Biology 2018 Exam 1

Made from Chapter 19,20, 21, 22, 24, 25

strata

Compressed layers of mud and rock in sedimentary rock

Lamark’’s Theory of Evolution

Use and Disuse

• parts of the body that are used to become larger and stronger, while the ones that aren’t deteriorate

Inheritance of Acquired Characteristics

• organisms can pass these modifications to its offspring, since they have an innate drive to become more complex

these theories are false!

Darwin’s Branching Tree

branch tips: present day species

unlabeled branches: extinct groups

each fork: most recent common ancestor

Darwin’s Theory of Evolution

• Organisms share many traits, showing a unity of life through a common ancestor

• As descendants spread to different environments, they accumulated adaptations

Artificial Selection

Humans have modified other species over many generations, selecting and breeding the most desirable traits

Homology

similarities resulting from a shared common ancestor

Homologous Structures

The same structure resulting from a shared common ancestor, but with different functions

• forelimbs in mammals (wings, arms, etc)

Vestigial Structures

remants of features that served a purpose in an organisms ancestors

• wisdom teeth

Convergent Evolution

evolution of similar featuresin different lineages

• sugar gliders and flying squirrel

Analogies

animals that have both adapted to their environments in similar ways and are said to be…

Fossil Record

fossils show that past organisms differed from living organisms

• also shows that many organisms have become extinct

• and that many species have evolved over time

• and that they document the origin of major new groups of organisms

Binomial Nomenclature

the two part format of the scientific name of an animal

• the first part is the name of the Genus ( and is capitalized

• the seond part is the specific epithet (and both parts are italicized)

Specific Epithet

The unique name for each species within a genus

Taxon

the named unit at any level

Phylogenic Tree

The evolutionary history of a group’s organisms depicted in a branching diagram

• depicts a hypothesized evolutionary relationship using two way branch points

Dichotomies

two way branching points

Sister Taxa

Groups of organisms sharing an immediate common ancestor

Evolutionary Lineages

sequences of ancestral organisms leading to a particular descendant taxon

• the order in which taxa appear does not represent the sequence of evolution

• all phylogenic trees are rooted, meaning a branch point represents the most recent common ancestor of all taxa in the tree

Basal Taxon

the lineage that diverges from all members of its groups the earliest

Cladistics

System of grouping common ancestors

• places species into groups called clades, which includes the ancestor and all descendants

Clades

Basic unit of grouping species

Monophyletic Groups

Has ancestral group plus all its descendants

• this is a clade

Paraphyletic Group

Has ancestral group and some, but not all descendants

Polyphyletic Groups

Includes descendants, but no common ancestor

Cladogram

The nested hierarchy of clades within clades

Synapomorphies

The shared derived character that is unique to a clade

Shared Ancestral Character

A characteristic derived from an ancestor older than the common ancestor

• ex: backbone in mammals

Outgroup

a species from a lineage close enough but not distinctly related to other animals in a group called the ingroup

Proportional Branch Lengths

In some tree diagrams, branch lengths are proportional to the amount of evolutionary change or length of time since particular events occur

• the cladogram has a timeline below it

Maximum Parsimony

Principle that states that the simplest explanation is consistent with the facts

Molecular Clocks

Method for estimating the time for a given amount of evolutionary change

• assumes that the number of genetic differences between two species is proportional to the time since they shared a common ancestor

  • not exactly accurate

Evolution

Changes in the genetic makeup of a population over time

• adaptations to environmental pressures

• changes in allele or genotype frequency

Population

Interbreeding members of the same species living in the same geographic area

• united by its gene pool

Hardy-Weinberg Equilibrium Conditions

the allele and genotypic frequencies will remain constant if the population...

