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Descent with Modification and The Evolution of Populations - Coggle Diagram
Descent with Modification and The Evolution of Populations
Challenging Traditional Views
evolution
Charles Darwin's summary of the process by which species accumulate differences from their ancestors as they adapt to different environments over time
scala naturae
life-forms could be arranged on a ladder, or scale, of increasing complexity
Lamarck
-use and disuse -inheritance of acquired characteristics
Natural Selection
adaptations
Inherited characteristic of an organism that enhances its survival and reproduction in a specific environment
natural selection
a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than do other individuals because of those traits
artificial selection
The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits
Evolution Supported
homology
Similarity in characteristics resulting from a shared ancestry
homologous structures
Structures in different species that are similar because of common ancestry
vestigial structures
A feature of an organism that is a historical remnant of a structure that served a function in the organism’s ancestors
evolutionary tree
A branching diagram that reflects a hypothesis about evolutionary relationships among groups of organisms
convergent evolution
The evolution of similar features in independent evolutionary lineages
analogous
Having characteristics that are similar because of convergent evolution, not homology
biogeography
The scientific study of the past and present geographic distributions of species
Genetic Variation
Differences among individuals in the composition of their genes or other DNA sequences
*some phenotypic variation does not result from genetic differences among individuals
Without genetic variation, evolution cannot occur
-mutation -gene duplication -other processes produce new alleles and new genes -sexual reproduction
neutral variation
Genetic variation that does not provide a selective advantage or disadvantage
Hardy-Weinberg equilibrium
The state of a population in which frequencies of alleles and genotypes remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work
gene pool
The aggregate of all copies of every type of allele at all loci in every individual in a population. The term is also used in a more restricted sense as the aggregate of alleles for just one or a few loci in a population
Altering Allele Frequences
adaptive evolution
a process in which traits that enhance survival or reproduction tend to increase in frequency over time, resulting in a better match between organisms and their environment
genetic drift
A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next
founder effect
Genetic drift occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population
bottleneck effect
Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population
-significant in small populations -cause allele frequencies to change randomly -cause loss of genetic variation within a population -can cause harmful alleles to become fixed
gene flow
The transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes
Consistency in Adaptive Evolution
relative fitness
The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals in the population
Directional selection
Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals
Disruptive selection
Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes
Stabilizing selection
Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes
sexual selection
A process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates
sexual dimorphism
iDifferences between the secondary sex characteristics of males and females of the same species
intrasexual selection
A form of natural selection in which there is direct competition among individuals of one sex for mates of the opposite sex
intersexual selection
A form of natural selection in which individuals of one sex (usually the females) are choosy in selecting their mates from the other sex; also called mate choice
balancing selection
Natural selection that maintains two or more phenotypic forms in a population
frequency-dependent selection
Selection in which the fitness of a phenotype depends on how common the phenotype is in a population
heterozygote advantage
Greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in a gene pool
