BIOL1070 Test 1

Geologic timescales

defined by major geologic and biological events

4.6 BYA

is when the Earth forms

The absence of _____ thought to be crucial for initial formation of bio molecules

Oxygen

The first ____ performed by Stanley Miller and Harold Urey sought to replicate prelife conditions, which resulted in the production of _____

prebiotic simulation experiment, amino acids

Prebiotic simulations replicating

hydrothermal events

Hot clays

may have provided scaffolding to allow formation of macromolecules. May have been the site of first RNA formation

liposomes

Formation of membranes from phospholipids possible under certain conditions. These membrane structures are called

progenotes by Carl Woese

First membrane bound aggregations of RNA, DNA, proteins, and lipid termed

Error prone translation apparatus eventually attained modern levels of fidelity, bringing about the____

Darwin Threshold

The origin of photosynthesis brings ____ into the atmosphere

molecular oxygen

Iron deposits

dating back 2 BYA are evidence of early oxygenation

Ozone (O3)

helps block harmful UV rays

Endosymbiont Theory

posits that mitochondria and chloroplast originated as free living bacteria

Mitochondria and Chloroplast

are similar in size to certain types of free living bacteria. Photosynthetic pigments in Cyanobacteria and chloroplast are similar. They are bound by not one but TWO membranes. The two organelles replicate in the same manner as free living bacteria by dividing. They have their on DNA, RNA, and ribosomes

DNA analysis

shows a close relationship between mitochondria and aerobic bacteria. Similarly close relationship between chloroplast and Cyanobacteria

Complex cells

eventually amalgamate to form multicellular organisms. First occurred about 1.2 BYA. Earliest fossils were from red algae

Endiacaran Period (635-543 MYA)

fauna preceded the eventful Cambrian Period

Paleozoic Era

Between 540-250 MYA. Encompasses major periods biological diversification. Contains the Cambrian Period, Ordovician Period, Silurian Period, Devonian Period, Carboniferous Period, Permian Period

Cambrian Period

This is when all major animal phyla evolve. Many of the organisms would be preserved in the famous Burgess Shale, in Canada

Ordovician Period

the first jawless vertebrates appear. The first life forms come to land in the form of simple plants

Silurian Period

first vascular plants appeared. First animals moved onto land and we have the arrival of jawed fish

Devonian Period

First amphibians appear

Carboniferous Period

the first primitive reptiles evolve. This is when our modern coal deposits were founded

Permian Period

the amniotic egg evolves in reptiles. Ends with the catastrophic Permian-Triassic extinction

Permian Triassic extinction

The most severe extinction event known in earth's history. Hypothesized causes include dropping sea levels and increased volcanism

Mesozoic Era (250-65 MYA)

The age of reptiles. Contains Triassic, Jurassic, and Cretaceous

Jurassic period

first flowering plants (the angiosperms)

Cretaceous Period

Brought on by an asteroid impact near the Yuctan Peninsula

7.4-10 million species of eukaryote

are alive today

Evolution

change in heritable characteristics of biological entities over time

Extant organisms

provide clues of evolution through DNA, embryonic development, and expressed structures

Fossils

provide the earliest evidence for evolution

Extinct organisms provide a rich ___ from which to glean patterns and clues

fossil record

A fossil

is any evidence of an organism that is older than 10,000 years (end of the Pleistocene)

Compression fossils

form when fine sediment compresses a specimen. Best for plants

Petrification fossils

form when an organism is buried, and dissolved minerals replace bone or other organic material. Can make for highly detailed fossils.

Impression fossils

form when an organism makes an impression in the mud. Can form trace fossils which can provide insight into animal behavior

Cast fossils

form when impressions are filled with mud, providing a mold

Intact preservation fossils

happen when tree resin traps an organism and hardens (called amber).

inclusions

Bodies lodged in amber that preserve amazing detail

Good are fossils typically

rapid burial, anoxic conditions, or very dry conditions

Fossilization

is a rare phenomenon. The majority are probably in places we can't get to

Erosion and continental shift

likely destroy many fossils

How do we know how old fossils are?

through relative dating, Stratigraphy, Absolute dating, Radiometric dating

relative dating

relies on stratigraphy, or evidence surrounding a specimen

Stratigraphy

the study of rock layers (strata) and their chronological relations and composition

Absolute dating

utilizes the actual fossil/specimen itself to determine the age

Radiometric dating

uses radioactive isotopes as clocks

Isotope

is an atom with a different number of neutrons. Particular ones exist in various proportion. As they decay, those proportions change