• is large

• mates at random

• has no mutations

• has no natural selection

p and q in the hardy-weinburg

the two possible alleles at a particular locus

p² and q² in Hardy-Weinberg

the frequency of the homozygotes genotype

2pq in Hardy-Weinberg

The frequency of the heterozygote genotype

Macroevolution

Evolution occurring above the species level, including the origination, diversification, and extinction of species over long periods of evolutionary time

Microevolution

evolution occurring within populations; changes in allele frequency from one generation to the next

Mutations

The ultimate source of heritable genetic variation within a population

• they are rare, but occur at a steady rate

• occur randomly all over the genome

• caused by various types of errors in the nucleotide sequences of DNA

  • Mutations in the germline are the only ones that get passed down to its offspring

Genetic Variation

Increases with sexual reproduction

• does not guarantee that a population will evolve

Species

Groups of actually or potentially interbreeding natural populations that are reproductively isolated from other groups

• common descent

Hardy Weinberg Equilibrium

Describes the genetics of non-evolving populations

• used to disprove the null hypothesis that evolution does not exist

Genetic Drift

Changes in allele frequencies of a gene pool due to random meeting of gametes in fertilization’

• effect is greater in smaller populations

• there are two types!

Bottleneck Effect

When a catastrophe occurs that wipes out a bunch of the population, and the remaining population (a tiny fraction really) has much lower genetic diversity.

Founder Effect

A type of bottleneck that occurs when a small group of the population leaves and forms their own colony

Natural Selection

The only force that consistently produces adaptive evolutionary changes

Three criteria:

• Variability for a trait

• Heritability of that trait

• Differential reproductive success based on that trait

  • REMEMBER: It has no goal.

Sexual Selection

Selection for traits that increase access to mates and reproductive success

Two types:

• Intrasexual: Occurs between members of the same sex

• Intersexual: Mate choice by members of the opposite sex

Prezygotic Barriers

blocks fertilization from occurring in 1 of 3 ways:

• impeding members of different species from attempting to mate

• preventing an attempted mating from being completed successfully

• hindering fertilization if mating is completed

Postzygotic Barriers

Barriers that contributes to reproductive isolation after hybrid zygote is formed

• reduced hybrid viability

• reduced hybrid fertility

• hybrid breakdown

Allopatric Speciation

Once physically separated, gene flow between the two steps and divergence begins

• leads to adaptive radiation

• and co-speciation

Adaptive Radiation

Explosive form of speciation leading to the formation of many new species

Co-Speciation

Occurs when two species that associate with each other speciate in response to each other and at the same time (Host-parasite)

Sympatric Speciation

individuals within a species that become specialized due to habitat differentiation, sexual selection, and polyploidy

• in plants, it happens almost instantly

• in animals, it occurs in tens of thousands of years

Habitat Differentiation

When two species occupy different components of the environment

Hybrid Zones

Members of different species that meet and mate, producing at least some offspring of mixed ancestry

Reinforcement (Hybrid Zones)

The process where natural selection actively strengthens the walls between two species to prevent them from making low quality hybrids

• They do this by favoring individuals that mate with their own species

  • strengthens pre-zygotic barriers

  • stronger in sympatric populations

Fusion (Hybrid Zones)

When two different species “forget to stay separated and merge back into one

• the two species that recently branched from a common ancestor meet in a hybrid zone and the barriers that are usually strong get weaker, so the interbreeding begins

  • the two species fuse into one

Stability (Hybrid Zones)

A permanent “middle ground” where hybrids are produced year after year

• they could be because the hybrids survive and/or reproduce better

• OR it could be due to a balance of selection against hybrids and gene flow from parents

The role of speciation and extinction

• speciation rate > extinction rate: rise of a group of organisms

• speciation rate < extinction rate: fall of a group of organisms

Speciation Rate

The number of species produced

Extinction Rate

The number of species dying

Plate Techtonics

Movements of the great plates of the Earth’s crust

• causes the continents on/part of the plates to also move, causing continental drift

  • alters the habitat of organisms, causing extinction/speciation

Mass Extinctions

Most of the species that have ever lived are now EXTINCT

• can be caused by habitat destruction or unfavorable environmental change

Permian Mass Extinction

• around 252 Million years ago

• defines the boundary between the Paleozoic and Mesozoic Eras

• wiped out 96% of marine animal species

• likely caused by intense volcanism

Cretaceous Mass Extinction

• around 66 million years ago

• marks the boundary between the Mesozoic and Cenozoic Era

• wiped out >50% of marine animals and many plants and land animals

• likely caused by a meteorite

Intrinsic Biological Mechanisms

Morphological differences that can arise from genes, altering many different things

