Comprehensive Evolution and Phylogeny Key Concepts for Biology

Biological evolution

the change in the genetic makeup of a species through time.

Natural selection

Individuals that are better suited for their environment will survive and pass on their traits to their offspring, while those that are not suited to the environment will not.

Punctuated Equilibrium

the hypothesis that evolution of a species occurs in periods of rapid change, separated by periods of little change.

Gradualism

the hypothesis that evolution of a species occurs at a slow constant rate.

Adaptation

a physical characteristic that makes an individual better able to survive.

Mimicry

gives individuals an advantage because they can hide from prey or predators and thus have a higher chance of survival.

Camouflage

gives individuals an advantage because they can hide from prey or predators and thus have a higher chance of survival.

Descent with modification

Over time, as species reproduce, new variations may appear that can change a species and could eventually lead to a new species.

Reproductive Isolation

formerly breeding species can no longer mate.

Divergence

species acquire different traits (accumulation of differences among members of a species).

Speciation

formation of new species.

Subspecies

members of the same species that differ genetically because of different living conditions.

Homology

Traits are inherited from a common ancestor.

Analogy

Traits are similar due to convergent evolution, not a common ancestor.

Common ancestor

a mutual ancestor of two or more groups of organisms that had diverged into separate groups over time.

Homologous structure

a structure found in two or more groups that is inherited from a common ancestor.

Vestigial structures

structures that are present in an organism but no longer function.

Embryonic development

the way embryos develop are very similar across a wide range of organisms.

Fossil Record

provides a record of many living things that once roamed the earth.

DNA

codes for amino acids (proteins).

Homologous structures in vertebrates

forelimbs are said to be homologous structures.

Vestigial pelvic bones in whales

pelvic bones are vestigial structures because they no longer function like the pelvis of a land animal.

Extinct species

if a species is no longer on this planet, but used to be, the species is extinct.

Causes of extinction

the species was unfit for their living conditions.

Galapagos Islands

located outside of South America.

Darwin's studies

Darwin noticed many different species there, but the most significant was all of the different finch species that lived among the islands.

Thomas Malthus' influence

Malthus concluded that population growth is limited by available resources, which applies to all of nature.

Lamarck vs. Darwin

Lamarck recognized that the environment impacted traits, but believed evolution strived for perfection, while Darwin thought it depended on random variation.

Genetic variation

has been crucial for the survival of a species; without it, there would be little opportunity for survival due to uniform traits.

Who originated the classification system in the 18th century?

Carolus Linnaeus

What is the most inclusive grouping in taxonomy?

Kingdom level

What is the scientific naming convention for species?

A species' scientific name is in Latin and composed of two names: Genus followed by species.

What is the scientific name of the cheetah?

Acinonyx jubatus

What are the three domains proposed by Carl Woese?

Archaea, Bacteria, and Eukarya.

What is a taxon?

A taxon is any group of species designated by name.

What is phylogeny?

The study of the evolutionary relationships among a group of organisms.

What does a phylogenetic tree represent?

A branching structure illustrating the evolutionary relationships of a group of organisms.

What are the main bases for constructing phylogenies?

Morphology, fossil records, embryology, and DNA/RNA/protein similarities.

What is the difference between a phylogenetic tree and a cladogram?

A phylogenetic tree represents the true evolutionary history, while a cladogram represents a hypothesis about evolutionary history.

What is a sister taxon?

Sister taxa are groups of organisms that share an immediate common ancestor.

What is a clade?

A clade is any taxon that consists of all the evolutionary descendants of a common ancestor.

What distinguishes a true clade from a paraphyletic group?

A true clade contains a common ancestor and all of its descendants, while a paraphyletic group has a common ancestor but does not include all descendants.

What is anagenesis?

Anagenesis is the accumulation of changes in one species leading to speciation over time.

What is cladogenesis?

Cladogenesis is the budding of one or more new species from a species that continues to exist.

What are homologous features?

Features shared by two or more species inherited from a common ancestor.

What is the difference between ancestral and derived traits?

Ancestral traits are original shared traits, while derived traits are those found in newly evolved organisms.

What are analogous structures?

Structures that are similar in function or appearance but not inherited from a common ancestor.

Why do analogous structures exist?

They evolve due to similar selection pressures or evolutionary reversals.

What is the molecular clock hypothesis?

It states that among closely related species, a given gene evolves at a reasonably constant rate.

How can molecular clocks be used in evolutionary studies?

They can predict times of evolutionary divergence based on mutation rates.

What is maximum likelihood in phylogenetic reconstruction?

It considers the phylogenetic hypothesis that reflects the most likely sequence of evolutionary events.

What does maximum parsimony state?

It suggests investigating the simplest explanation that is consistent with the facts when considering multiple explanations.

What is an outgroup in cladistics?

An outgroup is a group closely related to the taxa being examined but less closely related than the ingroup.

What is the significance of the fossil record in reconstructing phylogenies?

The location of fossils indicates their age, which helps in reconstructing evolutionary histories.

What is the role of genomic sequencing in identifying molecular homologies?

It helps identify common genetic sequences among related organisms.

