evolution quiz 3

what is the importance of an outgroup?

used as a reference point when figuring out the evolutionary relationships of a primary group of interest(the ingroup)

How do we go between unrooted and rooted trees?

• Identify your ingroup (the organisms you're studying).

• Identify an appropriate outgroup that is related to the ingroup but outside it.

• Place the root between the outgroup and the ingroup.

What rooted trees are consistent with a particular unrooted tree?

if you can place the root on any edge or node of the unrooted tree without changing the relative relationships

How can fossils put bounds on the ages of ancestral nodes?

A fossil gives us a minimum age for the ancestral node that led to that fossil.

What is phylogenetic non-independence?

related species inherit traits from common ancestor

What is one approach to statistical analysis that corrects for non-independence? How does it work?

compares evolutionary changes between related lineages rather than treating each species as an independent observation.

How can phylogenetics be used to investigate patterns of HIV transmission?

Compare HIV sequences from different people using a phylogenetic tree. Closely related HIV sequences can indicate a recent transmission or common source

HIV phylogenetic patterns: Close/sister relationship:

supports a recent transmission or common source.

HIV phylogenetic patterns: Source paraphyly:

recipient sequences nested within source sequences → can provide evidence for direction of transmission.

HIV phylogenetic patterns:Loss of source lineages over time:

makes direction of transmission harder to determine.

HIV phylogenetic patterns: Unrelated sequences:

argues against a recent direct transmission.

HIV phylogenetic patterns: Important:

A close relationship alone does not prove transmission or its direction.

In what country (and continent) did Stephen Dixon find stromatolite fossils? In what

state?

• Western Australia

• Region: Pilbara area

What was the primary significance of Stephen Dixon’s discovery?

provided evidence of some of the earliest known life on Earth.

What are some adventures did Dixon have on this trip?

Went rock collecting, found what he thought was a stromatolite, was told to put it in his bag and bring it back to the US

Where is one place that stromatolites are found today?

Shark Bay, Australia

What is some advice that Dixon gave to all of you?

dont be afraid to try new things, you never know what you might discover

How did the public react to Darwin’s ideas after the Origin was published?

they were mostly accepting

What parts of Darwin’s theory were quickly accepted by scientists?

common ancestry bc of overwhelming evidence

Which parts were not immediately accepted? why?

natural selection bc Darwin didnt fully understand inheritance + believed in blended inheritance

What was one of the critical missing pieces that kept Darwin from fully fleshing out his theory?

a mechanism for inheritance

Thomas Henry Huxley

known as “Darwins bulldog”, fiercely defended Darwins theory of evolution again Samuel Wilberforce (1860)

What alternative mechanisms for evolutionary change were proposed in the late 1800’s

and early 1900’s?

Theistic evolution, lamarckian evolution, orthogenesis, saltation

Theistic evolution

belief that god created life thru biological evolution

Lamarckian evolution

belief that traits gained during an organisms lifetime is passed to their offspring

Orthogenisis

life evolved in a straight, predetermined line due to internal force

Saltation

evolutionary change through large, sudden jumps

August Weismann

german evolutionary biologist responsible for germ plasm theory

Germ Plasm Theory

multicellular organisms contain 2 distinct types of cells (germ cells & somatic cells)

Which of the alternatives to natural selection persisted the longest? How did the

rediscovery of Mendel’s work play a role in this persistence?

saltationism

How did the rediscovery of Mendel’s work play a role in the persistence of saltation?

supported discrete inheritance, which some scientists interpreted as evidence for sudden, large evolutionary changes rather than gradual natural selection

Thomas Hunt Morgan

used fruit flies to show that genes are physical units carried on chromosomes. mapped genes using recombination

R.A. Fisher

founded quantitative genetics

What did R.A Fisher show about continuous traits?

that Mendelian inheritance can produce continuous variation

Sewall Wright

emphasized genetic drift and inbreeding. He developed the adaptive landscape concept to explain how populations evolve

Adaptive landscape

a simple map that shows how well an organism's traits or genes help it survive in its environment

J.B.S. Haldane

used mathematical models to show how natural selection explains observed evolutionary changes

In what ways were the work of Fisher, Wright, and Haldane overlapping?

used mathematical models to show how Mendelian genetics and natural selection were compatible

Did Fisher, Wright, and Haldane ever disagree?

they disagreed about the relative importance of evolutionary forces, especially natural selection versus genetic drift

Theodosius Dobzhansky

connected mathematical theories of evolution to real biological populations by studying fruit fly genetics in nature