Origins of Life & Early Earth
Earth formed approximately this many (billion) years ago.
4.54 billion years
A barrier that occurs after fertilization is called this type of isolation mechanism.
Post-zygotic barrier
This selection pattern favors phenotypes and often reduces variation
Stabilizing Selection
When unrelated lineages evolve similar traits due to similar pressures, it is called this.
Convergent
Structures with similar anatomy due to common ancestry are called these structures.
Homologous
The earliest fossil evidence for life dates to about this many (billion) years ago.
3.5 billion years
A mismatch in reproductive structures that prevents successful mating in this barrier.
Pre-zygotic barrier
This selection patter favors one extreme phenotype, shifting the population mean.
Directional selection
A trait share because of common ancestry (not convergent evolution) is called this.
Homologous traits
Similar features that evolved independently in different lineages are called these structures
Convergent evolution
A key implication of the RNA world model is that RNA could both store information and act as a(n) ___.
Catalyst
What is the defining characteristic of sympatric speciation?
The appearance of new species in the midst of old ones
In a changing environment, this type of selection is most likely when a new optimum trait value emerges.
Directional Selection
Phylogenetic trees are best described as testable ___ that can be revised with new evidence
Hypotheses
The geographic distribution of species is studied in this field
Biogeography
A major reason early Earth was initially hostile to life was this general condition. (Think thempreature/atomosphere)
Molten state of the planet's surface
All isolating mechanisms ultimately reduce or prevent this between populations.
Interbreeding
In disruptive selection individuals with intermediate phenotypes typically have this relative fitness.
DNA sequence data are often preferred over morphology because they are generally more ___ and ___.
Reliable -- Precise
A trait the increases survival/reproduction in a specific environment is called this
Adaptation
The RNA world hypothesis proposes early catalysis occurred without this type of molecule
DNA and proteins
What is the primary causes of allopatric speciation.
Geographical isolation
Selection patterns are typically inferred from changes in this distribution over time.
Natural selection
In cladistics, a "shared derived character" is also called this.
synapomorphy
A sequence of transitional forms in rock layers supports evolution via this type of evidence