BILD 3 Midterm Study Guide: Key Biology Terms

3 domains of life

Bacteria, Archaea, and Eukaraya

3 multicellular kingdom within Eukaraya

Fungi, Animalia, Plantae

Darwin's Theory of Evolution

Individuals that are best adapted to the environment will survive and reproduce; their advantageous traits help them. This is called natural Selection.

natural selection

(Not Random) A natural process resulting in the evolution of organisms best adapted to the environment.

Hypothesis

an explanation that is based on prior scientific research or observations and that can be tested

deductive reasoning

reasoning in which a conclusion is reached by stating a general principle and then applying that principle to a specific case (The sun rises every morning; therefore, the sun will rise on Tuesday morning.)

Homologous trait

trait shared between 2 species b/c both species inherited from shared ancestor

Convergent trait

trait shared between 2 species b/c it evolved multiple times

Hutton

Gradualism. earth is millions of years old, major changes are caused by small changes over time

Cuvier

catastrophism: believed that the extinction of species was caused by catastrophic events such as floods

Lamarck

Proposed theory that organisms pass on traits they acquire in their lifetime. Ex. giraffe necks

Adaptation

inherited characteristic that increases an organism's chance of survival and reproduction to a specific environment

artificial selection

selective breeding of plants and animals to promote the occurrence of desirable traits in offspring

Variation

differences in physical traits of an individual from the group to which it belongs

Heritability

the ability of a trait to be passed down from one generation to the next

Principles of Succession

living organisms are similar to the fossils in their region because they are descended from those ancestors with modification

Lyell

The theory that the earth has been formed over long periods of time with the geological features

evolutionary change (modification)

happens when groups of organisms encounter new environments and over time adapt to those environments via natural selection

descended with modification

according to the theory of evolution, species alive today have a common ancestor from species that lived in the past.

adaptive radiation

An evolutionary pattern in which many species evolve from a single ancestral species

Biogeography

Study of past and present distribution of organisms

Two structures shared by all vertebrate embryos

post-anal tail & pharyngeal arches (throat)

Tetrapods

vertebrate animals having four feet, legs or leg-like appendages. Ex. (amphibians, mammals, and reptiles)

homologous structures

Structures in different species that are similar because of common ancestry.

vestigial structures

remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species.

Microevolution

evolutionary change within a species or small group of organisms, especially over a short period.

Macroevolution

large-scale evolutionary changes that take place over long periods of time

Evolution (Micro and Macro)

change in heritable traits (gene pool) over time. Ex. (Mutation, gene flow, genetic drift, natural selection)

Tiktaalik

supposed link between fish and tetrapods (vertebrates with four legs)

Archaeopteryx

supposed link between birds and reptiles and dinosaurs

Extinction

A term that typically describes a species that no longer has any known living individuals.

Homology

A trait that two species share because both species inherited it from their common ancestor.

analogous structures

structures that do not have a common evolutionary origin but are similar in function

structural homology

The study of similar structures in different species

developmental homology

Species that differ as adults but bear striking similarities during embryonic stages

molecular homology

similar DNA (amino acid sequences) among different species from a common ancestor

Phenotypes can be determined by _____.

genes, the environment or both

Modes of Selection

directional, stabilizing, disruptive

directional selection

occurs when natural selection favors one of the extreme variations of a trait

directional selection effect

population mean: changes

population variation: decreases

stabilizing selection

natural selection that favors average individuals in a population; results in a decline in population variation

stabilizing selection effect

population mean: stays

population variation: decreases

disruptive selection

favors individuals at both extremes of the phenotype range

disruptive selection effect

population mean: stays

population: increases

relative fitness

The contribution of one genotype to the next generation compared to that of alternative genotypes for the same locus.

sexual selection

A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.

sexual dimorphism

Differences in physical characteristics between males and females of the same species.

intrasexual selection

competition among individuals of one sex (often males) for mates of the opposite sex

balancing selection

Natural selection that maintains stable frequencies of two or more phenotypic forms in a population.

Heterozygous

An organism that has two different alleles for a trait

Homozygous

An organism that has two identical alleles for a trait

frequency-dependent selection

the fitness of a phenotype depends on how common it is in the population

Heterozygous advantage

Heterozygous alleles have greater selective advantage than either homozygous condition.

BEST definition of evolution

Genetic change over time

Hardy-Weinberg equilibrium (HWE)

condition that occurs when the frequency of alleles in a particular gene pool remain constant over time

Process that violates HWE

1. Genetic Drift

2. Natural Selection

3. Gene Flow

4. Mutation

5. Non-random mating

genetic drift

A change in the gene pool of a population due to chance

gene flow

movement of alleles from one population to another

calculating OBSERVED HWE 1)Genotype

((TT or Tt or tt)/Total individuals)

To check work. All answers + together = 1

calculating OBSERVED HWE 2)Allele

(2(TT or tt)+Tt)/(2(Total individual))

To check work. All answers + together = 1

calculating EXPECTED HWE

p=Freq of T

q=Freq of t

Freq of TT= p^2

Freq of tt= q^2

Freq of Tt= 2pq

To check work. All answers + together = 1

Compare observed genotypes to predicted genotypes under HWE

Observed = expected genotype -> no evolution + random mating

Observed different from expected genotype -> may be evolving

gene pool

all copies of every type of allele at every locus in all members of the population

Hardy-Weinberg equilibrium

condition that occurs when the frequency of alleles in a particular gene pool remain constant over time

Bottleneck Effect

sudden change that drastically reduces population size, genetic diversity and allele frequencies

Ex) Natural disaster

Founder Effect

small number of individuals start a new population and new allele frequences

Ex) Finches moving to a new island

adaptive evolution

a process in which traits that enhance survival or reproduction tend to increase in frequency in a population over time

Phylogeny

Evolutionary history of a species or group of species.

phylogenetic tree

A family tree that shows the evolutionary relationships thought to exist among groups of organisms

Taxonomy

The scientific study of how living things are classified

Binomial

A polynomial with two terms

genus and species

scientific name

Linnaean System

Classification system useful for storing and finding information about living things

Taxon

group or level of organization into which organisms are classified

branch point

the representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor

sister taxa

Groups of organisms that share an immediate common ancestor and hence are each other's closest relatives.

Natural selection (genotype)

can select for same genotype and against others,

non-random mating (genotype)

mating between individuals of the same phenotype or by those who live nearby (excess homozygotes or heterozygotes)

non-random mating

mates chosen on basis of physical or behavioral characteristics

assortive mating (genotype)

an individual chooses mates that are similar to itself (produces excess homozygotes)

genetic variation

Differences among individuals in the composition of their genes or other DNA segments

neutral variation

differences in DNA sequence that do not confer a selective advantage or disadvantage

Adaptive Selection

evolution that results in a better match between organisms and their environment

root

the most ancestral branch in the tree

Analogy

phylogeny is similarity between organisms due to convergent evolution rather than to a shared ancestry (homology)

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments

Cladistics

classification based on common ancestry

monophyletic

ALL descendants came from one common ancestor

non-monophyletic

Pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants.

polyphyletic

pertaining to a group of taxa derived from two or more different ancestors

shared ancestral character

a character that originated in an ancestor of the taxon

shared derived character

an evolutionary novelty unique to a particular clade

outgroup

generally, any group that one does not belong to

Write this tree as a set of nested paratheses

((A,B),C)

Parsimony Tree

Tree with fewest evolutionary changes is most likely to be correct