Heterochrony

Morphological differences that can arise from genes, altering the rate of development

Paedomorphosis

Morphological differences that can arise from genes, altering the timing of development

Homeotic Genes

Morphological differences that can arise from genes, altering the spatial pattern of development, including…

• changes in gene sequence

• changes in gene regulation

Pattern of Early Earth

1. We start with small, simple organic molecules, such as amino acids and nitrogenous bases

2. The molecules join together, making macromolecules

3. The packing of these molecules into protocells

4. Origin of self-replicating molecules, making inheritance possible

Protocells

Droplets of membranes that maintained internal chemistry, different from its surroundings

once they retained self replicating DNA, natural selection began favoring the most efficient ones

Cynobacteria

The main photosynthetic organisms for over a billion years

• they transformed the atmosphere by releasing oxygen produced via photosynthesis

Stromalites

Fossils formed by cyanobacteria and several other types of photosynthetic bacteria

• the most abundant organisms on Earth

• They thrive in most environments

Fimbrae

Hairlike appendages that help cells adhere to other cells or to a substrate

Capsule

Sticky layer of polysaccharide or protein that can help cell adherence and/or evasion of a host’s immune system

Internal Organization

No nucleus or other membrane-enclosed organelles; usually no complex compartmentalization

Flagella

Structures used by most motile bacteria for propulsion; many species can move toward or away from certain stimuli

Cell Wall

Found in nearly all prokaryotes; structure differs in gram positive and gram negative bacteria

Circular Chromasome

Often accompanied by smaller rings of DNA called plasmids

Pilus

Appendage that facilitates conjugation

Reproduction in Bacteria

• Asexual

• Rapid reproduction due to smaller genome size

• Divide via binary fission

• Daughter cells are clones of the parents

Genetic Recombination

Horizontal Gene Transfer between members of different species

Transformation in Horizontal Gene Transfer

In this, the genotype and possibly phenotype of a prokaryotic cell are altered by the uptake of foreign DNA from its surroundings.

• A nearby nonpathogenic cell picks up pathogenic DNA from a dead pathogenic cell and replacing it with its own, becoming a recombinant cell

Transduction in Horizontal Gene Transfer

In this, phages carry prokaryotic genes from one host cell to another.

• essentially, DNA is transferred from a donor to a recipient through the virus

Conjugation in Horizontal Gene Transfer

DNA is transferred between two prokaryotic cells that are temporarily joined

• The DNA is copied and sent to the recipient, who integrates it into its own system

Major Roles of Prokaryotes

• Recycling chemical elements between living and nonliving components of the ecosystem

• Converting molecules into forms that can be taken up by other organisms

Decomposers

organisms that break down dead organic materials and release mineral nutrients

• some prokaryotes are these

Symbiosis

The relationship between two species that live in close contact with one another

Mutualism

Both organisms benefit from synbiosis

Commensalism

One organism benefits while neither harming nor helping the other in any significant way

Parasitism

An organism called a parasite harms but does not kill its host

• parasites that cause disease are pathogens

Nitrogen Fixation

The conversion of atmospheric nitrogen to ammonia

Endospore

A tough, dormant and non reproductive structure in certain bacteria that acts as an escape pod, allowing it to survive in even the harshest of environments that would normally kill it

Cytoskelaton

Helps the eukaryotic cell move around

Meiosis

Sexual reproduction that produces genetically unique gametes or spores

Endosymbiont Theory

Mitochondria and plastids were formerly small bacteria that began living within larger cells

Endosymbiont

A cell that lives within a cell

Serial Endosymbiont Hypothesis

Mitochondria evolved before plastids through a sequence of endosymbiotic events

What selective pressures favored the evolution of simple multicellular organisms from a single celled ancestor?

• Protection: Multicellularity helps organisms avoid being eaten

• Stability in the fluid environments: Multicellular organisms may be better able to maintain their position on a surface or in the water column

• Feeding Opportunities: Multicellularity may enhance feeding opportunities