BIOL 1105 Exam 1

cells

all organisms are made up of membrane bound cells

Replication

all organisms are capable of reproduction

Evolution

Populations of organisms are continually evolving

Information

All organisms process hereditary information encoded in genes as well as information from the environment

Energy

Need to acquire and use energy

Theory

An explanation for a very general class of phenomena or observations that are supported by a wide body of evidence

Cell theory states

All organisms are made of cells and all cells come from preexisting cells

Hypothesis

A testable statement that explains something observed

Experiment

Allows researchers to test the effect of a factor on a particular phenomenon

Prediction

A measureable or observable result that must be correct if a hypothesis is valid

Louis Pasteur’s hypothesis states

Cells arise from cells and cells do not arise by spontaneous generation

Theory of Evolution

A change in the characteristics of a population over time

Population

A group of individuals of the same species that are living in the same area at the same time

Natural selection

Explains how evolution occurs

Heritable

Can be passed on

Adaptation

A trait that increases the fitness of an individual in a particular environment

Chromosome theory of inheritance

Hereditary or genetic information is encoded in genes and genes are units located on chromosomes

Chromosomes

Molecules of DNA

DNA

The hereditary material

Genes

Segments of DNA that code for cells products

The Central Dogma

Describes the flow of information in cells

Tree of Life

A family tree of organisms that describes the genealogical relationships among species with a single ancestral species at its base

Phylogeny

The actual genealogical relationships among all organisms

Phylogenetic tree

Used to show the relationships between species

Branches that share a recent common ancestor represent species that are closely related

Branches that do not share recent common ancestors represent species that are more distantly related

Taxonomy

The effort to name and classify organisms

Taxon

A named group

Domain

New taxonomic level based in tree of life

Phylum

A major lineage within a domain

Scientific Theory

A well-tested and comprehensive explanation for a set of observations or natural phenomena, backed by a large body of evidence

Patterns

Observations about the natural world

Process

Mechanism that produces that pattern

Typological Thinking

A mental framework that views a category or type as fixed, real, and ideal, while treating individual variations as minor or unimportant deviations from a standard norm

Aristotle and the Great Chain of Being

Species were fixed types

Species were organized into a sequence based on increasing size and complexity

Sequence started with minerals and lover plants

Humans were at the top of the scale

Lamarck and Evolution as Change through Time

Based on Aristotle’s Great Chain of Being

Simple organisms originate at the base of the scale by spontaneous generation

Organisms evolve by moving up the scale over time

Lamarckian evolution is progressive - producing larger, more complex or “better” species over time

Inheritance of acquired characteristics

As individuals develop, their phenotype changes in response to environmental changes

These phenotypic changes are then passed on to their offspring

Example: Giraffes develop long necks from stretching to reach food and produce offspring with long necks

Darwin & Wallace: Evolution by Natural Selection

Based on variation among individuals in populations

Individuals with certain traits produce more offspring than others without these traits

Does not follow a linear, progressive pattern

Why was this theory revolutionary?

It overturned the idea that species are static and unchanging

It replaced typological thinking with population thinking

It was scientific

Descent with modifications

Change over time produced modern, modified species from ancestral species

Fossils

Traces of organisms that lived in the past

Fossil Record

The many fossils that have been found and described in the scientific literature

Sedimentary Rocks

Form from sand or mud

Form in layers

Geological time scale

Based on fossils’ relative positions in layers of sedimentary rock

Extinct

Species that no longer exists

Transitional features

Traits in a fossil that are intermediate between ancestral and derived species

Vestigial trait

Has a reduced or incompletely developed structure that has no (or reduced) function

Clearly similar to functioning organs or structures in closely related species

Homology

a similarity that exists in species descended from a common ancestor

Genetic homology

a similarity in DNA, RNA, or Amino Acids sequences

developmental homology

Seen in embryos of different species

Structural homology

A similarity in adult morphology

Speciation

A process that results in one species spiltting into two or more descendant species

Biological fitness

The ability of an individual to produce surviving, fertile offspring relative to that ability in other individuals in the population

Adaptation

A heritable trait that increases an individual’s fitness in a particular environment relative to individuals lacking that trait

Selection (biological context)

Differential reproduction as a result of heritable variation - NOT a purposeful choice

Fitness trade-off

A compromise between traits, in terms of how those traits perform in the environment

natural selection

increases the frequency of alleles that contribute to reproductive success in a particular environment

Genetic drift

Causes allele frequencies to change randomly

Gene flow

Occurs when individuals leave on population and join another and breed

Mutation

Modifies allele frequencies by continually introducing new alleles

Hardy-Weinberg Principle

Mathematical null hypothesis for study of evolutionary processes

Gene pool

Hypothetical scenario where all of the alleles from all gametes in each generation go into a single group

5 Hardy-Weinberg Assumptions

1. Random mating

2. No natural selection

3. No genetic drift

4. No gene flow

5. No mutations

Inbreeding

mating between relatives

Inbreeding depression

A decline in average fitness that takes place when homozygosity increases and heterozygosity decreases in a population

Directional selection

Changes the average phenotype in the population in one direction

Stabilizing selection

reduces genetic variation in a trait does no change average value of a trait over time

Disruptive selection

Intermediate phenotypes are selected against and extreme phenotypes are favored

Balancing selection

Occurs when no single allele has a distinct advantage

Heterozygote advantage

Heterozygous individuals have a higher fitness than homozygous individuals do

Frequency-dependent selection

Certain alleles are favored when they are rare but not when they are common

Intersexual selection

Selection of an individual of one sex for mating by an individual of other sex

Intersexual selection

Competition for mates

Sexual dimorphism

any trait that differs between males and females of the same species

Founder effect

Change in allele frequencies that occurs when a new population is established

Bottleneck effect

A sudden reduction in the number of alleles in population

Point mutations

Change in a single base pair in DNA

Chromosome-level mutation

Change in the number or composition of chromosomes

Lateral gene transfer

Transfer of genes from one species to another

Beneficial alleles

Should increase in frequency in a population doe to natural selection

Neutral alleles

Occurs when a point mutation does not change the amino acid sequences

Deleterious alleles

Tend to be eliminated by purifying selection

Species

an evolutionary independent population or group of populations

Biological species concept

Main criterion for identifying species in reproductive isolation

Prezygotic isolation

Individuals of different species are prevented from mating successfully

Postzygotic isolation

Hybrid offspring do not survive or reproduce

Morphospecies concept

Individual lineages differ in size, shape, or other morphological features

Phylogenetic species concept

Identifies species based on evolutionary history`

Monophyletic group

Consists of an ancestral population plus all of its descendants (aka clades or lineage)

Synapomorphy

Trait unique to a monophyletic group

Phylogenetic species

Smallest monophyletic groups

Subspecies

Population that live in discrete geographic areas, have distinguishing features, are not distinct enough to be considered a separate species, and can interbreed if geographical barriers are removed

Allopatry

Population that live in different areas

Allopatric speciation

Speciation that begins with geographic isolation

Dispersal

A population moves to a new habitat, colonizes it, and founds a new population

Vicariance

The physical splitting if a habitat

Niche

The range of ecological resources that a species can use and the range of conditions it can tolerate

Polyploidy

A mutation important in speciation

Autopolyploid

Individuals produced when a mutation results in a doubling of the chromosome number

Allopolyploid

Individuals of a different species mate and an error in mitosis

Results in viable, nonsterile offspring

Produces offspring with two different sets of chromosomes

Reinforcement

Natural selection for traits that prevent interbreeding among populations

Hybrid zone

a geographic area where interbreeding between two populations occurs and hybrid offspring are commong