Natural selection The process by which traits become more or less common in a population through...

Natural selection

• The process by which traits become more or less common in a population through differential survival and reproduction

Adaptive radiation

• A form of divergent evolution in which there is rapid speciation of one ancestral species to fill many different ecological niches

Evolution is not perfect

• Selection can act only on existing variations• Evolution is limited by historical constraints• Adaptations are often compromises• Chance, natural selection, and the

environment interact

1. Direct observation2. The fossil record

3. Homology4. biogeography

• Identify the 4 major types of evidence to support the theory of evolution.

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A population of rabbits may be brown (the dominant phenotype) or white (the recessive phenotype). Brown rabbits have the genotype BB or Bb. White rabbits have the genotype bb. The frequency of the BB genotype is .35.• What is the frequency of heterozygous rabbits? • What is the frequency of the B allele? • What is the frequency of the b allele?

Founder effect

• Genetic drift that 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 position

Sexual dimorphism

• Marked differences between the two sexes in secondary sexual characteristics, which are not directly associated with reproduction or survival

Speciation in which the populations are physically separated. A term for physically

separated populations.

Allopatric

species

• Group or population of individuals that can interbreed to produce viable offspring

Homeotic gene

• Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the developmental fate of groups of cells

Reduced hybrid viability

• The genes of different parent species may interact in ways that impair the hybrid’s development or survival in it’s environment

Convergent evolution

• The evolution of two or more lineages towards similar morphologies or adaptations so that the lineages appear similar despite their different ancestry

homology

• Similarity between species that results from common ancestry

Vestigial structures

• Structures that have apparently lost all or most of their original function in a species through evolution

speciation

• The division of one species, during evolution, into two or more separate species

Punctuated equilibrium

• Periods in the fossil record of apparent stasis punctuated by sudden change

Phylogenetic species concept

• A species is the smallest group of individuals that share a common ancestor, forming oine branch on the tree of life

Gene flow

• Genetic exchange between populations tends to reduce differences between populations over time.

Identify 5 conditions to maintain Hardy Weinberg Equilibrium

• No mutations• Random mating• No natural selection• Extremely large population• No gene flow

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

Temporal isolation

• Species that breed during different times of the day, different seasons, or different years cannot mix their gametes

Morphological species concept

• A species is characterized by structural features

• Can be applied to sexual and asexual organisms

evolution

• Changes in gene pools over time

mutation

• the ultimate source of new alleles

Hybrid breakdown

• Some first generation hybrids are viable and fertile, but when they mate with one another or with either parent species, offspring of the next generation are feeble or sterile

Jean-Baptiste de Lamarck

• Use and disuse• Inheritance of acquired characteristics

Intersexual selection

• Selection whereby individuals of one sex are choosy in selecting their mates from individuals of the other sex

• Also called “mate choice”