CHapter 19: Descent w/ Modification Terms

define homology

similarity in characteristics resulting from shared ancestry

define homologous structures

bones in different species that are similar because of common ancestry

vestigal structures

structure leftover from something that used to serve a function (usually from organisms ancestors(

The idea that all species descend from a common ancestor comes from:

all forms of life use the same genetic code

Define convergent evolution

2 organisms have similar features (usually due to environment) but no common ancestor.

why does convergent evolution occur when theyre distant from each other

although these two organisms have no common ancestor and evolved independently from one another, their similar features (convergent evo) occur due to their similar environments and their similar adaptations to said environment.

Define analogous

having a charachteristic that are similar due to convergent evolution (no common ancestorty)

what does the fossil record show concerning descent w/ modification?

over time, descent with modification produces large differences in related organisisms resulting in DIVERSITY

What does the fossil record do?

documents the pattern of evolution, showing that past organisms differ from those in the present.

define biogrography

scientific study of past and present geographical distrubtions of a species

What are geographical distributions influenced by?

continental drift

Define endemic

speciies that can be found nowhere else in the world

How does Darwin describe most island speciies?

He decribes them as being “colonized” by speciies from the mainland, these then speciate and youll never guess….become their own species (+ become endemic).

What is an example of the pattern of evolution

fossil records

Define pattern of evoluton

reocurring trends in how speciies change over time, adapt to environments, or speciiate

What are the types of patterns of evolution

Divergent and convergent evolution

define divergent evolution

one species gains so many variations in their traits that the populstion splits (speciates) into 2 different specieis.

what type of nucleotide sequence mutation would NOT alter the reading frame?

single susbsitution

Define microevolution

An evolutionary change in the allele frequencies of a population

The original source of genetic variation is ______.

Mutations - because it introduces new alleles

What are all the natural selection types

• genetic drift

• founder effect

• bottleneck effect

Define genetic drift

RANDOM CHANGE in allele frequency over time (most obvious in small populations)

Define founder effect

few individuals becomes ISOLATED from the main population and form a new gene pool aka a new species

Define bottleneck effect

the size of the population is reduced significantly due to naturali disaster

Genetic drift is a likely explanation of these evolutionary outcomes:

• decrease in genetic variation

• increase in frequencies of disadvantageous alleles in population

Why does genetic drift cause a decrease in genetic variation?

because of the random shuffle some alleles can dissapear or become fixed thus decreasing variation

What is the only evolutionary mechanism that leads to adaptive evolution?

Natural selection

Types of selection

• disrutpive

• stabilizing

• directional

Define disruptive selection?

Natural selection favors the extremes

Define stabilizing selection

Natural selection favors the average

Define directional selection

Natural selection favors ONE extreme

Which type of slection increases genetic variation?

DISRUPTIVE

The modern idea of extinction as a common occurence in earths history was first proposed in the 19th century by _____

Culvier

The smallest unit that can evolve is _____

population

To Cuvier, differences in fossils from different strata were evidence for

local catastrophic events such as droughts and floods.

Lyells principle of unformatarianism ______

influenced Darwins view of how living organisms could change over time.

Define Lyell’s Principle of uniformitarianism

mechanisms of change are constant over time.

The scale of nature (scala naturae) is based on the idea of _________

Aristotle

What did Darwin hain from reading Thomas Maths’s essay on human suffering

organisms have the capacity to overproduce.

Define Thomas Malthu’s theory on human suffering

Populations grow much faster than the food supply and there is a capacity (if helped) for organisms to ovverproduce in the idea that all offpsring may not make it.

Which aspect of population genetics is fundamental to the biological species concept?

GENE FLOW

According to the theory of natural selection, anatomical and molecular homologies should _______

indicate similar patterns of evolutionary relatedness

What influenced Darwin in creating the theory of evolution by natural selection

• Linnaeus’s hierarchical classification of species (binomial)

• biogeographic distribution on the galapagos island

• Lyell’s book on the gradualness of geological changes

• artificial selection that produced rapid changes in domesticated species.