Chapter 7 Flashcards
Allopatric speciation
geographic isolation separating populations
Sympatric
no geographic isolation needed to create a new species
Graduated model
Shows how a species developed over time
What do “trees” represent?
The evolutionary relationships among sets of organisms
Phylogenetic trees
One way to reflect the evolution of organisms
Who was the first to suggest change over time?
Lamarck
Which two observations led Darwin to conclude that there is competition for survival?
Overproduction and limited resources
A population is…
A group of individuals of the same species living in the same place at the same time that can interbreed.
gene pool
consists of all versions of all the genes carried by all the individuals in a population
Genetic variation in a gene pool can arise through…
Mutation
Sexual reproduction ensures that …
Genes are randomly mixed
microevolution
A generation-to-generation change in the gene pool
Changes to the genetic makeup of a population can arise via two mechanisms. What are they?
Mutations and sexual recombination
What proves that sexual reproduction leads to variation?
- Independent assortment
- Random fertilization
- Crossing over
Darwinian fitness
the contribution that an individual makes to the gene pool of the next generation in comparison to the contributions from other individuals.
What are other mechanisms that can also contribute to evolution in gene pools?
– Genetic drift
– Bottleneck
– Gene flow
– Sexual selection
Genetic drift
a change in a gene pool due to chance. Important in small or isolated populations
If a population is drastically reduced in numbers, that is a…
bottleneck
Gene flow
tends to reduce differences among gene pools.
Sexual selection
a form of natural selection that depends on an individual’s ability to obtain a mate.
nonbranching evolution
An ancestral population changing gradually over time
branching evolution
an ancestral population splits into two or more populations.
How many mass extinctions have been documented?
5
When did the dinosaurs go extinct?
65 mya
What are the highlights of the precambrian era?
– 4.6 bya: Earth forms
– 3.5 bya: Oldest known prokaryote
(primitive-celled) fossils
– 2.1 bya: Oldest known eukaryote (modern-
celled) fossils
What are the highlights of the Paleozoic era?
• 541 mya: Explosion in animal diversity within the oceans • 420 mya: Plant life begins on land • 370 mya: Animals migrate to land • 251 mya: Mass extinction event
Highlights from the mesozoic era?
• 230 mya: First dinosaurs
• 100 mya: Flowering plants begin to
dominate the land
Highlights from the Cenozoic era?
• 65 mya: Extinction of dinosaurs and
diversification of mammals
• 200,000 years ago: Appearance of anatomically modern humans
What did Aristotle believe about a species?
They were immutable
Who suggested that an old Earth had gradually changed
through slow, accumulating processes.
Lyell
What two points were made in Darwin’s “Origin of the Species”?
- modern species have descended from common ancestors (evolution).
- natural selection is the mechanism of evolution.
What year did the Voyage of the Beagle take place?
1831-1836
Evolution by Natural Selection is decidedly…
non-random
Factors that affect Natural Selection:
- overproduction and limited resources, resulting in competition
- Variation leading to natural selection
- heritability leading to evolution
adaptation
the accumulation of favorable traits over time
What areas in biology provide evidence for evolution?
Fossils, anatomy, molecular biology, biogeography, direct observation
How does the fossil record provide
evidence of evolution?
Fossil records reveal an ordered appearance of life on Earth
Transitional forms…
provide evidence of change within lineages.
