Evolution And Systematics Exam 1

evolution

Changes from one generation to the next

Etymology from latin (evolvere) means

unfold or reveal

T. Dobzhansky

nothing in biology make sense except in the light of evolution

Why is evolutionary biology important?

1. Provides a framework by which other fields can ask questions, experiment, develop principles, models, etc.

2. Tracing diseases

In the case of evolution it is a _____ of facts that don’t depend on a single test

network

What processes drive evolution?

Mutations lead to variation in phenotypes among individuals within a population

genetic drift

occurs when random and non-random representative samples from the population produces the next generation

migration

Variation can be introduced from other populations

methodological naturalism

“Naturalists” explain the world based on observable natural phenomena like deities

Anaximander (610-546 BCE)

proposed that the sun, moon, and stars were physical objects (not deities)

Aristotle

Logic: application of logical rules for formulating general principles

Hypothesis testing: “We must not accept a general principle from logic only but must prove its application onto each fact” (principles must agree with facts)

One of the most influential ideas from early thinkers (including the Greeks) was that the earth was ____

static

Catastrophism

sudden events would change geological features and presence of species at a given time

Xenophanes

questioned the date of the earth as he found marine fossils on the top of mountains

James Huton

Suggested the earth must be extremely old, based on observations of sediment layer which he attributed to natural events like erosion, pressure, sedimentation, etc.

Charles Lyell

1. Uniformitarianism: geological features we see today are changing gradually through time. Processes causing that change are happening today

2. Published his own book, Principles of Geology

Spontaneous generation

Hypothesis stating that life could arise from non-living matter

The book stating worms and mice were created from everyday objects

Mundus Subterraneus

Empedocles

one of the first thinkers to explain why species were different and lived in different places

Francesco Reddi

concluded that life could not come from non-living matter by putting raw meat in two jars, one sealed and one unsealed

Scala Naturae

all living organisms arranged in a linear order from simple to complex

Al-Jahiz

writes about the characteristics of organisms changing over time, hinting at natural selection, in the Book of Animals

George-Buffon

common morphological characteristics are an expression of close relationships between them

Erasmus Darwin

all life has evolved from a "single living filament” changing through time and noted struggle for existence

Jean Baptiste Pierre

organisms are well suited to their environments, embraced the great chain of being, and proposed a natural explanation for it, Inheritance of acquired characteristics

Inheritance of Acquired Characteristics (IAC)

an organism’s efforts during it’s lifetime causes changes to its phenotype, and these changes are passed to its offspring

• evolution is progressive

  • individuals change in response to environment

Patrick Matthew (1790-1874)

Wrote On Naval Timber and Arboriculture, suggested concepts similar to Darwin’s but went unnoticed

Development of Darwin’s theory

saw many things supporting gradual change during Voyage of the Beagle

• lots of fossils

• violent earthquake that left coastal organisms exposed to open air

• found similar species across geographic barriers

Darwin and Wallace

After Darwin returned from his expedition he kept his book in a cabinet to be published after he died… until hearing from Alfred Russel Wallace

Alfred R. Wallace

Studied species composition in the Malayan archipelago (living and fossils) and found closely related species on opposite sides of geographic barriers. Father of biogeography

Wallace’s Line

geographical distinction line on distinct fauna found btwn Asia and Australia

On the Origin of Species by Means of Natural Selection

published November 24, 1859

Artificial Selection

humans choose which individuals to mate (specifically in pigeons), to obtain desired characteristics

What are Darwin’s two main ideas?

1. Natural selection

   1. Organisms have common descent

2 main components of Natural Selection

1. variation in the population: differences between individuals that can lead to higher reproductive success

2. a selective agent: any component that can change the chanes of survival

Thomas Malthus (1766-1834)

Principles of Population: human populations would grow faster than the available food, so there would be overpopulation if not for war, famine, disease, etc.

Transformational process

Lamarck’s idea that each individual in the population changes over its lifetime

Variational process

Darwin’s idea of sorting of pre-existing variation. Individuals are not changing through lifetime, but frequencies of phenotypes in populations change over generations

Descent with modification

• species split from common ancestor and slowly gain differences

  • why closely related species are similar

natural selection and innumerable species

Darwin showed that differences between populations (variants) could lead to different species

4 problems in Origin of Species

1. How to account for complex structures

2. Vestigial traits

3. Persistance of variation

4. How are traits inherited

Natural Selection

Heritable variation leads to differential reproductive success

Variation

existing variation in phenotype is the ‘raw material’ for natural selection. Can be introduced by mutations and migrations

Selection

operates on the phenotype (size, behavior, toxins, proteins, etc.)

inheritence

phenotypic variants are associated with specific genotypes, which are inherited

• selected phenotypes pass the genetic information to their offspring

Adaptation

inherited trait that makes an organism more fit in its environment, as a result of natural selection

norms of reaction

environment effect on genotypes can produce different phenotypes

Selection and Reproductive success

individuals with phenotypic variations can have differences in reproductive success

fitness

heritable trait that gives individuals a reproductive advantage will increase in frequency in a population

life history

refers to how organisms invest their energy in reproduction over their lifetimes, selection will favor many small offspring

Antagonistic pleiotropy

a trait that increases fitness in one condition can decrease fitness in another setting

is evolution predictable?

somewhat, but there are random effects (mutations) that can introduce variation

True or False? In ancient time, one of the many evidences that hinted that the earth was polder than originally thought was the discovery of marine fossils in mountain tops, or areas far from the ocean.

