Exam 3 Flashcards
What are hybrid zones? Why are many hybrid zones narrow in width?
These are areas where two species come into contact and breed with one another
Usually narrow because of the possible outcomes of:
-REINFORCEMENT: selection to prevent hybrid formation
-FUSION: species fuse back into one species
-STABILITY: hybrids continue to form, don’t leave narrow zone
What is the difference between gradualism and punctuated equilibrium?
Gradualism: a process of evolution that suggests that changes occur slowly and constantly over time.
Punctuated Equilibrium: a process of evolution that suggests very short, rapid periods of change followed by long periods of stability.
Provide an example of gradualism and an example of punctuated equilibrium.
Gradualism: finches, whales
Punctuated Equilibrium: Cambrian explosion
Put the following groups of organisms in sequence from oldest to most recent, in terms
of their first appearance in the fossil record:
mammals, invertebrates, prokaryotes, land plants, algae
Prokaryotes
Algae
Land Plants
Invertebrates
Mammals
Given the age of the Earth, have humans been present for much of it? What about other animals?
NO - humans have only appeared around 200,000 years ago
Other animals first appeared 600 MILLION years ago
Why is it important to understand continental drift when studying evolution?
This is because it can lead to vicariance, which is when a natural situation arises to physically divide organisms.
Is continental drift still occurring?
YES - N. America and Europe drift apart about 2cm each year!
List two conditions or events that can lead to adaptive radiation. For each condition explain how the condition could lead to adaptive radiation. Provide examples.
Extinction - surviving organisms, say in the extinction of dinosaurs, have new environmental opportunities as the niches are “empty”
Geographic Isolation - dispersals to new areas, like Hawaiian Silverswords, has allowed for them to radiate into new species dependent on these new environments
When was the adaptive radiation of the mammals? Why? Was this adaptive radiation the first time mammals were present on Earth?
The adaptive radiation of mammals was AFTER THE EXTINCTION OF DINOSAURS - this led to empty niches for which surviving organisms could survive
Not the first time mammals were present, but there were much fewer before then
TRUE/FALSE: More than half of the species on Earth have been described/named.
FALSE - only about 2M have been described
It is estimated that there are 5 - 30 million species yet to be discovered
Which of the extinctions, the Permian or Cretaceous, is the oldest?
Permian
According to the geological evidence, which event may have triggered the Permian mass extinction?
global warming caused by massive volcanic eruptions
-release of greenhouse gases leads to warming
According to the geological evidence, which event may have triggered the Cretaceous mass extinction?
combination of volcanic eruptions and asteroid
Mass extinctions are often followed by ______________.
Increase in diversity
Define Systematics
Study of the diversity of life
What is taxonomy and why is it important?
Name and Classification of Species
important in categorizing and organizing to better communicate species
Which classification is more broad: Phylum or Family?
Phylum
KPCOFGS
What is phylogeny?
What type of data is used to construct phylogenies?
What does a phylogeny tell us?
Evolutionary hypothesis of a group of organisms
morphological/molecular homologies
shows a pictorial representation of evolutionary history and common ancestry
TRUE/FALSE: Evolutionary patterns convey a goal of evolution
FALSE - evolutionary patterns do NOT convey a goal of evolution (it shows a common ancestor)
What is the difference between a derived characteristic and an ancestral characteristic?
Derived = new traits unique to a lineage
Ancestral = characteristic that was present in the common ancestor/ancestral group
Where is the common ancestor to all of the organisms noted in the phylogenies?
at the Root
What does a Node represent on a phylogeny tree?
Speciation Event / Common Ancestor
TRUE/FALSE: No extant species are more “primitive” or “advanced” than others
TRUE - these have evolved for an equal amount of time
What is a Clade in phylogeny trees?
group of organisms containing the COMMON ANCESTOR and ALL OF ITS DESCENDANTS