Ex1 Study Guide Flashcards
What is Aristotle’s scala naturae?
A classification system arranging species on a ladder of increasing complexity
This concept aligns with the idea that species are fixed and perfectly designed, influenced by the Old Testament.
Who is known for advocating catastrophism?
Georges Cuvier
Cuvier speculated that each boundary between strata represents a catastrophe.
What does Charles Lyell’s uniformitarianism suggest?
Changes in Earth’s surface result from slow and continuous actions still operating today
This view strongly influenced Darwin’s thinking.
What hypothesis did Lamarck propose regarding species evolution?
Species evolve through use/disuse of body parts and inheritance of acquired characteristics.
What is natural selection?
The process where individuals with favorable inherited traits are more likely to survive and reproduce
Darwin’s theory includes two observations and two inferences.
What are Darwin’s two observations regarding natural selection?
- Members of a population vary in inherited traits
- All species can produce more offspring than the environment can support.
What are the two inferences drawn by Darwin from his observations?
- Individuals with favorable traits tend to reproduce more
- Unequal ability to survive and reproduce leads to accumulation of favorable traits.
Define ‘descent with modification’.
The concept that all organisms are related through descent from an ancestor that lived in the past.
What is artificial selection?
The process by which humans select and breed individuals with desired traits.
What significant event did Darwin witness during his voyage on the HMS Beagle?
An earthquake and the movement of strata on earth.
What is the difference between individuals and populations in terms of selection?
Individuals do not evolve; populations evolve.
What are vestigial structures?
Remnants of features that served important functions in the organism’s ancestors.
What distinguishes homology from analogy?
Homology refers to similarity resulting from common ancestry, while analogy refers to similarities due to convergent evolution.
What is biogeography?
The geographic distribution of species.
What is the significance of continental drift and Pangea in evolution?
Pangea was a supercontinent that separated, affecting species distribution and evolution.
Differentiate between microevolution and macroevolution.
- Microevolution: change in allele frequency in a population over generations
- Macroevolution: broad patterns of evolutionary change above the species level.
What is average heterozygosity?
The average percent of loci that are heterozygous in a population.
Define phenotypic plasticity.
Variation in phenotype that is not due to genotypic differences among individuals.
What is Hardy-Weinberg equilibrium?
A theoretical model describing a population that is not evolving.
List the conditions for Hardy-Weinberg equilibrium.
- No mutations
- Random mating
- No natural selection
- Extremely large population size
- No gene flow.
What is the Hardy-Weinberg equation?
p² + 2pq + q² = 1.
What is genetic drift?
Chance events cause allele frequencies to fluctuate unpredictably from generation to generation.
What is the founder effect?
A few individuals become isolated from a larger population, leading to different allele frequencies.
What is the bottleneck effect?
A sudden reduction in population size due to environmental changes, affecting allele frequencies.
Define gene flow.
The movement of alleles among populations, which can reduce differences between populations.
What is sexual selection?
Natural selection for mating success, which can lead to sexual dimorphism.
What is sexual dimorphism?
The difference in physical characteristics between males and females of the same species.
What is the biological species concept?
A species is a group of populations whose members can interbreed in nature and produce viable, fertile offspring.
What are prezygotic barriers?
Factors that prevent mating or fertilization between species.
What are postzygotic barriers?
Factors that prevent hybrid offspring from developing into viable, fertile adults.
What is allopatric speciation?
Speciation that occurs when populations are geographically isolated from one another.
What is sympatric speciation?
Speciation that occurs without geographic isolation.
What is punctuated equilibrium?
The theory that species evolve during short periods of rapid change interspersed with long periods of stability.
What is speciation genetics?
The study of the genetic changes that lead to the formation of new species.
What is roevolution?
The evolutionary change above the species level
Broad patterns of evolutionary change over long time spans & formation of new groups.
Define the Biological Species Concept.
A species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring
Emphasis on reproductive isolation.
What is the significance of reproductive isolation?
It impedes two species from producing viable, fertile offspring
Ongoing exchange of alleles between populations holds them together.
What are hybrids?
Offspring of interspecific mating
Can be classified by whether factors act before or after fertilization.
What are Prezygotic Barriers?
Factors that block fertilization from occurring
They prevent interspecies reproduction from occurring.
What is habitat isolation?
Differences in where species live, preventing them from encountering one another.
What is temporal isolation?
Differences in mating cycles.
What does behavioral isolation refer to?
Distinct differences in courtship behaviours/traditions that aren’t noticed/recognized by females of different species.
What is mechanical isolation?
Physical differences in genitalia preventing successful mating.
Define gametic isolation.
When sperm and egg of different species cannot fuse to form a zygote.
What are Postzygotic barriers?
Factors that reduce survival among hybrid embryos.
What is reduced hybrid viability?
Within areas where two species can breed, resulting embryos often do not survive or will have major morphological anomalies.
What does reduced hybrid fertility mean?
Offspring of hybrids will be sterile
Example: female horse mating with male donkey produces mules, which cannot reproduce.
What is hybrid breakdown?
A type of reproductive failure that appears after the generation of crosses between different species or subspecies.
What is the Morphological Species Concept?
Defines a species by structural features.
What does the Ecological Species Concept define species in terms of?
Ecological niche.
What is allopatric speciation?
Gene flow is interrupted/reduced when a population is divided into geographically isolated subpopulations.
What is sympatric speciation?
Speciation takes place in geographically overlapping populations.
What can drive sympatric speciation?
The appearance of new ecological niches or sexual selection.
Define polyploidy.
Presence of extra sets of chromosomes due to accidents during cell division.
What is an autopolyploid?
An individual with 2+ chromosome sets, derived from one species.
What is an allopolyploid?
A species with 2+ chromosomes, derived from a different species.
In which organisms is polyploidy much more common?
Plants than animals
Examples: oats, cotton, potatoes, tobacco, wheat.
What is a hybrid zone?
A region in which members of different species mate and produce hybrids.
What are the three possible outcomes when closely related species meet in a hybrid zone?
- Reinforcement
- Fusion
- Stability
What occurs during reinforcement in a hybrid zone?
Strengthening of reproductive barriers
Occurs when hybrids are less fit than the parent species.
What happens during fusion in a hybrid zone?
Weakening of reproductive barriers
Occurs if hybrids are as fit as parent species.
What does stability refer to in a hybrid zone?
Continued formation of hybrid individuals
Occurs when hybrids have increased fitness.