True

True or False? One of the main ideas behind uniformitarianism is that change is slow, and the processes that modify our surroundings are happening in the present.

True

Uniformitarianism was formally presented in the book written by who?

Charles Lyell

What suggests that changes in phenotype during the lifetime of an organism can be passed on to their offspring?

Inheritance of Acquired Characteristics (IAC) (Lamarck)

What are the main componenets for natural selection as described by Darwin (2)?

Phenotypic variation and selective agent

The processes suggested by Lamarck would be considered ______, while the processes by Darwin would be considered ______.

Transformation, variational

Under the theory of evolution as formulated by Lamarck, why would the traits of Pacific oysters change in response to ocean acidification?

Individuals in low pH conditions would become better at growing shells efficiently throughout their lifetime, and these changes would be passed on to their offspring

True or False? One of the main evidences that both wallace and Darwin had for common descent was finding different species on islands, which were phenotypically very similar to those on the mainland.

True

True or False? Following the ideas of Darwin, all species in nature would have to develop traits independently. For example, all mammals would have evolved hair independently.

False

Solution to evolution of complex traits

intermediate steps can be adaptive, complex eyes have evolved more than once.

Adaptation

a heritable trait that increases fitness in a certain environment was selected for its current function (cranial structures allow brain growth)

Exaptation

a heritable trait that increases fitness in. a certain environment but was originally selected for a different function but also advantageous (feathers not originally for flight)

Possible original purpose for feathers

thermo-regulation, signaling, defense, waterproofing, incubating, etc.

Nature of variation

• variation needed for adaptation may not exist

• variation in a trait may be correlated with other traits, and might produce challenges (antagonistic pleioptry)

Constrains of natural selection

1. Nature of variation

2. physical constraints

3. nature of the environment

4. lack of foresight

Physical constraints to natural selection

there a physical constraints that don’t allow for perfect organisms, selection cannot surpass the natural limits of the universe

nature of the environment and natural selection

abiotic environments are always changing, and this will allow for different species to thrive over time

• predators adapt, food evolves defenses, parasites evolving to evade immune system, etc.

coevolution

evolutionary changes in one species changes fitness of another species

Lack of foresight in natural selection

natural selection is not predictive, and it is unable to forecast the future

Carl Linnaeus

father of taxonomy, organized species together based on taxonomy and physical similarities

Darwin and systematics

ancestral species would change by natural selection, leading to the formation of new species in a branching pattern

Ernst Haeckel

coined the term phylogeny in 1866, suggested embryological stages of organisms represented their ancestors (now been rejected)

phylogeny

branching relationships of species as they give rise to descendant groups over time, can be based on morphological and/or genetic traits

building a phylogeny

need to provide evidence of common ancestry and information that supports why lineages are closely related

characters

any observable or measurable characteristic of an organism (anatomy, genetics, behavior)

traits

represent the specific state of a character

genealogy vs phylogeny

not similar, genealogy represent individuals, phylogeny represents entire species

Taxon

(plural: taxa) groups represented at the tip of a branch

Node

sections where the branches split. Represents the common ancestor. These are groups that existed in the past, and are not alive today

root

Is the base if the tree represents the common ancestor to all groups in the tree

True or false? Rotating the node of a phylogenetic tree changes the pyhlogeny

False

True or false? Phylogenies represent hypotheses about evolutionary history and can be tested, challenged, and refuted

True

outgroup

closely related group that has a known relationship to the taxa of interest, but can help us understand the order of appearance of groups in evolutionary time

polytomy

when more than one branch comes out of a node, because there is uncertainty about the relationships

monophyletic group

a group formed by all the descendants of the most common ancestor and no additional members

clade

refers to group of species that share single recent common ancestor

polyphyletic group

when a group does not include the most common ancestor of all members, nor all the descendants from that ancestor

paraphyletic group

contains the group’s most common ancestor but not all the descendants

rooted tree

the ancestor from which all other lineages derive is included in the tree

unrooted tree

not designed from the perspective of a single common ancestor

cladogram

no branch lengths, just relationships (A)

phylogram

branch lengths indicating some sort of evolutionary change (B)

chronogram

trees that provide information about the time of split between different groups (established by examining fossils, molecular clocks, and geological events)

taxonomy

the area of biology that is associated with describing, classifying, identifying, and naming organisms

systematics

the field associated with the classification of organisms based on their similarities, and their evolutionary history

traits on phylogenetic trees

allow us to understand when traits arise and how they evolve, we can estimate the states of the ancestor, and determine when structure/molecules were lost or gained through time

Analogy

Similarity in function or position between organs that have DIFFERENT evolutionary origin (same function, different origin)

Homology

structures that have same evolutionary origin, even if they have a different function (same origin but not always same function)