Ch 2 Flashcards
What are the different Species Concepts?
Morphological SC
Biological SC
Ecological SC
Phylogenetic SC
What is the morphological SC based on?
visual similarities
What is the biological SC based on?
based on reproduction / gene flow within a population
According to the biological SC, members of a different species do not interbreed because of pre-zygotic and post-zygotic “blocks.
What are the pre-zygotic blocks?
Mechanical Isolation Behavioral Isolation Temporal Ecological Isolation Gametic Isolation
What is mechanical isolation?
populations are structurally unable to reproduce
What is behavior isolation?
individuals don’t recognize mating rituals from other poulations
What is temporal isolation?
individuals have different mating times (day, year, age)
What is ecological isolation?
individuals have different mating locations
What is gametic isolation?
different chemical signals of gametes (do not fuse; are syngamy)
According to the biological SC, members of a different species do not interbreed because of pre-zygotic and post-zygotic “blocks.”
What are the post-zygotic blocks?
hybrid inviability
hybrid sterility
What is hybrid inviability?
zygote does not develop (death before development)
What is hybrid sterility?
hybrids are sterile
no gene flow between populations
What is the ecological SC?
otherwise similar organisms/groups may be distinguished by niche preference within a variable environment
What is the phylogenetic SC?
populations can be traced to a common ancestor that has evolved significantly different differences in diagnostic traits
How do new species form?
Speciation
What does speciation involve?
- reproduction isolation of 2 or more populations of an ancestral species
- genetic divergence of the isolated populations
What are the different types of speciation?
Allopatric speciation
sympatric speciation
What is allopatric speciation?
when formerly isolated population re-converges with and is no longer able to reproduce with ancestral population
Steps to allopatric speciation
- geographic isolation of 2+ populations from an ancestral species
- genetic divergence (mutations)
- reproductive isolating mechanism is evolved
- new species
What is Sympatrick Speciation?
A mutation occurs within the ancestral population
Steps to Sympatric Speciation
Ancestral population
- isolated mechanism is formed within population
- genetic divergence occurs
- new species
What are 2 changes that support Sympatric Speciation?
Ploidy Changes
Changes in Ecological Factors
What are Ploidy Changes
Part of Sympatric Speciation
- polyploidy: 3+ complete sets of chromosomes
What types of Ploidy Changes are there?
Autopolyploidy
Allopolyploidy
What is Autopolyploidy?
Polyploid is formed by non disjunction during meiosis
Is autopolyploidy more common or less common to allopolyploidy?
Less common
What is Allopolyploidy?
Closely related but differing species produce hybrid
- hybrid doubles the # of chromosomes through non disjunction
- results in allopolyploidy
- generic divergence occurs
- new species
What are Changes in ecological speciation?
Part of Sympatric Speciation
- simple mutation producing a change in niche preference / mating behavior
- this disrupts selection
What is adaptive radiation?
When 1 species grows into many more
What is character displacement?
When 2 similar, isolated species come together
They will have to compete not only within species, but with the new species as well
This causes each species average characteristics to move toward the extremes
What happens at the hybrid zone between closely related species?
Fusion
Reinforcement
Stability
What is fusion in the hybrid zone?
Gene flow occurs into both populations
-this merges the gene pools
What happens during reinforcement in the hybrid zones?
Hybrids are less successful in producing offspring
-this strengthens reproductive isolating factors over time
What is stability in the hybrid zones?
Hybrids are formed
-no significant fusion or reinforcement occurs
What is Phyletic Gradualism?
Steady change within a lineage
-older theory
What is Punctuated Equilibrium?
Rapid Speciation (a Speciation event) -followed by stability (stasis)
When was the earth formed?
4.5b yrs ago
When were the oldest fossils found
3.5b yrs ago
When did the banded iron formations occur?
2.2-2.8b yrs ago
What was the significance of the banded iron formations?
Pointed to massive amounts of free oxygen in the air
- likely causes by photosynthesis
- resulted in iron being oxidized and precipitating
When was the oldest eukaryotes fossils dated to?
2.1b yrs ago
When we’re the oldest tetrads dated to?
1.1b yrs ago
What’s the significance of tetrads?
Sexual reproduction
What’s the earliest multicellular animal fossil?
600m yrs ago
When’s the earliest plant?
425m yrs ago
When is the modern homo sapien dated?
30-50k yrs ago