Half life

the amount of time it takes for half the isotopes in a sample to decay into the parent atom

Carbon 14

decays to carbon 12 and has a half life of 5730 and can be used to age objects about 40,000 years old

Potassium 40

decays to Argon 40 and has a half life of 1.3 billion years and can be used for dating fossils 300,000 years or older

Biogeography

the study of how species are distributed across the planet

Enigmatic distributions

which many species and fossils have, can be explained by plate tectonics which posits that the earth's crust is made of moveable plates

Alfred Russel Wallace

the father of modern biogeography. Noted unusual split in faunal composition along the Wallace Line

Wallace Line

describes a shift from more Australian-like fauna, to more Asia-like fauna in Southeast Asia

Homologous structures

are those which share common ancestry. They do not necessarily share the same function. Identifying and assessing this is fundamental in evolutionary biology.

Vestigial structures

have no apparent function, but may be a sign of shared ancestry

Analogous structures

have similar functions but different ancestral origins. When interpreted as homologous, may be obscure evolutionary relationships

Evolutionary developmental biology

looks at developmental pathways and how they are related

Homeotic genes

lead to abnormal or misplaced structures when mutated

Genome

the complete set of genes or genetic material of an organism. One example of level sequencing techniques involves the use of Ultra-conserved Elements (UCEs)

George Louis Buffon

suggested that some groups may have arisen from a common ancestor

Uniformitarianism

suggests the slow processes acting today also occurred in the past

Catastrophism

states that violent events are responsible for geologic formations of today

George Cuvier

resisted uniformitarianism but developed the principle of superposition

Principle of superposition

states that lower rock layers were older than the ones above them

Charles Lyell

Convincingly argued that the Earth was not 6,000 years old, but rather hundreds of millions of years old

Jean-Baptiste Lamarck

Suggested that organisms acquired traits over their lifetimes and passed those on to successive generations

Charles E. Darwin

On his voyage on the HMS Beagle in 1831 with the mission of taking detailed hydrographic measurements, noticed a strange distribution of fossils, variety of species occupying similar habitats, and convergent evolution was apparent

Thomas Malthus'

Essay on the Principal of Population stated that resources are finite, and that not all organisms survive to reproduce

Variation

Some are better than other, and those are the ones to be propagated. Critical component of Darwin's theory

Natural selection

Darwin termed the preservation of favorable traits over inferior ones

Postulates of Natural Selection

1. variation within a population

2. some variations are passed down (heritable)

3. overproduction of offspring

4. survival and production is not random

Blending inheritance

it was thought that offspring were an even mix of parental characteristics

•Under this mechanism, favorable variations would be diluted out of the population

Artificial selection

Instead of environment, however, humans acted as agents of selection

Gregor Mendel's fertilization experiments with pea plants

demonstrated a mechanism of inheritance that would validate Darwin's theory

Modern Evolutionary Synthesis

Unified Mendel's and Darwin's ideas, further adding that mutations are responsible for observed variation

Mutation

Is a change in nucleotide sequence. It is a largely random process

Evolution acts on the level of the _____ which consists of interbreeding members of the same species

Population

Alleles

Variations of genes that are responsible for variability on which selection acts

Gene pool

The entire collection of genes and their alleles in a population

Phenotype

the physical manifestation of an organisms genetic make up

Adaptation

A variation which helps an organisms genetic survive

Survival is ___ the best way to quantify the success of a particular variation

Not

Fitness

An organisms genetic contribution to the next generation

We can observe selection at work by examining changes in ______ over generations

Allele frequencies

Hardy-Weinberg equilibrium

A set of theoretical circumstances where allele frequencies do not change

Directional selection

One extreme phenotype is fittest and the environment selects against other variations

disruptive selection

Occurs when two or more extreme phenotypes are selected

Stabilizing selection

Occurs when extreme variations are selected against, and intermediates are favored

balanced polymorphism

For some genes, multiple alleles can be maintained. (This may occur via heterozygote advantage)

Heterozygote advantage

Which occurs when an individual with two different alleles is favored over individuals with two of the same alleles

Sexual selection

A type of natural selection on variation in the ability to maintain mates

Sexual dimorphism

A difference in appearance between males and females of species

intrasexual selection

members of the same sex compete for mates

Intersexual selection

Where members of the opposite sex do the choosing

Genetic drift

A change in allele frequencies that happen purely by chance. Most likely to impact small populations. Involves a drastic reduction in population size. This is an example of sampling error

Sampling error

When a random subset of population is not representative of the population as a whole

Genetic bottlenecks

Occur when there is loss of alleles following a major drop in population