What is the significance of the length of branches in a phylogenetic tree?

The length of branches can indicate the time of divergent events.

What is the founder effect in genetic drift?

The loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.

What is the bottleneck effect in genetic drift?

A drastic reduction in population due to catastrophic natural events.

What is natural selection?

The gradual, non-random process by which biological traits become either more or less common in a population as a function of differential reproduction of their bearers.

What are the key components of natural selection?

Over-production of offspring, inherited variation, competition, adaptation, and fitness/survival of the fittest.

What is stabilizing selection?

A type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value.

What is directional selection?

A mode of natural selection in which a single phenotype is favored, causing the allele frequency to continuously shift in one direction.

What is disruptive (diversifying) selection?

Changes in population genetics in which extreme values for a trait are favored over intermediate values.

How does natural selection contribute to evolution?

It leads to the passing on and accumulation of advantageous traits to offspring.

What is the role of competition in natural selection?

It influences which individuals survive and reproduce based on their traits.

What is meant by 'fitness' in the context of natural selection?

The ability of an organism to survive and reproduce in its environment.

What happens to genetic diversity during stabilizing selection?

Genetic diversity decreases as the population stabilizes on a particular trait value.

In directional selection, what happens to allele frequency?

It continuously shifts in one direction favoring a specific extreme phenotype.

What is the outcome of disruptive selection on population traits?

Extreme values for a trait are favored over intermediate values.

What is the significance of inherited variation in natural selection?

It provides the raw material for evolution, allowing some traits to be favored over others.

What is natural selection?

Natural selection is the process where individuals with traits better suited to their environment are more likely to survive and reproduce.

What does natural selection act upon?

Natural selection acts on a range of phenotypes in a population, not on individuals.

What is a population in the context of evolution?

A population is all members of a species that live in a specific area.

How does evolution occur?

Evolution occurs as a population's genes and frequencies change over time, creating new phenotypes.

What is allelic frequency?

Allelic frequency refers to how often a specific allele appears in a gene pool.

What happens to the gene pool if individuals with a specific allele do not survive?

The allele would not be part of the population and would not be passed down, leading to changes in the population.

What are some causes of genetic changes?

Genetic changes can be caused by mutations, environmental changes, radiation, and chemicals.

What is an adaptation?

An adaptation is an inherited characteristic that increases an organism's chance for survival.

What types of adaptations exist?

Adaptations can be physical (like speed or camouflage) or behavioral (like living in herds or packs).

What is mimicry in evolutionary terms?

Mimicry is when one species resembles another species, often a harmful one, for protection.

What is camouflage?

Camouflage is a defense mechanism where an organism resembles its surroundings to avoid detection.

What is the role of natural selection in evolution?

Natural selection favors certain variations that survive and reproduce, leading to changes in the gene pool over generations.

What is the difference between natural variation and artificial selection?

Natural variation refers to differences among individuals of a species, while artificial selection is selective breeding to enhance desired traits.

When was Darwin's 'The Origin of Species' published?

Darwin's 'The Origin of Species' was published on November 24th, 1859.

What was the significance of Mendel's studies to Darwin's theory?

Mendel's studies provided the missing link in understanding how favorable variations could be transmitted to later generations.

What does 'common descent with modification' mean?

It means that organisms descended from common ancestors and changed over time, leading to the evolution of new species.

What is divergence in evolutionary biology?

Divergence is the accumulation of differences among two groups of the same species, potentially leading to the formation of new species.

What is speciation?

Speciation is the formation of a new species, often driven by divergence.

What are the two models of evolution?

The two models of evolution are gradualism, which involves gradual change over long periods, and punctuated equilibrium, which involves rapid changes separated by periods of little change.

What is macroevolution?

Macroevolution refers to long time scale events that create and destroy species.

What is microevolution?

Microevolution refers to short time scale events that change the genotypes and phenotypes of populations.

What is the significance of genetic variation in natural selection?

Genetic variation is the driving mechanism behind natural selection, as it provides the traits that may be favored.

How does natural selection influence phenotypes?

Natural selection acts upon phenotypes, which are the physical qualities of organisms, leading to changes in the gene pool.

What is an example of a subspecies?

An example of a subspecies is the various breeds of dogs (Canis familiaris) that differ genetically due to different living conditions.

What is the difference between gradualism and punctuated equilibrium?

Gradualism involves slow, gradual changes over time, while punctuated equilibrium involves rapid changes interspersed with periods of stability.

What does it mean that adaptations are a 'luck of the draw'?

It means that individuals do not choose their adaptations; rather, they are traits that are already present in some individuals of a population.

What is microevolution?

Evolution that can be observed in a short time frame, involving changes in genes over time, such as in peppered moths, antibiotic resistance, and pesticide resistance.

What are homologous body structures?

Related structures inherited from a common ancestor that have different mature forms but develop from the same embryonic tissues, providing evidence of common descent.

Give an example of a vestigial structure in humans.

The appendix.

What do similarities in DNA sequences indicate about organisms?

The more alike two organisms are, the more similar their DNA and amino acid sequences are.