring

Population

All individuals of a single species that live in the same area at the same time

Evolution Results in…

• result of changes in allele frequencies within a population

• works at the population level over generations

• evolution reflects adaptations of organisms

genetic trait

specific characteristics of individuals

Gene

segments of DNA on a chromosome that confer a genetic trait

Allele

a variation of a gene

haploid

1 copy of each chromosome

diploid

2 copies of each chromosome from 1 parent

homologous pair

look a like, but genes could have different alleles (one from mom and one from dad)

chromatids

arms of the chromosomes

sister chrmatids

exact copies of chromosome

centromere

thing that holds chromosome together

Cell Cycle

• G1

• S

• G2

• M

interphase

• during interphase the cell is doing regular cell functions

• this is the longest part of the cell cycle

Mitosis

• Prophase

• Metaphase

• Anaphase

• Telophase

• Cytokinesis

Prophase

• Nucleus breaks down

• chromosomes divded

• making spindle fibers

Meiosis

• goal: diploid —> haploid

  • reduction process

mitosis vs meiosis

• meoisis:

  • 4 NOT SAME cells

  • haploid

  • results in new gametes

• meitosis:

  • 2 SAME cells

  • diploid

  • results in new somatic cells

independent assortment

refers to the movement of chromosomes independent of one another during meiosis

Genetic Variation

The process of crossing over and independent assortment increases genetic variation within a population

Why is evolution considered a theory?

Because it is an Idea that is evolving based on new data

Theory

A well-substantiated explinatio of an aspect of the natrual world that can incorporate laws, hypotheses and facts

Scientific Law

Describes what happens

• ex) F=MA ; E=MC²

Scientific Theory

Explains why or how it happens

Scientific Law and Theory

Both based on hypothesis and can be used to make predictions. Can be revised.

what do mechanisms of evolution do for a population?

All mechanisms contribute to changes in allele frequencies

What determines fitness?

• Survival

• Number of offsprings

Genotype

Refers to the combination of alleles

• ex) EE, Ee, ee

Phenotype

refers to the physical characteristics

• ex) free or attached earlobe

Allelic Frequency

How often EE or Ee or ee appears

Mechanisms of Evolution

• natural selection

• gene flow

• genetic drift: bottle neck vs founder

• mutations

• non-random mating

• sexual selection

• random event

Mutation

Change in DNA sequence that leads to genetic variation.

• mutation rates for most organisms is pretty low

Non-random mating

Species will mate based on a particular genotype.

• ex) sexual selection

sexual selection

when (usually females) chose certain individuals with certain alleles and they are more likely to successfully mate than other individuals with different alleles.

what does sexual selection lead to?

sexual dimorphism

sexual dimorphism

when the males and females of a species have different phenotypes

• males usually more colorful and flashy

natural selection

a process where organisms with traits that better suit their environment are more likely to survive and reproduce, passing on those advantageous traits to their offspring, leading to a gradual change in the characteristics of a population over generations, also known as evolution

• a specific pressure pushing allelic frequency

How is fitness measured

by how many offspring that you can produce during your lifetime

4 principles of evolution and natural selection

• overproduction of offspring

• variation

• adaptation

• selection

overproduction of offspring

accounts for death of some offspring before they can reproduce

variation

due to mutations and random genetic variation

adaptation

some individuals in a population have a trait that makes them better able to survive

selection

organisms with beneficial adaptation more like to reproduce and pass on genes

evidence in support of natural selection

• those who have better-suited traits will pass them onto the next generation

• traits can change over time, leads to new species

• (natural selection is a theory)

microevolution

• small changes in allel frequency

• occurs with a speices or population

• occurs in a relatively short frame

• observable

• testable

macroevolution

• large changes in allele frequences

• produces a new species

• occurs over long periods of time

• evidence is often in fossils, hard to observe during the time of human life

Adaptive radiation

an evolutionary process where a single ancestral species rapidly diversifies into many new species, each with different adaptations that allow them to occupy various ecological niches within a given environment, often triggered by the environment

• creates ecological niches

What do populations NOT do

they are NOT moving towards a final state of perfection, but more fit and adaptation to enviornment

what changes the frequency of an existing allele in the population?

random chance

Genetic drift

a random change in the allelic frequency

• more likely to occur in small populations

fixed allele

all but one allele disappears for a gene

• the top allele and there is that only one allele

• can cause rare alleles to become much more frequent (even fixed)

bottle neck effect

sudden reduction in the number of alleles in a population

natural selection vs genetic drift

natural selection: selective pressure

genetic drift: due to chance

Why does little genetic diversity matter?

