Chapter 10: Evolution Flashcards
Jean-Baptiste Lamarcks 2 ideas about evolution
- Use and Disuse
2. Inheritance of acquired characteristics
Evolution
The changes in populations, species, or groups of species.
Charles Darwin believed in:
Natural Selection
5 pieces of Evidence for Evolution
- Paleontology
- Biogeography
- Embryology
- Comparative Anatomy (Homologous and Analogous Structures)
- Molecular Biology
Molecular Biology
Examines the nucleotide and amino acid sequences of DNA and proteins from different species.
Comparative Anatomy
Describes the two kinds of structures that contribute to the identification of evolutionary relationships among species.
Homologous Structures
Body parts that resemble one another in different species because they have evolved from a common ancestor.
Analogous Structures
Body parts that resemble one another in different species, not because they have evolved from a common ancestor.
Embryology
Reveals Similar stages in development (ontogeny) among related species. The similarities help establish evolutionary relationships (phylogeny).
Paleontology
Provides fossils that reveal the prehistoric existence of extinct species.
Biogeography
Uses geography to describe the distribution of species. This information has revealed that unrelated species in different regions of the world look alike when found in similar environments.
Natural Selection
The differences in survival and reproduction among individuals in a population as a result of their interaction with the enviornment.
Stabilizing Selection
Eliminates individuals that have extreme or unusual traits.
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Directional Selection
Favors traits that are at one extreme of a range of traits. Traits at the opposite extreme are selected against.
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Insecticide resistance
Occurs as a result of directional selection. Eventually the whole population is insecticide resistant.
Disruptive selection
Occurs when the environment favors extreme or unusual traits, while selecting against the common traits.
^^^^_____^^^^
Sexual Selection
The differential mating of males (sometimes females) in a population.
- Male Competition
- Female Choice
Artificial Selection
A form of directional selection carried out by humans when they sow seeds or breed animals that possess desirable traits.
Mutations
Provide the raw material for new variation
5 Sources of Variation
- Mutations
- Sexual reproduction
- Diploidy
- Outbreeding
- Balanced Polymorphism
Diploidy
The presence of two copies of each chromosome in a cell. In the heterozygous condition, the recessive trait is “hidden”, and will provide a source of variation for future generations.
Outbreeding
Mating with unrelated partners, increases the possibility of mixing different alleles and creating new allele combinations.
Balanced Polymorphism
The maintenance of different phenotypes in a population
In Africa, the heterozygous pair for Haemophelia
Heterozygote advantage
Occurs when the heterozygote condition bears a greater selective advantage than either homozygous condition.
ex. Hemophilia (Heterozygote)
Hybrid Vigor/ Heterosis
The superior quality of offspring resulting from crosses between two different inbred strains of plants.
Frequency-Dependent Selection/ Minority Advantage
Occurs when the least common phenotypes have a selective advantage.
Monocultures
Reduce genetic variation because only a few varieties of the many wild varieties of a plant are used. The unused ones are driven to extinction.
Overuse of Antibiotics
Reduces variation in bacterial populations by eliminating those individuals that are susceptible to the antibiotic.
Gene Flow
Describes the movement of individuals between populations.
Genetic Drift
A random increase or decrease of alleles.
Founder Effect
Occurs when allele frequencies in a group of migrating individuals are, by chance, not the same as that of their population of orgin.
ex. Amish people and extra toes
Bottleneck
Occurs when the population undergoes a dramatic decrease in size.
As a result, the population becomes susceptible to genetic drift.
Nonrandom Mating
Occurs when individuals chooses mates based upon their particular traits.
Inbreeding
Occurs when individuals mate with relatives.
Sexual Selection
Occurs when females choose males based upon their attractive appearance or behavior of their ability to defeat other males in contests.
Genetic Equilibrium/ Hardy-Weinberg Equilibrium
When the allele frequencies in a population remain constant from generation to generation.
5 things that must be in order for Genetic Equilibrium
- All traits are selectively neutral (No natural selection)
- Mutations do not occur
- The population must be isolated from other populations (no gene flow)
- The population is large (no genetic drift)
- Mating is random
Species
A group of individuals capable of interbreeding
Speciation
The formation of new species
Allopatric Speciation
Begins when a population is divided by a geographic barrier so that interbreeding between the two resulting populations is prevented.
Sympatric Speciation
The formation of new species without the presence of a geographic barrier.
Occurs by: Balanced Polymorphism, Polyploidy, Hybridization
Balanced Polymorphism
A system of genes in which two alleles are maintained in stable equilibrium because the heterozygote is more fit than either of the homozygotes.
Polyploidy
The possession of more than the normal two sets of chromosomes found in diploid (2n) cells.
Hybridization
Occurs when two distinctly different forms of a species (or closely related species that are normally reproductively isolated) mate and produce progeny along a geographic boundary called a hybrid zone.
Adaptive Radiation
The relatively rapid evolution of many species from a single ancestor. Occurs when the ancestral species is introduced to an area where diverse geographic or ecological conditions are available for colonization.
Pre-zygotic Isolating Mechanisms
Mechanisms that prevent fertilization.
Habitat Isolation
Occurs when species do not encounter one another.
Temporal Isolation
Occurs when species mate or flower during different seasons or at different times of the day.
Behavioral Isolation
Occurs when a species does not recognize another species as a mating partner because it does not perform the correct courtship rituals, display the proper visual signals, sing the correct mating songs, or release the proper chemicals (scents or pheromones).
Mechanical Isolation
Occurs when male and female genitalia are structurally incompatible or when flower structures select for different pollinators.
Gametic Isolation
Occurs when male gametes do not survive in the environment of the female gamete (such as internal fertilization) or when female gametes do not recognize male gametes.
Post-zygotic Isolating Mechanisms
Mechanisms that prevent the formation of fertile progeny.
Hybrid inviability
Occurs when the zygote fails to develop properly and aborts, or dies, before reaching reproductive maturity.
Hybrid Sterility
Occurs when hybrids become functional adults, but are reproductively sterile (eggs or sperm are nonexistent or dysfunctional).
Hybrid Breakdown
Occurs when hybrids produce offspring that have reduced viability or fertility.
Divergent Evolution
Describes two or more species that originate from a common ancestor and become increasingly different over time.
May occur as a result of allopatric or sympatric speciation, or adaptive radiation.
Convergent Evolution
Describes two unrelated species that share similar traits. They have similar traits because they have adapted to similar enviornments.
Parallel Evolution
Describes two related species or two related lineages that have made similar evolutionary changes after their divergence from a common ancestor.
Coevolution
The tit-for-tat evolution of one species in response to new adaptations that appear in another species.
Selection favors the better hunter, non-weed resistant weed.
Microevolution
Describes the details of how populations of organisms change from generation to generation and how new species originate.
Macroevolution
Describes general patterns of change in groups of related species that have occurred over broad periods of geologic time.
Phyletic Gradualism
Argues that evolution occurs by the gradual accumulation of small changes. Believes that speciation events or major changes in lineages occur over long periods of geologic time.
Punctuated Equilibrium
Argues that evolutionary history consists of geologically long periods of stasis, with little or no evolution, that are punctuated by geologically short periods of rapid evolution.