No genetic diversity could lead to a population going extinct because a pathogen that can kill one individual of the population might be able to wipe them all out because there is no genetic variability in levels of resistance

founder effect

the change in frequency of an existing allele in the population due to random chance. A small group of individuals from a larger population establishes a new population with reduced genetic diversity.

ex) Amish populations: the increased rate of Ellis-van Creveld syndrome among the Amish community in Pennsylvania due to their small founding population and practice of marrying within the community

gene flow

movement of individuals and genetic material they carry from one population to another.

gene flow vs founder effect

a founder effect occurs when a small group of individuals from a larger population establishes a new population with reduced genetic diversity, while gene flow involves the movement of genes between existing populations, often increasing genetic diversity within those populations

What happened during the galapagos islands?

• experiances macro evolution

• gene flow was present

  • one bird from the main island flew to the other smaller island and brought its genes to that population. Ever since, it has reproduced and created new species of birds (this is why it is macro evolution: new species evolved)

what explains evolution?

speciation explains how evolution happens

speciation

the process by which one species splits into two.

Species concept

a working definition of a species and/or a methodology for determining whether or not two organisms are members of the same spices

• biological

• morphological

Limitations of the biological species concept

• Asexual species

  • “are they still a species if they can’t reproduce??”

    • ex) bacteria

• Extinct forms of life not included

• Interbreeding is not always known

  • ex) horses + donkeys = mules

limitations of morphological species concept

the potential to interbreed is not considered

• if they don’t interbreed, its just a different spices who look a like

The process of speciation

• some type of barrier restricts gene flow

• one population starts to genetically diverge

• period (hybrid zone) when the 2 populations can mate and create hybrids

hybrid zone

when the populations can mate and create hybrids

2 methods of speciation

Allopatric and Sympatric

Allopatric

The formation of new species in populations that are geographically isolated from one another.

has to have: geographic barrier

• could be because of bottle neck effect

sympatric

formation of new species in population that live in the same geographic area

• also random event

Reproductive Barriers

Pre-zygotic barrier: prevents fertilization

Post-zygotic barrier: prevents embryo from developing normally

Prezygotic barriers

• habitat isolation

• temporal isolation: time based (different mating seasons)

• behavioral isolation

• mechanical isolation: physical differences in re-productive organs

• genetic isolation

postzygrotic barriers

• offspring are not viable

• offspring are infertile

Patterns of evolution

Divergent evolution vs Convergent

divergent evolution

species that evolve in diverse directions from a common ancestor

convergent evolution

similar traits evolve independently in species that do not shre a recent common ancestry

Who came up with Taxonomy

Carolus Linnaeus

Taxonomic Levels

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

• Levels get increasingly specific from Kingdom to Species

3 Domains

1. Bacteria

2. Archaea

3. Eukaryota

Both bacteria and Archaea DONT have nucli

Phylogenetics

Study of the evolutionary pathways and connections among organisms

Phylogenetic tree

a diagram used to reflect evolutionary relationships among organisms or groups of organisms

• they are considered hypotheses

parsimonious

the least amount of characters on a phylogenetic tree

Homologous

• Same ancestor

• same features

• DIFFERENT FUNCTIONS

Analogous

• different ancestors

• different features

• SAME FUNCTION

Prokaryotes

16s RNA

Eukaryotes

18s RNA

Basal taxa

common ancestor for sister taxa

sister taxa

evovled from their common ancestor, the basal taxa

Bias in Taxonomy

• Taxonomical

• location

• collector

• fossil

taxonomic bais

the bias that we study organisms that we care about the most. (Studying one species more than others)

Location bias

bias that study organisms that are closest to us

collectors bias

the effect of a collector's recording preferences on the overall composition of a biological collection.

• Most of the data that we get from the past was originally from somewhere else but colonialism drove identifying and naming species in another direction

• colonialism lead to species finding as bais

fossil bias

study based on fossils that we can find

• ex) we don’t have jellyfish fossils, so jellyfish are not studied

Monocots

• Veins usually parallel

• floral parts usually in multiples of 3

Dicots

• veins usually net like

• floral parts usually in multiples of 4 or 5

How germination works

1. imbibition of water

2. hrmone Gibberellic Acid stimulates the production of the enzyme Amylase

3. Amylase catalyzes the breakdown of starch into sugar

4. embryo uses the glucose for the growth = germination

How do plants grow?

Trees will grow horizontally

ex) the initials will stretch